JP2020039841A - Measurement imaging apparatus - Google Patents

Abstract

To improve measurement accuracy by overcoming the problem of reduction in the measurement accuracy caused by asymmetry of actually generated deflection waves with respect to an axial direction or the like of a rectangular coordinate system.SOLUTION: A measurement imaging apparatus comprises: a sensor; a signal processing unit; a measurement control unit that scans a measurement target in a lateral direction by generating a steered wave and controls the signal processing unit so as to generate a wave data signal; and a data processing unit that using a phase of a product of two complex signals or a conjugate product signal having as a core a change in an instantaneous phase of a product of two complex analytic signals or a conjugate product signal obtained from a spectrum corresponding to wave data signals generated in at least two time phase, divides a change or phase of instantaneous phases of new waves propagating in directions orthogonal to each other by instantaneous frequencies in the directions orthogonal to each other or a gravity center frequency of a corresponding spectrum to calculate displacement components in the directions orthogonal to each other and calculate a displacement vector.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a measurement imaging apparatus that performs measurement by performing beam forming (wave forming) on an arbitrary wave arriving from a measurement target.

  Furthermore, the present invention is an electromagnetic wave, light, mechanical vibration, sound wave, or an arbitrary wave such as a heat wave arriving from the measurement target, based on an arbitrary wave such as a heat wave, or, the temperature or displacement in the measurement target The present invention relates to a beam forming method and the like used for non-destructively measuring a physical quantity, a composition, a structure, and the like. The object to be measured is various, such as an organic matter, an inorganic matter, a solid, a liquid, a gas, a substance that follows rheology, a living thing, a celestial body, the earth, the environment, and the like.

  The present invention is applicable to nondestructive inspection, diagnosis, resource exploration, generation and manufacture of materials and structures, monitoring of various physical and chemical repairs and treatments, application of revealed functions and physical properties, etc. Relatedly, in those cases, accuracy may be required in a condition where non-invasive, minimally invasive, non-invasive conditions or the like are imposed without causing large disturbance to the measurement object. Ideally, it is desirable that the measurement target be observed in the in situ state at the original position.

  In addition, the treatment or restoration may be performed on the measurement target by the action of the wave itself, and the situation may be observed by performing beam forming on the response from the measurement target at that time. In addition, beamforming is performed in satellite communication, radar, sonar, and the like to realize an informationally safe environment while saving energy, and accurate communication is performed. Beamforming has also been applied to ad hoc communication devices and mobile communications. When the measurement target is dynamic, real-time performance is required, and it is required that beamforming be completed in a short time.

  2. Description of the Related Art Waves such as electromagnetic waves, light, mechanical vibrations, sound waves, and heat waves have different behaviors depending on the frequency, bandwidth, intensity, or mode. Many transducers for various waves have been developed so far, and these waves (the diffracted waves themselves), their transmitted waves, reflected waves, refracted waves, diffracted waves, or scattered waves (forward scattered waves, backscattered waves, etc.) ) Etc. are being used.

  For example, it is well known that ultrasonic waves having a high frequency among sound waves are used in nondestructive inspection, medical treatment, and sonar. Also, in the radar, electromagnetic waves (radio waves, FM waves, microwaves, terahertz waves, infrared rays, visible light, ultraviolet rays, radiation such as X-rays, and the like) having an appropriate frequency according to the measurement target are used. The same applies to other waves, and since each wave behaves differently depending on the frequency, a different name is used and various sensing and communication are performed according to the measurement target, medium, and frequency band (for electromagnetic waves, , Polarization can also be used).

  In those applications, the beam forming process is often performed by mechanically scanning a measurement target with a transducer, using the same transducer multiple times, or using a plurality of transducers arranged in an array in advance. . It is well known that when observing the earth, land, ocean, and weather with satellite or airplane radar, aperture synthesis processing is performed. In particular, in the case of imaging an object to be measured, the purpose of beamforming is often to provide appropriate directivity and to obtain high spatial resolution and high contrast in a region of interest or a point of interest.

  As a result, by acting on waves generated from the object to be measured, reflection and transmission caused by a spatial change in impedance, various scatterings (Rayleigh scattering, Mie scattering, etc.), attenuation, refraction, diffraction, or their frequencies Dispersion and the like can be observed, and the structure and composition of the inside and surface of the measurement target can be observed, as well as what the measurement target is. The measurement target may be observed with various spatial resolutions. Characterization can be at the level of structure or composition (eg, individual, molecular, atomic, nuclear, etc.).

  For the purpose of high-accuracy, high-resolution imaging, signal compression technology has been used for a long time, and chirp wave technology and coded compression technology have been used as typical ones. In some cases, such as ISAR (inverse synthetic aperture radar), the observed wave is subjected to inversion of beam characteristics to perform super-resolution, but it is not always the case when the aperture is synthesized. ), The resolution may be actively reduced. In them, singular value decomposition, regularization, Wiener filter, etc. are effective.

  In addition, the coding technique is also used in a case where a plurality of signals are separated, for example, in a case where a received signal is separated into reception signals corresponding to transmission signals having different transmission positions. In some cases, waves coming from different directions may be separated, and in other cases, the signal source may be specified or separated. May be treated). In such a case, there is much to rely on a matched filter having high signal detection ability. However, while signal energy can be obtained, when the movement, displacement, distortion, and the like of the measurement object accompanied by deformation are obtained, the spatial resolution is reduced, and the measurement accuracy is reduced. In separating waves and signals, the use of frequency, band, or multidimensional spectrum is also useful.

  In imaging using the above-described wave, the distribution of amplitude data obtained through orthogonal detection, envelope detection, or square detection is usually one-dimensional, two-dimensional, or three-dimensional as a grayscale image or color image. They are often displayed and become morphological images. Functional observation is also possible. For example, in Doppler measurement using those waves, a raw coherent signal is processed (ultrasonic Doppler, radar Doppler, laser Doppler, etc.).

  In addition, for example, in the field of medical ultrasound, there is a useful technique that can detect a moving tissue although there is no information on a displacement direction, unlike power Doppler. When microwaves, terahertz waves, or far-infrared rays are used, the temperature distribution of the measurement target can be observed. The measured physical quantities may be displayed so as to be superimposed on the morphological image. In the field of image measurement, it is well known that motion is observed using a signal made incoherent through detection (cross-correlation processing, optical flow, etc.). In medical ultrasound and sonar, imaging using physically generated harmonics, chords, and difference sounds is also performed. In particular, when the measurement target is dynamic, real-time performance is required for the beamforming process.

  In satellite communication, radar, sonar, and the like, beamforming is performed to realize an informationally safe environment while saving energy, and accurate communication is performed. Beamforming has also been applied to ad hoc communication devices and mobile communications. It is also effective for communication with a specific person, a specific signal source, and a specific position. In communication, information is sent from the transmitting side to the receiving side on the wave, and the purpose may be achieved by itself.The receiving side may respond to the transmitting side with the result of the communication, or the information may be transmitted to the transmitting side. May respond to the request, but of course, the example of communication is not limited to this. When the content of information is dynamic according to the communication target or the observation target, real-time property is required, and in that case, beamforming is required to be completed in a short time.

  Under such circumstances, the inventor of the present application has developed an ultrasonic imaging technique for differentially diagnosing, for example, cancer lesions and sclerosis in human tissues. The inventor of the present application has performed high resolution and high efficiency of HIFU (High Intensity Focus Ultrasound) treatment, together with high resolution of echo imaging and high precision measurement imaging of tissue displacement, and the like. Their imaging is also based on the reception of echoes during intense ultrasonic radiation. Such imaging is based on high-speed and appropriate beamforming, and high-speed and appropriate detection methods, tissue displacement measurement methods, and shear wave propagation measurement methods have been reported in the past.

  Medical ultrasound diagnostic imaging devices have been digitized for over 20 years. In older systems, mechanical scanning was performed using a single-aperture conversion element, and then electronic scanning was performed using a plurality of conversion elements and an array-type device composed of those elements. From digital devices. In fact, the classic aperture synthesis process itself was digital beamforming since the time it was used in radars onboard satellites and airplanes, but the received signal strength was weak For that reason, they have rarely been used in medical ultrasound.

On the other hand, in recent years, the inventor of the present application has invented a multidirectional aperture synthesis method, and has invented performing beamforming in multiple directions from received echo data for aperture synthesis. As a result, it is possible to obtain a multi-directional steering (deflection) image signal at the same frame rate as that of a normal electronic scan. It has a carrier frequency in the horizontal direction that is orthogonal to this, and has a higher spatial resolution (compared to normal imaging). Of course, normal focus beams and the like may be crossed, and waves determined by an aperture array shape without focus such as plane waves and spherical waves described later and waves generated by virtual sound sources and virtual receivers are crossed. Is also good. Normally, when performing two-dimensional lateral modulation imaging, the coordinate system should be symmetrical with respect to the axial coordinate axis (axial axis) of the orthogonal coordinate system for performing observation or the horizontal coordinate axis (horizontal axis) orthogonal thereto. The two waves are deflected (steered) and crossed. When performing three-dimensional lateral modulation imaging, three or four waves are deflected so as to be symmetrical with respect to a plane including an axial axis of a rectangular coordinate system for performing observation and a lateral direction orthogonal thereto. Intersect (ie, make all waves symmetric about the axial direction). Usually, an axial axis is set in the direction in which the aperture array element and the physical aperture face, but this is not a limitation. Waves may be generated not only in the positive direction of the axis coordinate axis but also in the negative direction. For convenience, the horizontal axis may be read as the axial axis for processing.
Furthermore, real-time measurement of the displacement vector distribution is possible by using the multidimensional autocorrelation method, multidimensional Doppler method, multidimensional cross spectrum phase gradient method or demodulation method also invented by the inventor of the present application. It became. In addition, in the case of incoherent addition, it is also possible to reduce speckles (normally, a transmit beam is generated in a different direction to reduce speckles. , High frame rates can be achieved). In fields other than the ultrasonic field, digitization is progressing in sensing devices that use radiation such as microwaves, terahertz waves, X-rays, other electromagnetic waves, vibration waves including sound, and heat waves for nondestructive inspection. Have been.

  For example, aperture plane synthesis in those sensing devices is active beamforming, and the waves to be processed are transmitted waves, reflected waves, refracted waves, or reflected waves from the measurement of those waves generated by the transducer. It is a scattered wave (forward scattered wave, back scattered wave, etc.). The diffracted waves include not only the waves generated by the transducer (signal source) but also the diffracted waves generated by sources other than the signal source. On the other hand, in passive beamforming, for example, as in the case of measuring the temperature distribution based on the above-mentioned microwave observation and observing the electric activity source due to the cerebral magnetic field of a living thing, the self-divergent A transmitted wave, a reflected wave, a refracted wave, or a scattered wave (a forward scattered wave, a back scattered wave, or the like) based on a wave emitted from a (self-emanating) signal source is an object. As with the active case, those diffracted waves are also of interest. There are many other examples that correspond to them, but as another example, recently, living organisms have been measured, called photoacoustic, and laser irradiation is performed on the measurement target, and frequency-dependent A volume change is caused by a certain heat absorption, an ultrasonic wave is generated using the volume change as a sound source, and as a result of the beam forming, differentiation of a peripheral blood vessel is performed.

  Digital devices require more processing time than analog devices, but their computational performance has been significantly improved, and their size has been reduced, and their cost has been reduced, including that of data storage media. There are many advantages such as easy application and high degree of freedom. As a matter of fact, even in the case of a digital device, in a sensing device, particularly, high-speed analog processing after receiving a signal by a sensor is extremely important, and AD conversion (Analog-to-Digital conversion) is relatively performed in the vicinity. ) Is appropriately realized in combination with the digital processing after the processing.

  In analog devices, beamforming for transmission and reception is performed by analog processing. On the other hand, in a digital device, transmission beamforming is performed by analog processing or digital processing, and reception beamforming is performed by digital processing. Therefore, in the present application, the digital beamformer refers to one that always performs reception beamforming by digital processing.

  After receiving a wave from a measurement object through mechanical scanning of a plurality of conversion elements or an array type device composed of them, or one or more conversion elements, DAS (Delay and Summation: phasing), which is a so-called aperture plane synthesis processing. Addition) processing is performed. In transmission, transmission beamforming may be performed by driving a plurality of elements, or classical aperture synthesis based on one-element transmission may be performed. , DAS processing is performed.

  That is, transmission beamforming is performed by analog processing or digital processing. On the other hand, in receive beam forming, a received signal is generated by receiving a wave by each element in the array or an element at a different position, and after analog adjustment or level adjustment by analog amplification or attenuation, analog reception signal is generated. A / D conversion is performed on the digital reception signal, and the digital reception signal is stored in the memory. After that, devices and computers with general-purpose calculation processing capability, PLDs (Programmable Logic Devices), FPGAs (Field-Programmable Gate Arrays), DSPs (Digital Signal Processors), Digital processing is performed on the received signal stored using a GPU (Graphical Processing Unit), a microprocessor, or a dedicated computer, a dedicated digital circuit, or a dedicated device. You.

  A device that performs such digital processing may include such an analog device, an AD converter, a memory, and the like. In some cases, a device or a computer having computing power is multi-core. Thus, at the time of reception, dynamic focusing, which is almost impossible with an analog device, can be easily performed. Parallel processing is also performed. In order to increase the speed of analog processing and digital processing, transmission lines (for example, stacked circuits) and broadband wireless paths are important.

  Dynamic focusing improves the spatial resolution of the generated image signal in the range direction and the depth direction (depth direction) of the measurement target. On the other hand, dynamic focusing of transmission is possible only in classical aperture synthesis by one-element transmission. In order to secure the energy of the transmission wave, transmission beamforming of a fixed focal position by driving a plurality of elements is often performed instead of combining aperture surfaces by one-element transmission.

  The inventor of the present application has invented a high frame rate echo imaging that transmits a wave such as a plane wave whose wave front spreads widely in the horizontal direction and interrogates a wide area in one transmission. Further, the inventor of the present application coherently adds (superimposes) a plurality of waves of this kind having different steering (deflection) angles to perform lateral modulation and broadband in the lateral direction (higher lateral resolution). For example, when the above-described multidimensional autocorrelation method is realized, the blood flow in the carotid artery with shear wave propagation and fast blood flow, or the blood flow in the heart cavity with complicated flow, etc. Has been invented as a multidimensional displacement vector. The same applies to the case where multidirectional aperture plane synthesis is performed and the case where transmission beamforming is performed. Also, waves having a plurality of different carrier frequencies may be generated and superimposed to realize a wider band in the axial direction (higher resolution in the axial direction).

  Such a process is performed in the case of active beamforming, but the transmitter is not used in passive beamforming. Thus, a digital beamformer usually consists of a transmitter (in the case of active beamforming), a receiver, and a DAS processing device, and is realized by assembling those devices. Small packages are now available at low cost.

  The DAS process includes a process of delaying a received signal at high speed with interpolation and approximation processing in a spatial domain for phasing, and a phase rotation process of multiplying a complex exponential function in a frequency domain, which requires an enormous amount of time. There is a method of applying a delay with high accuracy based on the Nyquist theorem (a past invention of the inventor of the present application), and adds received signals in a spatial domain after phasing (phasing addition). In a digital device, for example, a command signal generated by a control unit for a transmitter to generate a transmission signal to a driving element may be used as a trigger signal for digital sampling (AD conversion) of an analog reception signal. .

  Further, when a plurality of elements are driven with a transmission delay in one beam forming, an analog or digital transmission delay which is previously mounted on a transmission unit and realizes a transmission focus position and a steering direction which can be selected by an operator. May use patterns. Furthermore, in the reception digital processing, a command signal for an element to be driven first, a command signal for an element to be driven last, or a command signal for driving another element is used as a trigger signal, and In some cases, sampling is started for the signal of (1) and a digital delay is applied. These command signals may be generated based on a command signal for starting beam forming for one frame.

  When the digital delay is performed in the transmission delay, an error determined by the clock frequency for generating the digital control signal always occurs, unlike the analog delay. Therefore, the analog delay is better as the transmission delay. Further, if a digital delay is applied to the reception to realize the reception dynamic focusing, an error is generated according to the above interpolation approximation processing. The only option was to apply accurate digital delay (phase rotation processing) to achieve low-speed beamforming.

  In the former case involving interpolation approximation processing, phasing addition may simply add echo signals from a position including the coordinate position of a signal value to be generated, or may add bi-linear or multidimensional polynomial. In some cases, the accuracy may be improved by interpolation using such as. The former is much faster but less accurate than the latter using a complex exponential function. The latter is highly accurate but extremely slow. This phasing addition is performed under known or assumed hypothetical wave propagation velocities and is often assumed to be constant within the region of interest. On the other hand, measuring the propagation velocity and performing phase aberration correction is also performed.Before or after beamforming, for example, the cross-correlation function between adjacent beam signals or beam signals at different angles is evaluated to evaluate the phase. Aberrations can be determined (if the propagation speed is homogeneous, it will be an interference analysis).

  Compared to the case where the aperture elements form a distribution or an array in a one-dimensional space, the case where the aperture elements are distributed in a two-dimensional or three-dimensional manner, or the case where the aperture elements form a two-dimensional or three-dimensional array. In such a case, more processing needs to be performed for beamforming, and a large number of processors are mounted to perform parallel processing. In some cases, beamforming at distant positions with little interference, transmission beamforming in a plurality of directions with different steering angles, and single transmission beamforming are processed in parallel.

  In terms of communication control, it is necessary that waves are appropriately generated to reflect the type and amount of communication data or the characteristics of the medium. It is desirable that communication be performed. Separation of the interfering wave is also performed using an analog device or analog or digital signal processing. Controlled waves in the direction of propagation, coding, frequency, and / or bandwidth are important.

  As another invention of the present inventor, which is similar to the above-described multi-directional aperture plane synthesizing process, it is possible to improve the frame rate by performing multi-directional reception beam forming for one transmission beam forming. Also, in beamforming, apodization may be important. For example, each of the transmit and receive apodizations may be implemented to reduce side lobes, which has a trade-off with lateral resolution and should be implemented appropriately. On the other hand, in many cases, a simple beamformer that does not perform apodization with emphasis on spatial resolution is used. However, the inventor of the present application has reported that appropriate apodization is necessary in order to obtain a lateral resolution while suppressing side lobes during steering. Further, in the past invention of the inventor of the present application, there is one that removes a side lobe in a frequency domain.

  In addition, a contrast agent (for example, microbubbles in medical ultrasound imaging) may be used in order to apply the nonlinear characteristics of waves in an object. To irradiate high-intensity waves and waves containing harmonics (broadband transmission), and to perform nonlinear processing on received coherent signals and coherent signals after phasing and addition. High contrast imaging by suppressing lobes was invented. The inventor of the present application has also invented a highly accurate tissue displacement (vector) measurement based on the nonlinear processing.

  It is also possible to generate an imaging signal using a virtual source. As for the virtual source, it has been reported in the past that a virtual source was set before a physical aperture or a virtual source was set at a transmission focal position. Further, the inventor of the present application has proposed that a detector as well as a virtual source can be installed at an arbitrary position without using a focal point, and that a physical source or a detector of a wave can be provided by an appropriate scatterer or diffraction grating. It reports that it can be installed at a location. It is possible to increase the spatial resolution and widen the field of vision (FOV).

  As the imaging mode, quadrature detection, envelope detection, or squared detection is used.The inventor of the present application also actively displays the waving itself as a color image or a gray scale image, The emphasis is on displaying information. As described above, multi-dimensional devices using various waves are being developed for various purposes.

  There are several digital beamforming using the fast Fourier transform disclosed so far, and one of them is an analog processing performed through a Fourier transform (analysis solution of a classic monostatic aperture synthesis). (See Non-Patent Document 1), and indeed, a classical aperture synthesis is performed at high speed and with high accuracy through a fast Fourier transform (see Non-Patent Document 2). In this processing, interpolation approximation is not required, but in the case of steering (deflection) or multi-static aperture synthesis (generally, reception using the element or a plurality of peripheral elements in one-element transmission). No digital processing is disclosed.

  Other digital beamforming disclosed requires interpolation approximation processing and has low accuracy. For example, a method of performing wave number matching through fast Fourier transform including the case of performing steering in plane wave transmission has been disclosed (see Non-Patent Documents 3-5), but in this case, the aperture shape of the array is not flat. Interpolation approximation processing is required when calculating or displaying an image (when the array opening is an arc (see Non-Patent Document 6)), and the accuracy is low. Patent Literatures 1 to 4 disclose a technique using fast Fourier transform at the time of transmitting a plane wave, but all of them perform wave number matching through interpolation approximation. By performing wave number matching based on these interpolation approximations, a multi-dimensional spectrum is obtained at equal intervals in the wave vector coordinate system of the angular spectrum, and high-speed inverse Fourier transform is performed, thereby completing beamforming at high speed.

  Recent Non-Patent Document 5 discloses that Fourier transform is performed on wave number matching for non-equidistant sampling signals, but this is also based on interpolation approximation processing. As described above, digital beamforming has a long history, but when real-time performance (calculation speed) before displaying an image is most important, interpolation approximation is often performed, and the best accuracy is provided. Not necessarily. In addition, as for the most common fixed focus processing known to perform the DAS processing and the steering at that time, even a processing method performed through digital fast Fourier transform is not disclosed.

  There is also a report on the migration method (for example, see Non-Patent Document 7), which also requires interpolation approximation in wave number matching. In order to obtain the accuracy in the processing involving the interpolation approximation, it is usually necessary to increase the sampling frequency of the AD converter and perform oversampling more than enough.

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  As described above, if a digital delay is applied to the reception in order to realize the reception dynamic focusing, an error occurs according to the interpolation approximation processing, so that the sampling frequency of the AD converter is increased sufficiently at a high cost. Alternatively, the only option is to apply the above-described high-precision digital delay (phase rotation processing) to achieve low-speed beamforming.

  Up to now, reflected waves, transmitted waves, and scattered waves (forward waves) have been targeted for vibration waves (mechanical waves) including electromagnetic waves, sound waves (compression waves), shear waves, surface waves, and the like, or heat waves. A method of digital beamforming is disclosed for scattered or backscattered waves, refracted waves, diffracted waves, surface waves, shock waves, or those waves originating from self-emanating wave sources. As described above, only the monostatic aperture synthesis without steering and the plane wave transmission including steering, and the migration method are limited. Except for the monostatic aperture synthesis, digital beamforming could not be performed without the need for interpolation approximation. Therefore, its accuracy was low.

  On the other hand, when using a transmitting or receiving transducer array device having an arbitrary aperture shape (may be used for both transmitting and receiving, and transmitting and receiving may be related to different waves), or may be passive. When only the receiving transducer is used in simple beamforming, regardless of the presence or absence of focusing or steering of transmission or reception, even when the coordinate system of the transmitted and received beams and the coordinate system for displaying images are different, no interpolation approximation is required. In addition, it is desired to perform arbitrary beam forming at high speed and with high accuracy.

  For active beamforming, transmit and receive transducer array devices with arbitrary aperture shapes (transducers may be used for both transmit and receive) are used. In the case of passive beamforming, only a receiving transducer array device having an arbitrary aperture shape is used. In those cases, it is desired to realize arbitrary beamforming at high speed and with high precision by digital processing. It is desirable to perform virtually any focusing and any steering (deflection) using a transducer array device having any aperture shape.

  After beamforming with phasing addition, frequency or bandwidth in each direction, at least one of wave parameters such as pulse shape and beam shape is subjected to linear or non-linear signal processing to a plurality of different beams, A beam having a new value with respect to at least one of the wave parameters may be newly generated (frequency modulation, broadened band, multi-focus, etc.). In such beam forming, focusing is performed. Steering (deflection) and apodization are performed using a transducer array device having an arbitrary aperture shape based on DAS processing. In addition, as described later, a beam having a different value for at least one of these wave parameters may be generated and used due to a linear or non-linear phenomenon in the medium.

  Since the wave propagation speed is determined by the physical properties of the medium under physical conditions, if the aperture elements form a two-dimensional or three-dimensional distribution or a multi-dimensional array to perform multi-dimensional imaging, then one-dimensional In comparison with, a large number of beamformings will be performed, and the number of pieces of processing data used for one beamforming will also increase, which will take an enormous amount of time. It is desired to use an apparatus that performs these beam forming operations in real time or an apparatus that can display the results in a short time.

  In addition, digital beamforming through Fourier transform has been disclosed that is performed through interpolation approximation in a Cartesian coordinate system when a one-dimensional or two-dimensional linear array transducer is mainly used. Also, even when the coordinate system between the reception and the result (image) display is different, it is desired to perform digital beamforming without performing any interpolation approximation.

  The method disclosed for the case where the aperture shape of the array is not flat (for example, when the array aperture is a circular arc) also performs interpolation approximation. As a typical example, when a convex transducer is used, or when an electronic or mechanical sector scan or IVUS (intravascular ultrasound) scan is performed, transmission and reception are performed in an arbitrary coordinate system such as a polar coordinate system. It is desired to process a digital signal obtained from the generated wave and obtain a signal directly beamformed in an arbitrary image display system (arbitrary coordinate system) such as a Cartesian coordinate system without performing interpolation approximation.

  In recent years, memories and AD converters have become very inexpensive, but without oversampling, by sampling waves based on the Nyquist theorem, it is possible to perform DAS processing that takes time when interpolation approximation is not performed. It is desired that the beam forming can be performed at high speed. Proper apodization can also be important.

  As a result of solving these problems, the spatial resolution and contrast (including the effect of suppressing side lobes) of the image signal obtained in real time or in a short time are high, and the motion (displacement) of the object is obtained from the obtained signal. ), Deformation, temperature, etc., it is desired to realize highly accurate measurement. For example, in the field of medical ultrasound, in recent years, a Doppler method has been applied to an echo signal to measure tissue displacement or velocity, and then to perform spatio-temporal differentiation on the echo signal to obtain an acceleration, a distortion, and the like, and image the same. became. Spatio-temporal differentiation is a process that amplifies high-frequency measurement errors and degrades the signal-to-noise ratio, so it is necessary to realize highly accurate displacement measurement using phase. The highly accurate beamforming for realizing this is dynamic focusing based on so-called DAS processing. A three-dimensional imaging apparatus using a two-dimensional array or a three-dimensional array also tends to spread. As described above, it is desired that any beam forming including dynamic focusing be performed at high speed and with high accuracy without performing interpolation approximation.

  Recently, the inventor of the present application has developed a highly accurate measurement method of a relatively fast-moving tissue displacement or shear wave propagation based on high-speed beam forming (transmission and reception in a region of interest is fast) by polarized plane wave transmission. Although it has been realized, even when such focusing is not performed, it is desired that beamforming be performed at high speed and with high accuracy without requiring interpolation approximation. By performing high-speed beamforming while changing the steering angle and performing coherent addition, it is possible to obtain almost the same high-quality image (spatial resolution and contrast) at high speed as compared to scanning using a normal focusing beam. . High-speed beamforming is also effective for multidimensional imaging using a multidimensional array.

  In addition, steering and multi-static aperture synthesis in classical aperture synthesis (monostatic type) based on scanning by driving one element, which has not been disclosed, can be performed at high speed without interpolation approximation. It is desired to implement it with high precision. Even when so-called migration processing is used, similarly, it is desired to perform arbitrary beam forming at high speed and with high accuracy without performing interpolation approximation in an arbitrary coordinate system. Other specific examples of the beamforming that is desired to be realized are as described in other parts of the present specification, and it is similarly desired that the beamforming can be performed at high speed and with high accuracy. It is.

Therefore, one of the objects of the present invention is to use a digital beamformer having a digital operation function as a digital beamformer and perform arbitrary beamforming with high speed and high accuracy without performing an approximate calculation. This makes it possible to implement various applications of the waves described below, including super-resolution using non-linear processing. There are various other applications, such as imaging, displacement measurement, temperature measurement, etc., and the multidimensional Fourier disclosed in Non-Patent Document 13 has been proposed in order to enable those applications to be performed at high speed. High-accuracy and high-speed Hilbert transform processing using transform (performs a multidimensional Fourier transform on a received multidimensional signal, and performs zero-filling of the spectrum in the frequency domain. In this case, a quadrant spectrum is generated, and a multidimensional inverse Fourier transform is performed.
In particular, in displacement measurement, as a method of performing vector observation of displacement, a multidimensional autocorrelation method, a multidimensional Doppler method (Non-patent Document 13), a multidimensional cross-spectral phase gradient method (Patent Document 6, Non-Patent Document 15, etc.) , Demodulation methods (Patent Documents 7 and 8), non-linear processing methods, spectral frequency division methods, multidimensional phase matching methods, broadband methods using coherent addition, over-determined methods, and the like. Among them, there is a demand for improving a method based on demodulation processing performed at the time of lateral modulation, and dramatically improving measurement accuracy. In fact, in conventional demodulation (Patent Document 7 and Patent Document 8), in order to perform demodulation at the time of two-dimensional or three-dimensional lateral modulation, respectively, the axial direction of the orthogonal coordinate system where observation is performed or the direction thereof is performed. Symmetric with respect to the orthogonal transverse axes (the axis coordinate axis and the abscissa axis, respectively), and with respect to the axis coordinate axis and a plane including the transverse direction orthogonal thereto (that is, all waves are symmetrical with respect to the axial direction). Thus, even if the waves are deflected (steered) and intersected, the generated waves are not strictly symmetrical, and there is a problem that the measurement accuracy of the displacement vector is reduced. Further, there is a problem that the observation becomes impossible when the central axis of the deflection wave is positively deflected from the front direction of the opening. Further, there is a problem that a measurement error occurs when the instantaneous frequency in the propagation direction of the generated deflection wave (the deflection wave itself) or the center of gravity frequency of the local spectrum is different.

The present invention has been made to solve at least a part of the above problems. A measurement imaging apparatus according to a first aspect of the present invention includes at least one sensor that transmits a measurement target, or receives a wave reflected, refracted, scattered, or diffracted by the measurement target and outputs at least one reception signal. And a signal processing unit for processing the at least one received signal; and electronically or mechanically generating at least one steered wave to scan the object to be measured in a lateral direction, and in at least two time phases. A measurement control unit that controls the signal processing unit to generate a wave data signal; and a data processing unit that calculates a displacement vector by performing a displacement measurement method on the wave data signal generated in the at least two time phases. The data processing unit has a three-dimensional orthogonal coordinate system, and includes the wave generated by the signal processing unit at zero degree or non-zero. Zero or non-zero different deflection angles for the at least three steered waves having different deflection angles in degrees or including the waves generated by the signal processor in the case of a two-dimensional rectangular coordinate system. A single actant corresponding to a wave data signal generated by scanning the measurement object alone with each steered wave in the at least two time phases for at least two steered waves having The change of each instantaneous phase or the change of each instantaneous phase of a new wave propagating in a direction orthogonal to each other, which is represented by the signal of the product or conjugate product of two complex analytic signals obtained from the quadrant spectrum, respectively Representing each steered wave in said at least two phases The product or conjugate product of two complex signals having, at the nucleus, a change in the instantaneous phase of a wave obtained from the spectrum of a single actant or quadrant corresponding to a wave data signal generated by scanning the measurement object. A change in the respective instantaneous phase of a new wave propagating in mutually orthogonal directions represented by each of the two complex analytic signals or the product or conjugate product signal of the two complex signals using the respective phases of the signal; Is divided by each instantaneous frequency in the direction orthogonal to each other or the center of gravity frequency of the corresponding spectrum to calculate each displacement component in the direction orthogonal to each other, and in the case of the three-dimensional orthogonal coordinate system, A three-dimensional displacement vector is calculated, and in the case of the two-dimensional orthogonal coordinate system, a two-dimensional displacement vector is calculated.
In addition, the measurement imaging apparatus according to the second aspect of the present invention transmits at least one of a wave transmitted through a measurement target, or a wave reflected, refracted, scattered, or diffracted by the measurement target and outputs at least one reception signal. Two sensors, a signal processing unit that processes the at least one received signal, a depth direction of the measurement target, a horizontal direction orthogonal to the depth direction, and an elevation direction orthogonal to the depth direction and the horizontal direction. Generate at least three steered waves having different deflection angles of electronically or mechanically generated zero or non-zero in a three-dimensional rectangular coordinate system having three axes, or in a depth direction, and In a two-dimensional orthogonal coordinate system having two axes in a horizontal direction perpendicular to the depth direction, different deflection angles of zero degree or non-zero degree generated electronically or mechanically. A measurement control unit that generates at least two steered waves, scans the object to be measured in a lateral direction, and controls the signal processing unit to generate a wave data signal in at least two time phases; A data processing unit for performing a displacement measurement method on a wave data signal generated in at least two time phases to calculate a displacement vector, wherein the data processing unit is operated in each of the at least two time phases. A complex analytic signal centered on the instantaneous phase of a wave obtained from the spectrum of a single actant or quadrant corresponding to a wave data signal generated by scanning the object to be measured by a wave alone, or the at least two time phases Using a complex autocorrelation signal or a complex signal having the instantaneous phase change occurring during When calculating a three-dimensional displacement vector in the case of a coordinate system and calculating a two-dimensional displacement vector in the case of the two-dimensional orthogonal coordinate system, a complex analytic signal or complex signal corresponding to the spectrum of the single actant or quadrant is used. The magnitude of the instantaneous frequency vector of the autocorrelation signal or the complex signal or the magnitude of the centroid frequency vector of the spectrum is the same as that of the other complex analysis signal or the other complex autocorrelation signal or the other complex signal. When the complex analytic signal or the other complex autocorrelation signal or the instantaneous frequency vector component or the centroid frequency vector component of the other complex signal is multiplied by a constant, the instantaneous phase or the change in the instantaneous phase is also multiplied by a constant, or The magnitude of the instantaneous frequency vector or the centroid frequency vector of the complex analytic signal or the plurality of complex autocorrelation signals or the plurality of complex signals When normalizing, the plurality of complex analytic signals or the plurality of complex autocorrelation signals or the instantaneous frequency vector component or the center of gravity frequency vector component of the plurality of complex signals are normalized and their instantaneous phase or instantaneous phase is normalized. Is also normalized, and the superposition of the waves corresponding to the spectrum of the single actant or quadrant is the three-dimensional rectangular coordinate system, the two-dimensional rectangular coordinate system, or the three-dimensional rectangular coordinate system obtained by rotating them. Alternatively, the wave data signal is processed so as to have an instantaneous frequency or a center-of-gravity frequency independent of the direction of the axis of the two-dimensional rectangular coordinate system, and the superposition of the waves is imaged.

Furthermore, the beam forming method according to the third aspect of the present invention is characterized in that, in an orthogonal coordinate system using an axial direction determined by an opening direction of an arbitrary receiving aperture element array and at least one horizontal direction orthogonal thereto, A wave is transmitted from at least one wave source located in the direction toward the measurement target, and a wave coming from the measurement target is transmitted or received in an axial direction or a direction symmetric with respect to the axial direction by beam forming. In the case where two-dimensional two-waves and three-dimensional or three- or four-waves are superimposed in the case of transverse modulation, the waves coming from the measurement object are at least The step (a) of receiving a signal by one receiving aperture element to generate a received signal, and the step (a) (B) generating a multidimensional reception signal by performing beamforming processing and performing lateral modulation, and performing Hilbert transform processing on the multidimensional reception signal generated in step (b). (C) performing partial differential processing or one-dimensional Fourier transform in the axial or lateral direction, and in the case of two-dimensional, the multi-dimensional reception signal of each of the two waves. Generating an analytic signal and, in the case of three dimensions, generating an analytic signal of a multidimensional received signal for each of the three or four waves.
In addition, the beam forming method according to the fourth aspect of the present invention can be implemented in a Cartesian Cartesian coordinate system using coordinates in an axial direction y determined by the direction of an opening of a flat receiving aperture element array and a horizontal direction x orthogonal thereto. An arbitrary wave is transmitted from the wave source located in the direction to the object to be measured, and the wave arriving from the object to be measured is transmitted in a direction where the deflection angle (deviation) θ formed with the axial direction is zero degree or non-zero degree. Or, when the same wave arriving from the object to be measured is subjected to reception dynamic focusing in a direction in which the deflection angle (deviation angle) φ formed with the axial direction is zero degree or non-zero degree, the measurement is performed. (A) receiving a wave arriving from an object by at least one reception aperture element to generate a reception signal; and receiving the wave generated in step (a). (B) performing a beam forming process by performing at least Fourier transform and wave number matching on the received signal, wherein step (b) performs interpolation approximation on the received signal in the wave number domain or the frequency domain. The wave number k ₀ (= ω ₀ / c) expressed by using the wave number k of the wave and the carrier frequency ω ₀ of the wave in a Fourier transform of the received signal without performing the wave number matching including the processing, and Wave number matching in the horizontal direction x is performed by multiplying by a complex exponential function (101) expressed using an imaginary unit i,
Further, the product is Fourier-transformed in the horizontal direction x so as to have a resolution in the axial direction y, and a complex exponential function (excluding the effect of the wave number matching performed in the horizontal direction x) is obtained on the obtained operation result. At the same time as multiplying by 102), the wave number matching in the axial direction is performed by multiplying by a complex exponential function (103), where the wave number in the horizontal direction is represented by k _x ,
This includes generating an image signal directly in a Cartesian coordinate system by performing wave number matching without performing interpolation approximation processing.

  The present invention is based on fast Fourier transform, multiplication of complex exponential function, and proper execution of Jacobi operation, without performing the approximate calculation required in the case of performing ordinary digital processing, It includes an apparatus and a method for performing arbitrary beamforming at high speed and with high accuracy in an arbitrary rectangular coordinate system. In order to solve the problem, reflected waves, transmitted waves, and scattering waves are applied to vibration waves (mechanical waves) including electromagnetic waves, sound waves (compression waves), shear waves, surface waves, etc., or heat waves. Waves (such as forward scattered waves or back scattered waves), refracted waves, diffracted waves, surface waves, shock waves, those waves generated from a self-emanating wave source, waves generated from a moving object, or Appropriately set digital signal processing algorithms (in implemented digital circuits or software) or analog or digital hardware are used for observed waves, such as waves coming from unknown sources.

  The hardware configuration may include a device equipped with a phasing addition device of a normal digital beamformer of each wave device, and may further include a device having an arithmetic function for performing digital wave signal processing. May be implemented, or a digital circuit for implementing the operation may be configured and used. As other necessary devices, at least a normally used transducer, a transmitter, a receiver, a device for storing a received signal, and the like may be provided, as will be described later in detail. Harmonic waves are also processed. Beamforming using a virtual source and a virtual receiver is also performed. Parallel processing is also performed to generate multiple beams simultaneously.

  In the present invention, in order to realize high-speed and high-accuracy processing, in addition to the analog devices such as the above-described level adjustment by analog amplification or attenuation and analog filtering, an analog signal processing device (a waveform of a drive signal waveform) is used. Effective application of linear elements, especially non-linear elements, for changing waveforms, such as emphasizing or attenuating features), as described above, devices and calculators with general-purpose calculation processing capability, PLDs (Programmable Logic Devices) ), FPGA (Field-Programmable Gate Array), DSP (Digital Signal Processor), GPU (Graphical Processing Unit), or a microprocessor may be used, but a dedicated computer or a dedicated digital circuit, or Digital processing may be performed on the stored signal using a dedicated device.

  It is important that these analog devices, AD converters, memories, and devices that perform digital signal processing (such as multi-core) have high performance, but the number of communication times between devices, communication line capacity, wiring, or Broadband wireless communication is also important. In particular, in the present invention, in addition to the case where these functional devices are appropriately mounted on one chip or substrate (when they are detachable), those functional devices are directly mounted on one chip or substrate. (Including lamination) is desirable. Parallel processing is also important. If the device is non-detachable, when the computer also serves as the control unit, much higher security performance can be obtained as compared with the security obtained under normal program control. On the other hand, current legislation will require more disclosure of processing details.

According to one aspect of the present invention, in displacement vector observation using a conventional demodulation method (Patent Document 7 or Patent Document 8), demodulation is performed at the time of two-dimensional or three-dimensional lateral modulation, respectively. Therefore, it is symmetrical with respect to the axis direction of the orthogonal coordinate system for performing the observation or the horizontal axis orthogonal thereto (the axis coordinate axis and the horizontal coordinate axis, respectively) and the axis coordinate axis and the plane including the horizontal direction orthogonal thereto ( In other words, when the waves are deflected and crossed so that all the waves are symmetrical with respect to the axial direction, the waves actually generated are not strictly symmetrical with respect to them but the measurement accuracy Can be overcome, and the measurement accuracy can be dramatically improved. In addition, it is possible to solve the problem that the observation becomes impossible when the center axis of the deflection wave is positively deflected from the front direction of the opening, and it is possible to observe the displacement vector based on the demodulation using the wave in various cases. In addition, it is possible to overcome the problem that a measurement error occurs when the instantaneous frequency in the propagation direction of the generated deflection wave (deflection wave itself) or the center of gravity frequency of the local spectrum is different, and high-precision observation is possible.
Further, according to any aspect of the present invention, a new Hilbert transform using (partial) differential processing or (high-speed) Fourier transform can quickly perform wave imaging, displacement (vector) measurement, temperature measurement, and the like. Various applications can be implemented (the former is faster than the latter). When a plurality of beams and waves having different wave parameters and beam forming parameters such as ultrasonic waves are generated in each time phase, the number of reception signals received by the receiving transducer increases, and beam forming and Hilbert transform are performed. This is effective in such a case, since the number of times of performing is increased. A plurality of beamformed signals may be superimposed and Hilbert transformed at once, which is also effective. When the physical aperture elements form a two-dimensional or three-dimensional distribution or a multi-dimensional array, the problem of requiring a large amount of processing time is more effectively solved, and the high-speed Hilbert transform is more effective. .

In addition, it is possible to use a digital beamformer having a digital operation function and perform high-speed and high-precision arbitrary beamforming without performing approximate calculation through fast Fourier transform (Fourier beamforming). . As will be described in more detail below, the present invention provides for fast execution of arbitrary beamforming in any Cartesian coordinate system, including curved coordinate systems, based on the proper use of complex exponential multiplication and Jacobi operations. In addition, it includes realizing with high accuracy without interpolation approximation. When a plurality of beams or waves having different wave parameters or beam forming parameters such as ultrasonic waves are generated, the received echo signals received by the receiving transducers are superimposed and beam forming may be performed at once. .
Any beam forming including conventional beam forming can be realized using DAS (Delay and Summation) processing. However, according to the present invention, when the physical apertures constitute a one-dimensional array, a general-purpose PC (personal computer) is used. )), The calculation speed is significantly faster by more than 100 times. When the aperture elements form a two-dimensional or three-dimensional distribution or a multi-dimensional array, the problem that much processing time is required is more effectively solved, and the beam forming speed is more effective. Of course, DAS processing may be used.

  That is, according to the present invention, any beam forming can be quickly interpolated and approximated by using a transmitting or receiving transducer array device having an arbitrary aperture shape (sometimes used for both transmitting and receiving) or a sensor array device. , And can be realized by digital processing with high precision. Virtually any focusing, any steering (deflection), any apodization can be performed using an array device having any aperture shape.

  For example, in the field of medical ultrasonic imaging, in addition to a Cartesian coordinate system using a linear transducer, in a conveyor type, sector scan, or IVUS (intravascular ultrasound), transmission, reception, and digitization are physically performed using a polar coordinate system. What is performed is popular, and it depends on the observation target. For example, when observing the dynamics of the heart from the gap between the sternum, a sector scan is usually performed. Also, in an array-type aperture shape or otherwise a PVDF (polyvinylidene fluoride) based transducer, the aperture may be deformable. That is, according to the present invention, a digital signal obtained from a wave transmitted and received in an arbitrary coordinate system is processed, and a signal directly beamformed in an arbitrary coordinate system such as an image display system is obtained without performing interpolation approximation. be able to. A composite transducer of PVDF, which can generate high-frequency ultrasonic waves, and PZT (lead zirconate titanate), which can generate low-frequency but high-power ultrasonic waves, is used as a transducer for a wide band or for simultaneously generating a plurality of carrier frequencies. Sometimes used. A composite type with a single crystal is also possible. As a device for generating a plurality of different ultrasonic waves, devices having different sizes of elements, element intervals, or element thicknesses are arranged in an array, or an array of various configurations forms a layered structure. In some cases.

  In multi-static aperture synthesis, echo data frames composed of echo signals received at the same position among a plurality of reception positions with respect to the transmission position are generated by the number of reception elements, and each echo data frame is generated in the frequency domain. The data frame is subjected to the monostatic type aperture plane synthesizing process according to the present invention, and the result obtained by superimposing the processing results is subjected to inverse Fourier transform. As a result, echo data can be generated by the same number of aperture plane synthesizing processes as the number of channels of the receiving aperture. Therefore, a low spatial resolution image signal is generated by a DAS known as a multi-static processing method and superimposed to obtain a high spatial resolution. It is faster than the method of generating an image signal.

  Further, based on the multi-static processing according to the present invention, dynamic reception and steering at the time of general (fixed) transmission fixed focus can be performed at high speed and with high accuracy. Either case can be achieved by performing an appropriate phase rotation process using multiplication of a complex exponential function.

  Regarding the coordinate system, the present invention is based on performing Jacobi operation in the Fourier transform. For example, in a convex or sector scan, or IVUS signal processing, echo data transmitted and received in a polar coordinate system is used. Based on this, echo data can be directly generated in the Cartesian coordinate system of the display system with high accuracy and high speed without interpolation approximation.

  According to the present invention, even when so-called migration processing is used, arbitrary beamforming can be performed at high speed and with high accuracy without similarly performing interpolation approximation in an arbitrary coordinate system. Further, according to the present invention, imaging with a high SN ratio and high resolution using a virtual source can be performed at high speed. Further, according to the present invention, frequency modulation and broadening of a beam performed under linear processing or non-linear processing, multi-focus, parallel processing, virtual sources and virtual receivers can be performed at high speed under digital processing. It can be realized with high accuracy. The present invention is also useful in optimizing beamforming that requires computational complexity.

  A beam forming method according to another aspect of the present invention provides an array type aperture element group (each element is independently driven and independently received in various beam forming such as Fourier beam forming and DAS processing). Have independent transmission or reception channels from which signals can be obtained), and use the same transmission or reception delay or transmission or reception apodization for adjacent or distant elements as one aperture This includes using a wave having a higher strength than transmission or reception using one element for beamforming for transmission or reception. For example, in a one-dimensional array type transducer, when the element width and the element interval are shortened in order to improve the spatial resolution in the axial direction and the lateral direction, the intensity of the transmission and reception waves becomes weaker (the present inventor). Realizes high-precision displacement vector observation at or near the element pitch of 0.1 mm). This is also the case when a two-dimensional array or a higher-dimensional array is used (element width and element spacing in the direction of the number of dimensions are reduced). Even when the frequency is increased by reducing the element thickness, for example, in the case of using ultrasonic waves such as PVDF having a lower transmission intensity than PZT or the like, the strength of the wave is weakened. It is effective in such a case. By the way, if the element pitch is coarse, a signal in which aliasing has occurred in the element array direction (original digital space) is received and beamforming is performed. And removes the signal in the band. When the element width is reduced and the element pitch is shortened as described above, a wide band in the horizontal direction can be obtained as can be confirmed from the angular spectrum, and a signal having a wide band in the horizontal direction can be generated by beam forming, but the same applies when aliasing occurs. Need to be processed. These processes are required in all beamforming processes. Since the beamforming signal can be generated within the signal band of the angular spectrum of the received raw signal, the steering angle that can be realized by using the element array can be confirmed.

  As described above, according to the present invention, an electromagnetic wave, a sound wave (compression wave), a shear wave, a shock wave, a vibration wave including a surface wave (mechanical wave), or a wave such as a heat wave is targeted. Focusing on transmission or reception, steering on transmission or reception, and arbitrary beamforming regardless of the presence or absence of apodization on transmission or reception, even when the coordinate system for transmission and reception is different from the coordinate system for generating a beamformed signal Can be performed with high accuracy and high speed without performing interpolation approximation based on digital processing.

  This not only improves the frame rate when displaying the beamformed signal in an image, but also provides a high spatial resolution and high contrast with respect to the image quality, and further enables displacement and deformation using the beamformed signal. Or, if the temperature or the like is measured, the measurement accuracy is also improved. The high processing speed has a great effect in multidimensional imaging using a multidimensional array. The present invention relates to a mathematical algorithm related to wave propagation, and is a result of deriving a solution that does not include an approximate calculation through digital operation, but cannot be easily conceived.

FIG. 1 is a representative block diagram illustrating a configuration example of a measurement imaging apparatus according to a first embodiment of the present invention. FIG. 2 is a representative block diagram illustrating a configuration example of the apparatus main body illustrated in FIG. 1 in detail. FIG. 3 is a schematic diagram showing an example of arrangement of a plurality of transmission aperture elements in a transmission transducer. FIG. 2 is a block diagram showing a configuration of a receiving unit or a receiving device equipped with a phasing adder and peripheral devices thereof. FIG. 4 is a schematic diagram of transmission of a deflection plane wave. 9 is a flowchart showing digital signal processing at the time of transmitting a plane wave of deflection. FIG. 9 is a schematic diagram of a case where a wave that is wide in the angle θ direction is transmitted in the radius r direction in polar coordinates (r, θ) (cylindrical wave transmission). Schematic diagram of a case in which a wide wave is transmitted in the direction of the radius r in the polar coordinate system (r, θ) in the direction of the radius r using a virtual source installed behind a physical aperture having an arbitrary aperture shape (cylindrical wave transmission) . The schematic diagram in the case of generating the position of the physical opening of arbitrary opening shapes, or another opening or a wave behind or ahead of it. FIG. 4 is a schematic diagram of monostatic type aperture synthesis. FIG. 3 is a schematic view of a spectrum generated by steering in monostatic aperture synthesis (θ is a steering angle). FIG. 3 is a schematic diagram of multi-static type aperture surface synthesis. FIG. 2 is a schematic diagram of fixed focusing using a linear array. 9 is a flowchart showing digital signal processing when transmitting a cylindrical wave. FIG. 3 is a schematic diagram of fixed focusing using a convex type array. 9 is a flowchart illustrating a migration process when a plane-deflected wave is transmitted. FIG. 7 is a schematic diagram for explaining an example of phase aberration correction when steering is not performed when a linear one-dimensional array transducer is used. FIG. 9 is a schematic diagram for explaining an example of phase aberration correction when performing steering when a linear one-dimensional array transducer is used. FIG. 9 is a schematic diagram for explaining an example of phase aberration correction when performing steering when using a two-dimensional array transducer. FIG. 9 is a schematic diagram for explaining an example of calculating an element position of a deformable physical aperture array element group. The figure which shows the angular spectrum in a wave signal. FIG. 7 is a schematic diagram of motion compensation performed in a two-dimensional case by moving a search area provided in a next frame to be processed using an estimated value of a displacement vector of a point of interest or a local area including the point of interest. 9 is a flowchart illustrating an example of signal processing by Fourier transform using a Jacobi operation. The figure which shows the numerical value phantom used in the simulation. The figure which shows the sound pressure waveform of the transmission pulse used in the simulation. The figure which shows the image obtained using the method (1) in the deflection plane wave transmission. The figure which shows the image obtained using the method (1) in the deflection plane wave transmission. The figure which shows the deflection | deviation angle and error which were obtained using the method (1) in deflection plane wave transmission with respect to a set angle. The figure which shows the error of the deflection angle obtained using the method (1) in the deflection plane wave transmission. The figure which shows the image obtained by using the method (1) with the compound method in the deflection plane wave transmission. The figure which shows the point spread function implement | achieved using the method (1) in deflection plane wave transmission. The figure which shows the image obtained by using the migration method of the method (6) in the deflection plane wave transmission. The figure which shows the image obtained by the monostatic-type aperture surface synthesis of the method (2). The figure which shows the image obtained by the multi-static type | form aperture surface synthesis of the method (3). The figure which shows the point spread function implement | achieved by the multi-static-type aperture surface synthesis of the method (3). The figure which shows the image obtained by the fixed focusing transmission of the method (4). The image obtained by the method (5-1) in the cylindrical wave transmission using the convex type array and the image obtained by the method (5-1 ′) in the cylindrical wave transmission using the linear type array are shown. FIG. The figure which shows the image obtained by the convex type array and the fixed focusing transmission of the method (5-2). FIG. 4 shows an example of two steering beams in a two-dimensional case and the lateral modulation of their superposition. FIG. 4 shows an example of four steering beams in a three-dimensional case and a lateral modulation of their superposition. FIG. 9 is a block diagram illustrating a configuration example of a measurement imaging apparatus according to a third embodiment of the present invention. FIG. 11 is a block diagram illustrating a configuration example of a measurement imaging apparatus according to a fourth embodiment and a modification thereof. FIG. 4 is a schematic diagram showing an example of the arrangement of a plurality of transducers. The figure for demonstrating the form of a wave when a one-dimensional transducer array is used. The figure which shows the angle of the beam direction and the arrival direction of a wave in the space domain and the frequency domain in the case of two-dimensional measurement, and the gravity center of a spectrum. FIG. 3 is a diagram illustrating two deflection beams used in a lateral modulation method in a two-dimensional space. The figure which shows the example which rewrites a frequency coordinate axis and processes when a return arises in the two-dimensional spectrum of the band 2A of a depth direction by the demodulation at the time of two-dimensional horizontal modulation. The figure which shows the example which rewrites a frequency coordinate axis and processes when a return arises in the two-dimensional spectrum of the horizontal band 2B by the demodulation at the time of two-dimensional horizontal modulation. The figure which shows the example which performed frequency modulation in the example of demodulation. FIG. 4 is a diagram schematically showing two waves generated in a two-dimensional coordinate system and their spectra. The figure which shows typically the spectrum of the product of the complex autocorrelation signal of two waves produced | generated in the two-dimensional coordinate system, and the spectrum of a conjugate product. FIG. 4 is a diagram schematically showing displacements in a pseudo axial direction and a pseudo lateral spatial coordinate axis direction orthogonal to the pseudo axial direction in a two-dimensional orthogonal coordinate system. FIG. 4 is a diagram schematically illustrating a pseudo axial direction generated in a direction different from an axial direction of a two-dimensional orthogonal coordinate system and a spatial coordinate axis direction of a horizontal direction orthogonal thereto, and a pseudo horizontal direction orthogonal thereto. The figure which shows typically the pseudo axial direction which is not orthogonal, and the pseudo lateral direction. FIG. 4 is a diagram showing a change in the spectrum of an echo signal according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a change in an autocorrelation function of an echo signal according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a change in an autocorrelation function of an echo signal according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a change in an autocorrelation function of an echo signal according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a change in a B-mode echo image according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a change in a B-mode echo image according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a change in a B-mode echo image according to an embodiment of the present invention. The figure which shows the image of the displacement vector measured by the agar phantom by one Embodiment of this invention, a distortion tensor, and a relative shear modulus. The figure which shows the sound pressure change by one Embodiment of this invention at the time of using a concave HIFU applicator. The figure which shows the example of the optical ultrasonic image obtained by the human in vivo wrist. The figure which shows the example of the two-dimensional point spread function obtained by the human in vivo wrist. The figure which shows the example of the distortion image of the depth direction obtained with the human in vivo wrist.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the same components are denoted by the same reference numerals, and redundant description will be omitted. The measurement imaging apparatus according to the present invention can be used as a communication device. In the following, mainly, when the wave is a sound wave such as an ultrasonic wave, a sound pressure or a particle velocity, and when a mechanical wave is a compression wave (longitudinal wave) or a shear wave, a shock wave, a surface wave, or the like, a stress wave or When a distortion wave or an electromagnetic wave is targeted, an electric field or a magnetic field. A case where an image signal is generated will be described.

<< First Embodiment >>
First, the configuration of the measurement imaging apparatus according to the first embodiment of the present invention will be described. FIG. 1 is a typical block diagram illustrating a configuration example of a measurement imaging apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the measurement imaging apparatus according to the present embodiment includes a transmitting transducer (or applicator) 10 as a transmitting unit, a receiving transducer (or receiving sensor) 20 as a receiving unit, an apparatus main body 30, An input device 40, an output device (or a display device) 50, and an external storage device 60 are provided. Here, the transmitting transducer 10 and the receiving transducer 20 may be integrated or combined to constitute a sensor that transmits and receives a wave.

  FIG. 2 is a typical block diagram showing a detailed configuration example of the apparatus main body shown in FIG. The device main body 30 mainly includes a transmission unit 31, a reception unit 32, a digital signal processing unit 33, and a control unit 34. Here, the transmission unit 31 and the reception unit 32 form a signal processing unit that generates at least one drive signal and processes at least one reception signal to generate a wave data signal, and the digital signal processing unit 33 , A data processing unit configured to perform a displacement measurement method on the wave data signals generated in at least two time phases to calculate a displacement vector. The control unit 34 generates at least one steered wave electronically or mechanically (also referred to as a “steering beam”) to scan the measurement object laterally and to generate a wave data signal in at least two time phases. A measurement control unit that controls the transmission unit 31 and the reception unit 32 so as to generate them is configured. Further, the receiving unit 32 may include a digital signal processing unit 33. 1 and 2 are appropriately simplified block diagrams, and the present embodiment is not limited to these, and details of the present embodiment are as follows. As an example, between the above-mentioned apparatuses, between the units in the apparatus main body 30, and in each unit, communication is appropriately performed based on a wired technology or a wireless technology, and may be installed at a remote place. The apparatus main body 30 is composed of a plurality of such units, and is referred to as such for convenience.

<Transmission transducer>
The transmission transducer (or applicator) 10 shown in FIG. 2 generates and transmits a wave according to a drive signal supplied from a transmission unit 31 in the apparatus main body 30. In the present embodiment, a plurality of transmission aperture elements 10a of the transmission transducer 10 form an array.

  FIG. 3 is a schematic diagram illustrating an example of the arrangement of a plurality of transmission aperture elements in a transmission transducer. FIG. 3 (a1) shows a plurality of transmission aperture elements 10a densely arranged in a one-dimensional array, and FIG. 3 (b1) shows a plurality of transmission aperture elements 10a sparsely present in a one-dimensional array. Is shown. FIG. 3 (a2) shows a plurality of transmission aperture elements 10a densely arranged in a two-dimensional array, and FIG. 3 (b2) shows a plurality of transmission aperture elements 10a which are two-dimensionally sparse. Is shown. FIG. 3 (a3) shows a plurality of transmission aperture elements 10a densely arranged in a three-dimensional array, and FIG. 3 (b3) shows a plurality of transmission aperture elements 10a sparsely existing in a three-dimensional array. Is shown.

  Each transmitting aperture element 10a has a rectangular, circular, hexagonal, or other aperture shape, and can be various, such as flat, concave, or convex, and the array can be one-dimensional, two-dimensional, or There are three-dimensional ones. The directivity of one transmission aperture element 10a is determined by the frequency and bandwidth of the generated wave and the shape of the aperture of the transmission aperture element 10a, and is usually expressed in a two-dimensional or more space, but at least orthogonal. A device in which so-called openings are oriented in two orthogonal directions so as to have directivity in two directions may be referred to as one element, or three directions in which so-called openings are orthogonal so as to have directivity in three orthogonal directions. The one that is suitable for is sometimes counted as one element. Some devices have apertures that are oriented in more than three directions so as to have directivity in more than three independent directions. They differ depending on the position and may be mixed.

  The transmitting aperture element 10a may be spatially dense or sparse (separate position), but this embodiment will be described without distinction from a special one-dimensional to three-dimensional array type. The aperture element array is used for IVUS in linear type (array of elements is flat), convex (arrangement of convex arcs), focus type (arrangement of concave arcs), circular type (for example, medical ultrasonic wave etc.) ), Various shapes such as spherical, convex or concave spherical shell, and other shapes that are arranged in a convex or concave shape can be applied to objects that propagate waves (communication objects) or observation objects. However, the present invention is not limited to these. By appropriately driving these aperture element arrays, transmission and steering of waves whose wavefronts such as the above-mentioned plane waves spread widely in the horizontal direction, aperture plane synthesis, fixed transmission focus, and the like were performed, and one beam or a generated beam was generated. A transmitted wave having a wavefront is realized.

  Regarding the electronic scanning, as will be described later in detail, in order to generate a transmission wave having one transmission beam or wavefront, the driving is performed by independent driving signals generated by a plurality of transmission channels provided in the transmission unit 31 shown in FIG. The same number of transmission aperture elements 10a as the number of signals can be independently driven. A transmission aperture element array used to generate a transmission wave having one transmission beam or wavefront is also referred to as a transmission effective aperture. Further, it is distinguished from a physical aperture element array which collectively refers to all aperture elements, and a transmission aperture realized by the simultaneously driven transmission aperture element 10a may be referred to as a transmission sub-opening element array or simply as a transmission sub-opening. is there.

  In order to observe the whole area of interest or the wide area where the wave is to be propagated (communication target) at a time, the physical aperture element array has the number of transmission channels of the total number of aperture elements, and all of them can be used at all times. However, in order to make the device inexpensive, electronically switching the transmission channel to shift the transmission sub-aperture element array (electronic scanning) or mechanically scanning the physical aperture element array (mechanical scanning) The waves may be transmitted over the entire region of interest using a minimum number of transmission channels. If the object (communication object) through which the wave propagates is large or the size of the observation object is large, both electronic scanning and mechanical scanning may be performed.

  When a sector scan is performed, a spatially fixed aperture element array of the type described above is electronically driven and scanned (electronic scanning), or the aperture element array itself is mechanically scanned. (Mechanical scanning) or both. In classical aperture synthesis, electronic scanning is performed by electronically driving each element of the aperture element array or mechanical scanning of one aperture element to transmit at different positions to form a transmission aperture array. In, the transmission unit 31 may have the number of transmission channels equal to the number of elements of the physical aperture array. However, if a switching device is used, the number of transmission channels can be reduced. Need. When transmitting polarized waves, the transmitting unit 31 needs at least the number of channels obtained by multiplying the number of elements driven at a time by the number of polarized waves.

<Reception transducer>
The receiving transducer (or receiving sensor) 20 shown in FIG. 2 transmits at least one wave transmitted through the measuring object or reflected, refracted, scattered, or diffracted by the measuring object and outputs at least one received signal. The receiving transducer 20 may also serve as the transmitting transducer 10, but may be an array-type sensor that is used separately from the transmitting transducer 10 and is dedicated to receiving. Therefore, the receiving transducer 20 may be set at a different position from the transmitting transducer 10. Further, the receiving transducer 20 may sense a wave different from the wave generated by the transmitting transducer 10 in some cases. Such a receiving transducer 20 may be installed at the same position as the transmitting transducer 10 or may be integrated.

  In the receiving transducer 20 of the present embodiment, at least one or more receiving aperture elements 20a constitute an array, similarly to the transmitting transducer 10, and the signals received by each element are stored in the apparatus main body 30 in an independent state. To the receiving unit 32 (FIG. 2). Like the transmit aperture element 10a, the receive aperture element 20a has a rectangular, circular, hexagonal, or other aperture shape, and can be flat, concave, or convex, with an array of one. There are two-dimensional, two-dimensional, or three-dimensional shapes. The directivity of one receiving aperture element 20a is determined by the frequency and bandwidth of the wave to be received and the shape of the aperture of the receiving aperture element 20a, and one having a plurality of apertures may be counted as one element. The number of openings in one element differs depending on the position and may be mixed. In addition, the reception aperture elements 20a may be spatially dense or sparse (separate positions), and are not distinguished from the array type here (see the example of the transmission array in FIG. 3).

  The aperture element array is, similarly to that of the transmission transducer 10, a linear type (the array of elements is flat), a convex (an array of convex arcs), a focus type (an array of concave arcs), and a circular type (for example, Used for IVUS in medical ultrasound, etc.), spherical, convex or concave spherical shells, other types of convex or concave lines, etc. Therefore, various aspects are taken and are not limited to these. Waves are received using these aperture element arrays, and the wavefronts such as the above-described plane waves are spread and spread in the horizontal direction. Wave reception and steering, aperture synthesis, fixed reception focus, dynamic focus, and the like are performed. A received wave having a beam and a generated wavefront is realized.

  Transducer apertures (elements) may not be spatially dense, but may be sparse (distant locations), or may transmit or receive by mechanically scanning a measurement object. In the case where a transducer not referred to as an array type is used, the received signal may be processed in the same manner.In this application, without specially distinguishing them, a case where an array type device is used will be described. The present invention will be described. For example, if there is a radar aperture at a remote location on land, each radar may or may not form an array.

  In addition to radars mounted on satellites and airplanes, there are cases where the measurement target is mechanically scanned with a transducer, and in such a case, the transducer may or may not constitute an array, Signals may be transmitted or received continuously and densely or spatially sparsely at remote locations. Therefore, the signal may be received while performing the transmission beamforming as well as the classical aperture synthesis (transmission by one aperture element). The aperture element may exist in a one-dimensional shape, or may exist in a two-dimensional or three-dimensional space. Also, mechanical scanning may be performed while performing electronic scanning.

  Regarding the electronic scanning, as will be described later in detail, in order to realize one reception beam or a reception wave having a generated wavefront, reception signals independent of the number of reception channels provided in the reception unit 32 are received at a time by the aperture element. (The effective receiving aperture is determined). The receive effective aperture may be different from the transmit effective aperture. The full aperture element is distinguished from the physical aperture element array which is collectively referred to, and the reception aperture realized by the simultaneously used reception aperture element 20a may be referred to as a reception sub aperture element array or simply a reception sub aperture.

  In order to observe the whole area of interest or the case where the object (communication object) through which the wave propagates is wide, the receiving unit 32 includes the number of receiving channels of the total number of aperture elements provided in the physical aperture element array. All may be used, but electronically switching the receive channel to shift the receive sub-aperture element array (electronic scanning) or mechanically scanning the physical aperture element array to reduce the cost of the device Due to (mechanical scanning), a wave arriving from the entire region of interest may be received using a minimum number of reception channels.

  If the object (communication object) through which the wave propagates is large or the size of the observation object is large, both electronic scanning and mechanical scanning may be performed. When a sector scan is performed, a spatially fixed aperture element array of the type described above is electronically driven to scan while alternately repeating transmission and reception (electronic scanning), or The aperture element array itself may be mechanically scanned (mechanical scanning), or both may be performed together. Further, in the classical aperture synthesis, regarding transmission, as described above, transmission is performed at different positions through electronic scanning that is electronically driven for each element of the aperture element array or mechanical scanning of one aperture element. In order to configure the transmission aperture array, the transmission unit 31 may have the number of transmission channels equal to the number of elements of the physical aperture array in the electronic scanning. However, by using the switching device, at least one channel is necessarily provided like the mechanical scanning. Need.

  On the other hand, regarding the reception at that time, in a monostatic type in which reception is performed only by the same element as the active transmission element, the reception unit 32 may have a reception channel in the same manner as the transmission channel. In a multi-static type in which reception is frequently performed by a plurality of surrounding elements including an active transmission element, the reception unit 32 may include the number of reception channels equal to the number of elements of the physical aperture array in electronic scanning. By using the switching device, it is sufficient that the receiving unit 32 has at least the number of receiving channels equal to the number of elements of the effective receiving aperture in both the electronic scanning and the mechanical scanning. When receiving polarized waves, the receiving unit 32 needs at least the number of channels obtained by multiplying the number of receiving elements by the number of polarized waves.

<Specific example of transducer>
There are various transducers 10 or 20 that can generate or receive arbitrary waves such as electromagnetic waves, light, mechanical vibrations, sound waves, or heat waves. For example, the transducer 10 transmits an arbitrary wave to a measurement object, and also transmits the wave itself (diffraction wave), a reflected wave reflected within the measurement object, a refracted refracted wave, a scattered wave backward or forward scattered, and a diffraction wave. The received diffracted wave or the like may be received (also serving as the transducer 20). For example, when the arbitrary wave is an ultrasonic wave, an ultrasonic transducer that transmits an ultrasonic wave according to a drive signal and receives the ultrasonic wave to generate a reception signal can be used. It is well known that the ultrasonic element (PZT (Pb (lead) zirconate titanate: lead zirconate titanate), polymer piezoelectric element, or the like) is different depending on the application, and the transducer structure is different.

  In medical applications, blood flow measurement has historically used narrow-band ultrasonic waves. However, the present inventor has proposed a soft tissue displacement or strain (static case) that has been put into practical use in recent years. And the use of broadband transducers for (echo) imaging, including measurements of shear wave propagation (velocity). As with HIFU treatment, continuous waves may be used. However, the inventor of the present application has also developed an applicator using a high-frequency or broadband device in order to achieve high-resolution treatment. I have. In the case of using high-intensity ultrasonic waves, a tissue is stimulated within a range that does not cause a heating effect, and a power source may be generated in the measurement target as described above, and a transducer for (echo) imaging is used. Sometimes. Heat treatment, force source generation, and (echo) imaging may be performed simultaneously. The same is true for other wave sources and transducers.

  In the digital signal processing unit 33, a plurality of force sources can be generated in the object in time or space, and the propagation direction of the shear wave can be controlled by superimposing the shear wave. The shear elastic modulus and the anisotropy of the propagation velocity can be measured. Since shear waves generated almost simultaneously are physically overlapped, the shear waves may be separated under spectrum analysis after the observation of the shear waves through ultrasonic displacement meter measurement. If they do not physically overlap, the shear wave generated by each force source is analyzed by observing the ultrasonic signal, the results are superimposed, and the propagation direction, propagation velocity, and propagation In some cases, the shear modulus (Patent Document 11 and the like) is required. However, the ultrasonic signals generated when the respective force sources are generated are analyzed by superposition, and the superposition of the shear waves is observed to obtain them. Sometimes it is done. The same applies to the case where a heat source is generated to observe heat waves and thermophysical properties. Hereinafter, various other processes are performed.

  The shape of heat source, power source and sound pressure can be adjusted by the apodization and delay of transmission / reception, the radiation intensity, and by detecting the transmitted wave or reflected wave when they are generated and optimizing them, Desired heat source, power source and sound pressure can be realized. The shape of the signal may be observed with high sensitivity using a hydrophone, or the shape may be estimated by obtaining an autocorrelation function for the signal captured by the detector (Patent Document 11 etc.). Based on these processes, linear or non-linear optimization is performed. In some cases, the propagation direction of the shear wave or the heat wave is optimized. In each of these cases, it is desirable to use the estimation results of mechanical properties and thermophysical properties.

  For example, when a concave-type applicator is used, high-intensity ultrasonic waves can be focused on the focal position, and a wide band is provided in the lateral direction. However, since the sound pressure shape has a distribution that draws a foot from the focal position, the spectrum obtained after receiving the reflected or transmitted wave is processed (filtering, weighting, etc.) to make the sound pressure shape elliptical. It can be processed (Patent Document 7). It may be applied that spectral components in each direction of a wave or a beam are confirmed as a spectrum in the same direction in a frequency domain. As a result, the quality of imaging is improved and the accuracy of displacement measurement is improved.

  As wave parameters and beamforming parameters, focus position with transmission focusing, plane wave, cylindrical wave, spherical wave, etc. without transmission focusing, deflection angle (including zero degree without deflection), apodization or None, F number, transmission ultrasonic frequency or transmission band, reception frequency or reception band, pulse shape, beam shape, etc. When generating waves or beams with new characteristics that cannot be generated by wave generation or beam forming by multiple transmissions and receptions (for example, when the waves or beams are crossed and superimposed for lateral modulation or broadband, multi-focus , Etc.), the same effect may be obtained by performing the same processing. Note that the superposition may be performed at the same time in real time, or may be performed on data received at different times in the same time phase of the subject. Each of them may be subjected to reception beamforming and superimposed, or those not subjected to reception beamforming may be superimposed and subjected to reception beamforming.

  A single wave or beam, or a received signal obtained from a superposition of a plurality of waves or beams is weighted in the frequency domain and widened, and super-resolution may be performed (higher resolution). . This is the so-called inverse filtering or deconvolution. In some cases, the method described in paragraph 0009 may be used, and the conjugate or reciprocal of the frequency response may be applied to the observed wave as an inversion of the beam characteristic. Also, the conjugate of the observed wave or the conjugate of the frequency response may be applied (these are the detection processes, the former obtains the square of the envelope, and the latter uses the auto-spectrum, that is, the auto-correlation function). can get). Super-resolution may be applied to the beam-formed one (including aperture synthesis), or super-resolution to the one before reception beam-forming or no beam-forming (transmission / reception signal for aperture synthesis). Beam forming may be performed after performing image processing.

  In the displacement (vector) measurement, in order to increase the accuracy of the displacement component, the frequency in the direction of the displacement component may be increased. If high resolution is also required, it is necessary to widen the band. For example, the low frequency spectrum can be discarded and the frequency can be increased to increase the accuracy of displacement measurement. The amount of calculation can also be reduced. When multiple waves or beams are physically generated, or when multiple waves or beams are generated by dividing the spectrum by signal processing, an over-determined system is configured to perform high-precision displacement measurement, etc. In some cases, when the angular spectrum before beamforming is divided, beamforming is performed for each, and it is often better to divide the spectrum after beamforming. In the imaging, envelope detection, square detection, and absolute value detection are performed. By superimposing a plurality of waves or beams after detection, it is possible to reduce the number of speckles and enhance specular reflection.

  Note that these processes can be similarly performed not only when using ultrasonic waves and in medical treatment, but also when using electromagnetic waves and in various fields. For example, it is possible to observe audible sound waves using ultrasonic waves (that is, Doppler effect), observe sound waves and heat waves using electromagnetic waves and light, and observe seismic waves using them. In conjunction therewith, it is also possible to observe related physical properties (distribution).

  Transducers are classified into contact type and non-contact type. Each time, a matching material is inserted through a matching material (eg, gel or water in the case of ultrasonic waves), or a matching material previously incorporated into the transducer (ultrasonic wave). In this case, a matching layer is used and the impedance matching of each wave is appropriately performed for the measurement target. Power element, carrier frequency, band (wide or narrow band, determine axial spatial resolution), waveform shape, element size (determine horizontal spatial resolution), directivity, etc., aperture element level and array Those designed in terms of both performance are used (details are omitted). As an ultrasonic transducer, there is a composite ultrasonic transducer such as one in which PZT or PVDF is laminated and has both transmission acoustic power and broadband characteristics.

  In the case of forcibly vibrating by a drive signal, the frequency and the band of the generated ultrasonic wave may be adjusted or coded according to the drive signal. , Using analog or digital filters). In some cases, aperture elements having different characteristics such as frequency and sensitivity are arranged. Medical ultrasound transducers were originally handy and easy to use, but recently, non-cable transducers have been used with handy sized device bodies. If the sound has a low frequency (for example, audible sound), there are a speaker and a microphone. Other wave transducers may be implemented with similar perspectives, but not limited to.

  Alternatively, a transmitting transducer that generates an arbitrary wave and a receiving transducer (sensor) that receives an arbitrary wave may be used as the transducer 10 and the transducer 20. In that case, the transmitting transducer transmits an arbitrary wave to the measurement target, and the sensor uses the wave itself (diffraction wave), a reflected wave reflected in the measurement target or a scattered wave backscattered, or A transmitted wave or a forward scattered wave transmitted through an object, a refracted wave refracted or diffracted in an object to be measured, or the like can be received.

  For example, when the arbitrary wave is a heat wave, a heat source that is not intentionally generated such as sunlight, lighting, metabolism in a living body, etc. may be used, but such as an infrared heater or a heater, etc. An ultrasonic transducer (which may generate a force source in the object to be measured), an electromagnetic transducer, a laser, etc., which transmits a comparatively stationary or heating ultrasonic wave which is often controlled according to a drive signal. used. In addition, infrared sensors that receive heat waves and generate received signals, pyroelectric sensors, microwave and terahertz wave detectors, temperature sensors such as optical fibers, and ultrasonic transducers (temperature-dependent such as sound speed and volume change of ultrasonic waves) A nuclear magnetic resonance signal detector (detecting a temperature using a chemical shift of nuclear magnetic resonance) can be used. For each wave, an appropriately receivable transducer is used.

  Optical digital cameras and mammography use a charge coupled device (CCD) technology, and an integrated circuit and a sensor body may be integrated. The same technology is applied to an ultrasonic two-dimensional array, and real-time three-dimensional imaging is possible. A combination of a scintillator and a photocoupler is used to detect X-rays, but it has been long since they have been observed as waves. When capturing a high-frequency signal as a digital signal, it is effective to perform analog detection or modulation in preprocessing, convert the signal to a low frequency, perform A / D conversion, and store it in a memory or a storage device (storage medium). Sometimes, it is digitally detected. These may be integrated with a transmitter or a receiver by a chip or a substrate.

  In addition, each aperture may form an array, such as when a radar is located at a remote position on land, or may not be limited to this. The aperture may be mechanically scanned to obtain a wide directivity. Apertures are anomalous under certain regularities, such as spatially dense and continuous, densely sparse at distant locations, and evenly spaced, and under physical constraints In some cases, it is installed. In addition, the position may be fixed with respect to the object (communication target) or the observation position where the wave propagates, such as in the ocean, a building, or an indoor space. They may be dedicated apertures for transmitting or receiving waves. Further, each opening may serve as both, but it is not limited to receiving the response of the wave transmitted by itself, and may receive the wave transmitted by another opening. In medical and biological observations, ultrasonic waves generated by laser irradiation, sometimes referred to as photoacoustic, may be observed (a plurality of wave transducers may be integrated). According to the present invention, the photoacoustics by the combined use of the ultrasonic diagnostic apparatus and the OCT can be used, for example, to distinguish not only arteries and veins, but also to measure the blood flow velocity in each of them. it can). In addition, a magnetic substance having an affinity for a lesion may be injected intravenously as a contrast medium, and vibration such as ultrasonic waves may be applied to the affected part to observe electromagnetic waves. It may communicate with various mobiles using radio waves.

  Various transducers (arrays) used for passive observations such as seismic waves (seismographs), magnetoencephalograms (SQUID arrays), brain waves, electrocardiograms, neural networks (electrode arrays), radio waves (antennas), radars, etc. Some are used to observe wave sources. The propagation direction of the arriving wave is obtained based on multidimensional spectral analysis (the past work of the inventor of the present application). Further, in the measurement and imaging apparatus of the present invention, a plurality of transducers provided at different positions or reception effective Even when information on the propagation time cannot be obtained using the aperture (usually, the position of the wave source is determined from the time when the wave is observed at a plurality of positions), the position of the wave source is determined geometrically. It is possible. Waves can be observed not only in pulse waves or burst waves but also in continuous waves. Through any processing, when the arrival direction of the wave is known, various beams can be steered and focused in that direction to observe in detail. In those processes, always, with emphasis on the likely direction, perform reception beamforming while changing the steering angle, and observe the obtained image or image, spatial resolution, contrast, signal strength, or Through multi-dimensional spectral analysis, the direction of the wave source can also be specified. Therefore, the transducer used in the measurement imaging apparatus of the present invention may be provided with a mechanism that is also used for steering and performs electronic scanning, mechanical scanning, or both scanning.

  As transducers that can demonstrate the effectiveness of the present invention, typical transducers that are relatively familiar and some special ones are listed, but those used in the present invention include those including applications. The present invention is not limited thereto, and various types of devices that can generate or receive arbitrary waves such as electromagnetic waves, light, mechanical vibrations, sound waves, and heat waves can be used.

<Beam forming>
Simultaneous phase, simultaneous phase in which the state of the object (communication target) or observation target in which the wave propagates or the observation target is the same or almost the same, or at another time or another time phase, one or more beam forming at each aperture Alternatively, transmission or reception may be performed. Similarly, one or more combinations of apertures may provide one or more beamformings, or transmission or reception. Similarly, each of a plurality of combinations of apertures may perform one or more beamformings, or transmit or receive. Also, in such cases, new data may be generated through linear or non-linear calculation using the results, including a case where a plurality of results of beamforming and reception are obtained. There are times when the received signal to be processed is overlapped with that when it originally overlaps.

  Also, for spatially moving objects such as satellites and radars mounted on airplanes, the mounted apertures may or may not form an array, and mechanical scanning In some cases, wide directivity can be obtained, and under certain regularities such as spatially continuous high density, or spatially sparsely spaced at equal distances, or evenly spaced. , Or irregularly as needed. There are various other moving objects such as cars, ships, trains, submarines, and mobile robots. In addition, there are also cases where the creatures, such as those distributed, move regularly or randomly. In such a case, a mobile communication device is used. An RFID (Radio Frequency Identification) tag, an IC card, or the like may be used.

  At that time, not only classical aperture synthesis (opening synthesis based on transmission for each aperture element) is performed, but also reception beamforming may be performed while generating transmission beamforming. In addition, mechanical scanning may be performed regularly or irregularly while performing electronic scanning. Waves may be appropriately propagated over a wide spatial range (communication) or a wide spatial range may be appropriately observed. Sometimes. Of course, by using a multi-dimensional array, waves may be appropriately propagated over a wide spatial range (communication) or a wide spatial range may be appropriately observed only by electronic scanning (physical aperture). Not only becomes larger, but also multi-directional steering becomes possible).

  The mounted aperture may also serve as both apertures for transmitting and receiving waves, but it is not limited to receiving the response of the waves transmitted by itself, and receives the transmitted waves of other arbitrary apertures Sometimes. In addition, there are cases where a plurality of moving objects have openings, and simultaneous or simultaneous phases in which the state of a wave propagation target (communication target) or observation target is the same or substantially the same, or at a different time or At another phase, one or more beamformings or transmissions or receptions may occur at each aperture.

  Similarly, one or more combinations of apertures may perform one or more beamformings, or transmit or receive. Further, similarly, each of the plurality of combinations of apertures may perform one or more beamformings or transmit or receive. Also, in those cases, new data may be generated through linear or non-linear calculation using them, including a case where a plurality of results of beamforming and reception are obtained. In the above description, a combination of an opening of a moving object and a fixed opening may be used for an object (a communication object) or an observation object that propagates a wave.

  Thus, in the present embodiment, there are a plurality of transmission aperture elements 10a and a plurality of reception aperture elements 20a (one aperture element may also serve as the transmission aperture element 10a and the reception aperture element 20a), Active beamforming is performed. In this active beamforming, arbitrary beamforming can be realized by digital processing without performing interpolation approximation at high speed through fast Fourier transform. Also, virtually any focusing and any steering can be performed using a transducer array device having an arbitrary aperture shape.

  The transmission is generally performed in an orthogonal coordinate system determined by the shape of the physical aperture element array to emphasize the direction of each aperture element (a virtual sound source will be described separately). In order to generate a signal that directly represents a wave in a simple display coordinate system, the center is to perform reception digital beamforming without performing interpolation approximation processing. There is also forming. In addition, a virtual source, a virtual receiver, and the like may be used, and beamforming is performed in the same manner as in the case of the physical aperture element array.

<Transmission unit>
Next, the transmission unit 31 (FIG. 2) included in the device main body 30 will be described. The transmission unit 31 includes transmitters 31a for a plurality of transmission channels. The number of lines for transmitting different drive signals to the aperture elements used for performing one beam forming is the number of transmission channels. For example, as described below, there are various forms of this transmission channel. The frequency, bandwidth, waveform, and directivity of the wave generated in each transmission aperture element 10a are determined by the transmission aperture element 10a and the transmission unit 31.

  When an impulse signal is applied to the transmitting aperture element 10a, a wave is generated which is determined by the shape (thickness and size and shape of the aperture) of the transmitting aperture element 10a and the material (a typical example of an ultrasonic element is a single crystal). , By forcibly exciting the transmitting aperture element 10a with a drive signal having a frequency, a bandwidth, and a waveform (which may be encoded) generated in the transmitting unit 31, The width, waveform and directivity are adjusted. The characteristics of the generated drive signal are set as parameters under the control of the control unit 34. The control unit 34 recognizes the transducer to be used, and the recommended setting may be automatically made. However, the setting or adjustment using the input device 40 is also possible.

  Normally, in performing one beam forming, the transmission unit 31 is equipped with an analog or digital delay pattern in order to drive a plurality of aperture elements by drive signals with different delays. In some cases, a delay pattern that realizes a transmission focus position, a steering direction, and the like that can be selected by using a command is used. These patterns are programmable, and depending on the purpose, patterns to be used and selectable patterns may be installed through various media such as a CD-ROM, a floppy disk, or an MO. In some cases, a pattern can be interactively selected from the input device 40 by activating the program, or a delay (pattern) value can be directly input, or a file in which data is recorded is read and set. It may be. In particular, in the case of an analog delay, the delay value to be used may be changed in an analog or digital manner, or the delay circuit or pattern itself may be replaced with another one or switched separately.

  In the apparatus main body 30 (FIG. 2), a command signal for generating a drive signal (which may be coded) for driving the corresponding transmission aperture element 10a is transmitted from the control unit 34 to the transmitters 31a of a plurality of channels. You. These command signals may be generated based on a command signal for starting beam forming for one frame. When the transmission delay is digital, for example, a command signal sent to the transmitter 31a for the transmission aperture element to be driven first is used as a trigger to apply a digital delay, and the command signal is sent to each transmitter 31a. is there. A digital circuit delay device may be used for the digital delay.

  Further, the drive signal itself generated in the transmitter 31a for the element to be driven first may be subjected to analog delay and transmitted to each aperture element. In this case where an analog delay that does not require synchronization is used, the transmitter 31a can drive a plurality of transmission aperture elements 10a with at least one device. Therefore, the transmission analog delay is provided before or after or inside the transmitter 31a, or in the control unit 34, while the transmission digital delay is provided inside or before the transmitter 31a, or in the control unit 34. There is.

  A pattern may be selected by switching an analog circuit or an analog device, or a digital circuit or a digital device, but the delay of those delay devices may be changed under the control of the control unit 34. , May be programmable through installation or input settings. Further, a delay device may be provided in the control unit 34. Further, when the control unit 34 is configured by a computer or the like as described below, a command signal with a delay may be directly output from the control unit 34 under software control.

  The control unit 34 and the digital delay are a device or a computer having a general-purpose calculation processing capability, a PLD (Programmable Logic Device), an FPGA (Field-Programmable Gate Array), a DSP (Digital Signal Processor), a GPU (Graphical Processing Unit), or , A microprocessor or the like, or a dedicated digital circuit or a dedicated device. They are desirably of high performance (such as multi-core) and may also carry analog devices, AD converters 32b, memories 32c, and / or digital signal processing units 33 that perform transmit or receive beamforming.

  In addition, the number of times of communication between devices, communication line capacity, wiring, or broadband wireless communication is important. Particularly, in the present invention, when these functional devices are appropriately mounted on one chip or substrate ( If it can be removed). In addition, they may be directly mounted on one chip or substrate (including lamination). Parallel processing may be performed. If the device is non-detachable, when the computer also serves as the control unit 34, it is possible to obtain much higher security performance than the security obtained under normal program control. On the other hand, current legislation will require more disclosure of processing details.

  Some control software and delay values are directly coded or input, and some are installed. How to apply digital delay is not limited to these. When this digital delay is performed in the transmission delay, an error determined by the clock frequency for generating the digital control signal always occurs, unlike the analog delay. Therefore, the analog delay is better as the transmission delay in terms of accuracy. Basically, the error is reduced by using a high clock frequency at a cost. On the other hand, the analog delay can be changed in an analog manner or can be made digitally controllable and programmable. However, when the degree of freedom is lower than that of the digital delay and the cost is reduced, a delay pattern mounted as an analog circuit may be switched and used.

  Note that the transmission apodization is performed by the temporal change of the energy of the drive signal of the aperture element and the amplitude of the time-varying waveform (which may be coded). The drive signal is adjusted based on the calibration data of the conversion efficiency (conversion ability) of the drive signal of the aperture element into a wave. For other purposes, adjustment of the drive signal may be performed solely for calibration. The command signal sent from the control unit 34 to the transmitter 31a may be a signal representing the waveform and phase information of the drive signal generated by the transmitter 31a in a time series, or may be a predetermined signal that the transmitter 31a recognizes and outputs. It may be a coded signal that can generate a drive signal, or simply sends a transmission command to a transmitter 31a that generates a predetermined drive signal for the position of each aperture element to be driven within the effective aperture. There may be.

  Further, similarly to the delay, the transmitter 31a may be programmable so as to generate a predetermined drive signal for the position of each driven aperture element in the effective aperture, and may take various forms. A power supply or an amplifier is used to generate a drive signal, but power supplies or amplifiers with different amounts of power or energy supplied are switched and used, or simultaneously used to generate one drive signal. And may be directly set or programmable as described above, similar to the transmission delay pattern. The delay and the apodization can be implemented in the same or different hierarchical levels in the same or different form in the transmission unit.

  The transmission channel for driving the aperture element in the transmission effective aperture is switched through a switching device such as a shift register or a multiplexer, and the effective aperture at another position is used to scan the region of interest while performing beamforming. There is. Some delay elements have variable delay values, and delay patterns (delay element groups) are sometimes switched. Further, steering in a plurality of directions may be performed in one effective opening, and steering may be performed in a plurality of directions while appropriately changing an opening position and an effective opening width.

  When switching a high voltage signal, a dedicated switching device is used. Further, there is a case where the apodization value of the apodization element is variable in the transmission time direction or the array direction of the aperture element, and the apodization pattern (apodization element group) is sometimes switched. May be adjusted depending on the beam shape. Specifically, a transmitting element having an apodization value of zero means that the transmitting element is not active but is off, and the apodization also serves as a switch for the effective element and can determine the effective aperture width (apodization in the direction of the aperture element array). If the function is a rectangular window, the switch is on; otherwise, it is weighted on.)

  Further, regarding the delay pattern and the apodization pattern, the device main body 30 may include a plurality of patterns or may be programmable. Based on a response from a transmission target or a result of beamforming by the receiving unit 32 described below, In a digital signal processing unit 33 (FIG. 2) in the apparatus main body 30 described later, attenuation and scattering (forward scattering or back scattering, etc.), transmission, reflection, refraction, diffraction, sound speed, etc. The frequency dispersion and the spatial distribution of the propagation velocity of the beam are calculated, and the delay and strength of the wave transmitted from each aperture, the steering direction of the beam and the wavefront, the apodization pattern, and the like may be optimized.

  Note that the classical aperture synthesis includes a monostatic type and a multi-static type that are performed in transmission by one aperture element, and the active transmission aperture element 10a is operated under switching or apodization as described above. Can be switched. In some cases, all transmitting elements have a transmission channel including the transmitter 31a. In aperture synthesis, it is necessary to generate a wave of sufficient intensity or energy, and the transmission apodization function itself is not always important. Substantially, the aperture plane synthesis is usually performed simultaneously with the reception apodization in the phasing adder. In the present invention, the digital signal processing unit 33 often performs the synthesis simultaneously with the reception apodization. As described above, the representative transmission unit according to the present embodiment has been described. However, any unit can be used as long as transmission beamforming can be performed.

<Reception unit and digital signal processing unit>
Next, the receiving unit 32 and the digital signal processing unit 33 (FIG. 2) included in the apparatus main body 30 will be described. The receiving unit 32 includes receivers 32a for a plurality of receiving channels, an AD converter 32b, and a memory (or a storage device or a storage medium) 32c. The frequency, bandwidth, waveform, and directivity of the reception signal generated by each reception aperture element are determined by the reception aperture element 20a and the reception unit 32. When the wave arrives at the reception aperture, a reception signal determined by the shape (thickness and size and shape of the aperture) of the reception aperture element 20a and the material (single crystal as a typical ultrasonic element) is generated. The frequency, bandwidth, and directivity of the received signal generated by the filtering process in the unit 32 (which may also serve as an analog amplifier) are adjusted. The generated received signal is substantially adjusted based on filter parameters (frequency characteristics such as frequency and bandwidth) set under the control of the control unit 34. The control unit 34 recognizes the transducer to be used, and the recommended setting may be automatically made. However, the setting or adjustment using the input device 40 is also possible.

  A typical digital receiving unit or digital receiving device has such a function, and further has a phasing addition function. That is, the DAS processing in the digital receiving unit or the digital receiving apparatus performs phasing processing on a plurality of reception signals and adds the plurality of reception signals that have been subjected to the phasing processing. As the phasing processing, the reception signal is AD-converted in the reception channels of the plurality of reception apertures, and is basically stored in a memory, a storage device, or a storage medium capable of high-speed reading and writing, and each of the signals in the region of interest To delay the received signal read from the storage destination at high speed with interpolation approximation processing in the spatial domain in order to delay the phase with respect to the position of interest, it takes much time. In the above, there is a method of applying a delay with high precision based on the Nyquist theorem by phase rotation multiplied by a complex exponential function (the past invention of the inventor of the present application, Patent Document 6, Non-Patent Document 15, etc.). In the storage destination, the reception signal of each reception aperture may be stored at a position corresponding to the reception delay, and these reception signals are read out and added, or the above processing is further performed on them. Sometimes they are added.

  FIG. 4 is a block diagram showing a typical configuration of a receiving unit or a receiving apparatus equipped with a phasing adder for realizing the phasing addition processing and peripheral devices thereof. The receiving unit (or receiving device) 35 illustrated in FIG. 4 performs a phasing addition process in addition to the receivers 35a of a plurality of receiving channels, the AD converter 35b, and the memory (or storage device or storage medium) 35c. It has a phasing adder 35d for performing a digital signal processing of the generated image signal and another data generating unit 35e for performing digital signal processing. For example, the other data generating unit 35e generates image display data, calculates a displacement based on a Doppler method by a higher-order calculation, calculates a temperature, and the like. Perform analysis.

By performing this phasing addition processing at each position in the region of interest, dynamic focusing is performed. Originally, dynamic focusing was a term used in the range direction received at the effective aperture, but in fact is not the case in receive digital beamforming implemented according to the present invention. The receiving unit 32 in the embodiment of the present invention shown in FIG. 2 has a high-precision digital processing in which an arithmetic process for performing a phasing addition (DAS) process does not require a high-speed and approximation process different from the above-described arithmetic process. Beam forming is performed. Therefore, in the embodiment of the present invention, the digital signal processing unit (data processing unit) 33 shown in FIG. 2 is used instead of the phasing adder 35d shown in FIG. In the digital signal processing unit 33, various data described in the present application may be generated based on the image signal.
For example, the digital signal processing unit 33 performs a beam forming process on a reception signal generated by a receiving unit such as the transducer 20 to generate a multidimensional reception signal. In some cases, conversion, spectral frequency division, superposition, and the like are performed. In addition, the digital signal processing unit 33 may generate data of a constituent component or a structure to be measured, or various physical quantities or physical properties. The data generated in the digital signal processing unit 33 is not limited to the data described in the present application. As described above, the receiving unit 32 may include the digital signal processing unit 33, and vice versa. The control unit (measurement control unit) 34 sends and controls a command signal to the digital signal processing unit 33 and other units, but may also serve as a digital signal processing unit, and vice versa.

  Although a normal phasing adder can be similarly realized by the digital signal processing unit 33 in the embodiment of the present invention, in particular, the feature of the receiving unit 32 in the embodiment of the present invention is that a high-speed and high-precision In order to realize the processing, the reception signal normally generated in the reception aperture element 20a is level-adjusted by analog amplification or attenuation or analog filtering (programmable, and operates under frequency characteristics and parameters set through the control unit 34). In addition to using analog devices to ensure signal strength and reduce noise, the advantage of analog signal processing being faster than digital signal processing is to use linear or especially non-linear as needed. Through the effective use of devices that perform analog signal processing, The resulting signal is AD converted and stored in the fast memory (or storage device or storage medium) 32c of reading and writing digital signal obtained as a result.

  Also, as the digital signal processing unit 33 to be mounted, a device or a computer having a general-purpose calculation processing capability, a PLD (Programmable Logic Device), an FPGA (Field-Programmable Gate Array), a DSP (Digital Signal Processor), a GPU (Graphical Processing) Unit) or a microprocessor or the like, or a dedicated computer or a dedicated digital circuit or a dedicated device is used, and the digital wave signal processing of the present invention is performed on the stored digital signal. Will be applied.

  It is important that the analog devices and the devices that carry the AD converter 32b, the memory (or storage device or storage medium) 32c, and the digital signal processing unit 33 (such as a multi-core) have high performance. The number of times of communication, communication line capacity, wiring, or wideband wireless communication is important. In particular, in the present invention, when these functional devices are appropriately mounted on one chip or substrate (when they are detachable) ), Or they may be directly mounted on one chip or substrate (including lamination). Parallel processing may be performed.

  If the device is non-detachable, a significantly higher security performance can be obtained when the computer also serves as the control unit 34 as compared with the security obtained under normal program control. On the other hand, current legislation will require more disclosure of processing details. Further, the digital signal processing unit 33 may also serve as a control unit 34 for sending command signals to other units and controlling them.

  In the receiving unit 32 embodied in the present invention, a trigger signal that causes the AD converter 32b to start sampling (AD conversion) of the reception signal generated by the reception transducer (or reception sensor) 20 (that is, by starting AD conversion). The acquisition start command signal for starting to store the digital signal in the memory (or the storage device or the storage medium) 32c is the same as the trigger signal used in a normal receiving unit. For example, any command signal generated by the control unit 34 such that the transmitter 31a generates a transmission signal to the transmitting aperture element 10a to be driven may be used. In the case of receiving waves, a command signal for an element to be driven first, a command signal for an element to be driven last, or a command signal for driving another element is used, and a predetermined signal is used as appropriate. A / D conversion may be started by applying a digital delay.

  These command signals may be generated based on a command signal for starting beam forming for one frame. That is, the number of times the transmission trigger signal is generated is counted, and a predetermined number or, as appropriate, reaching a number that may be a programmable parameter such as input and set from the input device 40 or the like, When confirmed in the control program, a command signal may be generated to start generating a new frame. The number, like the other parameters, may be installed through various media such as a CD-ROM, a floppy disk, or an MO. In some cases, the program can be started and interactively selected from the input device 40. In other cases, there are various cases, such as when a numerical value is directly input or when a file in which data is recorded is read and set. The number can be determined by using a dip switch or the like. When it is not necessary that the number of reception delay patterns is large, a signal obtained by multiplying a received signal by a mounted analog delay pattern may be subjected to AD conversion.

  In order to realize high-speed reception dynamic focusing, the present inventor's past invention applies a product of a complex exponential function to a signal in the frequency domain and uses a normal high-speed method without using a method based on the Nyquist theorem. When the receiving digital delay is multiplied, an error determined by the sampling interval of the AD conversion occurs. Therefore, the sampling frequency of the AD converter 32b is increased sufficiently at a high cost, or a highly accurate digital delay (phase rotation processing) is used. The only option was to perform slow beamforming. On the other hand, according to the present invention, as described above, if the received signal is synchronously digitally sampled, high-speed reception digital beamforming can be performed without causing such an approximation error. Such receiving digital beamforming is also much faster than the method of computing the product of complex exponential functions in the frequency domain, which is the past invention of the present inventor.

  Also in the present invention, the number of lines for transmitting the signal received by the receiving aperture element 20a used for performing one beam forming to the receiving unit 32 is usually the number of reception channels. In that regard, the receiving unit 32 is as follows, and there are various types of receiving channels. That is, in performing the normal beamforming once, the receiving unit 32 is equipped with an analog or digital delay pattern as described above in order to apply different delays to the signals generated in the plurality of receiving aperture elements 20a. A delay pattern that realizes a reception focus position, a steering direction, and the like that can be selected by the operator using the input device 40 may be used.

  These patterns are programmable, and depending on the purpose, patterns to be used and selectable patterns may be installed through various media such as a CD-ROM, a floppy disk, or an MO. In some cases, a pattern can be interactively selected from the input device 40 by activating the program, or a delay (pattern) value can be directly input, or a file in which data is recorded is read and set. It may be. In particular, in the case of an analog delay, the delay value to be used may be changed in an analog or digital manner, and the delay circuit or the pattern itself may be replaced with another one or switched separately. Sometimes.

  If the reception delay is digital, the reception signal stored in the memory (or storage device or storage medium) 32c of each reception channel is read and phased (added). In the measurement imaging apparatus of the present embodiment, the digital signal processing unit 33 delays the digital reception signal, passes the digital reception signal through a delay device of a digital circuit, or stores the AD converter 32b and the memory (or storage). It is possible to apply a delay to the command signal for starting the capture from the control unit 34 for turning on the (device or storage medium) 32c. Therefore, the digital delay can be applied at an arbitrary position or in the control unit 34 after the inside of the AD converter 32b.

  In the case of an analog delay, a delay can be applied at an arbitrary position or in the control unit 34 after a reception signal is generated in the reception aperture element 20a. When an analog delay pattern is used, at least one receiver 32a can receive reception signals of a plurality of aperture elements. Therefore, in the storage destination of the reception signal, the reception signal of each reception aperture may be stored at a position corresponding to the reception delay, or the reception delay may not be applied at all. The digital signal processing unit 33 may execute digital wave signal processing described later (the digital signal processing unit 33 may also be able to execute normal phasing addition processing).

  A pattern may be selected by switching an analog circuit or an analog device or a digital circuit or a digital device. Further, the delay of these delay devices may be changed under the control of the control unit 34, or may be programmable through installation, input setting, or the like. Further, a delay device may be provided in the control unit 34. When the control unit 34 is configured by a computer or the like as described above, the command signal delayed by the software control is controlled. It may be output directly from the unit 34.

  The control unit 34 and the digital delay may be a device or a computer having a general-purpose calculation processing capability, a PLD, an FPGA, a DSP, a GPU, a microprocessor, or the like, or a dedicated digital circuit or a dedicated device. They are desirably of high performance (such as multi-core) and may also carry analog devices, AD converters 32b, memories 32c, and / or digital signal processing units 33 that perform transmit or receive beamforming.

  In addition, the number of times of communication between devices, communication line capacity, wiring, or broadband wireless communication is important. Particularly, in the present invention, when these functional devices are appropriately mounted on one chip or substrate ( If it can be removed). In addition, they may be directly mounted on one chip or substrate (including lamination). Parallel processing may be performed. If the device is non-detachable, when the computer also serves as the control unit 34, it is possible to obtain a much higher security performance than the security obtained under normal program control. On the other hand, current legislation will require more disclosure of processing details. Some control software and delay values are directly coded or input, while others are installed. How to apply digital delay is not limited to these.

  In the present embodiment, based on the trigger signal sent from the control unit 34 (FIG. 2) of the apparatus main body 30, a trigger signal (command signal) for instructing the start of AD conversion is sent to the AD channel of each reception channel. It is supplied to the converter 32b. In accordance with this command signal, A / D conversion of the received analog signal of each channel and storage of the digitized signal in the memory (or storage device or storage medium) 32c are started. The transmission unit 31, the reception unit 32, and the digital signal processing unit 33 control the transmission aperture position and the transmission effective aperture width under the control of the control unit 34 until all the reception signals for one frame are stored, or While changing the transmission steering direction and the like, and further changing the reception aperture position and the effective reception aperture width each time a wave or beam is transmitted, or the reception steering direction, the processing from transmission to storing the digital signal is repeatedly performed. Each time a received signal for one frame is stored, a digital wave signal processing method used in the present invention, that is, a digital beam forming method, is applied to the received signal group to generate a coherent signal.

  Therefore, even if the measurement / imaging apparatus according to the present invention is equipped with the analog or digital delay described above, it is not always used as a delay for beamforming, and may be used as a memory, a storage device, or a storage medium. Is used to delay the timing of starting the A / D conversion of the received signals and storing them in the memory (or storage device or storage medium) 32c in order to save and effectively use and reduce the access time. is there. The reception delay in beamforming is mainly digital wave signal processing performed by the digital signal processing unit 33, and in the present invention, saving and shortening the access time are significant. In addition, physical beamforming at the time of transmission (for example, physical processing using a computer or a dedicated device, which is different from that performed in software beamforming using a computer or a dedicated device, In the case of performing classical aperture synthesis without performing focusing, steering, apodization, or the like that may be performed at the time of reception or reception, the transmission delay is the same as the reception delay in digital wave signal processing. Multiplied at the timing.

  In view of the above, in the present invention, the receiving unit 32 must be an independent analog or digital delay, a receiver 32a, an AD converter 32b, and a memory (or a storage device or a storage medium) in each reception channel. 32c, and if necessary, a level adjustment by analog amplification or attenuation, an analog filter, and other analog operation devices. That is, in the measurement and imaging apparatus according to the present invention, when the digital delay is performed by the reception delay, an error that depends on the clock frequency does not occur as in the analog delay unless a delay for beamforming is applied.

  In other words, an error determined by the clock frequency always occurs in the digital delay of transmission, so it is necessary to reduce the error by using a high clock frequency at a high cost, but this is not necessary in the digital delay of reception. . When a digital delay is used for the reception delay, the accuracy is not reduced, and the degree of freedom in setting the delay pattern is high. When an analog delay is used for the transmission delay, the accuracy and the clock frequency can be reduced. The analog delay can be changed in an analog manner or can be made digitally controllable and programmable. However, the analog delay has a lower degree of freedom than the digital delay, and in order to reduce the cost, the delay pattern mounted as an analog circuit may be used by switching or replaced by an appropriate one. If a high degree of freedom is required for setting the transmission delay pattern, it is necessary to operate the digital delay with a high clock.

  Hereinafter, a coherent signal generated by the beam forming itself of the present invention is referred to as an image signal. The effective receiving aperture elements and their positions are controlled similarly to the effective transmitting aperture elements (the details will be described later). Note that this digital beam forming is not always performed every time a received signal for one frame is stored. For example, the effective aperture width or a predetermined number other than that, or an input from the input device 40 or the like as appropriate. The number of received signals may be the number of hardware channels, such as the number of hardware channels to be set, or the number of received signals, which may be a programmable parameter (there are various input means as described above). Further, an image signal generated by partially beamforming may be combined into an image signal of one frame.

  In that case, the received signals processed at successive positions in the scanning direction may overlap, and when combining these received signals, simple superposition is performed (overlapping in the frequency domain). May be combined and inverse Fourier transformed), may be superimposed with appropriate weighting, or may simply be connected. The number of stored received signals can be confirmed in hardware or a control program by counting a trigger signal (command signal received from the control unit 34) for taking in the received signal. The command signal for starting the one-frame digital wave signal processing generated by the control unit 34 for each frame can be similarly confirmed, and the one-frame image signal is continuously generated appropriately.

  The maximum achievable frame rate depends on the form of beamforming to be performed, and is basically determined by the propagation speed of the wave. However, in actual applications, the time required to digitally calculate one frame of image signal is obtained. Decided. Therefore, it is useful to perform the above-described process of partially generating an image signal by parallel processing. In addition, as described above, the multi-directional aperture synthesis developed in the past by the inventor of the present application, generation of reception beams at a plurality of positions and reception beams in a plurality of directions for one transmission beam, and multi-focus It is useful to implement, and to perform them at high speed, it is useful to perform parallel processing. In any case, based on the above-described transmission and reception, a received signal for beamforming for one frame or partially may be stored, and digital wave signal processing according to the present invention described later in detail may be performed. Further, when an image signal cannot be generated in real time, the frame rate may be reduced, or the image signal may be processed off-line.

  The reception apodization is for weighting a reception signal in a reception channel of each aperture element, and may be variable in the range direction. It is not impossible to make it variable in an analog manner, but it is easy to make it digital. In a normal receiving unit, when performing phasing addition, it is performed at each position or each range position, and is often variable. Will be. On the other hand, non-variable apodization is rarely performed, but in such a case, apodization is performed when performing level adjustment by analog amplification or attenuation on the received signal generated by the aperture element.

  In a different meaning from apodization, at least the level calibration may be performed based on the calibration data of the conversion efficiency (conversion ability) of the drive signal of the aperture element into a wave, and at the same time, the apodization is performed at the same time as the level calibration. May be asked. The processing may be for the purpose, or the dynamic range of the waveform of the received analog signal may be nonlinearly expanded or compressed, and other analog devices such as nonlinear elements are used in each receiving channel. Sometimes. Analog devices used, including those amplifiers, may be programmable, and the setting method may take various forms. Like other parameters, they may be set directly using various input devices. Usually, the delay and the apodization are implemented in the same or different hierarchical levels in the receiving unit 32 in the same or different form, but usually in a phasing adder, the present invention Can be implemented in the digital signal processing unit 33 with a high degree of freedom.

  The receiving channel of each aperture element in the receiving effective aperture is switched through a switching device such as a shift register or a multiplexer, and the effective area at another position may be used to scan the region of interest while performing beamforming. Further, the delay value of the delay element may be variable, or the delay pattern (delay element group) may be switched. Further, steering in a plurality of directions may be performed in one effective opening, and steering may also be performed in a plurality of directions while appropriately changing an opening position and an effective opening width. In some cases, access time may be reduced by saving the device or storage medium. The effect of storing frequently used data in a small-sized memory that is easy to read and write is also great.

  In the present invention, the saving and the shortening of the access time are significant. The apodization element group forming the apodization pattern may be switched. The beam shape may be adjusted depending on the opening position, the range direction, and the steering direction. In detail, a receiving element having an apodization value of zero means that the receiving element is not active but is off, and the apodization also serves as a switch for the effective element and can determine the effective aperture width (apodization in the direction of the aperture element array). If the function is a rectangular window, the switch is on; otherwise, it is weighted on.) Therefore, the apodization element is at the same level as the switch.

Further, when the delay pattern or the apodization pattern includes a plurality of patterns or is programmable, the digital signal processing unit 33 in the apparatus main body 30 propagates the signal based on the response from the transmission target and the result of beamforming. Wave dispersion and spatial distribution of propagation velocity such as attenuation, scattering (forward scattering, back scattering, etc.), transmission, reflection, refraction, diffraction, impedance, or sound velocity in the process medium are calculated and transmitted from each aperture. The delay and intensity of the wave received at each aperture, the steering direction of the beam or wavefront, or the apodization pattern may be optimized. Instead of using the instantaneous frequency and instantaneous phase of the received wave for the transmitted wave such as a pulse wave, the frequency response of the characteristics of those media is to divide the frequency response of the received wave by the frequency response of the transmitted wave at each frequency. It is effective to perform an inverse Fourier transform on it to obtain the spatiotemporal distribution of the characteristics of the medium. At this time, as described in paragraphs 0363 and 0371, it is effective to correct the waveform distortion generated in the observation device (device) before processing. As in the case of the super-resolution using division, if the signal is divided by a small spectral component, noise is enhanced and a large error occurs, so that regularization, a Wiener filter, and the like are effective. Maximum likelihood estimation is also effective, and MAP (maximum a posteriori) may be used together. In addition, they may be integrated and fused. In some cases, echoes of the same location are acquired a plurality of times and their processing is performed. Similar to another super-resolution, conjugate multiplication of the frequency response may be effective instead of dividing by the frequency response. Various super-resolutions, including those super-resolutions, are also described herein. Even when the above instantaneous frequency or instantaneous phase is used, or when performing various other types of imaging (including, for example, a reflection method or a transmission method such as basic ordinary echo imaging), the observation apparatus (device) may be used. It is effective to perform processing after correcting the generated waveform distortion.
In addition, instead of the frequency response of the transmitted wave, the same transmitted wave is referred to as a reference substance (simple ones with uniform medium propagation characteristics such as irregular scatterer distribution, reflectors or scattering media provided at representative positions, etc.). For elaborate objects such as the body, it can offset the accumulation of changes in the wave spectrum caused by the characteristics of the medium during propagation of a homogeneous medium, such as frequency-dependent propagation speed, impedance, scattering, attenuation, etc. It is also effective to divide by the frequency response of the received wave obtained by applying it to the sample, make maximum likelihood estimation, or multiply the conjugate of the frequency response. (Which is an application of a linear system). It may produce diffraction.
The above calculation may be performed at once for the entire region of interest, or locally or locally depending on the spatial inhomogeneity of the point spread function represented by the propagation characteristics of the wave itself. (The former is easier to calculate). The latter local processing has a precedent (Non-Patent Documents 35 and 36) in super-resolution processing, and is a point observed locally for a reference substance (irregular distribution of scatterers, scatterers at a representative position, etc.). In some cases, division is performed using the frequency response of the spread function. In other super-resolution processes, it is equally effective to perform the process once for the entire region of interest or for each local region.

  In the classical aperture synthesis, all the receiving elements may include a receiving channel including the receiver 32a. Usually, the aperture synthesis is performed simultaneously with the reception apodization in the phasing adder. In the present invention, the aperture synthesis may be performed simultaneously with the reception apodization in the digital signal processing unit 33.

  In addition, the ultrasonic frequency and the bandwidth, the sign, the delay pattern, the apodization pattern, the analog device for the purpose of signal processing, the effective aperture width, the focus position, the steering direction, The number of times of transmission and reception required for performing beamforming is installed in various functional devices in the unit through various media such as a CD-ROM, a DVD, a floppy disk, or an MO. Sometimes.

  In some cases, the program can be started to select them interactively from the input device 40, or the user can directly input numerical values, select them on the operation panel of the input device 40, or delete a file in which data is recorded. There are various cases such as a case of setting by reading. It is also possible to determine them using a dip switch or the like. It may be due to unit replacement or switching. Further, when a measurement object is selected or a transducer to be used is mounted on the measurement imaging apparatus, the measurement imaging apparatus may recognize them and operate automatically under the recommended parameters. Subsequent adjustments are also possible. In addition, if a functional device of a normal receiving unit is mounted, an image obtained by using the measurement imaging apparatus of the present invention and a process including interpolation approximation through normal phasing and addition can be obtained as appropriate. It is possible to compare with an image image.

<Input device>
The input device 40 is used, for example, to set various parameter values as described above. The input device 40 itself includes various devices such as a keyboard, a mouse, a button, a panel switch, a touch command screen, a foot switch, and a trackball, but is not limited thereto. Install or upgrade the operating system (OS) or device software from a storage medium such as a general-purpose memory, USB memory, hard disk, flexible disk, CD-ROM, DVD-ROM, floppy disk, or MO, and upgrade various parameters. May set or update values. The input device 40 includes various devices that can read data from the storage medium, or the input device 40 includes an interface, and various devices are mounted and used as needed.

  The input device 40 is used not only for setting parameters of various operation modes of the measurement and imaging apparatus according to the present embodiment, but also for controlling and switching operation modes. If the operator is a human, those input devices 40 may be so-called man-machine interfaces, but are not always controlled by a human. As described above, parameter values, data, or control signals are received from other devices through various standards and connectors, or received through wired or wireless communication (ie, at least a communication device having a receiving function). The effect may be obtained, and the invention is not limited to the above example. A dedicated or regular network may be used.

  The input data is stored in an internal or external memory, storage device, or storage medium, and a functional device in the device operates with reference to the stored data. Alternatively, if the functional device in the apparatus is equipped with a dedicated memory, data is written to it and the operation setting is determined by software, or updated, or set by hardware, Or it may be changed. A calculation function in the device may be operated to calculate and use an optimized setting parameter based on the input data, sometimes considering the resource of the device. The operating mode may be determined by a command. In addition, the wave to be measured (wave type and characteristics, intensity, frequency, bandwidth, or code, wave source, diffraction, etc.) and the propagation target and medium (propagation speed, physical properties related to the wave, attenuation, forward Additional information on scattering, backscattering, transmission, reflection, refraction, diffraction, etc., or their frequency dispersion, etc. may be provided, and the received signal may be appropriately processed in an analog or digital manner.

<Output device>
A typical output device 50 is a display device. The display device not only displays a generated image signal, but also outputs various results measured based on the image signal as numerical values, images, and the like. Used to display. The image signal is converted (scan-converted) into an image display or moving image or still image format by a calculation process, but a graphic accelerator may be used in some cases. A luminance image (grayscale image) or a color image is displayed, and the meaning of the luminance or color may be displayed as a scale (bar) or a logo. In addition, the result may be displayed in a bird's-eye view or a graph, and the method of displaying the result is not limited thereto.

  When the result is displayed, various parameter values and patterns (names) when the operation mode is operating may be appropriately displayed simultaneously as logos or characters together with the operation modes. Further, supplementary information and various data on the measurement target input from the operator or another device may be displayed. The display device may be used to display a GUI (Graphical User Interface) used when setting each parameter value or pattern using the input device 40, and may use a touch command screen. It is also used when specifying an arbitrary position or an arbitrary range of the image to be drawn and displaying it in an enlarged manner, or when displaying various numerical values, and may serve as one end of the input device 40.

  As the display device, various devices such as a device using a CRT, a liquid crystal, or an LED are used. However, the display device is not limited thereto, for example, a dedicated three-dimensional display device is used. Further, the output data is not necessarily used directly by humans by interpretation and interpretation, and the apparatus body (computer) understands the output data based on predetermined calibration data and calculations and displays the result. Sometimes (for example, the composition or structure of the measurement target is understood from the spectrum analysis of the received signal), the output data is output to another device and interpreted by another device, and furthermore, the same device (for example, a robot, etc.) Or another device may apply the output data.

  One device receives a plurality of types of waves to generate an image signal, and data mining and fusion may be performed, or another type of processing may be performed using another device. is there. The characteristics (intensity, frequency, bandwidth, sign, etc.) of the generated image signal may be analyzed. As described above, data obtained by the measurement imaging apparatus according to the present embodiment may be used in another apparatus, and a communication apparatus having at least a transmission function may be one of the output apparatuses 50. is there. A dedicated or regular network may be used.

<Storage device>
The generated image signal and various results (numerical values, images, and the like) measured based on the image signal are stored in an internal or external memory, storage device, or storage medium that also serves as the output device 50. Here, they are referred to as “storage devices” and are distinguished from display devices. FIG. 2 and the like also show an external storage device 60. When the image signal is stored, an operation mode, a setting parameter value, supplementary information on a target input from an operator or another device, or various data may be stored together with the image signal. As the storage device, a general-purpose or special memory, a USB memory, a hard disk, a flexible disk, a CD-R (W), a DVD-R (W), a video recorder, an image data capturing device, or the like is used. The device is not limited to them. The storage device is appropriately used in accordance with its application, including the amount of data to be stored, writing and reading times, and the like.

  The image signals and other data stored in the past may be read out from the storage device and played back. It is. Each functional device may have a dedicated storage device. Removable storage devices may be used in other devices.

  The apparatus main body 30 reads out the image signal stored in the storage device, performs high-order digital signal processing, and re-combines the image signal (frequency modulation or widening of the band by linear processing or non-linear processing, or multi-focus). Performs various measurements such as image processing (super-resolution, enhancement, smoothing, separation, extraction, or CG conversion) of an image signal, displacement or deformation of an object, or various other time changes, and the like. The measurement results may be output, and may be displayed on the display device.

  Also, the stored measurement results include the wave itself, attenuation and scattering of the wave (forward scattering, back scattering, etc.), transmission, reflection, refraction, diffraction, etc., which are read out and used to read the image signal. It is used for optimizing various parameters to be generated, and may be stored in a storage device and used. The optimization is performed by a calculation function provided in the control unit 34 or the digital signal processing unit 33.

<Control unit>
The control unit 34 controls the operation of the entire device. The control unit 34 is composed of various computers, dedicated digital circuits, and the like, and may also serve as the digital signal processing unit 33. Basically, the control unit 34 performs wave transmission / reception and wave digital signal processing based on various control programs and various data read from the storage device in response to various requests input via the input device 40. The transmitting unit 31, the receiving unit 32, and the digital signal processing unit 33 are controlled to generate an image signal.

  When the control unit 34 is configured by a dedicated digital circuit, the parameters may be variable, but there may be cases where only a fixed operation can be realized, including the case where the operation is switched by switching. When a computer is used as the control unit 34, the degree of freedom is high, including the case of version upgrade. The basics of the control unit 34 are the number of aperture elements for transmission and reception (the number of channels for each), the number of beams to be generated, the number of frames (some continue to operate unless stopped unless specified), frame rate, etc. According to the above, the scanning control and the generation control of the image signal are performed by providing the repetition frequency and the transmission / reception position information to the transmission unit 31 and the reception unit 32 in order to realize the various operations described above. Is also controlled. In addition, various interfaces are provided, and various devices may be used in conjunction with each other.

  The measurement imaging apparatus according to the present embodiment may be used as one of devices such as a general network and a sensor network, may be controlled by a control device of a network system, and may control a network device. It may be used as a control device that controls the network configured locally, or may be a control device that controls a locally configured network. An interface for that purpose may be provided.

<Beam forming method>
Next, useful high-speed processing through digital Fourier transform in the case of using a plurality of transmitting / receiving aperture elements (including those arranged in an array) implemented in the digital signal processing unit 33 of the apparatus main body 30 shown in FIG. The digital beam forming method will be described. In digital signal processing, intermediate data generated in the calculation process and data used repeatedly may be stored in a storage device or an attached memory as appropriate, and when a plurality of image signals are generated in the same phase, Also, the storage device is used efficiently. Small-sized memory can be useful.

  The generated image signal may be displayed as a moving image or a still image on an output device 50 such as a display device, or may be stored in an external storage device 60 using a recording medium such as a hard disk. In the case where the digital signal processing unit 33 is a computer, various languages can be used and the assembler is useful. In, optimization and parallel processing may be performed at the time of compilation to realize high-speed operation. A general-purpose device such as Matlab, various control software, or a device equipped with a graphic interface may be used, or a special device may be used.

  Hereinafter, as an example, a description will be given of a beam forming method used in the measurement imaging apparatus of the present invention through a case where a wave is an ultrasonic wave. The beamforming methods that can be used in the present embodiment are the following methods (1) to (7). In the method (7), the beamforming method is generated in the digital signal processing unit 33 in addition to various beamforming methods. We disclose representative observation data.

  The method (1) is an interpolation which has been required so far in performing wave number matching in Fourier space in reception beamforming at the time of transmission and / or reception of a plane wave including deflection (steering) of the transmission direction. This method does not require approximation processing. The method (1) is an invention in which wave number matching in the depth direction and the horizontal direction is performed by multiplying a received signal by dividing a complex exponential function relating to the cosine and sine of a deflection angle in wave number matching in the case of performing deflection. The accuracy of the measurement result is improved as in the case of the classic monostatic type aperture synthesis. Further, as a method (2), a high-speed digital processing of deflection dynamic focusing by monostatic aperture synthesis is disclosed.

  Furthermore, as a method (3), a high-speed digital processing of multi-static aperture synthesis is disclosed. In the digital monostatic aperture synthesis that performs deflection, the center of gravity (center) or instantaneous frequency of a multidimensional spectrum of a generated image signal is ideally represented using a deflection angle and a carrier frequency (described later). As described above, the wave number matching is performed in the same manner as in the method (1) so that the wave number vector becomes the carrier frequency multiplied by the sine and cosine of the deflection angle. Can be realized with high accuracy. On the other hand, the multi-static aperture plane synthesis generates echo data frames including echo signals received at the same position among a plurality of reception positions with respect to the transmission position, the number of which is equal to the number of reception elements, and in the frequency domain, each echo data frame is generated. The data frame is subjected to the above-described monostatic type digital aperture plane synthesis processing, and a result obtained by superimposing the processing results is inversely Fourier-transformed to achieve high precision. As a result, in the method (3), echo data can be generated by the digital aperture plane synthesizing process as many times as the number of channels of the receiving aperture. It is much faster than the conventional DAS (Delay and Summation) method of generating frames.

  Incidentally, the DAS method includes a method in which phasing is applied to a received signal at high speed (delay) with interpolation approximation processing in a spatial domain, and a method in which a delay (delay) is applied with high precision in a frequency domain ( (The past results of the inventor of the present application), and sums received signals in the spatial domain. The former has a high speed but low accuracy, and the latter has a high accuracy but extremely low speed.

  As a method (4), a method of performing digital dynamic focus reception at the time of fixed transmission focus with high accuracy based on the beamforming of the method (1) or the method (3) is disclosed. As method (5), echo data transmitted and received in the polar coordinate system is processed through Jacobi calculation for application to convex and sector scan or IVUS, and displayed with high accuracy without interpolation approximation processing. It discloses that echo data can be generated directly in the Cartesian coordinate system of the system.

  Also, as a method (6), it is disclosed that migration processing can be performed with high accuracy and high speed without similarly performing interpolation approximation processing by using the present invention. All beam forming processes of the methods (1) to (5) can be performed based on the migration process. Finally, we disclose these beamforming based applications as method (7). Thus, it can be demonstrated that any beam forming based on focusing and steering can be performed.

Method (1): Beam forming of plane wave transmission and / or plane wave reception (i) Echo signal (image signal) during plane wave transmission
FIG. 5 is a schematic diagram of the transmission of a polarized plane wave. Plane wave transmission is a method of simultaneously radiating ultrasonic waves from all elements in a linear array type transducer to radiate a plane wave. When the wave number is k and a plane wave of the wave number vector represented by the equation (0) is transmitted (x is the scanning direction, y is the depth direction, and the position of the receiving effective aperture element array is set to zero on the y coordinate. , The sound pressure field at the position (x, y) is represented by equation (1).

Here, A (k) is the frequency spectrum of the transmitted pulse, and has the relationship of equation (2).

When there is a scatterer having a reflection coefficient f (x, _yi ) at a depth y = _yi , an echo signal from this scatterer is represented by Expression (3).
The angular spectrum of this equation is represented by equation (4).

Assuming that the frequency response of the probe is T (k), based on the principle of the angular spectrum, the angular spectrum at the aperture plane (y = 0) of the echo signal from the depth y = y _i is expressed by Expression (5). Is done.

Therefore, by adding the angular spectra from the respective depths, the angular spectrum of the echo signal represented by the equation (6) is obtained.

Therefore, by performing wave number matching as Expressions (7) and (8), the echo signal (image signal) can be expressed as Expression (9) by the inverse Fourier transform.

  Considering transmit and receive in reverse, any transmit beamforming (eg, deflected plane wave, deflected fixed focusing beam, steering dynamic focusing based on aperture synthesis, undeflected wave or beam, etc.) Is performed on the object to be measured, it is possible to realize a situation in which the wave arriving from the object to be measured is received as a plane wave having a deflection angle θ (including the case where the angle is zero degree). This idea has not been disclosed before. Considering this, it is possible to receive waves at the same or different steering angles θ (zero or non-zero) when transmitting any beam or any wave at any steering angle (zero or non-zero). . Furthermore, any wave source, any transmission effective aperture array (for example, one having the same shape as the reception effective aperture array or having an arbitrary shape in a different shape from the reception effective aperture array and having an aperture in any direction, or one existing at another position) Or, for any wave transmitted from the same physical aperture but from a different effective aperture), receive beamforming can be performed in a coordinate system defined by the receive aperture.

  When the plane wave is transmitted, the steering is physically performed at the deflection angle α (including zero degree), and the steering at the deflection angle θ (including zero degree) in the method (1) is performed in a soft manner. Then, the plane wave is steered at the deflection angle (α + θ) (the transmission deflection angle finally generated is the average thereof). This soft steering (deflection angle θ) can be considered to reinforce the physical transmission steering (deflection angle α), or to purely realize the steering of plane wave transmission as software, It can be considered that the reception steering is performed by the plane wave.

  In the method (1), the plane wave is steered at the physical deflection angle α or the soft deflection angle θ or both the deflection angles α + θ during transmission, and dynamic focusing is performed at the steering angle φ during reception. In this case, the soft steering described in the method (2) may be performed, which will be described later (the finally generated deflection angle is an average of the transmission deflection angle and the reception deflection angle). In this case, the soft steering (deflection angle θ) can be considered to reinforce the physical transmission steering (deflection angle α) or to realize pure steering of the plane wave transmission by software. However, in addition to the dynamic reception focusing (including the case where the deflection angle φ is zero degree), it can be considered that the reception steering is performed by a plane wave in a software manner.

  In these cases, soft transmission and reception can be considered in reverse. The processing is the same (equivalent) even if the soft deflection plane wave transmission (including the case where the deflection angle is zero degree) and the reception deflection dynamic focusing (including the case where the deflection angle is zero degree) are exchanged. It is also possible to interpret that a signal generated by transmission beamforming is physically received by a deflection plane wave (including a case where the deflection angle is zero degree) and beamformed. Normally, it is not reasonable to physically perform transmission dynamic focusing regardless of the presence or absence of deflection, but it can also be interpreted as physically receiving a polarized plane wave.

  In addition, any transmit beamforming (eg, deflected plane wave, deflected fixed focusing beam, steering dynamic focusing based on aperture synthesis, undeflected wave or beam, etc.) is performed using this method. it can. That is, by the same processing using a plane wave for transmission, it is possible to handle an arbitrary wave or beam (for example, the above example) generated physically by beamforming. That is, no matter what kind of transmission is performed, reception beamforming (such as dynamic focusing) can be performed. It can be processed at once when a plurality of transmissions are performed. Further, in addition to the transmission deflection angle (including the case where the steering angle is zero degree), it is possible to perform the steering of the plane wave or the dynamic focusing (including the case where the steering angle is zero degree) in transmission or reception in software. (The resulting deflection angle is the average of the transmission deflection angle and the reception deflection angle). As described above, transmission and reception can be considered in reverse, and various combinations of beamforming are possible. Beamforming is performed in each of transmission and reception, and plane wave processing may be performed for both transmission and reception by software. The same applies to three-dimensional beam forming using a two-dimensional array described later.

The calculation method disclosed by J.-y. Lu et al. (Non-Patent Documents 3 and 4) first performs a high-speed two-dimensional Fourier transform on a received signal in time and space based on the above theory, and obtains R (k _x , k) is calculated, and then wave number matching is performed according to equation (7), and high-speed two-dimensional inverse Fourier transform is performed (also described in paragraph 0354). Wave number matching is performed through linear interpolation approximation or approximation using the nearest data itself, and oversampling of a received signal is required to obtain accuracy. A higher-order interpolation approximation may be performed, or a sinc function may be used. In the case of three-dimensional, similarly, fast three-dimensional Fourier transform and fast three-dimensional inverse Fourier transform are used. One feature of the present invention is that wave number matching is performed without performing interpolation approximation. However, as described in paragraphs 0192 to 0196, when the present invention is applied to various beamformings, interpolation approximation processing is performed to perform high-speed approximation. Another feature is that a solution may be found.

(Ii) Calculation procedure of echo signal (image signal) at the time of transmission and / or reception of a plane wave according to the present invention Hereinafter, the case of transmitting and / or receiving a plane wave having a deflection angle θ will be described. In the present invention, wave number matching is firstly performed in the horizontal direction by multiplying a complex exponential function (Equation (9a)) before the Fourier transform of the received signal in the space (lateral direction), and is performed in the depth y direction. Is multiplied by a complex exponential function (equation (9b)) excluding the above-described horizontal matching processing so as to have a resolution in the depth y direction, and simultaneously by a complex exponential function (equation (9c)). . Of course, the deflection angle θ can be used not only at non-zero degrees but also at zero degrees. This processing is not disclosed in the prior art document.

FIG. 6 is a flowchart showing digital signal processing at the time of transmitting a polarized plane wave. The calculation procedure is as follows. First, in Step S11, as shown in Expression (10), the received signal is Fourier-transformed with respect to time t (FFT is preferable).
However, when ω is the angular frequency (angular frequency) and c is the speed of sound, the wave number k = ω / c. Thus, an analysis signal is obtained. Here, in accordance with the above description, a process in which the sign of the core of the complex exponential function is positive is shown as the Fourier transform, but the sign of the kernel of the complex exponential function is calculated as negative as in the normal Fourier transform. It is also possible. In any case, in the inverse Fourier transform to be calculated later, a complex exponential function whose sign is opposite to that of the Fourier transform is always used (that is, the first and last conversion processes are performed when the sign of the core of the complex exponential function is reversed). It is sufficient that the inverse Fourier transform is generally performed first, and then the Fourier transform generally performed last, and the order may be reversed. The same applies to the other methods (2) to (7).

Next, in step S12, a matching process is performed on the wave number k _x for deflection, and equation (10) is multiplied by equation (11). In step S13, the received signal is Fourier transformed (FFT Good), the equation (12) is obtained. For calculating the product of the result (10) of the fast Fourier transform with respect to time t and the complex exponential function (11), a dedicated fast Fourier transform that directly generates the calculation result is useful.
Incidentally, the result of Expression (12) can also be obtained by direct calculation.

The received signal is decomposed into a plane wave component by the two Fourier transforms. As described above, the angular spectrum formed by each plane wave at an arbitrary depth y is obtained by multiplying the expression (13) and shifting the phase.

Further, in step S14, a matching process is simultaneously performed on the wave number ky by simultaneously multiplying the expression (14).

In step S15, an angular spectrum at each depth y is calculated. That is, Expression (16) is obtained by multiplying Expression (15).

The sound pressure field created by each plane wave component at the depth y is obtained as Expression (17) by performing an inverse Fourier transform (IFFT) on the horizontal direction x.
By adding this to a plurality of wave number k components (or frequency components), an image signal is obtained.
Here, the order of integration of the wave number k (or frequency) and the spatial frequency kx can be interchanged. Therefore, adding the wavenumber k component of the angular spectrum in step S16, even if the inverse Fourier transform with respect to the transverse direction of the wave number _{k x} a (IFFT) in step S17, the image signal is obtained in step S18. In this case, calculation can be performed by one inverse Fourier transform, and the calculation is faster. The same applies to other methods (1) to (6). Matching of wave numbers for deflection is performed by Expressions (11) and (14). Unlike the method of wave number matching through interpolation approximation in the frequency domain (Non-Patent Documents 3 and 4), the present invention does not perform approximation processing, and therefore can calculate with high accuracy.

Physically and mathematically, wave number matching can be performed at the time of the first Fourier transform, and wave number matching can be performed at the time of the last inverse Fourier transform. The same applies to other methods (1) to (6). As described in paragraph 0199, in accordance with the above description, a process in which the sign of the core of the complex exponential function is positive is shown as the Fourier transform, but the sign of the core of the complex exponential function is negative as in the ordinary Fourier transform. It is also possible to calculate. In any case, in the inverse Fourier transform to be calculated later, a complex exponential function whose sign is opposite to that of the first Fourier transform is always used (that is, the first and last transform processes are performed by using the sign of the core of the complex exponential function). Can be reversed, and the inverse Fourier transform can be performed first and then generally performed and the order can be reversed. First, when performing wave number matching in the first Fourier transform, the received signal r (x, y) (here, unlike equation (10), the propagation time t of the wave is different) in order to realize equation (8). (Where the depth distance y is used instead), Equation (11) is used to perform the Fourier transform in the lateral direction x as shown in Equation (12), and Equation (13) is used for the Fourier transform in the depth direction y. ) And Expression (15) expressed by Expression (14), but since wave number matching is performed simultaneously in two directions, correction of ksinθ is not necessary in Expression (15).
(Generally the result of applying the inverse Fourier transform). When the deflection angle θ is 0 degree, first, a one-dimensional Fourier transform may be performed in the horizontal direction x, and the fast Fourier transform is effective (when calculation is performed as in the above equation, a general method is used). To perform the inverse Fourier transform.) Then, in order to perform a Fourier transform on the calculated R '(kx, y) in the depth direction y and perform wave number matching,
And one-dimensional processing. It is faster than calculating each R '(kx, ky) according to equation (16'). Finally, two-dimensional inverse Fourier transform in the x and y directions is performed on equation (16 ′) or equation (16 ″), and an image signal f (x, y) is obtained. One-dimensional inverse Fourier transform may be performed in each of the x direction and y direction, and fast inverse Fourier transform is effective. (When calculated as in the above equation, it is generally necessary to perform two-dimensional inverse Fourier transform. become).
Conversely, when performing wave number matching in the last inverse Fourier transform, first, a two-dimensional Fourier transform is performed on the received signal r (x, y) to obtain R (kx, k), and finally In order to realize the formula (8) in the inverse Fourier transform of the following equation, the formula (11) is used in the inverse Fourier transform in the horizontal direction x, and the equations (13) and (14) are used in the inverse Fourier transform in the depth direction y. However, since wave number matching is performed in two directions at the same time, no correction of ksinθ is required in equation (15), and the image signal is
Is obtained. When the deflection angle θ is 0 degree, first, in order to perform inverse Fourier transform in the depth direction y and perform wave number matching,
Then, a one-dimensional inverse Fourier transform may be performed in the horizontal direction x, and a high-speed inverse Fourier transform is effective. It is faster than calculating each f (x, y) according to equation (16 ″ ′).
Further, in these, in the wave number matching, the expressions (11) and (14) are subjected to frequency modulation with respect to kx and ky which are multiplied by a spatio-temporal signal using their complex exponential functions instead. It may be added. In this case, first, it is sufficient to perform one-dimensional conversion in the horizontal direction x, and high-speed conversion is effective. Next, by performing one-dimensional processing using Expression (13), wave number matching is performed together with conversion in the depth direction y. It just needs to be applied, and it can speed up.
The same applies to the three-dimensional case, and the three-dimensional Fourier transform and the three-dimensional inverse Fourier transform may be performed. The same applies to other methods (1) to (6).

In addition, an arbitrary wave is transmitted from a wave source located in an arbitrary direction toward a measurement object using a two-dimensional aperture element array, and a wave arriving from the measurement object is received as a plane wave to generate a three-dimensional wave. In the case of performing digital signal processing, for example, a Cartesian rectangular coordinate system (x, y, z) using the coordinates of the axial direction y determined by the direction of the aperture of the flat receiving aperture element array and the horizontal directions x and z orthogonal thereto. )), When the zero-degree or non-zero-degree deflection angle formed by the direction of reception as a plane wave and the axial direction is expressed using the elevation angle θ and the azimuth angle φ, the Fourier transform is performed in the depth y direction and the lateral directions x and z. The three-dimensional Fourier transform of the received signal is performed in the same manner as in the case of performing the two-dimensional wave digital signal processing described above, with respect to the three-dimensional Fourier transform R ′ (k _x , k, k _z ) of the received signal.
Is performed without interpolation approximation as follows. As described in paragraphs 0192 to 0196, as in the two-dimensional case, wave number matching is performed by performing interpolation approximation processing in accordance with Equations (7 ′) and (8 ′), as described in paragraphs 0192 to 0196. There be performed in, in which case _{the, F (k x ', k} y', k z ') are three-dimensional inverse Fourier transform.

When the interpolation approximation processing is not performed in the wave number matching, first, a complex exponential function (C21) represented by using the wave number k of the wave and the imaginary unit i is multiplied by the Fourier transform of the received signal in the axial direction y. Perform wave number matching on the lateral x and z,
Further, the product can be implemented on an angular spectrum obtained by performing a Fourier transform on the lateral directions x and z so as to have a resolution in the axial direction y, excluding the effect of the wave number matching performed on the lateral directions x and z. At the same time as multiplying the complex exponential function (C22), the wave number matching in the axial direction is performed by multiplying the complex exponential function (C23), where the wave numbers in the horizontal direction are represented by k _x and k _z ,
By performing wave number matching without performing interpolation approximation processing, an image signal can be directly generated in a Cartesian coordinate system. That is, the sound pressure field created by each plane wave component at the depth y is subjected to a two-dimensional inverse Fourier transform (IFFT) in the horizontal direction x and z, and a plurality of wave number k components (or frequency components) are added. As a result, an image signal is obtained. Of course, it can be used when the deflection angle is zero degree (that is, the elevation angle θ and the azimuth angle φ are zero degree) or when at least one of the angles is zero degree.

  In the above calculation, only the signal component in the band determined by the transmission signal or in the band determined in consideration of the SN ratio of the reception signal is to be calculated. For example, when generating an analytic signal based on Equation (10), only a signal within a required band may be generated and stored (corresponding to downsampling). In the method or apparatus of the present invention, interpolation approximation processing is not performed when performing wave number matching.However, by oversampling the echo signal in the depth direction or the horizontal direction, an effect of being robust against mixed noise can be obtained. is there. The same applies to the other methods (1) to (6).

  In addition, in Expressions (13) to (15), Expressions (C22), and Expression (C23), the position coordinate and range in the depth y direction to be calculated, the interval between the coordinates, and the like are determined, so that an arbitrary depth position or An image signal in an arbitrary depth range or at an arbitrary interval or an arbitrary density in the depth direction can be generated without performing interpolation approximation processing (with or without downsampling described in the preceding paragraph). The down-sampling is effective as long as the Nyquist theorem is satisfied, except that high-frequency signal components may be intentionally processed out of band (filtering out). Regardless of the presence or absence of downsampling, downsampling is possible as long as the Nyquist theorem is satisfied). Further, in the inverse Fourier transform in the horizontal direction such as Expression (17), by determining the position coordinates and the range in the horizontal x direction to be calculated (if necessary, the complex exponential function of the inventor's past invention Analog space shifting by phase rotation using multiplication), an image signal at an arbitrary horizontal position or an arbitrary horizontal range can be generated without performing interpolation approximation processing, and the same inverse Fourier transform can be performed. In the conversion, a band is narrowed in the horizontal direction except for the frequency coordinates of the high frequency band (spatial density reduction), or a band is widened in the horizontal direction by zero-fill processing of the angular spectrum (spatial density increase). Thus, image signals having arbitrary intervals and arbitrary densities in the horizontal direction can be generated without performing interpolation approximation. Of course, the raw received signal before processing needs to secure bands in all directions based on the Nyquist theorem. The band in the horizontal direction and the elevation direction determined by the wave frequency and the array element is also important.

  In this manner, an image signal can be generated at any desired position, range, interval, and density. That is, the image signal can be generated at an interval shorter than the sampling interval of the reception signal and shorter than the interval between the reception aperture elements. In each direction, the interval between image signals can be made coarse (however, the Nyquist theorem must be satisfied). Similarly to the two-dimensional case (paragraph 0205), wave number matching can be performed physically and mathematically at the time of the first Fourier transform, and wave number matching can be performed at the time of the last inverse Fourier transform. It is possible. When steering is not performed, similarly, in the conversion processing involving wave number matching, the conversion processing can be performed first in the horizontal x direction or the z direction, and finally the conversion processing in the depth direction y can be performed, and the speed can be increased. . Further, in these, in the wave number matching, the expression (C21) and the expression (C23) are replaced by performing frequency modulation for multiplying by a spatio-temporal signal using their complex exponential functions and adding them. good. In this case, first, one-dimensional conversion may be performed in the horizontal x or z direction, and high-speed conversion is effective. Next, conversion in the depth direction y is performed using equation (C22), and the wave number is converted. What is necessary is just to perform the matching, and the speed can be increased. In order to increase the accuracy when performing wave number matching through interpolation approximation according to Equations (7) and (8) or Equations (7 ′) and (8 ′), at the cost of an increase in the amount of calculation, It needs to be processed under proper oversampling. In such a case, it is necessary to pay attention to an increase in the number of data of the Fourier transform, unlike a case where a signal at an arbitrary position can be selectively generated without performing the interpolation approximation processing. The same applies to the other methods (1) to (6).

  In a convex type transducer, sector scan, or IVUS, when transmitting or receiving in the radius r direction of polar coordinates to generate a wide wave (cylindrical wave) in the angle θ direction (FIG. 7), or in other aperture shapes, When performing the same beam forming (cylindrical wave) using a virtual source installed behind (see FIGS. 8A (a) to 8 (c), Patent Document 7 and Non-Patent Document 8, etc.), The processing may be performed by replacing the Cartesian coordinates (x, y) with polar coordinates (r, θ), and an image signal can be generated at the polar coordinates (r, θ). The same applies to a spherical wave in a spherical coordinate system. 8B (d) to 8 (f), transmission or reception at an arbitrary distance position using a physical aperture element array represented by a polar coordinate system or a physical aperture having an arbitrary aperture shape as described above. Alternatively, both plane waves may be generated, and beamforming may be performed in the same manner. This is equivalent to generating a virtual linear aperture array (or plane wave) at that distance position. If the distance position is set to zero, this corresponds to a case where a linear aperture array is virtually used. The distance position can be set not only in front of the physical aperture but also behind it, and a virtual linear aperture array (or plane wave) can be generated at those locations. The virtual linear aperture array may be used not as a virtual source but as a virtual receiver, and may also serve as a virtual source.

  FIG. 7 is a schematic diagram of a case where a wave that is wide in the direction of the angle θ is transmitted or received in the direction of the radius r in polar coordinates (r, θ) (cylindrical wave transmission). FIG. 7A shows cylindrical wave transmission using a convex type aperture element array, and FIG. 7B shows cylindrical wave transmission using a sector type aperture element array. (C) shows cylindrical wave transmission using an IVUS (circular) aperture element array. In FIG. 7B, an arc-shaped opening is shown. A sector having a flat opening may be used for the sector scan. Also, these apertures may be used to generate a focus beam.

  FIG. 8A shows a case where a wide wave is transmitted in the direction of an angle θ of a polar coordinate system (r, θ) in the direction of a radius r using a virtual source installed behind a physical aperture having an arbitrary opening shape (cylindrical wave transmission). FIG. FIG. 8A (a) shows a cylindrical wave transmission using a linear type aperture element array, and FIG. 8A (b) shows a cylindrical wave transmission using a convex type aperture element array. (C) shows a cylindrical wave transmission using another arbitrary aperture element array. Receiving may be performed similarly. 8B (d) to 8 (f) show a case where a transmission plane wave is generated at an arbitrary distance position using a physical aperture element array represented by a polar coordinate system or a physical aperture having an arbitrary aperture shape. (In the figure, a convex type aperture element array is physically used). Assuming that the distance position is zero, this corresponds to a case where a linear aperture array is used virtually (FIG. 8B (d)). The distance position can be set not only behind the physical aperture (FIG. 8B (e)) but also in front (FIG. 8B (f)), and a virtual linear aperture array (or plane wave) is generated at those positions. You can also. Receiving may be performed similarly. FIG. 8B (g) shows a special case where, for example, when a linear array transducer is physically used, a case where a cylindrical wave is generated using a virtual source behind a physical aperture is applied. FIG. 7 is a schematic diagram of a case where a plane wave or a virtually linear array type transducer that is spread in a lateral direction is generated. Receiving may be performed similarly. A virtual linear array transducer may be used as a virtual receiver instead of a virtual source, or may serve as a virtual source.

  Non-patent document 6 reports the case of transmission focusing, and similarly, a result is obtained at polar coordinates (r, θ). For example, there is an effect that a wide FOV can be obtained. As a method different from Non-Patent Document 6, as one feature of the present invention, the present method (1) is used for them, and further, a steering having a steering angle even at the coordinate position of these polar coordinate systems (r, θ). A beam can be generated, and the same applies to the following methods (2) to (4) and (6) in which the Cartesian coordinates (x, y) are converted to the polar coordinates (r, θ). Should be read and processed. However, when these beamformings are performed, it is necessary to perform an interpolation process in order to obtain a signal value at the coordinate position of the display system in the Cartesian coordinate system. The strict interpolation process used is performed over time, or the interpolation approximation process is performed as a short-time process involving an approximation error. The same applies to spherical coordinates.

  In these cases in which beamforming is performed in a polar coordinate system, displacement measurement can also be performed, for example, measurement of a displacement component in the radius r direction or angle θ direction can be performed, or a displacement component in both directions can be measured. The displacement vector can be measured. However, it is necessary to perform interpolation processing to obtain the measurement result at the coordinate position of the Cartesian coordinate system of the display system after the measurement, and the phase rotation by the product of the complex exponential function in the frequency domain is performed as in the case of the interpolation of the echo signal. The strict interpolation processing used is performed over time, or the interpolation approximation processing is performed as a short-time processing involving an approximation error. The same applies to the spherical coordinate system.

  From the results of the displacement measurement, strain, strain rate (tensor), speed (vector), acceleration (vector) are obtained by partial differential processing using a differential filter, and furthermore, mechanical properties (for example, bulk modulus and The shear modulus (for example, Non-Patent Document 7), the elastic modulus tensor of an anisotropic medium, and the like, the temperature, and the like may be obtained through calculation. When performing interpolation approximation, it is often possible to shorten the calculation time by performing approximation processing and performing those calculations in the Cartesian coordinate system.However, the calculation is performed in the polar coordinate system, the result is obtained, and the interpolation approximation is performed. In this case, the error propagation can be reduced. That is, the only error that occurs in the processing process after the displacement measurement is interpolation approximation when obtaining the last display data (a plurality of display data may be obtained from the same displacement data).

  As described above, it is also possible to represent the echo signal in the Cartesian coordinate system and perform displacement measurement and a series of measurements through the interpolation processing. An error occurs when the approximation process is performed in the interpolation process, but the amount of calculation required for the entire process is small. Even when performing measurement based on processing of other echo signals, the processing can be performed as described above. The same applies to three-dimensional beam forming using a two-dimensional array.

  In addition, in any of the above, similar processing can be performed for an arbitrary rectangular coordinate system other than the polar coordinate system.

  On the other hand, similarly, in a convex-type transducer, sector scan, or IVUS, a wave that is wide in the angle θ direction in polar coordinates (r, θ) is transmitted or received (cylindrical wave) in the radius r direction (FIG. 7). And a wave that is wide in the angle θ direction of the same polar coordinate system (r, θ) as in FIG. 7 and is transmitted in the radius r direction (cylindrical wave) using a virtual source installed behind a physical aperture having an arbitrary aperture shape. (See FIGS. 8A to 8C), the method of directly generating an image signal in Cartesian coordinates is method (5), method (5-1), and method (5-1 ′), respectively. ). Further, using a physical aperture element array represented by a polar coordinate system as described above or a physical aperture having an arbitrary aperture shape, at an arbitrary distance position, transmitting or receiving, or generating a plane wave of both, and similarly emitting a beam. Forming may be performed, and an image signal may be generated in a Cartesian coordinate system (see FIG. 8B (d) to (f)). This is equivalent to generating a virtual linear aperture array (or plane wave) at that distance position. If the distance position is set to zero, this corresponds to a case where a linear aperture array is virtually used. The distance position can be set not only behind the physical aperture but also in front of it, and a virtual linear aperture array (or plane wave) can be generated at those locations. The virtual linear aperture array may be used not as a virtual source but as a virtual receiver, and may also serve as a virtual source. Similarly, beamforming methods are described as method (5) and methods (5-1), (5-1 ′), and so on. In these cases, imaging of echo signals and displacement measurement can be performed consistently in the same Cartesian coordinate system. The same applies to the polar coordinate system. In such a case, it is also possible to convert the echo signal or the measured value from the Cartesian coordinate system to the polar coordinate system through interpolation processing. The same applies to three-dimensional beam forming using a two-dimensional array. Transmission focusing may be performed.

  In addition, in any of the above, similar processing can be performed for an arbitrary rectangular coordinate system other than the polar coordinate system. Further, as described above, the virtual source and the virtual receiver are not always installed behind the physical aperture, and may be installed in front of the aperture, and may be installed arbitrarily regardless of the shape of the physical aperture. (Patent Document 7, Non-Patent Document 8). Thus, the present invention is not limited to the above. In wave number matching in these beamformings, an interpolation approximation process may be performed to quickly obtain an approximate solution. In addition, any of the methods (1) to (7) may be similarly processed.

  In the methods (1) to (7), transmission or reception, or both apodization processes for a received signal can be performed at various timings because the process is a linear process. That is, it can be performed by hardware at the time of reception, or can be performed at various timings by software after reception. As described above, physical apodization may be performed at the time of transmission (the same applies hereinafter).

  As a matter of course, when beamforming is performed by receiving a transmitted wave instead of an echo signal, the coordinate y is half the reciprocating distance (expressed as ct / 2 using the propagation time t). Instead, it is the distance (ct) from the aperture element in the coordinate system determined by the reception aperture element array.

Next, the case where the aperture surfaces are synthesized will be described. There are a monostatic type and a multi-static type in the aperture surface synthesis.
Method (2): Monostatic Opening Surface Synthesis FIG. 9 is a schematic diagram of monostatic opening surface synthesis. In the monostatic aperture synthesis, an ultrasonic wave is emitted from one element of an array, and the element itself receives an echo. Also in the aperture plane synthesis, an echo signal (image signal) can be calculated by performing wave number matching in the procedure of FIG.

Since transmission and reception are performed by the same element in the monostatic aperture synthesis, the propagation path of the sound to the scatterer during transmission is the same as the propagation path of the reflected sound of the scatterer during reception. Therefore, when steering is not performed (θ is zero degree) in the Cartesian orthogonal coordinate system where the position of the reception effective aperture element array is zero in the axial y-coordinate, the wave number k is doubled as shown in Expression (18a). (In the case of a reflected wave, s = 2, the same applies hereinafter), and the matching of the wave numbers represented by Expressions (7) and (8) is performed. In the case of a transmitted wave, k is used instead of wave number 2k (s = 1, the same applies hereinafter).

When the steering angle θ is non-zero, the wave number vector (0, k ₀ ) having the wave number k ₀ (= ω ₀ / c) expressed using the carrier frequency ω ₀ of the ultrasonic signal is Beamforming for shifting the spectrum is performed to generate an image signal having the vector (sk ₀ sin θ, sk ₀ cos θ) as the center of gravity or the instantaneous frequency of the multidimensional spectrum (see FIG. 10). That is, wave number matching represented by Expression (18b) is performed in Expressions (7) and (8).

The signal processing is performed in the same manner as in the method (1). In particular, the wave number matching is performed by using an ultrasonic wave instead of the complex exponential function (Equation (9a)) before the Fourier transform of the received signal in space (lateral direction). Multiplying by a complex exponential function (Equation (19a)) expressed by using the carrier frequency ω _{0 of the} signal, the processing is first performed in the horizontal direction, and in the depth y direction, in order to have a resolution in the depth y direction, Instead of the complex exponential function (Equation (9b)), the complex exponential function (Equation (19b)) excluding the horizontal matching process (Equation (19a)) is multiplied. Instead, it is performed by multiplying by a complex exponential function (Equation (19c)). Of course, it can also be used when the deflection angle is zero degrees. This processing is not disclosed in the prior art document.

Further, for example, in echo method (reflection method), there is a case where the deflection angle of the transmit and receive beams are different, in that case, when each deflection angle of the transmit and receive beams and theta _t and theta _r In equations (7) and (8), the wave number matching represented by equation (18c) is performed under s = 2.

The signal processing is performed in the same manner as in the case where the transmission beam and the reception beam have the same deflection angle. In particular, wave number matching is performed by using a complex exponential function (formula (4)) before performing a Fourier transform on the received signal with respect to space (lateral direction). (19a)) is multiplied by a complex exponential function (Equation (19d)) expressed by using the carrier frequency ω ₀ of the ultrasonic signal instead of (19a)). In order to have a resolution in the y direction, a complex exponential function (equation (19e)) excluding the horizontal matching processing (equation (19d)) is multiplied instead of the complex exponential function (equation (19b)). This is performed by multiplying a complex exponential function (equation (19f)) instead of the exponential function (equation (19c)). Of course, it is also used when the deflection angle theta _t and theta _r is zero degrees. This processing is not disclosed in the prior art document.

From the equations (19a) to (19c) and the equations (19d) to (19f), the two-dimensional Fourier transform R ′ (k _x , k) of the received signal is expressed by the following equations (7) and (8). , (18b) and (18c) can be realized without performing interpolation approximation. In contrast, it may perform beamforming by performing the interpolation approximation process at high speed, in which _{case, F (k x ', k} y') is the inverse Fourier transform 2-D. Similarly to the method (1), regarding the equations (18a) to (18c), wave number matching can be performed physically and mathematically at the time of the first Fourier transform, and the last inverse Fourier transform can be performed. At times, wave number matching can be performed (paragraphs 0205 and 0210). However, in these cases, even in the steering operation, in the conversion processing involving wave number matching, one-dimensional conversion processing is first performed in the x direction, and then one-dimensional conversion processing in the y direction (wave number mapping in the x direction) is performed. Since this processing is performed later, the equations (19b) and (19e) can be used, and the processing speed can be increased. In the wave number matching, the expressions (19a) and (19c), and the expressions (19d) and (19f) are replaced by kx multiplied by a spatiotemporal signal using their complex exponential functions. Frequency modulation for ky may be performed. In addition, in the equations (18b) and (18c), the approximation processing including the approximate wave number matching processing corresponding to the equation (18a) when the deflection angle is set to zero degree is also disclosed in the prior art document. Absent.

When performing three-dimensional wave digital signal processing using a two-dimensional aperture element array, for example, an axial direction y (y of the position of the reception effective aperture element array) determined by the direction of the opening of the flat reception aperture element array is used. Zero or non-zero deflection in the Cartesian Cartesian coordinate system (x, y, z) using the x and z coordinates in the transverse direction orthogonal to this, with the direction and axis of the generated beam forming In the case where the angle is represented using the elevation angle θ and the azimuth angle φ, the Fourier transform performs a three-dimensional Fourier transform on the depth y direction and the lateral directions x and z (the wave number in the axial direction y and the lateral directions x and z is calculated). each _k y, _{k x,} and, k _z the wavenumber region _{(k x, k y, k} z) consider), similarly to the case of the two-dimensional wave digital signal processing described above, are treated as follows You.

First, for a wave number vector (0, k ₀ , 0) having a wave number k ₀ (= ω ₀ / c) expressed using the carrier frequency ω ₀ of the wave, the wave number vector (sk ₀ sin θ cos φ, sk ₀ cos θ, (sk ₀ sin θ sin φ) is subjected to Fourier transform with respect to the axial direction y in order to perform dynamic focusing of transmission and reception accompanied by spectrum shifting in order to generate an image signal having a centroid (center) or an instantaneous frequency of a multidimensional spectrum. In addition, a parameter s having a value of 2 when the y coordinate of the transmitting aperture element is zero and a value of 1 when the y coordinate of the transmitting aperture element is non-zero, a center of gravity (center) frequency k _{0 of} the wave, and , Multiplying by a complex exponential function (C41) expressed by using an imaginary unit i, thereby performing wave number matching in the horizontal direction x and z,
Further, the product is converted to an angular spectrum obtained by performing a Fourier transform on the lateral directions x and z so as to have a resolution in the axial direction y, and a complex spectrum that can be implemented without the effect of the wave number matching performed on the lateral directions x and z. At the same time as multiplying the exponential function (C42), the wave number matching in the axial direction is performed by multiplying the complex exponential function (C43).
By performing wave number matching without performing interpolation approximation processing, an image signal can be directly generated in a Cartesian coordinate system. That is, the sound pressure field created by each plane wave component at the depth y is subjected to a two-dimensional inverse Fourier transform in the horizontal direction x and z, and an image signal is obtained by adding a plurality of frequency k components. Of course, the calculation can be performed when the deflection angle is zero degree (that is, the elevation angle θ and the azimuth angle φ are zero degree) or when at least one of the angles is zero degree.

As a result, the following wave number matching (formula (C44)) is performed on the three-dimensional Fourier transform R ′ (k _x , k, k _z ) of the received signal as shown in formulas (7 ′) and (8 ′). Situation can be realized. Similarly to the two-dimensional case, the wave number matching can be performed physically and mathematically at the time of the first Fourier transform, and the wave number matching can be performed at the time of the last inverse Fourier transform. It is also possible (paragraph 0229). At the time of steering also, in the conversion processing involving wave number matching, one-dimensional conversion processing is first performed in the x direction or z direction, and finally one-dimensional conversion processing in the y direction (after wave number mapping in the x and z directions). Since this is a process, equations (C42) and (C43) can be used, and the processing speed can be increased. Further, in the wave number matching, the frequency modulation of multiplying the space-time signal by using the complex exponential functions may be performed instead of the expressions (C41) and (C43) (each of kx And kz, ky frequency modulation). In the above description, this wave number matching is performed without performing interpolation approximation. However, interpolation approximation processing may be performed at high speed in accordance with equation (C44). In this case, F (k _x ′, _ky ', k _z ') are subjected to a three-dimensional inverse Fourier transform. This processing is not disclosed in the prior art document.

Also, for example, in the echo method (reflection method), the deflection angles of the transmission beam and the reception beam may be different, and in that case, each deflection angle is (elevation angle, azimuth angle) = (θ _t , φ _t). ) And (θ _r , φ _r ), the signal processing is performed under s = 2 in the same manner as in the case where the deflection angles of the transmission beam and the reception beam are equal. In the wave number matching, a complex exponential function (using a carrier frequency ω ₀ of an ultrasonic signal instead of a complex exponential function (Equation (C41)) is used before a Fourier transform of a received signal in space (lateral direction). Equation (D41)) is multiplied, and is firstly executed in the horizontal direction. In the depth y direction, horizontal matching is performed instead of the complex exponential function (Equation (C42)) in order to provide resolution in the depth y direction. Complex exponential function excluding processing (Equation (D41)) Simultaneously multiplying (formula (D42)), is performed by multiplying the complex exponential function instead of complex exponential function (Equation (C43)) (formula (D43)). Of course, it can also be used when the deflection angles of the transmission beam and the reception beam are zero degrees (that is, θ _t , φ _t , θ _r , and φ _r are zero degrees). This processing is not disclosed in the prior art document.
It should be noted that the same processing is performed even if the beam forming is performed by exchanging the transmission and the reception in the aperture plane synthesis in which both the beam forming for the transmission and the beam reception are performed by software.

As a result, the following wave number matching (formula (D44)) is performed on the three-dimensional Fourier transform R ′ (k _x , k, k _z ) of the received signal as shown in formulas (7 ′) and (8 ′). Situation can be realized. Similarly, with respect to the formula (D44), it is possible to physically and mathematically perform wave number matching at the time of the first Fourier transform, and it is also possible to perform wave number matching at the time of the last inverse Fourier transform. (Paragraph 0232). At the time of steering also, in the conversion processing involving wave number matching, one-dimensional conversion processing is first performed in the x direction or z direction, and finally one-dimensional conversion processing in the y direction (after wave number mapping in the x and z directions). Since the processing is performed, the equation (D42) and the equation (D43) are used), and the processing speed can be increased. Further, in the wave number matching, the frequency modulation for multiplying by the space-time signal using the complex exponential functions may be performed instead of the expressions (D41) and (D43) (each of kx And kz, ky frequency modulation). In the above description, the wave number matching is performed without performing interpolation approximation. However, interpolation approximation processing may be performed at high speed according to equation (D44). In this case, F (k _x ′, _ky ', k _z ') are subjected to a three-dimensional inverse Fourier transform. This processing is not disclosed in the prior art document.

In the aperture synthesis, an arbitrary beamforming can be generated using echo signals collected for the aperture synthesis (not only in the monostatic method of the method (2) but also in the multistatic method of the method (3)). However, an image signal can be generated even if the processing described in the methods (1) and (4) to (7) is performed on the data. Also in the processing of the plane wave in the method (1), the aperture plane synthesis processing can be performed by using the code. That is, it is possible to decode the coded reception signal at the time of transmitting the plane wave to obtain a signal for aperture synthesis.
Further, as described in the method (1), the steering can be performed in the dynamic focusing. In the method (1), when the plane wave is transmitted, the steering is physically performed at the deflection angle α (including the case of zero degree), and the steering of the method (1) with the deflection angle θ (including the case of zero degree) is performed. When applied, it can be interpreted that the plane wave is steered at the steering angle (α + θ) (the steering angle finally generated is an average thereof). Therefore, in the method (1), when the plane wave is steered at the deflection angle α or θ or α + θ at the time of transmission, and dynamic focusing is performed at the steering angle φ (including the case of zero degree) at the time of reception, The reception steering described in this method (2) may be performed, and the finally generated steering angle is an average of the transmission deflection angle and the reception deflection angle. As described in the method (1), the soft plane wave steering (deflection angle θ) reinforces the physical transmission steering (deflection angle α) or purely changes the plane wave transmission steering. It can be considered that the reception steering is performed by a plane wave in a software manner in addition to the reception dynamic focusing (including the case where the deflection angle φ is zero degree).

That is, in the case of two dimensions, (9a) and (19a), (9b) and (19b), (9c) and (19c) are combined, respectively, (F41), (F42), (F43) May be processed in the same manner.

In the three-dimensional case, that is, when a plane wave is physically transmitted by steering at deflection angles (α, β) of the elevation angle α and the azimuth angle β, or when at least one of the angles is zero degree When softly steering a plane wave at a deflection angle (θ ₁ , φ ₁ ) to perform steering dynamic focusing at a deflection angle (θ ₂ , φ ₂ ) (at least one of the angles is zero degree) (Including cases), (G41), (G42), and (G43), which are combinations of (C21) and (C41), (C22) and (C42), and (C23) and (C43), respectively, are used. In this case, the average deflection angle of the transmission deflection angle and the reception deflection angle can be finally generated.

  As described in the method (1), the processing is the same even if the beamforming of the transmission and the reception of the software is exchanged, and the processing is the same as the one performed the beamforming with the exchanged. In other words, in these cases, soft transmission and reception beamforming can be considered in reverse, and any physical transmission beamforming (for example, a polarized plane wave, a deflected fixed focusing beam, an aperture plane) can be considered. In the case of steering dynamic focusing based on synthesis, non-deflected waves and beams, and the like, various other beamformings can be softly performed. In addition to the steering angle (including zero degrees) of any physically generated wave or beam (eg, such as in the above example), the steering (steering) of a plane wave or dynamic focusing in transmission or reception in software. Angles, including zero degrees). This soft plane wave steering can be considered as, in particular, augmenting the physical transmit steering, purely steering any physically transmitted wave or beam, or receiving dynamic focusing (deflection). In addition to the case where the angle φ is zero degrees, it is also possible to consider that the reception steering is performed by software. The same applies to three-dimensional beam forming using a two-dimensional array. Others are as described in the method (1).

Similarly to the methods (1) and (2), it is possible to physically and mathematically perform wave number matching at the time of the first Fourier transform and perform wave number matching at the time of the last inverse Fourier transform. Is also possible. In the conversion processing involving wave number matching depending on the steering, the conversion processing can be divided into directions and one-dimensional processing can be performed, and the speed can be increased. In the wave number matching, the expressions (F41) and (F43), and the expressions (G41) and (G43) are used instead of frequency modulation for multiplying by a space-time signal using their complex exponential functions. (Frequency modulation of kx, kz, and ky, respectively).
Wave number matching in beamforming using equations (F41), (F42), and (F43) in the two-dimensional case and equations (G41), (G42), and (G43) in the three-dimensional case is performed through interpolation approximation. In some cases, results are obtained at high speed.
In the case of the two-dimensional case, the wave number matching of the expression (18b) or the expression (18c) together with the expressions (7) and (8) is interpolated with respect to the two-dimensional Fourier transform R ′ (k _x , k) of the received signal. made through (formula _{(F44)), F (k} x ', k y') are two-dimensional inverse Fourier transform. This approximation process is not disclosed in the prior art document.
In addition, in the case of three-dimensional, for the three-dimensional Fourier transform R ′ (k _x , k, k _z ) of the received signal, together with equations (7 ′) and (8 ′), equation (C44) or equation (D44) performed through interpolation approximate wavenumber matching) (formula _{(G44)), F (k} x ', k y', k z ') are three-dimensional inverse Fourier transform. This processing is not disclosed in the prior art document.

  Further, in a convex type transducer, sector scan, or IVUS or the like, a wave that is wide in the angle θ direction in polar coordinates (r, θ) is transmitted or received (cylindrical wave) in the radius r direction (FIG. 7), A case where a wide wave is transmitted in the radius r direction (cylindrical wave) in the same angle θ direction of the polar coordinate system (r, θ) as shown in FIG. 7 by using a virtual source installed behind a physical aperture having an arbitrary aperture shape. 8A (see FIGS. 8A to 8C) and the echo signals collected for aperture synthesis in the polar coordinate system, the Cartesian coordinates (x, y) are converted to the polar coordinates (x) in the same manner as in the method (1). r, θ) and perform the processing, and an image signal can be generated in the Cartesian coordinate system (x, y) or the polar coordinates (r, θ). Also, a plane wave for transmission or reception may be generated at an arbitrary distance position using a physical aperture element array represented by the above-described polar coordinate system or a physical aperture having an arbitrary aperture shape, and beamforming may be performed similarly (see FIG. 8B (d)-(f)). This is equivalent to generating a virtual linear aperture array (or plane wave) at that distance position. If the distance position is set to zero, this corresponds to a case where a linear aperture array is virtually used. The distance position can be set not only behind the physical aperture but also in front of it, and a virtual linear aperture array (or plane wave) can be generated at those locations. The virtual linear aperture array may be used not as a virtual source but as a virtual receiver, and may also serve as a virtual source. The same applies when other transmission beamforming is performed or when they are performed in a spherical coordinate system. On the other hand, similarly, when a convex type transducer, sector scan, IVUS, or the like is used, or when a virtual source placed behind a physical aperture having an arbitrary aperture shape is used, the method is directly performed according to the method (5). An image signal can be generated in Cartesian coordinates. Also, a plane wave for transmission or reception may be generated at an arbitrary distance position using a physical aperture element array represented by the above-described polar coordinate system or a physical aperture having an arbitrary aperture shape, and beamforming may be performed similarly (see FIG. 8B (d)-(f)). This is equivalent to generating a virtual linear aperture array (or plane wave) at that distance position. If the distance position is set to zero, this corresponds to a case where a linear aperture array is virtually used. The distance position can be set not only behind the physical aperture but also in front of it, and a virtual linear aperture array (or plane wave) can be generated at those locations. The virtual linear aperture array may be used not as a virtual source but as a virtual receiver, and may also serve as a virtual source. In these cases, imaging of echo signals and displacement measurement can be performed consistently in the same Cartesian coordinate system. The same applies to the polar coordinate system. In these, similarly to the method (1), processing can be performed in an arbitrary rectangular coordinate system or by converting to an arbitrary rectangular coordinate system and similarly. In these, transmission focusing may be performed. Further, as described above, the virtual source and the virtual receiver are not always installed behind the physical aperture, and may be installed in front of the aperture, and may be installed arbitrarily regardless of the shape of the physical aperture. (Patent Document 7, Non-Patent Document 8). Thus, the present invention is not limited to the above. In wave number matching in these beamformings, an interpolation approximation process may be performed to quickly obtain an approximate solution.

  Further, the transmission and / or reception apodization process for the received signal can be performed at various timings because of linear processing (hardware upon reception or software after reception). As described above, physical apodization may be performed during transmission. In the case where the wave number matching is performed through interpolation approximation using Expressions (7) and (7 '), when the accuracy is improved, processing is performed under appropriate oversampling at the expense of an increase in the amount of calculation. There is a need. In such a case, it is necessary to pay attention to an increase in the number of data of the Fourier transform, unlike a case where a signal at an arbitrary position can be selectively generated without performing the interpolation approximation processing. These processes can be performed in the same manner as in the method (1), and also in the other methods (3) to (7).

Method (3): Multi-Static Opening Surface Synthesis FIG. 11 is a schematic diagram of multi-static opening surface synthesis. Multi-static aperture synthesis is a method in which ultrasonic waves are emitted from one element of an array and echoes are received by a plurality of elements around the element. A low-resolution image signal is obtained for each radiation, and a high-resolution image signal is generated by superimposing a plurality of obtained low-resolution image signals. The present invention may be used to generate this low-resolution echo signal.

  As described above, the conventional method usually generates a low-resolution echo signal from an echo signal received for each emission of each element and superimposes them. On the other hand, in the present invention, a signal group consisting of signals having the same transmission / reception position relationship is set as one set, and a digital monostatic aperture plane synthesis is performed for each set. The processing is completed by superimposing the obtained low-resolution image signals. In practice, superposition, which is a linear process, can be performed in the frequency domain before the horizontal inverse Fourier transform process, which is faster, and the horizontal alignment for performing the superposition is also: At the time of superposition, the image signal can be generated at high speed by multiplying a complex exponential function for performing horizontal shifting processing and rotating the phase in the horizontal direction without performing interpolation approximation. The inverse Fourier transform may be performed by performing the fast inverse Fourier transform once. In addition, in order to generate each low-resolution echo signal, when performing the inverse Fourier transform in the horizontal direction, simultaneously multiply the complex exponential function for performing the horizontal shifting process and rotate the phase in the horizontal direction, It can also be superimposed on the area. In that case, a dedicated fast inverse Fourier transform may be performed.

However, what is important is that when applying the program of the monostatic aperture plane synthesis processing, when s = 2, the distance in the x direction between the reception position of y = 0 and the transmission position of y = 0 is Δx. This is to calculate and use the converted distance y ′ of the propagation path until reception at a position separated by Δx with respect to the distance y (coordinate y) of the point of interest, and when the deflection angle is zero degree, the equation (20a) is used. ) Is calculated. Further, when s = 1, the distance in the x direction between the reception position at the y coordinate y = 0 and the transmission position at the non-zero y coordinate y = Y is Δx. When the angle is zero degrees, the conversion distance represented by Expression (20b) is calculated (the y-coordinate of the transmission position and the reception position may be reversed).

  When the deflection angle is θ (including zero degree), multi-static aperture plane synthesis for generating a beam subjected to at least dynamic focusing of reception (when s = 2, dynamic focusing of transmission can also be realized) is performed. As a beam forming method to be performed, a wave is transmitted from each of a plurality of transmission aperture elements in a transmission effective aperture element array, and a wave arriving from an object to be measured is transmitted by at least one of a plurality of reception aperture elements at different positions. It receives and produces a received signal (even if it is one, it can be processed by the measurement and imaging apparatus of the present invention), and its transmission aperture element is such that the wave is generated by at least reflection or back scattering on the measurement object. (S = 2) or at least transmission, forward scattering, or refraction in the measurement object The effective aperture having an arbitrary x-coordinate without depending on the x-coordinate of the reception aperture element generating the reception signal and further having a zero y-coordinate so that the generated aperture (s = 1). A receiving effective aperture element array which also serves as any of the receiving aperture elements in the element array, or one of a plurality of transmission aperture elements different from any of the reception aperture elements, or has a non-zero constant y coordinate (One of a plurality of transmission aperture elements in a transmission effective aperture element array at a position opposed to the above) (when s = 1, the y coordinate of the transmission position and the reception position may be considered in reverse).

That is, when steering is performed, the steering process described in the method (2) is performed on each of the monostatic aperture plane synthesis data groups generated from the same combination of the transmitting element and the receiving element. And then perform the same treatment. The same applies when the transmission and reception steering angles are different. However, even when the deflection angle is non-zero, the distance y of the point of interest (coordinate y) is set to s, as in the case where the deflection angle is zero, in applying the program of the monostatic aperture synthesis process. = 2, the converted distance expressed by the equation (20b) is used when s = 1. Therefore, similarly to the methods (1) and (2), in the deflectable program, the deflection angle may be set to zero or non-zero, and the processing may be performed.
Further, the transmission can be processed when the plane wave of the method (1) is transmitted, and can also be processed when any transmission beamforming such as fixed focusing is performed.

Further, as another method, for each of the received signal groups obtained by arranging the received signals having the same distance Δx in the horizontal coordinate between the transmitting position and the receiving position, the y coordinate of the transmitting and receiving aperture elements is zero. When (s = 2), the distance between the transmitting aperture element, the point of interest, and the receiving aperture element expressed using the declination θ, the y coordinate of the point of interest including the positions of the transmitting and receiving apertures, and the distance Δx , Or when the y coordinate of the transmitting aperture element is non-zero (s = 1, the y coordinate of the transmitting position and the receiving position may be considered in reverse). , The y-coordinate of the point of interest, the y = Y coordinate of the transmitting aperture element, and the distance Δx, expressed by using the argument θ, the distance between the transmitting aperture element, the point of interest, and the receiving aperture element (Equation (20d)) Image signal obtained by setting the deflection angle in the above monostatic aperture synthesis using Can be corrected with respect to the horizontal position in the frequency domain, and they can be superimposed to generate an image signal without performing interpolation approximation processing. Although the spatial resolution in the depth direction is reduced, a large steering angle can be generated.

When three-dimensional wave digital signal processing is performed using a two-dimensional aperture element array, for example, the axial direction y determined by the direction of the aperture of the flat receiving aperture element array and the horizontal directions x and z orthogonal thereto In the Cartesian rectangular coordinate system using the coordinates of the above, the same processing can be performed, and the zero-degree or non-zero degree deflection angle formed by the generated beam direction and the axial direction is expressed using the elevation angle θ and the azimuth angle φ. , A wave is transmitted from each of a plurality of transmission aperture elements in a transmission effective aperture element array, and a wave arriving from an object to be measured is received and received by at least one of a plurality of reception aperture elements at different positions. A signal generated by the transmitting aperture element, wherein the wave is generated at least by reflection or backscattering on the object to be measured (s = 2), or , Any x-coordinate and z-coordinate without depending on the x- and z-coordinates of the receiving aperture element that generates the reception signal so that at least the one generated by transmission, forward scattering, or refraction (s = 1) And furthermore, having zero y-coordinate, also serving as any of the receiving aperture elements in the receiving effective aperture element array, or one of a plurality of transmitting aperture elements different from any of the receiving aperture elements, or , One of a plurality of transmission aperture elements in the transmission effective aperture element array having a non-zero constant y coordinate and located at a position facing the reception effective aperture element array (when s = 1, transmission is performed). The y coordinate of the position and the reception position may be considered in reverse.) When the deflection angle is zero degree (without steering) or non-zero degree (with steering), similarly to the two-dimensional wave digital signal processing using the one-dimensional aperture element array described above, the transmission element and the reception element are connected. The processing with or without the steering described in the method (2) may be performed on each of the monostatic type aperture plane synthesizing data groups generated from the same combination of the positions, and the processing may be performed similarly. The same applies when the transmission and reception steering angles are different. However, what is important is that when the deflection angle is zero degree (without steering) or non-zero degree (with steering), when the program of the monostatic type aperture synthesis processing is applied, when s = 2, y Assuming that the distance in the x direction (horizontal direction) between the reception position = 0 and the transmission position y = 0 is Δx, and the distance in the z direction (elevation direction) is Δz, reception is performed at positions separated by Δx and Δz in two directions. This is to calculate and use the converted distance y 'of the propagation path before performing the calculation, and to calculate the converted distance represented by Expression (20e). Further, when s = 1, if the distance in the x direction between the reception position at the y coordinate y = 0 and the transmission position at the non-zero y coordinate y = Y is Δx and the distance in the z direction is Δz, Expression (20f) is used. This is to calculate the converted distance represented (the y coordinate of the transmission position and the reception position may be considered in reverse).

  Further, the transmission can be processed when the plane wave of the method (1) is transmitted, and can also be processed when any transmission beamforming such as fixed focusing is performed.

  Further, as another method, transmission and reception are performed for each reception signal group obtained by arranging reception signals having the same distance Δx and Δz in the horizontal x coordinate and z coordinate between the transmission position and the reception position. When the y-coordinate of the aperture element is zero (s = 2), the transmission aperture represented using the y-coordinate of the point of interest including the elevation angle θ and the azimuth angle φ, and the aperture position for transmission and reception, and the distances Δx and Δz. The distance of half the linear distance between the element, the point of interest, and the receiving aperture element, or the y coordinate of the transmitting aperture element is non-zero (s = 1, and the y coordinate of the transmitting position and the receiving position can be considered in reverse. Good), the elevation angle θ and the azimuth angle φ, the y coordinate of the point of interest, the y coordinate of the transmission aperture element, and the distances Δx and Δz between the transmission aperture element, the interest point, and the reception aperture element Deflection angle is set in the above monostatic aperture synthesis using the distance of Each image signal obtained Te was corrected for lateral position in the frequency domain, can generate an image signal without performing the interpolation approximation process by superimposing them. Although the spatial resolution in the depth direction is reduced, a large steering angle can be generated.

  Further, in order to generate an image signal representing the propagation of the unknown wave source or the wave generated by the unknown wave source (so-called passive mode), the y coordinate of the estimated unknown wave source is set to the y coordinate of the transmitting aperture element, It is good to perform beam forming. It is also effective to try and observe while changing the y-coordinate by trial and error. For example, it is desirable to obtain effects such as imaging, increased spatial resolution, increased signal intensity, and increased contrast, and automatically perform a series of processes using these as a criterion. Is also possible.

  As described later, a position with respect to the receiving aperture element, a direction or distance of an existing position, an opening direction, or a propagation direction of a generated wave may be given as information on the wave source position or the transmitting aperture element. Also, the time at which the wave was generated by an arbitrary wave source may be given. The signal may be observed by another device, or the received signal itself or a wave propagating at a higher speed may be emitted and transmitted from the wave source.

  For the received signal, the center of gravity (center) frequency or instantaneous frequency of the multidimensional spectrum is obtained, the direction in which the wave source is present or the propagation direction of the wave is obtained, and the deflection angle of the transmission or reception is adjusted. Forming may be performed. Further, for the beamformed image signal, the center of gravity (center) frequency or instantaneous frequency of the multidimensional spectrum is obtained, and the direction in which the wave source exists or the propagation direction of the wave is obtained, and the transmission or reception deflection angle is obtained. May be adjusted to perform beamforming. These processes can be performed at a plurality of reception apertures or reception apertures to geometrically determine the position or direction where the wave source exists. These processes are useful and may be applied to other beamforming.

  As described in the method (2) of the monostatic aperture synthesis, in the method (3) of the multistatic aperture synthesis as well, an arbitrary beamforming can be generated using the echo signals collected for the aperture synthesis. (Actually, an image signal can be generated even if the processing described in the methods (1) and (4) to (7) is performed on the data). It is sometimes effective to have a large amount of data as compared with the monostatic type, but the amount of calculation increases. Also in the processing of the plane wave in the method (1), the aperture plane synthesis processing can be performed by using the code. Further, in a convex type transducer, sector scan, or IVUS or the like, a wave that is wide in the angle θ direction in polar coordinates (r, θ) is transmitted or received (cylindrical wave) in the radius r direction (FIG. 7), A case where a wide wave is transmitted in the radius r direction (cylindrical wave) in the same angle θ direction of the polar coordinate system (r, θ) as shown in FIG. 7 by using a virtual source installed behind a physical aperture having an arbitrary aperture shape. 8A (see FIGS. 8A to 8C) and the echo signals collected for aperture synthesis in the polar coordinate system, the Cartesian coordinates (x, y) are converted to the polar coordinates (x) in the same manner as in the method (1). r, θ) and perform the processing, and an image signal can be generated in the Cartesian coordinate system (x, y) or the polar coordinates (r, θ). The same applies when other transmission beamforming is performed or when they are performed in a spherical coordinate system. On the other hand, similarly, in a convex transducer, sector scan, or IVUS, an image signal can be directly generated in Cartesian coordinates according to the method (5). In that case, imaging of echo signals, displacement measurement, and the like can be performed consistently in the same Cartesian coordinate system. In these, similarly to the method (1), processing can be performed in an arbitrary rectangular coordinate system or by converting to an arbitrary rectangular coordinate system and similarly. In addition, beamforming described in paragraphs 0111 to 0222 of method (1) and paragraph 0240 of method (2) can be performed in the same manner. For example, a virtual source, a virtual receiver, etc. It can be installed arbitrarily regardless of the shape (Patent Document 7, Non-Patent Document 8). In addition, the present invention is not limited thereto (the same applies hereinafter).

  Further, as described above, although the spatial resolution in the depth direction is reduced, it is possible to deflect as another method in order to generate a large steering angle. Can be processed in a similar manner when the steering angles are different. The reduced distance may be calculated using the horizontal distance between the transmission aperture element and the reception aperture element, the transmission steering angle and the reception steering angle, and in the case of the transmission type, the distance between the transmission aperture element and the reception element.

  Any of the steerings in the method (3) is basically performed by software. In addition, an apodization may or may not be performed at the time of transmission. Further, the reception apodization process is also a linear process, so that it can be performed at various timings (hardware or software). Can be easily implemented at an appropriate timing by taking into account the amount of calculation that depends on the effective aperture width or the like that determines the number of. For example, each set for initiating the generation of a low-resolution echo signal can be weighted, or the generated low-resolution signal can be apodized in the frequency domain or the spatial domain.

In applying the monostatic aperture synthesis in the method (2), wave number matching can be performed physically and mathematically at the time of the first Fourier transform, and wave number matching can be performed at the time of the last inverse Fourier transform. It is also possible to do. In addition, wave number matching may be performed at high speed through the above interpolation approximation. In the interpolation approximation, a linear interpolation approximation or an approximation using the nearest data itself may be performed, a higher-order interpolation approximation may be performed, or a sinc function may be used. In order to increase the accuracy of wave number matching through the interpolation approximation, it is necessary to perform processing under appropriate oversampling at the expense of an increase in the amount of calculation. In such a case, it is necessary to pay attention to an increase in the number of data of the Fourier transform, unlike a case where a signal at an arbitrary position can be selectively generated without performing the interpolation approximation processing.
In the horizontal alignment for superposition described in paragraphs 0243, 0247, and 0250, the phase is rotated in the horizontal direction by multiplying by a complex exponential function for performing horizontal shifting. Instead, spatial shifting processing may be performed through interpolation approximation in order to realize faster processing. In the interpolation approximation, a linear interpolation approximation or an approximation using the nearest data itself may be performed, a higher-order interpolation approximation may be performed, or a sinc function may be used. Even in this case, in order to improve the accuracy of the interpolation approximation, it is necessary to perform processing under appropriate oversampling at the cost of an increase in the amount of calculation.

Method (4): Fixed Focusing FIG. 12 is a schematic diagram of fixed focusing using a linear array. The fixed focusing is a method in which one point is set as a focus point and each element is delayed so that ultrasonic waves reach the focus point at the same time. A part or all of the physical aperture of the array type transducer is received as an effective aperture, and the object to be measured is scanned. Of course, there is also steering. The transmission and reception steering angles may be different.

In the fixed focusing, an image signal is generated by a method (1): beam forming at the time of plane wave transmission, or a method (3): multi-static aperture synthesis, or a beam forming and a method of plane wave transmission by the method (1). This is performed by a method that combines the reception dynamic focusing of the method (2) or the method (3). In that case, there are the following three methods.
(I) A single image signal generation process is performed for each received signal obtained in the effective aperture width.
(Ii) A so-called ordinary low-resolution image signal is generated by using the received signal for each transmission, and they are superimposed.
(Iii) As in the case of the multi-static aperture plane synthesis, image signals are generated by setting those having the same positional relationship of transmission and reception, and are superimposed.

  In the case of transmitting and receiving in the radius r direction of the polar coordinate in the convex type transducer or sector scan, or IVUS, or in the case of performing beamforming using a virtual source installed behind in an arbitrary aperture shape, Cartesian coordinates ( x, y) may be replaced with polar coordinates (r, θ) for processing, and an image signal can be generated at polar coordinates (r, θ). As mentioned above, interpolation approximation may be required after the generation of the image. The same applies to transmission and reception using the spherical coordinate system. There is a report of a process that performs an approximation process when performing transmission focusing (Non-Patent Document 6), and similarly, a result is obtained in polar coordinates (r, θ). The inventor of the present application has proposed a method for directly generating an image signal in a Cartesian coordinate system as a result of transmission or reception beamforming in such a polar coordinate system, a spherical coordinate system, or an arbitrary orthogonal coordinate system (5). , (5-1), (5-1 ′), and (5-2) were also invented. In such a case, imaging of a transmission signal, a reflection signal, a scattering signal, an attenuation signal, and the like, displacement measurement, and the like can be consistently performed in the same Cartesian coordinate system. In these, similarly to the method (1), processing can be performed in an arbitrary rectangular coordinate system or by converting to an arbitrary rectangular coordinate system and similarly. In addition, beamforming described in paragraphs 0111 to 0222 of method (1) and paragraph 0240 of method (2) can be performed in the same manner. For example, a virtual source, a virtual receiver, etc. It can be installed arbitrarily regardless of the shape (Patent Document 7, Non-Patent Document 8). In addition, the present invention is not limited thereto (the same applies hereinafter). As described above, it is possible to deflect, but it is also possible to handle the case where the deflection angles of physical transmission beamforming and soft reception beamforming are different. The transmission steering can be performed by software. In that case, the deflection angle may be different from other deflection angles. Beamforming can also be performed physically during reception. Transmission and reception can be interpreted in reverse. Apodization may be performed at the time of transmission, or reception apodization processing may be performed on a received signal (hardware at the time of reception or software after reception). When apodization is performed in a software manner, it is performed according to the method (1) or the method (3). Apodization is performed in the same manner when using a method in which the beamforming of the plane wave transmission is combined with the receiving dynamic focusing of the method (2) or the method (3).

  Note that any processing of the method (4) using the method (1) of performing the plane wave processing can theoretically and practically perform any physical transmission or reception beamforming. By performing the processing as described above, various combinations of beamforming can be performed (for example, physical beamforming using a computer or a dedicated device, which is different from that performed in software beamforming using a computer or a dedicated device, etc.). Each or both of those involving processing such as focusing, steering, and apodization that may be performed at the time of transmission and reception can be subjected to plane wave transmission and reception processing, or transmission and reception are reversed as described above. And process it.) For example, regarding simultaneous transmission of a plurality of beams described in paragraphs 0109, 0112, 0365, 0367, 0368, etc., when the plurality of beams interfere with each other with or without physical deflection, and do not interfere with each other Including the case, or when the focus beamforming is performed at different timing in the simultaneous phase of the object, or when both of the received signals are mixed, the physical focus (sub aperture width, distance and depth, Irrespective of whether the position and the like are the same or different, and irrespective of whether the physical transmission deflection angles are the same or different, the above processing of the method (4) is effective. If a method of performing one image signal generation process on the superposition of the respective received signals obtained in the effective aperture width of (1) is used, a high frame rate can be realized. It is intended to. In the method (4), it is not necessary to perform beam forming at a position where the wave does not interfere (described in paragraphs 0030 and 0364, etc.), and even when the waves interfere, such as when overlapping sub-apertures are used simultaneously. High frame rate can be realized by processing. At this time, if the soft transmission deflection angle and the reception deflection angle applied to the plurality of focus beams to be performed are the same, the above processing may be performed. In addition, even in the case of performing transmission a plurality of times, such as when performing focusing at a plurality of positions or performing dynamic transmission focusing in the simultaneous phase of the target, the same processing can be performed as the superposition of the received signals. This processing can be performed on all of the received signals received in the target simultaneous phase, as long as the received signals are superimposed in a state where the times are aligned based on the position and timing of the transmitting element.

  If any of the soft transmission deflection angle and the reception deflection angle to be applied to a plurality of focus beams includes different ones, they are divided into the same beam, the same process is performed for each same beam, and the final result is obtained. What is necessary is just to superimpose in a frequency domain to obtain | require. Multiple deflection reception beams (including a deflection angle of 0 °) may be generated for one physical transmission beam (with or without deflection), and are similarly processed. Even when a plurality of different physical deflections are performed, processing may be performed by dividing them into the same one and obtaining the respective processing results. When divided, superposition may be performed in the spatial domain or the frequency domain.

  In the case of physical transmission in multiple directions, transmission and reception deflections specific to software may be performed for each transmission deflection angle, in which case the transmission beams must be separated in the frequency domain. Or separation processing such as independent component analysis (ICA: there are many references including relatively old books such as Te-Won Lee, Independent Component Analysis: Theory and Applications, Springer, 1998). May be applied and treated. Analog devices may be used. As an example, a soft transmission or reception deflection angle may be set in the same manner as each physical deflection angle. Signal separation is described elsewhere (eg, paragraph 0370).

  Here, it has been described that the present method is performed for various fixed focusing processes. However, the present method is not limited to these, and can be used when other transmission beamforming is performed. With focusing (multi-focus for realizing a plurality of different focus positions with respect to the effective aperture) or without, with deflection (several steerings with different deflection angles) or without, with apodization (including different positions) Also, when performing multiple transmissions or receptions with different wave or ultrasonic parameters, such as different or no, F number, transmission ultrasonic frequency or transmission band is different, reception frequency or reception band, pulse shape is different, beam shape is different, etc. , And can perform beamforming with new features that cannot be generated by one beamforming with them fixed. For example, although it is known that a plurality of focuses can be obtained by superposition and that a wide band (high resolution) can be obtained in both the depth direction and the horizontal direction, these processes can be performed at high speed. When a so-called pulse inversion method (emission of pulses having different polarities as ultrasonic parameters) or the like is used to obtain harmonics, the received signals can be superimposed and similarly processed at high speed. Of course, the received signals can be superimposed after performing beamforming. In some cases, received signals of two or more beams are superimposed.

  The above processing may be applied to simultaneous reception beamforming on the basis that the above transmission and reception are considered in reverse. The above processing may be performed for both transmission and reception.

  When processing is performed by dividing into a plurality of beamformings, parallel processing may be performed. Depending on various waves such as the above-mentioned deflection angles, ultrasonic parameters, the position of the region of interest, and the like, the beamforming may be divided into a plurality of beamformings. One received signal may be used for multiple purposes such as imaging, measurement, treatment, etc., and a beam of a large amount of information, for example, a transmission signal, a reflection signal, a scattered signal, an attenuated signal, etc., which has high precision and high resolution, In some cases, a signal that is generated by forming and is subjected to post-processing such as filtering to generate a signal tailored to the purpose. However, appropriate beamforming is performed according to the purpose, and they may be processed in parallel.

In addition to an arbitrary beam such as a fixed focus beam, beam forming at the time of transmitting an arbitrary wave (including a wave that has not been beam formed), superposition processing at the time of transmitting a plurality of beams and waves, and simultaneous multiple beams And processing when transmitting waves. That is, even when any one or more transmissions are performed, reception beamforming (such as dynamic focusing) can be performed at once. The plurality of beamformings may be performed using a multidirectional aperture plane synthesis method, and in such a case, the beamforming is performed at a high speed. Further, the present invention is not limited thereto.
Physically and mathematically, wave number matching can be performed at the time of the first Fourier transform, and wave number matching can be performed at the time of the last inverse Fourier transform. One of the features of the present invention is that interpolation approximation processing is not performed in wave number matching. However, even in the present method (4) to which the methods described in the above methods (1) to (3) are applied. In the same manner as in the methods (1) to (3), interpolation approximation processing may be performed in wave number matching. Approximate wave number matching described therein is performed, and beam forming is performed at high speed. There is. In order to perform approximate approximate wave number matching, it is necessary to appropriately oversample a received signal at the cost of an increase in the amount of calculation. In such a case, it is necessary to pay attention to an increase in the number of data of the Fourier transform, unlike a case where a signal at an arbitrary position can be selectively generated without performing the interpolation approximation processing.

Method (5): Image signal generation in polar coordinate system Method (5) transmits or receives (part of) an ultrasonic cylindrical wave in a two-dimensional polar coordinate system (r, θ) such as convex array, sector scan, and IVUS. This is a method of generating an image signal in the Cartesian coordinate system in the case (see FIG. 7). Methods (1) to (4) and (6) can be performed.

Hereinafter, the polar coordinate display of the Fourier transform will be described. The two-dimensional Fourier transform is represented by equation (22).
Since the received echo signal in the polar coordinate system is represented by f (r, θ), Expression (23) holds.
Therefore, equation (24) is obtained through the Jacobi operation. In this way, degradation of the wave represented in a polar coordinate system plane wave components in a Cartesian coordinate system (k _x, k _y) in the. Similarly, a wave represented in arbitrary orthogonal curve coordinates can be decomposed into a plane wave component (k _x , k _y ) in a Cartesian coordinate system.

Method (5-1): Generation of Image Signal for Cylindrical Wave Transmission or Reception FIG. 13 is a flowchart showing digital signal processing at the time of cylindrical wave transmission. From equation (24), the Fourier transform in the angle θ direction on the aperture is expressed by equation (25).
Here, r ₀ is the radius of curvature of the convex probe, and x ₀ and y ₀ are the x-axis and y-axis coordinates representing the array element position of the convex probe. In step S21, the received signal is Fourier-transformed with respect to time t, and in step S22, the received signal is subjected to Fourier transform (FFT) with respect to the angle θ to convert the signal received in the polar coordinate system into a plane wave component (k _x , k _y ).

Therefore, for example, an image signal can be generated by performing a wave number matching represented by the equation (26) (step S23) and performing an inverse Fourier transform on the space (x, y).

Further, in step S24, a two-dimensional spectrum is multiplied by the following complex exponential function to calculate an angular spectrum at each depth y.
Alternatively, the calculation may be performed with step 23 and step 24 reversed.

Alternatively, without using Equations (26a) and (26b), the following complex exponential function is multiplied according to the method (5), wave number matching is performed, and the angular spectrum at each depth position y is obtained. good.

  Further, for example, by adding the frequency component k of the angular spectrum in step S25 and performing an inverse Fourier transform (IFFT) on the horizontal wave number kx in step S26, an image signal is obtained in step S27. A purely two-dimensional inverse Fourier transform may be performed.

  When steering is performed, wave number matching in the x and y directions may be performed and spatial resolution may be obtained in accordance with Equations (9a) to (9c) using the deflection angle θ according to the method (1). As will be described later, when performing calculations in the polar coordinate system (r, θ), it is also possible to provide a steering angle (an angle formed with the radial direction) in the polar coordinate system and perform steering in the same manner. It is possible to implement physical steering, transmit or receive, or implement soft steering for transmission and reception, or to implement physical steering and soft steering in combination. There are other methods such as method (1).

  This method, when obtaining an image signal of the Cartesian coordinate system (x, y) from the signal of the polar coordinate system (r, θ), does not require interpolation processing for wave number matching and conversion of the coordinate system, and is fast and highly accurate. Beam forming is performed. Similar to plane wave transmission in a linear array transducer, a cylindrical wave can also be deflected in a polar coordinate system. The same processing can be performed when the steering angles of the transmission beamforming and the reception beamforming are different. Soft steering can also be applied. Apodization can be performed similarly. In the case of a cylindrical wave, at the different position in the z-axis direction orthogonal to the two-dimensional polar coordinate system (that is, the z-axis in the cylindrical coordinate system (r, θ, z)), the above-mentioned transmission is performed simultaneously and received. The above-described processing may be performed by overlapping the transmissions and receptions performed at the same time but at different times. In the z-axis direction, focusing may be performed by an analog device (lens), or arbitrary processing may be performed by the digital signal processing of the present invention. The same calculation can be performed when the propagation direction of the wave is in the center direction (for example, it is useful for HIFU treatment, various kinds of imaging using a circular-based array transducer surrounding an object, CT, and the like). Of course, in these, beamforming only for reception may be performed, and the same processing is performed. Note that the received signal represented by the polar coordinates (r, θ) can be processed by replacing the Cartesian coordinates (x, y) of the method (1) with the polar coordinates (r, θ). , θ), the image signal can be generated as described above. In the subsequent processing, interpolation approximation is performed. In these, steering can be performed similarly. The methods (2) to (4) and (6) can be similarly performed.

  When the received signal is represented as a digital signal of the Cartesian coordinates (x, y), the processing is performed by performing a Fourier transform on f (x, y) with respect to the radius r and the angle θ, contrary to the equation (22). After all, it is also possible to generate the image signal in the polar coordinate system (r, θ), or to generate the image signal in the Cartesian coordinate system (x, y) using each method. Steering and apodization may be performed as well.

  Further, as shown in FIGS. 8B (d) to 8 (f), transmission or reception is performed at an arbitrary distance position by using a physical aperture element array represented by the above-described polar coordinate system or a physical aperture having an arbitrary aperture shape. Alternatively, both plane waves may be generated, and beamforming may be performed in the same manner.An image signal is generated in a Cartesian coordinate system or a polar coordinate system, or an orthogonal curved coordinate system set according to a physical aperture shape. Sometimes. This is equivalent to generating a virtual linear aperture array (or plane wave) at that distance position. If the distance position is set to zero, this corresponds to a case where a linear aperture array is virtually used. The distance position can be set not only behind the physical aperture but also in front of it, and a virtual linear aperture array (or plane wave) can be generated at those locations. The plane wave may be steered, or the virtual linear aperture may be tilted (virtually mechanically steered). Of course, the physical aperture is mechanically steered as needed. When only these plane waves are transmitted or only received, each beamforming is performed on the basis of transmitting and receiving a cylindrical wave, and sometimes other beamforming is performed.

Method (5-1 ′): Image Signal Generation Using Virtual Source and Other Arbitrary Shaped Aperture Array When transmitting a wave not only from a circular aperture array but also from an arbitrary aperture shape such as a linear array type transducer, a backward direction is required. A case where a part of a cylindrical wave is generated using the installed virtual source (see FIGS. 8A to 8C) will be described.

  (I) When the received signal acquired for monostatic aperture plane synthesis is used, a complex exponential function is applied to the Fourier transform, if necessary, of the received signal transmitted and received by each element and stored in a memory or the like. Multiplying the response of the wave generated from the virtual source into a digital reception signal represented by polar coordinates (r, θ), and then following the method (5) or using the method (5-1) Image signals can be generated directly in the (x, y) coordinate system. Similarly, the received signal may be represented as a digital signal of polar coordinates (r, θ), and the process (1) in which the Cartesian coordinates (x, y) are replaced with polar coordinates (r, θ) may be performed. An image signal can also be generated at (r, θ). Of course, the monostatic processing of the method (2) is also possible in the polar coordinate system (r, θ).

  (Ii) In the case of using the received signal acquired for the multi-static aperture plane synthesis, it is necessary for the received signal transmitted by each element to be received by the surrounding elements and stored in a memory or the like. For example, the Fourier transform is multiplied by a complex exponential function, and the response of the wave generated from the virtual source is converted into a digital reception signal represented by polar coordinates (r, θ), and the multi-static aperture plane synthesis of the method (3) is performed. it can. As another processing, according to the method (5), or by superimposing the digital reception signal at each receiving element and then using the method (5-1), the (x, y) coordinate system is directly obtained. Can generate an image signal. Similarly, it is also possible to superimpose the digital reception signal at each receiving element, and then perform the process of reading Cartesian coordinates (x, y) into polar coordinates (r, θ) in method (1). An image signal can also be generated at (r, θ). Of course, without superposition, the multi-static processing of the method (3) can also be performed in the polar coordinate system (r, θ).

  (Iii) In these processes, in order to omit the process of rewriting the signal received by the physical aperture array into a digital signal in the polar coordinate system (r, θ), sampling is performed in the polar coordinate system (r, θ) from the beginning. In some cases, transmission and reception sampling is performed from each aperture element using a transmission or reception delay pattern. Then, based on the method (5-1) or the method (2) or the method (3) based on the method (5), an image signal can be directly generated in the (x, y) coordinate system. Similarly, the received signal is represented as a digital signal of polar coordinates (r, θ), and the processing of reading the Cartesian coordinates (x, y) of the methods (1) to (3) into polar coordinates (r, θ) is performed. Alternatively, an image signal can be generated in polar coordinates (r, θ).

  (Iv) Similarly, in the case where a part of a cylindrical wave is generated using a virtual source placed behind in an arbitrary aperture shape (see FIGS. 8A (a) to (c)), the above (i) to (c) In iii), the Fourier transform of the received signal received by each element and stored in a memory or the like is multiplied by a complex exponential function to represent the received signal as a digital signal in Cartesian coordinates (x, y) (where time is represented by Necessary) or an interpolation approximation is performed, and contrary to the equation (22) in the method (5-1), the f (x, y) is subjected to the Fourier transform with respect to the radius r and the angle θ, and the polar coordinates are eventually obtained. The image signal can be generated in the system (r, θ), or the image signal can be generated in the Cartesian coordinate system (x, y) using each method. Similarly, an image signal can be generated in an orthogonal curve coordinate system (curved coordinate system) set according to the opening shape.

  In (i) to (iv), various other beamformings described in the method (5-1) can be performed.

  As described in the method (1) and the like, a virtual source (FIG. 8A (FIG. 8A)) is set behind an arbitrary aperture (an aperture of a linear array transducer or other pseudo array aperture obtained by mechanical scanning). a) to (c)) (in the case of transmitting a cylindrical wave) (using a transmission delay), each element is coded and transmitted in the same manner as in the case of plane wave transmission, and then received. Decoding a reception signal to generate a reception signal group for aperture synthesis, and directly generating an image signal in an arbitrary orthogonal curve coordinate system such as a Cartesian coordinate system or a polar coordinate system by the above processing. Can be. In addition, a virtual receiver may be set instead of a virtual source, and a virtual receiver may also serve as a virtual source.

In addition, a virtual source (FIG. 8A (FIG. 8A)) set behind an arbitrary aperture (an aperture of a linear array transducer or other pseudo array aperture obtained by mechanical scanning) described in the method (1) or the like. a) to (c)) (when a transmission delay is used), the following can be performed using the above method.
(A) The method (1) is directly applied to a received signal represented by a Cartesian coordinate system (x, y) obtained by a linear array transducer or a mechanical scan, and an image is formed in the Cartesian coordinate system. Get the signal.
(B) A signal received at each receiving position by a linear array transducer or mechanical scan is spatially multiplied by a complex exponential function in a y-direction by multiplying a frequency response obtained by a (fast) Fourier transform in the y-direction. In the polar coordinate system (r, θ) with the virtual source as the origin, the coordinates are corrected to the position coordinates in the radius r direction under θ determined by the reception position, and the method (5) or the method (5-1) is performed. , An image signal is obtained in a Cartesian coordinate system (x, y) or a polar coordinate system (r, θ). Instead of spatial shifting using complex exponential functions, approximate spatial shifting may be performed by zero padding of signal values in the r coordinate system. It is necessary to note that an AD converter with a high sampling rate and a lot of memory are required, and the number of data increases before Fourier transform.
(C) A method (5) or a method (5-1) is applied to a signal received in an arbitrary aperture shape different from a pseudo linear array aperture by a linear array transducer or a mechanical scan, and the Cartesian Similarly, an image signal can be generated in a coordinate system (x, y), a polar coordinate system (r, θ), or an orthogonal curve coordinate system (curved coordinate system) set according to an opening shape.
(D) A virtual receiver may be used instead of a virtual source, and a virtual receiver may also serve as a virtual source.

As a result of these methods (5-1 ′), for example, using a different type of transducer or another mechanical scan, a convex or sector type transducer as shown in FIG. An image signal in the case of using (abbreviated) can be generated in a Cartesian coordinate system (x, y), a polar coordinate system (r, θ), or an orthogonal curve coordinate system (curved coordinate system) set according to the opening shape. .
On the other hand, conversely, when a linear type transducer is virtually used by using a physically different type of transducer (for example, FIGS. 8B (d) to (f) when a convex type transducer is physically used). ), The virtual source or virtual receiver is at or behind the physical aperture, or in front of it), and the image signal is similarly calculated in a Cartesian coordinate system (x, y) or a polar coordinate system (r, θ), it can also be generated in an orthogonal curve coordinate system (curved coordinate system) set according to the opening shape.
As a special case, for example, when a linear array transducer is physically used, a case where a cylindrical wave is generated using a virtual source or a virtual receiver behind a physical aperture is applied, and a horizontal position is set at an arbitrary distance position. An image signal can also be generated in the case of generating a plane wave or a virtually linear array type transducer that spreads in the direction (FIG. 8B (g)).
In these, the generated transmitted or received wave may be steered or the opening may be virtually tilted (virtually mechanically steered). Of course, the physical aperture is mechanically steered as needed.

Method (5-2): Image Signal Generation During Fixed Focus FIG. 14 is a schematic diagram of fixed focusing using a convex type array. Also in the convex array, fixed focusing can be performed as shown in FIG. Each of FIGS. 14A and 14B is a schematic diagram showing an example in which the fixed focusing position is equidistant from each effective aperture and a case where the fixed focusing position is set at an arbitrary distance from the convex array. As in the case of the linear array type (method (4)), an image signal can be generated by the same calculation processing as in the case of cylindrical wave transmission. That is, there are the following three methods based on the processing of the method (1) or the method (3).
(I) Image signal generation processing is performed once for each of the received signals obtained in the effective aperture width.
(Ii) A so-called ordinary low-resolution image signal is generated by using the received signal for each transmission, and they are superimposed.
(Iii) As in the case of the multi-static aperture plane synthesis, image signals are generated by setting those having the same positional relationship of transmission and reception, and are superimposed.
As described above, the image signal can be directly generated in the Cartesian coordinate system. However, the image signal can be generated in the polar coordinate system by performing the method (4) using the coordinate axes of the polar coordinate system. Similarly, deflection and apodization can be performed. The processing in the z-axis direction can be performed in the same manner as in (5-1).

  Further, when the received signal is represented as a digital signal of the Cartesian coordinates (x, y), f (x, y) is subjected to a Fourier transform with respect to the radius r and the angle θ, and eventually processed in the polar coordinate system (r , θ), or each method can be used to generate an image signal in a Cartesian coordinate system (x, y). Steering, apodization, and processing in the z-axis direction may be performed similarly.

  When performing steering, it is sufficient to perform wave number matching in the x and y directions and obtain spatial resolution according to the method (4). As will be described later, when performing calculations in the polar coordinate system (r, θ), it is also possible to provide a steering angle (an angle formed with the radial direction) in the polar coordinate system and perform steering in the same manner. It is possible to implement physical steering, transmit or receive, or implement soft steering for transmission and reception, or to implement physical steering and soft steering in combination. There are other methods such as method (1).

  When a virtual source or a virtual receiver is used, a virtual opening is realized at or before or after the position using the physical opening described in the method (5-1 ′). Transmission fixed focusing can be performed. For example, a linear array transducer may be virtually realized. In addition, a transducer having an arbitrary opening shape may be realized. An image signal is generated in a Cartesian coordinate system or a polar coordinate system, or a rectangular coordinate system set according to the physical aperture shape. It is possible to implement physical steering, transmit or receive, or implement soft steering for transmission and reception, or to implement physical steering and soft steering in combination. There are other methods such as method (1). In these, the generated transmitted or received wave may be steered or the opening may be virtually tilted (virtually mechanically steered). Of course, the physical aperture is mechanically steered as needed.

  As described above, the beam forming of the methods (1) to (4) can be performed, but the present invention is not limited thereto, and the same effect can be obtained by adapting to any beam forming. In particular, when the method (4) is used, reception beamforming can be performed for any transmission beam or wave in addition to the transmission fixed focus beam. Of course, the beam forming of the collective reception signal at the time of simultaneous transmission of a plurality of different beams or waves and the superposition of the reception signal for each transmission can be similarly performed.

Method (5-3): Generation of Image Signal at the Time of Reception in Spherical Coordinate System When a spherical nucleus wave aperture element array is used, three-dimensional digital wave signal processing is performed. When the element array is so, the reception of the wave is performed in the spherical coordinate system (r, θ, φ), and the received signal of the received wave is represented by f (r, θ, φ). Also in this case, various beamformings can be performed through the Jacobi operation, as in the case of the two-dimensional polar coordinate system (r, θ).

Specifically, a three-dimensional Fourier transform performed on the received signal f (r, θ, φ) to decompose the received wave into a plane wave in the Cartesian coordinate system (x, y, z) is performed by using the Cartesian coordinate system ( Expression (27) expressed in the wave number domain or the frequency domain (k _x , k _y , k _z ) of _x , _y , _z ) is expressed by Jacobi using x = rsin θcosφ, y = rcosθ, and z = rsinθsinφ. By the calculation, the image signal can be calculated as in Expression (28), and the image signal can be directly generated in the Cartesian coordinate system without performing the interpolation approximation processing. Needless to say, the beam forming of the methods (1) to (4) and (6) can be performed, but the present invention is not limited to this. In particular, when the method (4) is used, similarly to the case of the two-dimensional case, the reception beam forming can be performed for all the transmission beams or waves in addition to the transmission fixed focus beam. Of course, the beam forming of the collective reception signal at the time of simultaneous transmission of a plurality of different beams or waves and the superposition of the reception signal for each transmission can be similarly performed. In addition, when using a virtual source or a virtual receiver, when performing steering, etc., all can be performed in the same manner as in the two-dimensional case, and can be performed according to the Cartesian coordinate system or the spherical coordinate system, or the physical aperture shape. An image signal can be generated in the set orthogonal curved coordinate system.

Method (5 "): Generation of Image Signal in Arbitrary Orthogonal Curve Coordinate System When Transmitting or Receiving in Cartesian Coordinate System Contrary to the above series of methods, reception obtained by performing transmission or reception in Cartesian coordinate system From the signal, it is also possible to directly obtain an image signal represented by a two-dimensional polar coordinate system or a spherical coordinate system without performing interpolation approximation, which can be realized by a similar calculation, for example, when the received signal is f (x, y, z), a calculation that performs a Fourier transform in the r, θ, and φ directions to decompose the received signal into a circular wave or a spherical wave corresponding to a plane wave in a Cartesian coordinate system is performed through a Jacobi operation. These methods may also be used to change the FOV (e.g., may be wider), using the Jacobi operation, also in an arbitrary Cartesian coordinate system. And an image signal can be similarly generated in an arbitrary rectangular coordinate system when transmitted or received in an arbitrary coordinate system (a different orthogonal coordinate system such as an orthogonal Cartesian coordinate system or various curved rectangular coordinate systems). (This includes cases where the coordinate system is used, the origin is different or rotated, or even if the same orthogonal coordinate system is used, the origin position is different or rotated.) Other methods described in the method (5). Similarly, any transmitted beam or wave can be processed, steering can be implemented as well, and virtual sources and receivers can be used.

  Physically and mathematically, wave number matching can be performed at the time of the first Fourier transform, and wave number matching can be performed at the time of the last inverse Fourier transform. One of the features of the method (5) is that beamforming is performed in an arbitrary coordinate system without performing interpolation approximation processing in wavenumber matching. However, the method (1) is applied by applying the method (5). When performing the beamforming described in the methods (4), (6), and (7) in an arbitrary coordinate system, an interpolation approximation process may be performed in wave number matching, and each of them is described. Approximate wave number matching is performed, and beam forming may be performed at high speed. In order to perform approximate approximate wave number matching, it is necessary to appropriately oversample a received signal at the cost of an increase in the amount of calculation. In such a case, it is necessary to pay attention to an increase in the number of data of the Fourier transform, unlike a case where a signal at an arbitrary position can be selectively generated without performing the interpolation approximation processing.

Method (6): Migration Method In the migration processing, the measurement imaging apparatus of the present invention can perform the wave number matching without performing the interpolation approximation processing. The migration equation (the following equation (M6 ′)) itself is well known, and the derivation of the equation is also well known, so the derivation of the equation is omitted here.

  Non-Patent Document 12 describes a normal migration process based on one-element reception by one-element transmission (that is, non-deflection processing using transmission / reception data for monostatic aperture synthesis in method (2)). As a basis, in the case of plane wave transmission and / or reception with and without steering (processing corresponding to method (1)), a wave is generated from an arbitrary transmission aperture element for an arbitrary same position. Since the propagation time, which is the time until the wave is received by the receiving aperture element also serving as the transmitting aperture element, is different from that of the normal migration, the propagation velocity and the coordinates of the target position are replaced with the following equation (M1 )), A method of calculating a value represented by the same form (formula (M6)) is disclosed.

  However, the processes of the other methods (2) to (5) are not disclosed in Non-Patent Document 12 (the case where steering is performed in the method (2) is not disclosed). Further, in calculating the equation (M6 ′), interpolation approximation has conventionally been performed when performing wave number matching (formulas (M4) and (M4 ′)). Performs wave number matching with high accuracy without performing interpolation approximation (Equation (M7) and Equation (M7 ′)).

Two-dimensional coordinates with the x-axis in the horizontal direction and the y-axis in the depth direction are taken, and the coordinate of time is t. Table Specifically, in its normal migration, any opening devices position (x, 0) and an arbitrary position (x _s, y _s) the propagation time required for the wave reciprocates between, by the equation (M0) Is done.

On the other hand, in plane wave transmission in which the steering angle is θ (including 0 °), the propagation time is represented by Expression (M0 ′).

Therefore, in the calculation performed based on the migration method at the time of transmitting the deflection plane wave in the method (1), each of the transport speed c and the coordinate system (x _s , y _s ) representing the position of the target is read as equation (M1). , A normal migration formula is calculated (Formula (M4) and Formula (M5)).

  In summary, of the methods (1) to (5), the migration is the same except for the normal migration of performing the non-deflection processing using the transmission / reception data for monostatic aperture synthesis in the method (2). Can be processed. For example, a description will be mainly given of the procedure of calculating the migration in the method (1) when transmitting the polarized plane wave (including 0 °).

  FIG. 15 is a flowchart showing a migration process when a deflection plane wave is transmitted. When the received signal is represented by r (x, y, t), the received signal at the aperture element array position is represented by r (x, y = 0, t).

First, as shown in the equation (M2), the received signal is subjected to two-dimensional Fourier transform with respect to time t and the horizontal direction x (two-dimensional fast Fourier transform is preferable).
Here, k = ω / c, and the wave number k and the angular frequency (angular frequency) ω are related by a proportionality constant 1 / c, and have a one-to-one correspondence, and are expressed using ω instead of k. Can be calculated.

  As described above, a special two-dimensional fast Fourier transform method can be used. However, as a general method, first, in step S31, the received signal is compared with the time t at the horizontal coordinate x. A fast Fourier transform (FFT) is performed to obtain a spectrum of the analytic signal. Then, at each frequency coordinate within the band k, fast Fourier transform in the horizontal direction x may be performed (faster than calculating each of the two-dimensional spectra according to the formula (M2)).

When the plane wave is not transmitted by deflection, the above calculation is sufficient. However, when the plane wave is deflected, trimming must be performed. For this purpose, in step S32, the fast Fourier related to the time t is trimmed for trimming. Multiply the transformed R ′ (x, 0, k) by the complex exponential function (M3) (similar to the complex exponential function (11) in the method (1)). The operation can be calculated directly at a time, or a dedicated fast Fourier transform capable of such calculation is also useful).

Then, in step S33, a fast Fourier transform (FFT) is performed on the received signal in the horizontal direction x. Here, the result is represented as R '' (k _x , 0, k). By the way, even if it is programmed to perform trimming, it can handle the case where a plane wave is transmitted without deflection (steering angle 0 °).

Usually, wave number matching (or mapping) is then performed. Beam forming, when the normal migration method other than (method (when there is no steering 2)) (1) to (5), the propagation velocity c and the coordinate system (x _s, y _s) of the above formula As in (M1), the processing is performed by reading the propagation speed (E1) and the coordinate system (E2) for each beamforming.

For the two-dimensional Fourier transform R ″ (k _x , 0, k) calculated in the case of the method (including the method (1)) other than the normal migration (when there is no steering in the method (2)), Alternatively, for the above R (k _x , 0, k) calculated in the normal migration, through interpolation approximation (such as bi-linear interpolation using the angular spectrum closest to the frequency coordinate) , Respectively, the wave number matching represented by Expression (M4) or Expression (M4 ′) is performed.
However, when the received signal is a reflected signal, s = 2, and when the received signal is a transmitted signal, s = 1.
However, when interpolation approximation is not performed in the wave number matching of Expression (M4) and Expression (M4 ′), the wave number in the depth direction expressed by the proviso in each expression is used. Each wave number in the depth direction is obtained by dividing the angular frequency ω by the propagation velocity c and the equation (E1). Hereinafter, the same applies.

The wave number matching is performed as described above, and the following function (M4 ″) is obtained.
Further, the following equation (M5) or equation (M5 ′) is obtained using the function (M4 ″).

By applying the two-dimensional inverse Fourier transform on the wave number k _x and the wave number (E3) to the equation (M5) or (M5 ′) as represented by the equation (M6) or (M6 ′), A signal f (x, y) is generated.
The two-dimensional inverse Fourier transform in the calculation of the equations (M6) and (M6 ′) may be performed by performing a fast two-dimensional inverse Fourier transform (IFFT), and a special fast two-dimensional inverse Fourier transform may be used. common (popular) method, in each of formulas (M6) and the formula (M6 '), first, with respect to one of the wave number k _x in the signal band, the inverse fast Fourier transform about the other wavenumber (E3) Then, a fast inverse Fourier transform on the wave number k _x (within the signal band) may be performed on each of the generated spatial coordinates y (each of the two-dimensional image signals is expressed by the formula (M6) or Faster than calculating according to equation (M6 ')).

Non-Patent Document 12, y _S equation (M6) using have not been disclosed in the formula, was calculated using the y rather than y _S, after calculation, it is disclosed that correct the coordinates . The coordinates are corrected by performing approximation processing or by multiplying time based on multiplication of a complex exponential function, which is a past invention of the inventor of the present application, without performing the approximation processing. Equation (M6) can also be used when the deflection angle is 0 °.

In the measurement imaging apparatus of the present invention, the wave number matching is performed together with the two-dimensional inverse Fourier transform or the inverse Fourier transform in the depth direction without performing interpolation approximation. That is, the two-dimensional Fourier transform R ″ (k _x , 0, k) calculated in the case of the method (including the method (1)) other than the normal migration method (when there is no steering in the method (2)) For the above or R (k _x , 0, k) calculated in the normal migration method, first, as expressed by the equation (M7) or (M7 ′), performing integration over k for each _{k x,} perform wave number matching and the inverse Fourier transform of the depth direction of the wave number (E3) and (IFFT) at the same time (step S34), thereafter, the horizontal (x) direction Perform fast inverse Fourier transform.
Non-Patent Document 12, the formula (M7) using y _S in the formula are not disclosed. Equation (M7) can also be used when the deflection angle is 0 °. Like method (1) to (6), in terms of the sum of the frequency k components of the spectrum, inverse Fourier transform about the wave number k _x lateral performed (IFFT) can be calculated by inverse Fourier transform of one, Calculation is fast.

Further, if the migration is different from the normal migration (the processing corresponding to the case without the steering in the method (2)), the position in the horizontal (x) direction is corrected in the process of calculating the equations (M6) and (M7). It can be performed. For example, when the deflection plane wave of the method (1) is transmitted, first, in step S34, the calculation relating to the wave number (E3) is performed as described above, and in step S35, each result is obtained for position correction. for the function (M8), multiplied by a complex exponential function (M9), carried out thereafter, in step S36, inverse fast Fourier transform relates to lateral wavenumber _{k x} a (IFFT). Alternatively, calculation may be performed by multiplying the complex exponential function of the inverse Fourier transform with respect to the wave number k _{x in the} horizontal direction by the equation (M9), or a dedicated inverse fast Fourier transform may be performed. Equation (M9) can also be used when the deflection angle is 0 °. As described above, in step S37, the image signal f (x, y) is generated.
In summary, a new process can be performed using Expression (M6), Expression (M7), or Expression (M7 ′), and the image signal f (x, y) can be removed at high speed except for an error due to interpolation approximation. ) Can be generated.

When the same result is obtained without approximation without multiplying the equation (M9), the following equation (N4) can be used instead of the equation (M4) to calculate the equation (M6) or the equation (M7). good.
That is, in the wave number matching, if interpolation approximation is not performed, the wave number in the depth direction represented by the proviso in the equation is used, but the wave number in the depth direction when performing interpolation approximation propagates the angular frequency ω. It is divided by the speed (E1).
The equation of the wave number in the depth direction expressed in this equation is similar to the equation (13) in the method (1), but in the method (1), kx in the equations (13) to (15) is used. In the case where the same result is obtained without using -ksinθ of -ksinθ (calculated as zero), similar to the case of performing the inverse Fourier transform by multiplying the equation (M9) in the method (6), Before performing the processing described, equation (16) may be multiplied by equation (M9). However, the plane wave deflection realized by the method (6) is realized only by approximation calculation. Therefore, when the equations (N4) and (M7) are used in the method (6). Is highly accurate without any approximation processing, but the accuracy decreases when the equation (M9) is used in the method (1). When the last inverse Fourier transform is performed by a two-dimensional fast inverse Fourier transform (as will be described later, in the case of three dimensions, a three-dimensional fast inverse Fourier transform), if those processes are performed, the calculation speed becomes In the method (6), the speed is increased, but in the method (1), the speed is reduced (the process described in paragraph 0204 is fast).
In each of the modified methods (1) and (6), when performing interpolation approximation processing in wavenumber matching, when obtaining the same result using equations (M9) and (N4), , The interpolation approximation formula changes correspondingly (described in each of (A) and (B) in paragraph 0354).
In each of the modified methods (1) and (6), when the interpolation approximation processing is performed in the wave number matching, the above equations (11) and (M3) are used (deflection angle data θ ) And the case where equations (11) and (M3) are not used (deflection angle θ is set to zero), the interpolation approximation equation also changes correspondingly (when not used). Is described in each of (A ′) and (B ′) in paragraph 0354).
The beamforming using the plane wave transmission is applied to various beamformings as described in the specification of the present application, but the processing described in this paragraph may be used in those applications instead. It should be noted that when receiving dynamic focusing is performed on an arbitrary beam-formed beam, such as the beam focused by applying the method (6), as described later, the angular frequency ω (M3 ″) expressed by using the wave number (Equation (M13)) expressed by using Eq. (E1) and the converted propagation speed (E1), the -ksin θ in the interpolation approximation equation is used instead of the equation (M3). _For the wave number k of _t , it is necessary to use equation (M13) instead.
In each of the method (1) and the method (6), the method described in this paragraph may be implemented in combination. For example, similar to the method of J.-y. Lu et al. (See paragraph 0197, the expression is described in (C ′) of paragraph 0354) in which interpolation approximation is performed in method (1), wave number matching is performed in method (6). Can be performed through interpolation approximation, and the first two-dimensional Fourier transform and the last two-dimensional inverse Fourier transform can be performed by a high-speed two-dimensional Fourier transform (described in (D ′) of paragraph 0354. As described later, In the case of three dimensions, three-dimensional fast Fourier transform). In each of these, equation (11) may be used (using deflection angle data θ) and equation (M3) may be used (described in each of (C) and (D) in paragraph 0354). Of course, it can be used even when there is no deflection.
As described above, the plane wave transmission based on the method (1) and the method (6) is applied to various beamforming.

  Here, it has been mainly described that the beam forming at the time of plane wave transmission with and without steering in the method (1) is performed at high speed without interpolation in wave number matching by using the migration method. Method (2) (monostatic aperture synthesis including steering), method (3) (multistatic method with or without steering), method (4) (fixed transmission focus with or without steering), and All the beamforming described in each of the methods (5) (beamforming in a polar coordinate system and an arbitrary orthogonal curve coordinate system) can be similarly performed. The same processing can be performed when the deflection angle is different between transmission and reception. Apodization may be performed similarly.

  The same processing can be performed for a three-dimensional case. When the received signal obtained using the two-dimensional aperture element array is represented by r (x, y, z, t), the received signal at the aperture element array position (y = 0) is r (x, y = 0, z, t).

First, as shown in the equation (M'2), the received signal is subjected to three-dimensional Fourier transform with respect to time t, lateral direction x, and elevation direction z (three-dimensional fast Fourier transform is preferable).
Here, k = ω / c.

Generally, the received signal is subjected to a fast Fourier transform (FFT) with respect to time t at each position coordinate (x, 0, z) to obtain a spectrum R (x, 0, z, k) of the analysis signal. Can be Then, at each frequency coordinate in the band k, a fast Fourier transform is performed on the horizontal direction x and the elevation direction z, and R (k _x , 0, k _z , k) is obtained (each of the three-dimensional spectrum is Faster than calculating according to equation (M'2)).

In the case where the plane wave is not deflected and transmitted, the above calculation may be performed. Must be trimmed, for which, multiply the complex exponential function (M′3) by R ′ (x, 0, z, k) after the fast Fourier transform for the above time t (fast Fourier for time t). The conversion and the multiplication of the complex exponential function can be calculated directly at once, or a dedicated fast Fourier transform that can perform such a calculation is also useful.)

Then, a fast Fourier transform (FFT) is performed on the received signal in the horizontal direction x. The result is defined as R ″ (k _x , 0, z, k). By the way, even if it is programmed to perform trimming, it can handle the case where a plane wave is transmitted without deflection (steering angle 0 °).

Next, wave number matching (or mapping) is performed. Beam forming, in the case of conventional migration methods (1) to the other (when there is no steering of the method (2)) (5), the propagation velocity c and coordinate system _{(x s, y s, z} s) The processing is performed by reading the propagation speed (E'1) and the coordinate system (E'2) for each beamforming.

For the three-dimensional Fourier transform R '' (k _x , 0, z, k) calculated in the case of the method (including the method (1)) other than the normal migration (without the steering of the method (2)) Or the above R (k _x , 0, z, k) calculated in a normal migration, by interpolation approximation (using the angular spectrum closest to the frequency coordinate, bi-linear) Through interpolation or the like, the wave number matching represented by Expression (M'4) or Expression (M'4 ') is performed, respectively.
However, when the received signal is a reflected signal, s = 2, and when the received signal is a transmitted signal, s = 1.
However, when interpolation approximation is not performed in the wave number matching of Expressions (M'4) and (M'4 '), the wave number in the depth direction indicated by the proviso in each expression is used. Is performed, the wave number in each depth direction is obtained by dividing the angular frequency ω by the propagation velocity c and the equation (E′1). Hereinafter, the same applies.

The wave number matching is performed as described above, and the following function (M′4 ″) is obtained.
Further, the following expression (M'5) or expression (M'5 ') is obtained using the function (M'4'').

For the expression (M'5) or (M'5 '), as represented by the expression (M'6) or the expression (M'6'), the wave numbers k _x and k _z , An image signal f (x, y, z) is generated by performing a three-dimensional inverse Fourier transform on the wave number (E′3).

The three-dimensional inverse Fourier transform in the calculation of the equations (M'6) and (M'6 ') may be performed by performing a fast three-dimensional inverse Fourier transform (IFFT), and using a special fast three-dimensional inverse Fourier transform. However, as a general method, in each of the equations (M′6) and (M′6 ′), first, for two wave numbers k _x and k _z in the signal band, A fast inverse Fourier transform on the other wave number (E′3) is performed, and then a fast inverse Fourier transform on the wave numbers k _x and k _z (within the signal band) is performed on each of the generated spatial coordinates y. (Which is faster than calculating each of the three-dimensional image signals according to equation (M'6) or equation (M'6 ')).

In the measurement imaging apparatus of the present invention, the wave number matching is performed together with the three-dimensional inverse Fourier transform or the depth direction inverse Fourier transform without performing interpolation approximation. That is, the three-dimensional Fourier transform R ″ (k _x , 0, k _z , calculated in the case of the method (including the method (1)) other than the normal migration method (when there is no steering in the method (2)) k) or the above R (k _x , 0, k _z , k) calculated by the ordinary migration method, is expressed by the equation (M′7) or (M′7 ′). First, the integration with respect to k is performed for each (k _x , k _z ) in the band, and the wave number matching of the wave number in the depth direction (E′3) and the inverse Fourier transform (IFFT) are performed. At the same time, after that, a fast inverse Fourier transform in the horizontal (x) direction and the elevation (z) direction is performed.

Non-Patent Document 12, the formula (M'6) or (M'7) using _{y S} in the formula are not disclosed. Both methods can be used even when the deflection angle is 0 °. Like method (1) to (6), in terms of the sum of the frequency k components of the spectrum, performs inverse Fourier transform (IFFT) relates wavenumber k _x and k _z lateral and elevation direction, once the reverse Calculation can be performed by Fourier transform, and the calculation is fast.

Furthermore, if the migration is different from the normal migration (the processing corresponding to the case without the steering in the method (2)), the horizontal (x) direction is calculated in the process of calculating the equations (M′6) and (M′7). And the position in the elevation direction (z) can be corrected. For example, when the deflection plane wave of the method (1) is transmitted, first, as described above, the calculation regarding the wave number (E′3) is performed, and the function (M′8) obtained as a result is obtained for position correction. Is multiplied by a complex exponential function, and then a fast inverse Fourier transform (IFFT) is performed on the wave numbers k _x and k _{z in} the lateral direction and the elevation direction.
In summary, a new process can be performed using the formula (M'6), the formula (M'6 '), the formula (M'7), or the formula (M'7'). The image signal f (x, y, z) can be generated at high speed except for errors.

When the same result is obtained without approximation processing without multiplying the complex exponential function corresponding to the equation (M9) in the two-dimensional case, the following equation (N'4) is used instead of the equation (M'4). Equation (M6) or Equation (M7) may be calculated using.
That is, in the wave number matching, when interpolation approximation is not performed, the wave number in the depth direction represented by the proviso in the equation is used, but the wave number in the depth direction when performing interpolation approximation propagates the angular frequency ω. It is divided by the speed (E'1).
The equation of the wave number in the depth direction expressed in this equation is similar to the equation (C22) in the method (1), however, in the method (1), kx in the equations (C22) and (C23) is used. If the same result is obtained without using -ksinθcosφ and -ksinθsinφ of -ksinθcosφ and kz-ksinθsinφ, the complex corresponding to the equation (M9) in the two-dimensional case in the method (6) As in the case of performing the inverse Fourier transform by multiplying by the exponential function, the multiplication may be performed during the processing described in paragraph 0207. However, the plane wave deflection realized by the method (6) is realized only by approximation calculation. Therefore, similarly to the two-dimensional case, the method (6) uses the equation (N'4) When the equation (M7) is used, the precision is improved without any approximation processing. However, when the complex exponential function corresponding to the equation (M9) in the two-dimensional case is used in the method (1), the precision becomes higher. descend. When the last inverse Fourier transform is performed by a three-dimensional fast inverse Fourier transform, when these processes are performed, the calculation speed is increased by the method (6), as in the case of the two-dimensional inverse Fourier transform. The method (1) is slow (the process described in paragraph 0204 is fast).
In each of the modified methods (1) and (6), when performing interpolation approximation processing in wave number matching, a complex exponential function and an expression (N When the same result is obtained using '4), the interpolation approximation equation changes correspondingly as described in the two-dimensional case (described in each of (A) and (B) in paragraph 0354).
In each of the modified methods (1) and (6), when the interpolation approximation processing is performed in wavenumber matching, the above equations (C21) and (M'3) are used (deflection angle The same result is obtained when the data θ and φ are used) and when the equations (C21) and (M′3) are not used (all the deflection angles θ and φ are set to zero). Similarly to the above, the expression of the interpolation approximation changes correspondingly (the case where it is not used is described in each of (A ′) and (B ′) in paragraph 0354).
The beamforming using the plane wave transmission is applied to various beamformings as described in the specification of the present application, but the processing described in this paragraph may be used in those applications instead. It should be noted in the same manner as in the case of the two-dimensional case that the dynamic dynamic focusing is performed on a beam that has been subjected to arbitrary transmission beamforming such as a beam that has been transmitted and focused by applying the method (6). As described later, (M′3 ″) expressed by using the wave number (Equation (M′13)) expressed by using the angular frequency ω and the converted propagation velocity (E′1) is expressed by the following equation (M for use instead of '3), the wave number k of -ksinθ in interpolation approximation formula _{1 (cosφ 1 x + sinφ 1} z), it is necessary to use the formula (M'13) instead.
In each of the method (1) and the method (6), the method described in this paragraph may be implemented in combination. For example, similar to the method of J.-y. Lu et al. (See paragraph 0197, the expression is described in (C ′) of paragraph 0354) in which interpolation approximation is performed in method (1), wave number matching is performed in method (6). Can be performed through interpolation approximation, and the first three-dimensional Fourier transform and the last three-dimensional inverse Fourier transform can be performed by a fast Fourier transform (described in (D ′) of paragraph 0354). In each of these, equation (C21) is used (using deflection angle data θ) and equation (M'3) is sometimes used (described in each of (C ') and (D') in paragraph 0354). . Of course, it can be used even when there is no deflection.
As described above, the plane wave transmission based on the method (1) and the method (6) is applied to various beamforming.

  Also in this migration method, in a manner similar to the method (2) or the method (3), monostatic or multistatic aperture plane synthesis can be performed without performing interpolation approximation processing in wave number matching.

In the case of monostatic synthetic aperture, when each of the reception angle and soft transmissions deflection angle is θt and [theta] r, using instead, the propagation velocity c and the ultrasonic angular frequency omega ₀ of the formula (M3) Table Wave number
Represented using
Similarly, in the equation (M7 ′) in the case where interpolation processing is not required in wave number matching in normal migration processing,
However, when the received signal is a reflected signal, s = 2, and when the received signal is a transmitted signal, s = 1.
It is good.

Further, in the case of the three-dimensional case, it is assumed that each of the deflection angles of the transmission beam and the reception beam is expressed by using (elevation angle, azimuth angle) = (θ _t , φ _t ) and (θ _r , φ _r ). The wave number matching is first performed in the horizontal direction by multiplying by a complex exponential function (Equation (D41)) expressed by using the carrier frequency ω ₀ of the ultrasonic signal in the same manner as in the method (2), and the depth y With respect to the direction, a complex exponential function (Equation (D43)) excluding the horizontal matching processing (Equation (D41)) is applied to give a resolution in the depth y direction, and at the same time, a complex exponential function (Equation (D43)) is applied. )). That is, equation (D41) is used instead of equation (M3 ') in the two-dimensional case, and the product of equation (D42) and equation (D43) is used instead of equation (M11).

  Thus, the migration processing in the present invention corresponding to the method (2) and the method (3) based on the method (2) is equivalent to the method (2) and the method (3).

Also in these cases, it is possible to perform the fast inverse Fourier transform by performing the interpolation process in the wave number matching as in the case of the normal migration process. In that case, the method (2) and the method ( 3) is not equivalent, and after the above-described processing using the equation (M3 ′) and the like, instead of the equation (M4 ′) that is the wave number matching with the interpolation processing, based on the equation (M11),
However, when the received signal is a reflected signal, s = 2, and when the received signal is a transmitted signal, s = 1. When interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used. It is divided by c. Hereinafter, the same applies.
Equation (M4 ″) is obtained, and the two-dimensional inverse Fourier transform (Equation (M6 ′)) of the equation (M5 ′) expressed using the same ky of (M4 ′ ″) is performed. Or, instead of formula (M4 ′),
However, when the received signal is a reflected signal, s = 2, and when the received signal is a transmitted signal, s = 1. When interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used. It is divided by c. Hereinafter, the same applies.
Equation (M4 ″) is obtained by performing wave number matching with interpolation processing represented by the following equation, and into equation (M5 ′) represented using the same ky of (M4 ″ ″),
May be subjected to a two-dimensional inverse Fourier transform (corresponding to equation (M6 ′)).

  Also in this case, the multi-static aperture synthesis is performed in exactly the same manner as when the method (3) is realized by applying the method (2). It can be realized by applying the aperture synthesis method.

The same processing can be performed for a three-dimensional case. That is, after the processing using the equation (M'3 ') in the three-dimensional case, the equation (D42) and the equation (D42) are used instead of the equation (M'4') which is the wave number matching with the interpolation processing. D43) (corresponding to (M11) in two dimensions)
However, when the received signal is a reflected signal, s = 2, and when the received signal is a transmitted signal, s = 1. When interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used. It is divided by c. Hereinafter, the same applies.
Equation (M′4 ″) is obtained, and the three-dimensional inverse Fourier transform (formula (M ′)) of the equation (M′5 ′) expressed using the same ky of (M′4 ″ ′) is obtained. 6 ′)) or, instead of formula (M′4 ′),
However, when the received signal is a reflected signal, s = 2, and when the received signal is a transmitted signal, s = 1. When interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used. It is divided by c. Hereinafter, the same applies.
Expression (M′4 ″) is obtained by performing wave number matching with interpolation processing represented by the following expression, and expression (M′5 ′) expressed using the same ky of (M′4 ″ ″) )
May be subjected to a three-dimensional inverse Fourier transform (corresponding to equation (M'6 ')).

  Also in this case, the synthesis of the multi-static aperture surface is performed in exactly the same manner as when the method (3) is realized by applying the method (2). It can be realized by applying a synthesis method.

  Based on these migration methods, all beamformings described in the methods (2) and (3) can be similarly performed.

  Also, by using the above-described migration processing at the time of plane wave transmission (Equation (M7) or the like) corresponding to the method (1), any beam such as a fixed focus beam of the method (4) can be used without performing interpolation approximation in wave number matching. In addition to the above, it is possible to perform beamforming when transmitting an arbitrary wave (including a wave that has not been beamformed), superimposing processing when transmitting a plurality of beams and waves, and processing when simultaneously transmitting a plurality of beams and waves. . A plurality of beamformings may be performed using a multidirectional aperture synthesis method, and in such a case, the beamforming is performed at a high speed. Also, they are not limited. In those cases, as in the case of using the method (1), in combination with the method (2), deflection dynamic focusing of reception can be performed for arbitrary transmission beamforming.

When the physical transmission deflection angle of the focus beam is A and the software transmission deflection angle and the reception angle are θ (= θt) and θr, respectively, instead of the equation (M3), the angular frequency ω Wave number expressed using reduced propagation velocity (E1)
Represented using
Similarly, when the physical transmission deflection angle of the plane wave is A, and if the soft transmission deflection angle and the reception angle are θ (= θt) and θr, respectively, the equation (M3) can be replaced by To
Is similarly used, and in the formula (M7),
It is good.

Further, the same processing can be performed in the case of three dimensions. When the physical transmission deflection angle of the focus beam is represented by an elevation angle A and an azimuth angle B (including a case where at least one of the angles is zero degree), a soft transmission deflection angle (elevation angle θ ₁ and When steering is performed at an azimuth angle φ ₁ ) and steering dynamic focusing is performed at a deflection angle (elevation angle θ ₂ , azimuth angle φ ₂ ) (including a case where at least one of the angles is zero degree), the following expression is used. Wave number expressed using angular frequency ω and reduced propagation velocity (E′1) instead of (M′3)
Represented using
Similarly, when the physical transmission deflection angle of a plane wave is represented by an elevation angle A and an azimuth angle B (including a case where at least one of the angles is zero degree), a soft transmission deflection angle is used. Steering at (elevation angle θ ₁ and azimuth angle φ ₁ ) to perform steering dynamic focusing at deflection angle (elevation angle θ ₂ , azimuth angle φ ₂ ) (including a case where at least one of the angles is zero degree) ) Includes, instead of equation (M'3),
Is similarly used, and in the formula (M'7),
It is good.

In this case as well, it is possible to perform the fast inverse Fourier transform by performing the interpolation process in the wave number matching in the same manner as the normal migration process. Instead of (M4), based on equation (M11 ″ ′),
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction indicated by the proviso in the equation is used. It is divided by the speed (E1). Hereinafter, the same applies.
Equation (M4 ″) is obtained, and the two-dimensional inverse Fourier transform (Equation (M6)) of Equation (M5) expressed using the same ky of (M4 ′ ″ ″) is performed. Or, instead of equation (M4),
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction indicated by the proviso in the equation is used. It is divided by the speed (E1). Hereinafter, the same applies.
Equation (M4 ″) is obtained by performing wave number matching with interpolation processing expressed by the following equation. Equation (M5) expressed using the same ky of (M4 ″ ″ ″)
, A two-dimensional inverse Fourier transform (corresponding to equation (M6)) may be performed.

In the above, if the equations (M3 ″) and (M3 ″ ′) are exchanged and processed, an error occurs in which the imaging position shifts when performing soft transmission steering (when θt is non-zero). Is generated. In these processes, the wave number represented by using the ultrasonic angular frequency ω ₀ and the converted propagation velocity (E1) instead of the equation (M10) which is the wave number corresponding to the ultrasonic frequency.
Is used, when soft reception steering is performed (when θr is non-zero), an error (deflection angle 20 °) in which the generated deflection angle is larger than that in the case of using the equation (M10) is generated. Is realized, about 1 or 2 °), but an image is obtained.

Further, the same processing can be performed in the case of three dimensions. That is, after the processing using the equation (M'3 '') in the case of three-dimensional, etc., instead of the equation (M'4) which is the wave number matching with the interpolation processing, the equation (M'11 '') is used. ')On the basis of the,
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction indicated by the proviso in the equation is used. It is divided by the speed (E'1). Hereinafter, the same applies.
Equation (M′4 ″) is obtained, and the three-dimensional inverse Fourier transform (Equation (M′5)) of Equation (M′5) expressed using the same ky of (M′4 ″ ″ ′) is obtained. '6)) or, instead of equation (M'4),
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction indicated by the proviso in the equation is used. It is divided by the speed (E'1). Hereinafter, the same applies.
Expression (M′4 ″) is obtained by performing wave number matching with interpolation processing expressed by the following expression, and expression (M ′) expressed using the same ky of (M′4 ″ ″ ″) 5)
, A two-dimensional inverse Fourier transform (corresponding to equation (M'6)) may be performed.

In the above, if the equations (M′3 ″) and (M′3 ″ ″) are exchanged and processed, the result is obtained when soft transmission steering is performed (when the deflection angle is non-zero). An error occurs in which the image position shifts. In these processes, the wave number represented by using the ultrasonic angular frequency ω ₀ and the converted propagation velocity (E ′ 1) instead of the equation (M′10) that is the wave number corresponding to the ultrasonic frequency.
Is used, when soft reception steering is performed (when the deflection angle is non-zero), an error occurs in which the generated deflection angle is larger than when the equation (M'10) is used. However, an image is obtained.

In this case, when the migration method based on the equation (N4) described in paragraph 0316 is used, when the physical transmission deflection angle of the focus beam is A, the soft transmission deflection angle and the reception angle Are represented by θ (= θt) and θr, respectively, and are expressed by using the wave number (M13) expressed by using the angular frequency ω and the reduced propagation velocity (E1) instead of the equation (M3) (M3 ′). '), And when the physical transmission deflection angle of the plane wave is A and the soft transmission deflection angle and the reception angle are θ (= θt) and θr, respectively, the equation (M3) is obtained. May be used instead of (M3 ′ ″), and the following equation (N4 ′) may be used instead of equation (N4) in equation (M6) or (M7).
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction expressed by the proviso in the equation is used, and the wave number in the depth direction when performing interpolation approximation is obtained by converting the angular frequency ω into the converted propagation velocity ( E1). Hereinafter, the same applies.

In addition, the same processing can be performed in a three-dimensional case (when a migration method based on Expression (N′4) described in paragraph 0331 is used). When the physical transmission deflection angle of the focus beam is represented by an elevation angle A and an azimuth angle B (including a case where at least one of the angles is zero degree), a soft transmission deflection angle (elevation angle θ ₁ and When the steering is performed at the azimuth angle φ ₁ ) and the steering dynamic focusing is performed at the deflection angle (elevation angle θ ₂ , azimuth angle φ ₂ ) (including a case where at least one of the angles is zero degree), the following expression is used. Equation (M′3 ″) expressed using the wave number (M′13) expressed using the angular frequency ω and the converted propagation velocity (E′1) instead of (M′3) is similarly used. Used, and when the physical transmission deflection angle of the plane wave is represented by an elevation angle A and an azimuth angle B (including a case where at least one of the angles is zero degree), a soft transmission deflection angle (elevation angle θ) ₁ and azimuth angle phi ₁₎ steering to the deflection angle at (elevation theta _2, the azimuth angle In the case of performing the steering dynamic focusing in ₂₎ (including those which are the zero either at least one angle), instead of equation (M'3), similarly formula (M'3 ''') In equation (M'6) or (M'7), the following equation (N'4 ') may be used instead of equation (N'4).
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction expressed by the proviso in the equation is used, and the wave number in the depth direction when performing interpolation approximation is obtained by converting the angular frequency ω into the converted propagation velocity ( E'1). Hereinafter, the same applies.

  In this manner, beamforming based on these migration methods can be performed with or without performing interpolation approximation processing in wavenumber matching, similarly to the method described in paragraphs 0316 and 0331.

Further, the processing described in paragraphs 0316 and 0331 with respect to the method (1) is performed by combining the method (1) and the method (2) (when the reception deflection dynamic focusing is performed in the method (1) described in the paragraphs 0235 to 0238). ) Can be similarly implemented. That is, in the two-dimensional case, when the same result is obtained when the deflection angle θ in Equation (F42) and Equation (F43) is calculated as zero, the inverse is obtained by multiplying Equation (M9) in Method (6). As in the case of performing the Fourier transform, the expression corresponding to the expression (16) may be multiplied by the expression (M9) before performing the processing described in paragraph 0204. In addition, in the case of three dimensions, when the same result is obtained when all the deflection angles θ and φ in Equations (G22) and (G23) are calculated as zero, the two-dimensional case in the method (6) is used. As in the case of performing the inverse Fourier transform by multiplying the complex exponential function corresponding to the equation (M9), the multiplication may be performed during the processing described in paragraph 0207.
As described in paragraphs 0316 and 0331, such beamforming can also be performed with or without performing interpolation processing in wavenumber matching. Others are as described in the same paragraph.

  Based on these migration methods, all beamformings described in the method (4) can be similarly performed.

  Also, as described in the method (5), when transmission / reception is performed in an orthogonal coordinate system other than a Cartesian coordinate system such as a polar coordinate system, the expressions (M6), (M6 ′), and ( M7), the result of performing the Jacobi operation on the equation (M7 ′) is calculated, and the above-described beamforming is performed, so that the result can be directly obtained in the Cartesian coordinate system. Also in the case of three dimensions, the Jacobian operation is applied to the equations (M'6), (M'6 '), (M'7), and (M'7') in exactly the same manner. Can be processed. In addition, all beamforming described in the method (5) can be similarly performed.

One of the objects of the present invention is to realize high-speed and high-precision beamforming based on the Fourier transform. However, interpolation approximation using the above methods (1) to (6) is performed. Any of these processes can be modified and used as processes with various forms of interpolation approximation, and may be used at a higher speed, although the accuracy is reduced. In the horizontal direction, the elevation direction, and the depth direction, at least one or two directions, whether to perform wave number matching in all three directions by approximation, or to use multiplication of a complex exponential function, The method can be modified and used. The speed can be increased by performing many approximations, but the accuracy decreases. Some of the explanations so far have already been made. In this paragraph, (A), (A '), (B), (B'), (C), (C '), and (C) described in paragraphs 0316 and 0331 are respectively related to the two-dimensional and three-dimensional cases. Interpolation approximation formulas for the eight cases D) and (D ') are shown.
For example, when the plane wave steering is performed by the migration method of the method (6), the same processing can be performed. When the wave number matching in all directions is approximated by interpolation (corresponding to (D ′)), the interpolation approximation is performed by the method (1). Similar to the method of J.-y. Lu et al. (See paragraph 0197, corresponding to (C ')) for performing the processing, the calculation is the fastest when using migration. However, accuracy is the lowest in migration. On the other hand, in the method of J.-y. Lu et al. (See paragraph 0197, corresponding to (C ′)), for example, if only the horizontal wave number matching is performed before the Fourier transform, the accuracy is improved, but the calculation speed is increased. Lower (corresponds to (C)). In addition, the interpolation process (formula) for the two-dimensional case (paragraph 0316) including the cases of (A), (A '), (B), and (B') is shown below (for the three-dimensional case (paragraph 0331)). ) Is similarly expressed, abbreviation). Note that (A), (A '), (C), and (C') are represented according to equations (7) and (8). In (B ′) and (D ′), the inverse Fourier transform in the horizontal direction is performed not on kx but on kx ′.
Wave number k _y in the depth direction of the case of performing the interpolation approximation in wavenumber matching, but is obtained by dividing the angular frequency ω in propagation velocity c, can be processed as described above when no interpolation approximation.
Wave number k _y in the depth direction of the case of performing the interpolation approximation in wavenumber matching, but is obtained by dividing the angular frequency ω in propagation velocity c, can be processed as described above when no interpolation approximation.
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction indicated by the proviso in the equation is used. It is divided by the speed (E1).
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction indicated by the proviso in the equation is used. It is divided by the speed (E1).
Wave number k _y in the depth direction of the case of performing the interpolation approximation in wavenumber matching, but is obtained by dividing the angular frequency ω in propagation velocity c, can be processed as described above when no interpolation approximation.
Wave number k _y in the depth direction of the case of performing the interpolation approximation in wavenumber matching, but is obtained by dividing the angular frequency ω in propagation velocity c, which is one of the present invention, when no interpolation approximation method According to (1), processing can be performed as described above.
However, in the case where interpolation approximation is not performed in the wave number matching, which is one of the present invention (one of the methods (6)), the wave number in the depth direction expressed by the proviso in the equation is used. Is obtained by dividing the angular frequency ω by the reduced propagation velocity (E1).
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction indicated by the proviso in the equation is used. It is divided by the speed (E1).
Also in these, the method (2) may be used together in the reception beamforming.
It is important to perform the first multidimensional Fourier transform and inverse multidimensional inverse Fourier transform at high speed, and various fast Fourier transform algorithms can be used appropriately. Physically and mathematically, wave number matching can be performed at the time of the first Fourier transform, and wave number matching can be performed at the time of the last inverse Fourier transform. In addition, all of the methods other than the beamforming (methods (1) to (6)) described in the present specification can be similarly realized without interpolation approximation processing or processing through the approximation processing. In the case of performing the interpolation approximation processing, the sampling frequency may be increased in order to increase the accuracy. However, unlike the case where the signal of an arbitrary position can be generated without performing the interpolation approximation processing, the number of data of the Fourier transform increases. Be careful with this. However, even when the interpolation approximation process is not performed, it is important to appropriately perform oversampling and realize a situation in which the signal is processed with a high SN ratio.
In such a case, even when the migration processing is based (method (6)), the beam forming described in the methods (1) to (5) (the collective reception signal or the simultaneous reception signal at the time of simultaneous transmission of a plurality of different beams or waves) is used. (Including beamforming of superposition of received signals for each transmission, use of a virtual source and a virtual receiver, etc.) can be performed when interpolation approximation is performed and when interpolation is not performed.

Method (7): Others In the above methods (1) to (6), the case where a one-dimensional array is mainly used has been described. However, in the case of a two-dimensional array or a three-dimensional array, the method is performed as described above. In each case, the processing performed in the lateral direction may be similarly performed in the other one or the other two axial directions. These can be implemented in any rectangular coordinate system including a rectangular coordinate system. That is, the above methods (1) to (6) may be simply extended to higher dimensions. Further, during the processing of the methods (1) to (6) and the method (7) described here, a DC component or a low frequency component in the horizontal or vertical direction may be generated. It is preferable to perform a spectrum zeroing process at a stage before the inverse Fourier transform. When starting the digital signal processing, analog processing or digital processing is performed as a preprocessing to cut off the direct current, but the spectrum may be zero-filled in the angular spectrum.
In addition, when performing the digital Fourier transform, the periodicity (ie, cyclicity) of the distribution of the raw signal before processing and the image signal after processing in a finite spatial domain is assumed. (Mainly, a boundary in a direction parallel to the surface of the physical aperture element array, a boundary running in a so-called lateral direction or an elevation direction, etc.), and other side surfaces or vertical boundaries (mainly, a surface of the physical aperture element array). There may be a problem that the raw signal component before processing and the image signal after processing cyclically appear around a boundary in a direction orthogonal to the axis or a boundary running in a so-called axial direction.
In both the case where the reflected wave is targeted and the case where the transmitted wave is targeted, as the signal propagates away from the transmission aperture surface, the signal intensity decreases due to diffusion, attenuation, scattering, and reflection phenomena. Has such a raw signal, the boundary between the upper and lower portions of the region of interest (mainly, the boundary in the direction parallel to the plane of the physical aperture element array or the boundary running in the so-called lateral direction or elevation direction). Etc.) may not be a problem, but it is a problem when the intensity of the raw signal is not small at the upper and lower portions. If the receiving aperture is different from the transmitting aperture for the transmitted wave, the signal strength at the position of the receiving aperture may be problematic. In such a case, the region of interest of the raw signal is added to the region of the zero signal (strictly speaking, the distance between the upper portion and the lower portion) in a direction (length direction) approaching from the upper portion of the region of interest toward the transmission aperture plane (length direction). A region with a zero signal (strictly speaking, a region with a length between the upper and lower parts) in a direction (length direction) away from the transmission aperture plane below the region of interest. In addition, after processing by expanding the region of interest in the direction (length direction) away from the transmission aperture and the reception aperture, the image signal obtained in the added area may be discarded, or the raw signal may still be discontinuous. Therefore, the raw signal may be processed by multiplying the raw signal by a so-called window in the length direction, and the image signal obtained near the foot of the window may not be regarded as important.
On the other hand, on other side surfaces, vertical boundaries, and the like (mainly, boundaries in a direction orthogonal to the surface of the physical aperture element array and boundaries running in the so-called axial direction), raw signals representing different spatial positions are used. An image signal is synthesized, and the raw signal is often strong, and in most cases, the same phenomenon (artifact) becomes a problem. In such a case, a direction (width direction) away from the region of interest from at least one of the two boundaries forming a pair of a side surface and a vertical boundary of the region of interest in the region of interest of the raw signal. To the zero signal area (strictly speaking, the area having the larger width of the effective aperture width for transmission or reception), expand the region of interest in the horizontal direction, and process the image signal. Or the raw signal still has a discontinuous state, so instead of multiplying the raw signal by a so-called width direction window and processing it, it is important not to focus on the image signal obtained near the foot of the window is there. In the case of three dimensions, the windows are multidimensional in the lateral and elevation directions, so-called separable or non-separable windows. If steering is not performed, a problem occurs. However, when steering processing is performed, the processing is often required.
It may be useful to perform these processes simultaneously. If windows are used, the windows are multi-dimensional, so-called separable or non-separable windows. Further, in the image signal obtained without performing such processing, when there is an image signal that appears cyclically, the region of the image signal may be excluded from the region of interest.
Compared to two-dimensional imaging processing using a one-dimensional array sensor, multi-dimensional imaging processing using a two-dimensional or three-dimensional array sensor handles a larger amount of data, and high-speed Fourier beamforming increases its effectiveness. I can. In these cases, it is effective to store a complex exponential function or its nucleus depending on a depth position or a position in a distance direction as data in a memory in order to perform a calculation at high speed. Practically, data relating to a plurality of beamformings used in the apparatus is stored in a memory and used, or when the beamforming is selected, the data is loaded into the memory. Such data may be stored in advance in a medium such as a hard disk, or may be calculated when the apparatus is activated or when beam forming is selected. However, when the memory is insufficient in these multidimensional processing, the data cannot be stored in the memory, and it is used while appropriately calculating or reading from a medium such as a hard disk. Calculation speed decreases. The analysis signal or its spectrum in the calculation process may be used by storing only the signal components within the bandwidth of the original signal in the memory.

Also, in beamforming using other Fourier transforms described in Non-Patent Document 9, etc., the methods disclosed in Methods (1) to (7) can be used, and the same effect can be obtained. .
For example, Section 2.4 of Non-Patent Document 9 discloses a method of calculating an arbitrary beam or wave using a general solution (Green function) of a wave equation. Here, spherical waves, cylindrical waves, and plane waves are used as examples of analytical calculation. As a feature using the Green's function, the signal to be obtained is represented by a denominator in the frequency domain,
have. By using the method, it is possible to calculate using the Green's function in a cylindrical coordinate system, a spherical coordinate system, or any other orthogonal coordinate system.
That is, in the methods disclosed in the methods (1) to (7) or the mathematical expressions (with and without interpolation approximation in wavenumber matching), the spectrum of the signal to be obtained is represented by the formula (GR1) or (GR2) in the denominator. The calculation may be performed in a situation having. The methods and formulas described in the methods (1) to (7) can be applied to various other methods and beamforming.
In these cases using the Green's function, since a point source can be considered, it is suitable for representing a virtual source (Patent Document 7 and Non-Patent Document 8) set before and after a physical aperture. In that case, the processing on the actual radiation pattern of the physical aperture (element) described in the next paragraph is important.

  In addition, the methods (1) to (7) can apply, for example, a calculation in consideration of a radiation pattern of an aperture (element) described in Section 3.2 of Non-Patent Document 9. At that time, the signal intensity may be appropriately corrected by physical or soft apodization, and the signal may be processed. As described variously in this specification, for example, various processes such as ISAR (the motion of the observation target is sometimes applied), nonlinear processing, adaptive beamforming (Non-Patent Document 10), and the like are performed. In some cases, the resolution may be increased (particularly in the direction orthogonal to the propagation direction) or the contrast may be increased by suppressing side lobes. The coherent factor and the like described in Non-Patent Document 11 and the like can also be applied. In addition, the present invention is not limited to these, and apodization (which may also serve as a delay using a complex signal) is appropriately performed. The apodization includes a case where the apodization is variable not only in the propagation direction but also in the scanning direction.

  In addition, the methods (1) to (7) can be used also when transmitting or receiving apertures at various positions are used or when performing various other beamforming. For example, Non-Patent Document 9 provides various examples. For example, Geophysical Imaging (for example, paying attention to the shapes of Expressions 7.9 to 7.12) in Section 7.3 and so-called X-ray CT (Computed Tomography) are described. Also, the methods (1) to (7) can be used. Also noteworthy is FIG. 7.3 and equations 7.5 to 7.9, which are disclosed in the case of transmission imaging described in section 7.2 of Non-Patent Document 9. In these, processing can be performed without performing interpolation approximation processing, including wave number matching and the like (in those cases, interpolation approximation processing may be performed). Data such as apodization and complex exponents or their nuclei used in the Fourier beam forming process have data calculated or set in advance and stored in a storage device together with position coordinates, similarly to apodization and delay time data in the DAS process. Or read and used during processing (when starting up the device, connecting or selecting a sensor to be used with the device, changing beamforming parameters, etc.), or performing those processes. May be used while calculating.

  In addition, the methods (1) to (7) are predetermined biplanes or multiple planes, planes or tomographic planes extending in a desired arbitrary direction (they are not necessarily flat such as planes or tomographic planes, but are curved surfaces). Or an image signal on a line instead of a plane (a line is a straight line or a curved line) can be selectively and directly generated. For example, while images can be presented based on three-dimensional or two-dimensional image signals, images may be presented based on those image signals, or those images may be presented alone. It is possible. In signal processing, such image signals and images may be presented through interpolation approximation. Further, in these, measurement data such as displacement, strain, and temperature measured based on an image signal or an image may be displayed alone, or may be displayed by being superimposed on the image.

  As described multiple times herein, apodization can be determined and performed in a variety of ways. There are various adaptive beamforming, minimum variance beamforming, Capon method, and the like described in Non-Patent Document 10 and the like. In these, when the covariance matrix is regularized, the parameter (regularization parameter) for adjusting the degree of regularization can be appropriately determined for each position based on the SN ratio of the signal at each position. It can be spatially variant and processed. Alternatively, instead of using a unit matrix for the regularization operator, it is also possible to use other positive definite operators such as gradient operators and Laplacians. The resolution of the image signal can be increased (in particular, the direction orthogonal to the propagation direction), and the contrast can be enhanced by suppressing the side lobe. In the independent component analysis (independent signal separation), it is also effective to regularize the covariance matrix in the same manner. These regularization methods have not been disclosed before. Alternatively, in both processes, the rank is lowered based on singular value decomposition or eigenvalue decomposition to stabilize the process. These processes are also effective in other methods in beamforming. As described elsewhere, MIMO (Multiple-input and Multiple-output: a wireless communication technology that expands the band of a transmission / reception signal by combining a plurality of antennas on a transmission side and a reception side) and SIMO (Single-input and Multiple-output) It is also effective to use a single communication antenna on the transmitting side and a plurality of antennas on the receiving side to expand the band of the received signal. In addition, the inventor of the present application has favorably used absolute value detection and power-law detection in addition to envelope detection, but the coherence factor described in Non-Patent Document 11 and the like is effective. Absolute value detection and exponentiation detection are effective when visualizing the undulation of a wave. If an absolute value is taken or raised to a power, especially when the order is high, it will have a high frequency component. However, brightness may be assigned to the amplitude of the wave itself, or a color may be assigned to display. Can also be considered as detection with bias.) Non-Patent Document 10 describes various other adaptive beamforming, and also in this specification, MUSIC (Multiple Signal Classification: a radio communication technique using an eigenvalue or an eigenvector of a correlation matrix of a received signal) and the like. Various processes are described. In addition, the effective processing is not limited thereto, and there are various other processings. Such various processes can be performed before, during, and after beamforming, and can also be performed at the apodization level. In that case, it is extremely effective to perform processing after performing spatiotemporal alignment based on the correlation processing (the details will be described later).

  Further, in the present invention, in particular, the integration process (operation) may be performed in the time direction (distance direction) in which the rf data is obtained to improve the signal-to-noise ratio. This integration process is also performed by analog processing (so-called integrator) or digital processing (integrator or integration operation).

  Further, in the above description, the apodization process has been described to calculate the product of the weight value, which is easy and requires a small amount of calculation. However, the present invention is not limited to this, and the spatial domain and the frequency domain are used in a linear system. The convolution integral may be performed based on the dual relationship between the product and the convolution integral in. Appropriate apodization can be performed at each depth position or at the same distance from each aperture element.

The above-described lateral modulation signal (image signal) or lateral signal is obtained by a process of superimposing multi-directional deflection beams and plane waves generated by the measurement imaging apparatus according to the present embodiment using the methods (1) to (6). In some cases, a signal (image signal) having a wider bandwidth and higher resolution in the horizontal direction may be generated. As in the case of the single transmission, the steering may be performed physically or softly, or both may be performed individually, or the same steering may be applied to all of them. Although the description has been made focusing on performing the reception beamforming in a software manner, the reception beamforming using the reception delay or the reception apodization may be performed physically, alone or in combination, as necessary. On the other hand, transmission beamforming is mainly described as being physically performed, but for example, a high-speed frame rate can be obtained by transmitting a plane wave, transmitting a plurality of beams or waves, etc. In order to perform surface synthesis, transmission may be performed one element at a time (multidirectional aperture synthesis is also possible, and plane waves, cylindrical waves, spherical waves, etc. are coded and transmitted, decoded, and aperture synthesis is performed. Is also possible). As described above, it is possible to consider transmission and reception in reverse and to implement them in software. The plane wave arrives at a deeper position than the focus beam (echo is also obtained from the deep position compared with the echo), but the S / N ratio as a wave or beam for the purpose of measuring displacement is compared. And low. In the first place, the resolution in the horizontal direction is also low. On the other hand, when plane waves in multiple directions are superimposed, substantially the same lateral resolution can be obtained regardless of the position. On the other hand, when a focus beam is used, it is effective to cross beams in multiple directions at the focus position, but when trying to obtain high lateral resolution at multiple positions, multi-focusing is required. Will do. In any case, it is possible to achieve high-speed beamforming with respect to a reception signal when a plurality of waves or beams are transmitted at the same time, or a superposition of signals received and transmitted at different times even when the target is in the same phase. . In addition, a signal (image signal) whose bandwidth is increased in the axial direction and whose resolution is increased in the axial direction may be generated by using a plurality of waves having different carrier frequencies. In those cases, the bandwidth may be widened so that the spectra overlap, and the resolution may be increased. These plural beams may be simultaneously generated in parallel, and the measurement targets may be generated at the same time but at different times. Multi-directional waves may be generated by the above-described multi-directional aperture plane synthesis.
When the deflection angle is increased, the imaging positions of the reflector and the strong scatterer may be spatially shifted. For example, if the deflection angle is transmitted to the front of the aperture element and the plane wave is transmitted while changing the deflection angle in small increments (for example, every 1 °) to ± 45 °, and the beamformed signals are superimposed, the aperture in the front direction is increased. The case where the surfaces are combined can be simulated, and it is not possible to obtain a band corresponding to a deflection angle of ± 45 ° in the horizontal direction (the signal is canceled at the time of superposition). It is natural to consider the case where beamforming in the front direction is decomposed into plane waves as angular spectra. When broadening in the horizontal direction by superposition in space-time or frequency space is performed, not only in the case of transmission of polarized plane waves, but also in the case of performing other deflection beamforming, the spectrum that does not overlap in frequency space. Although it is necessary to superimpose, the cause of the spatial displacement of the imaging position can be found there. That is, an error occurs in the control of the focusing and the propagation direction due to the spatial inhomogeneity of the sound velocity of the medium (depending on the temperature and pressure) as well as the directivity of the aperture especially at the time of steering with a large steering angle. Therefore, when superimposing signals having a large deflection angle, at the time of transmission at the time of beamforming, or at the time of at least one of the reception signal before reception beamforming, during reception beamforming, and after beamforming, In some cases, it is necessary to perform signal position correction (phase aberration correction). When performing super-resolution by spectral processing or non-linear processing of these signals, when superimposing processing (superimposing spectral processing or non-linear processing, or superimposing spectral processing or non-linear processing) is used together, The effect of the position shift on the result (position error or the like) becomes significant, and such position correction may be important. In addition, the frequency dependence of the reduced propagation speed is also a factor that causes a position shift. In addition, the same problem may occur when signals of different frequencies are superimposed, and the same processing may be performed. In addition, waveform distortion may occur due to a phase delay or a phase change having a frequency dependency in a device (for example, a phase change in a sensor or a phase delay in an amplifier in a circuit). There is a case where the waveform is shaped by correction (the analog shifting of a digital signal that rotates the phase of each signal component by multiplying by a complex exponential function for each frequency in the frequency domain is effective). Determine the phase change that occurs in the device in advance, and appropriately drive the sensor appropriately with the aim of generating a wave having a desired waveform or generating a desired waveform at the observation position or reception position. There is also. As a result, the observation of the observation target is improved in accuracy (various observations using phases, observations of frequency-dependent propagation velocity, scattering, attenuation, etc.). In some cases, only the amount that occurs in the receiving device is corrected. The same processing may be performed for the above-mentioned other types of displacement. The position correction is also described in paragraph 0371 and the like. Various signal processing techniques such as motion compensation and phase aberration correction can be used. The signal strength correction is also described in paragraph 0694 and the like. In addition, regarding the beam forming component and the speckle component of the weakly scattered signal, unlike the definitive signals, a virtual sound source and a virtual receiver assuming a scatterer or the like invented by the inventor of the present application (Patent Document 7, As confirmed through an experiment using Non-Patent Document 8, it can be used for imaging and displacement measurement without performing position correction processing (for example, a combination of plane wave transmission and Gaussian apodization is effective for displacement measurement. In focusing, a power-type apodization such as a square function is effective, and the latter has high resolution even in single beam forming.)

  In addition, it is different to form multi-focus (not limited to normal multi-focus in which transmission focus is formed at a plurality of positions in the beam propagation direction, but also includes taking transmission focus at arbitrary plural positions including a horizontal direction). A process of transmitting a plurality of waves focused on a position and performing reception beamforming may be performed. Further, processing for generating a reception beam at a plurality of positions or a reception beam in a plurality of directions may be performed on one transmission beam. In addition, beamforming based on transmission in a plurality of directions having different steering angles may be performed. In addition, there is a case where beamforming is performed at a distant position where interference is small, and beamforming is performed at each portion divided within one frame based on performing transmission and reception. May be performed in parallel, and in each case, a process of superimposing the results at each position in the region of interest where a plurality of beamforming results are obtained may be performed. The method (4) itself has a feature that if the wave propagates in the region of interest, the received signal of the interfered wave can be processed, and by utilizing this, a high frame rate can be realized. (Method (4) allows receive beamforming for any transmit beam, wave, singular or multiple transmissions). In addition, after performing various signal separation processes, beamforming may be performed using an appropriate signal component. Depending on the degree of interference, processing may be performed without removing waves outside the region of interest.

  In addition, the wave transmission or reception aperture may be a dedicated aperture for each, but may also serve as both, not only receive the response of the wave transmitted by itself, transmitted from other apertures Waves may be received and again the resulting beamforming results may be superimposed, including when processed in parallel. In summary, the above-mentioned superimposition is performed simultaneously, or in a simultaneous phase in which the state of the object (communication target) or the observation target in which the wave propagates or the observation target is the same or substantially the same, or at another time, or at another time. In a phase, one or more beamforming or transmission or reception may occur at each aperture, and similarly, one or more beamforming or transmission or reception at one combination of apertures. Sometimes it is done. Similarly, each of a plurality of combinations of apertures may perform one or more beamforming or transmission or reception. In addition, when a plurality of beamforming or transmission or reception results are obtained, new data may be generated through an operation of superimposing them.

  Since these superposition processes are linear processes, a plurality of complex spectrum signals having the same frequency in the frequency domain can be superimposed in the calculation process of the above methods (1) to (6). It is sufficient to perform the inverse Fourier transform on the superimposed complex spectrum at a time, and when the plurality of beam-formed waves are superimposed in the spatial domain as described above, the inverse Fourier transform of the number of the superimposed waves is performed. Processing can be completed faster than required. Although not limited thereto, such as an arriving wave, those superimposed in a state of an angular spectrum may be processed in, for example, a single direction or a plurality of directions. As the processing itself, it is preferable to perform a Fourier transform by superimposing a plurality of waves in the spatial domain and obtain a superimposed angular spectrum (the Fourier transform has an effect of being performed only once). In some cases, the position or the like where the object exists can be confirmed.

  Also, in the above, when transmitting a plurality of beam-formed waves (at least a predetermined transmission delay is applied and a transmission apodization may be applied) (methods (1) to (6) In methods (2) and (3) other than the aperture synthesis, in the case of simultaneous physical transmission (the first excited aperture element in the effective aperture array of each transmitted wave) Are excited at the same time), since the received signals are stored in a memory or a storage device (storage medium) in an overlapping state, the image signal of one frame may be generated according to each method. (Parallel processing for dividing one frame and processing each part may be performed.)

  On the other hand, in the above another case where beamforming is performed a plurality of times at different times, in the channel of each receiving aperture element, it is possible to grasp the timing of transmission from the first excited aperture element in the effective aperture array. In the measurement imaging apparatus according to the embodiment, in the digital signal processing unit, a plurality of received signals may be appropriately overlapped to obtain the same signal as a received signal when a plurality of waves are transmitted at the same time, and the same processing may be performed. (In this case as well, parallel processing for dividing one frame and processing each part may be performed). In these cases, the first Fourier transform only needs to be performed once (there may be a case where each part is divided and processed).

  In the case of such an active state, beam forming can be completed at a higher speed in beam forming except for combining aperture surfaces (methods (2) and (3)). However, the reception signals for aperture plane synthesis collected for the methods (2) and (3) are subjected to transmission beam forming (transmission delay or transmission apodization as necessary) and superimposed. And may be processed in the same way. By the way, if the received signals are superimposed without applying a transmission delay, in this case, a received signal when a plane wave is transmitted without steering can be generated. In the aperture plane synthesis processing, the division parallel processing may be performed to speed up the processing. In particular, when performing the multidirectional aperture plane synthesis which is the past invention of the inventor of the present application, one time phase is required. Can generate beams in multiple directions from the signals collected in step (1). In the case of processing in the apparatus or method of the present invention, the same angle obtained by one Fourier transform under a deflection angle in each direction can be obtained. A calculation using the spectral data is performed, and finally, the multidimensional spectra obtained for each deflection angle are superimposed without performing the inverse Fourier transform a plurality of times. A final image signal can be generated at high speed by Fourier transform (division processing may be performed). However, even in the case of aperture plane synthesis, when performing passive processing even in fixed focusing of reception and other beamforming, as described above, for the superimposed received signal (that is, one angular spectrum), For example, it is effective to perform processing in a single direction or a plurality of different directions.

  In addition, in the case where a plurality of waves obtained by these processes are superimposed, for example, if the propagation direction, the frequency, or the band is different, it is also effective to separate and process the spectrum. , Besides, encoding, MIMO, SIMO, MUSIC, independent signal separation (independent component analysis), principal component analysis, code, or a parametric method can be used to separate the digital signal units. Note that the superposition process may be effective in other cases (for example, the SN ratio is improved by using a plurality of signals obtained in the simultaneous phase).

  Independent signal separation (independent component analysis) is effective, for example, to separate a specular reflected signal and a scattered signal, and separates an independent scattered signal between two or more frames with respect to a signal including the specular reflected signal. If the processing is performed by realizing a state of having a scattered signal or a state of being mixed with an independent scattered signal, it is possible to effectively separate a specular reflection signal which is commonly present. It is useful for automating detection / separation (removal) of high-intensity signals from blood vessels and the like when measuring tissue displacement such as blood flow, and identification (detection) of a blood flow region range. is there. In addition, it is useful for detecting and extracting boundaries of organs, tumors, and the like. Similarly, it can detect specular reflection (tissue), separate (remove), and specify (detect) the range of a characteristic region. . At the same time, it is also possible to separate the mixed independent scattered signals, and to perform independent component analysis (independent component analysis) rather than detecting the corresponding signal from each of the sum (that is, the averaging) and the difference between the frames. The use of (component separation) has higher ability to detect a specular reflection signal and to separate mixed signals. The higher the processing is, the higher the detection performance (envelope detection, square detection, absolute value detection, etc.). This can be confirmed not only visually but also quantitatively and deterministically or stochastically. In addition, by applying measurement of displacement, distortion, and the like, performing motion compensation (translation, rotation, expansion / contraction) on translation, rotation, deformation, and the like, and performing alignment and processing, the performance is improved (for example, 3 MHz). In frequency simulation, when cross-correlation-based displacement measurement is performed, when the standard deviation of the scattered signal is 1.0, the specular reflectance distribution of 0.1 to 0.5, even if the scattered signal of similar intensity is mixed Motion compensation). Processing with spatial resolution is desirable. Note that measurement of displacement and the like is more accurate when performed before detection, but may be performed after detection. In addition, when displacement measurement is performed with high accuracy using various measurement methods before detection, block matching (phase matching) in the spatiotemporal domain, which may be performed through oversampling or upsampling, or in the frequency domain. Motion compensation by phase matching based on phase rotation is effective. If the independent signal is a medical ultrasonic transducer, the transducer may be tilted to pick up a specular reflected signal at the same position from another angle, or a signal may be picked up using another sub-aperture based on steering processing, or It is also effective to shift the scan plane to collect signals including specular reflection signals from the same specular reflection signal source (a series of the same structure and composition) (measurement technique). It is also possible to positively apply the movement of the object (the scan plane is shifted or signals from other tissues are mixed) and the deformation (considered to contain noise), as described above. What is necessary is just to collect the included signal. Similarly, when using ultrasonic waves (such as sonar) and electromagnetic waves other than medical ultrasonic waves, the movements of sensors, signal sources, and detectors (including camera shake and disturbance of their holders), waves, A reflected wave or a transmitted wave may be collected and processed by applying beam steering, movement or deformation of an object. Noise generated in the circuit may be mixed to produce an effect, or analog or digital (including software-like noise generated by a program) generated positively may be mixed. In addition, these processes can be used not only for separating the specular reflection signal and the scattered signal but also for obtaining the same effect in the common signal and the mixed signal existing between the signals, and the application range is limited to this. Not something. The spatio-temporal shift of the signal is not limited to displacement or distortion, but also the directivity of the aperture (particularly during steering), the heterogeneous propagation speed of the medium itself, disturbance of the medium, and changes in conditions (for example, pressure and temperature changes). Etc.), and may be processed purely in signal analysis, depending on changes in the propagation velocity, etc. Also, waveform distortion may occur due to a phase delay or phase change having a frequency dependency in a device (for example, a phase change in a sensor or a phase delay in an amplifier in a circuit), and similarly, the phase of a received signal is changed. There is a case where the waveform is shaped by correction (rotating the phase of each signal component by multiplying by a complex exponential function for each frequency in the frequency domain is effective). Determine the phase change that occurs in the device in advance and appropriately drive the sensor appropriately with the aim of generating a wave having a desired waveform or generating a desired waveform at the observation position or reception position. There is also. As a result, the observation of the observation target is improved in accuracy (various observations using phases, observations of frequency-dependent propagation speed, scattering, attenuation, etc.). In some cases, only the amount that occurs in the receiving device is corrected. The same processing may be performed for the above-mentioned other types of displacement. Although the frame signal has been described, the signal may be applied to a beamformed one (including aperture synthesis), or may be applied before or after receiving beamforming (transmission / reception signal for aperture synthesis). And then beam forming is performed. That is, it may be performed before, during, and / or after beamforming. In each case, super-resolution may be used in combination. The above-described motion compensation processing is effective not only for correcting a spatio-temporal shift, but also for correcting, for example, a shift when a signal at the time of transmitting a focusing beam or a plane wave is compared and referenced (for example, in super-resolution). . Further, the above-described motion compensation processing that may be performed before or during beam forming may also serve as a delay (delay) processing in the DAS processing. In addition, high resolution through detection (absolute value detection, square detection, envelope detection, etc.) and linear or non-linear processing to be described in detail later are similarly applied to those subjected to beam forming (including aperture surface synthesis). In some cases, beamforming may be performed before receiving beamforming or after performing processing on a beamforming-free signal (transmission / reception signal for aperture plane synthesis) at all. That is, it may be performed before, during, and / or after beamforming. When widening is performed in such processing, oversampling or upsampling is performed in space and time, or broadening is performed through zero-filling of the spectrum in the frequency domain as necessary (inverse Fourier transform is performed). For example, a result of oversampling or upsampling is obtained).

  For the position correction and the phase aberration correction, a cross-correlation method can be used as a correlation-based method, and various displacement measurement methods can be applied. It may be processed as a one-dimensional signal or as a multidimensional signal. For example, there are a (multidimensional) cross-spectrum phase gradient method, a (multidimensional) autocorrelation method, a (multidimensional) Doppler method, and the like. If there is an effect of the matched filter as in the case of the cross-correlation method such as the cross-spectral phase gradient method or the auto-correlation method, it becomes robust to the noise contained in the wave signal as described above. As described above, it is effective to use the (iterative) phase matching method (shift in space time or phase rotation in frequency space) when applying these displacement measurement methods to phase aberration measurement. Here, an example of a method for automatically determining the phase aberration and the effective aperture width in beamforming using an array-type aperture to which these are applied will be described. As described below, discrimination based on a correlation value between local signals (for example, in the case of an ultrasonic wave, a local echo signal or a local transmitted ultrasonic signal), and detection of an occurrence of a delay time (time difference) estimation error itself in beamforming. By doing so, it is possible to automatically determine the effective aperture width and perform beamforming. In that case, the iterative phase matching method is effective. For example, as described above, when applied to the case where coherent compounding (superposition) is performed in beamforming with different steering angles, an image can be obtained, and the effects of increasing the contrast and increasing the resolution can be obtained. In addition, as described above, MIMO, SIMO, MUSIC, independent signal separation (independent component analysis), principal component analysis, parametric method, etc., adaptive beamforming, minimum variance beamforming, Capon method, etc. Also applicable to 10). These not only increase the accuracy, but also reduce the amount of calculation. The adaptability itself depends on a reflection characteristic, a scattering characteristic, an attenuation characteristic, or the like of the measurement object, and it is desirable that the spatial resolution is provided.

  A description will be given of at least a reception signal that has not been subjected to reception beamforming (as described above, processing may be performed on a signal that has been subjected to reception beamforming). The transmission beamforming includes, but is not limited to, fixed focus beamforming and waves that spread widely in a direction intersecting the propagation direction of waves such as plane waves and spherical waves. The latter realizes a high frame rate as described above. In addition, when transmission beamforming is not performed, the present method is used for so-called classical aperture synthesis, which may be effective in both the monostatic type and the multistatic type.

In those signals, a reception position (a position where beamforming is performed) including a local signal including a signal from a position of interest in a region of interest is included in a signal sequence received at each position around the reception position. The local signal having the highest correlation and the reception time thereof are searched for (see FIGS. 16 to 18). A search area for that purpose is set to include a highly correlated local signal. High-precision phase rotation by multiplying by a complex exponential function in the frequency domain is applied to the signal in the search area, and the signal appearing cyclically is cut out by a window to find the phase aberration in the area of the local signal (local area) The search area is set appropriately larger than the local area so that it does not appear in (The increase in the size of the dark area only increases the amount of calculation, and the local area does not always need to be set at the center. It is determined appropriately from the estimated magnitude and sign of the phase aberration). When the phase aberration between the local signals is estimated to be Δt, exp {iωΔt} is added to the spectrum A (ω) of the signal in the search area to shift the signal in the search area by −Δt and correct the phase aberration. Multiplication and inverse Fourier transform may be performed (Patent Document 6, Non-Patent Document 15, etc.). Although the calculation time is required, if this process is repeatedly performed on the signals of the same pair, the correlation between the local signals gradually increases, and it is possible to finally estimate the phase aberration with high accuracy ( Iterative phase matching is described in detail in Patent Document 6 and Non-Patent Document 15).
FIG. 16 is a schematic diagram for explaining an example of phase aberration correction when steering is not performed when a linear one-dimensional array transducer is used. FIG. 17 is a schematic diagram for explaining an example of phase aberration correction when steering is performed when a linear one-dimensional array transducer is used. FIGS. 16A and 16B show received signal groups obtained using different parameters, and FIGS. 17A and 17B show received signal groups obtained using different parameters. The group is shown. As shown in FIGS. 16 (a) and 17 (a), processing is performed only in a frame composed of a received signal group including a point of interest A for performing beamforming, and FIGS. 16 (b) and 17 ( As shown in FIG. 16B, received signal groups (frames) having different wave parameters and beamforming parameters are obtained, and the received signals at the point of interest A shown in FIGS. 16A and 17A are respectively obtained. May be performed. The figures show the case of processing a plurality of frames obtained at different steering angles for transmission or reception.
FIG. 18 is a schematic diagram for explaining an example of phase aberration correction when steering is performed when a two-dimensional array transducer is used. FIGS. 18A and 18B show received signal groups obtained using different parameters. Although this transducer is of the linear type, there are various types of two-dimensional array type transducers as well as one-dimensional array type transducers. There is also a transducer (even in the case of a transducer other than the linear type, there is a case where steering is performed in an axial direction determined by the direction in which the element opening surface faces). Since the digital signal stored in the memory after reception is the object of processing, if the cross-correlation processing itself is performed, the reception time of the signal of a highly correlated local signal will be evaluated at the sampling interval. Has reported a cross-spectrum phase gradient method capable of analog evaluation of a digital signal based on the Nyquist theorem. For example, this method can be used. As described above, another displacement measurement method can be used for phase aberration correction. However, when the SN ratio of a received signal is high, processing using a window (Patent Document 6 and Non-Patent Document 15) In the case of iterative phase matching, the window may be a rectangular window in many cases. In particular, it is desirable to use a rectangular window at the end of the number of iterations. The estimation using the received signal (instantaneous data) of the point of interest A shown in FIG. In addition, the reception signal to be processed in this processing may be a signal that has been subjected to transmission or reception beamforming.
In the cross-spectrum phase gradient method, if the time difference between local signals is large, the phase spectrum is inverted, so that it becomes necessary to perform unwrapping. Therefore, first, so-called Coarse estimation and phase matching (spatial shift) using the cross-correlation method itself including the effect of unwrapping are performed, and then Fine estimation using the cross spectrum phase gradient method is performed. In this Fine estimation, phase rotation using a complex exponential function is performed as phase matching, and it is possible to achieve high accuracy while repeatedly improving the correlation value (the processing target is a digital signal, but the phase matching is performed analogously. it can). This approach is based on the phase matching method that we have established as a displacement measurement method (Patent Document 6, Non-Patent Document 15, etc.). The calculation speed is faster in the cross-spectral phase gradient method than in the cross-correlation method, and therefore, the cross-spectral phase gradient method with unwrapping is also effective (basically, the distance between the point of interest and the element position). It is sufficient to perform unwrapping determined by the difference, which is easier than when observing displacement when moving in any direction.) In this iterative phase matching, it is also possible to gradually shorten the window length and finally obtain a high-resolution result. Physically determined by the assumed propagation speed, Coarse searches for the possible range of the corresponding signal, and then Fine estimation can be performed, without requiring Coarse estimation, Fine estimation only, In some cases, the unwrapping process is not required.
The effective aperture width is related to the point of interest A at each element position for performing beam forming in the aperture array in a direction away from the point of interest A (FIGS. 16 and 17: left and right in the case of a one-dimensional array, (FIG. 18: 2 The above processing is performed on the received signal received at the position (in the case of the dimension, in the circumferential direction), and before (i) the correlation value obtained by the inner product between the local signals after the matching processing falls below the set threshold value And (ii) before the time difference from the obtained local signal becomes larger than a preset threshold value (the estimated value becomes discontinuously large during the execution of the processing). May change and may be considered to detect an error).
It is also effective to perform this processing when performing beamforming only with the received signal in its own frame.For example, in the case of plane wave transmission that achieves a high frame rate, it is generated in the case of single transmission. Since this wave has a narrow band in the horizontal direction, it is also effective to perform this processing when performing a plurality of steering transmissions with different steering angles as described above to perform a coherent compounding process (broadbanding). The effect of widening the band is also obtained in focusing beam forming, and it is of course effective. Similarly, a received signal when performing beamforming with different beamforming parameters and wave parameters different from the steering angle is also processed (see FIGS. 16 and 17). The above processing can be performed by performing the same processing at each position A of the received signal frame under the same or different reception steering angle as the transmission steering angle. However, if the transmission and reception steering angles are greatly different, compounding is performed. May not be imaged. Therefore, after determining the transmission steering angle of the generated wave, one reception steering angle which is the same as or different from the transmission steering angle is determined, and for each position A set only in the reception signal frame of the transmission steering angle, its own reception steering angle is determined. The same process is performed not only for the signal frame (when the compounding is not performed, the process for only this frame is performed), but also for the received signal frame of another transmission steering angle. In order to pursue accuracy, the transmission and reception steering directions should be determined in the direction in which the aperture has high directivity as much as possible (that is, the front direction of the aperture surface). Furthermore, it is also possible to generate and compound with different combinations of the transmission and reception steering angles, but if the transmission and reception steering angles are greatly different, an image may not be formed.
For compounding, for example, for one transmission steering angle in a front direction or an arbitrary direction, a plurality of signals are generated at a plurality of different reception steering angles, or in a plurality of directions by using aperture plane synthesis data. It also reports that transmission and reception steering and compounding are performed, and this can be applied to the above-described transmission steering in a plurality of different directions.
In this processing, the length of the local signal (window length) needs to be set appropriately (the initial window length when performing iterative matching). The shorter the value, the higher the correlation value is obtained, and the spatial resolution of the estimation result of the local signal (that is, the estimated value of the phase aberration) is high, but another similar signal may be detected. If the window length is long, the correlation value becomes low, and it becomes impossible to search for a signal. (For example, when a plane wave of an ultrasonic wave having a nominal frequency of 7.5 MHz is transmitted by a human soft tissue agar graphite phantom, the echo signal is converted to 30 MHz When sampling at, 64 points and 128 points were appropriate, but 32 points and 256 points were inappropriate.) This is similar to the case of observing displacement and displacement vector. As described above, it is good to perform phase matching with such an appropriate window length, and when performing iterative phase matching, it is effective to gradually reduce the window length during repeated phase matching. Yes (finally, high-resolution results can be obtained). In the case of aperture plane synthesis or the like, a scattered signal that is not formed when the number of times of phase matching is several is sometimes formed by repeating the number of times of repetition, so that iterative phase matching is effective. The above-described highly accurate phase aberration correction or iterative processing requires a long calculation time, but is suitable for a close inspection. In medical ultrasound, real-time performance is emphasized, but the above process may be a novel medical ultrasound precision inspection method. The iterative phase matching can have an upper limit for the number of times it is performed, and is terminated when the updated value of the estimated value of the phase aberration becomes smaller than a preset value or becomes sufficiently smaller. As long as the condition (i) or (ii) is satisfied, the same process is performed on the received signal at the next position in the horizontal direction. It is also effective to use the estimation result obtained for the initial value of the phase aberration at the next position in order to shorten the calculation time. In the case of the one-dimensional array type, it is possible to perform the processing left and right around the point A (the effective aperture width obtained by the processing (i) or (ii) above corresponds to each position A). It is not necessarily symmetrical about the center). In the case of the secondary array type, it is possible to carry out the processing around the point A in the peripheral direction. Alternatively, the maximum effective aperture width including the point A is determined in advance, and the phase aberration is estimated from the end. If the correlation value of the condition (i) is larger than the predetermined value, It is also possible to determine the effective aperture width based on the estimated value of the aberration itself. In any case, each time the estimation result of the phase aberration is obtained, the local signal (local signal with the delay) subjected to the phase aberration correction is obtained. Therefore, each time the final estimation is completed, It is efficient to perform the addition processing (that is, DAS processing using phase aberration). At that time, a signal having a component different from a signal having the same component as the reference signal (a signal having higher accuracy than the above-mentioned sum (average averaging)) by performing independent signal separation (independent component analysis) or principal component analysis. (A signal with higher accuracy than the above-described subtraction), and it is useful to perform an addition process on the former signal component. To determine the former and latter signal components, the correlation with the reference signal may be calculated, and the signal with the higher correlation value may be the former, and the signal with the lower correlation value may be the latter. The latter signal component may be used after performing an addition process. Then, the phase aberration can be similarly corrected for another position A in the depth direction or the lateral direction in the region of interest. If the purpose is only to estimate the phase aberration, the addition process is unnecessary. In addition, a signal group subjected to phase aberration correction within the effective aperture width estimated at each point of interest A is subjected to independent signal separation at a time, and a signal component common to all (the signal having the highest correlation value) And the other signal components, and the former may be used as a result of the DAS processing.
As described above, the phase aberration correction is effective even in the deformable physical aperture array. As shown in FIG. 19, a point of interest is determined, and the position of each array element in the physical aperture array, the direction of each array element aperture, and the effective aperture width can be estimated. Each array element may or may not be deformed. The deformable physical aperture has the effect of increasing the contact area when the contact surface with the sensor aperture surface to be observed has a complicated shape, and if necessary, includes an object that is rich in wave transmission Sometimes used. A deformable physical aperture is particularly effective when the observation target is hard and does not deform.However, when the observation target deforms, it is possible to reduce the applied deformation or observe without deforming. is there. In these, the deformable physical aperture is particularly effective for near-field observation. As described above, the same processing may be performed on a plurality of wave signals acquired from an observation target. In that case, a plurality of waves may be observed in different physical aperture shapes or effective aperture width shapes, and in such a case, the same processing as described above is performed. Further, as described above, the physical aperture shape and the effective aperture width shape are obtained by this processing, and Fourier beam forming processing may be performed instead of the DAS processing-based processing (as described in the specification of the present application). , And can be performed in any opening shape). In these, the point of interest may be determined as a node of a desired orthogonal coordinate system, or may be determined as a node of a Cartesian coordinate system or an orthogonal curve coordinate system determined by a physical opening shape or an effective opening width shape to be obtained. , Etc., may be arbitrarily set at a desired position. Further, the point of interest may be a plurality of positions or a single point.
As shown in FIG. 19, the point of interest is set considering one time-series signal (reference signal) received by a certain element as a reception signal from the front direction of the aperture or the direction having the maximum directivity. It is desirable. Depending on the existence of obstacles, the direction may be considered in another direction, but it is desirable to select the direction with high directivity. When steering is performed at a non-zero steering angle, as in the case of phase aberration correction, the array element group is viewed from the point of interest and the array element (reference signal) at a position having an angle as close as possible to the steering angle. It is desirable to decide. When setting a plurality of points of interest, the points of interest may be set at a plurality of positions in the time series signal (reference signal), or different points of interest may be set within the effective aperture width. It may be set to a position in a different time-series signal (reference signal) received by the element. It may include both. In these cases, it is desirable to select an element that can acquire a received signal from within a direction or a distance where the propagation speed such as the sound speed is considered to be constant. The position of the array element within the effective aperture width including that element is geometrically estimated using the phase aberration estimates described above. The positions of adjacent elements may be obtained in order, or may not be. For example, known data of element width, element gap, and element pitch may be used together. In addition, for one array element, the position may be determined with respect to a plurality of points of interest, and one estimation result may be obtained by a statistical process or an optimization method (such as an averaging process or a least squares method). Not limited). When the propagation speed is heterogeneous, known data of the propagation speed distribution, estimation results, and reconstruction results are used, and the propagation speed distribution and the apparent propagation speed up to the position of interest in the region of interest or its part are both estimated. Various statistical processes and optimization methods described in the specification of the present application are effective, and are not limited thereto. These estimations are also effective when the propagation speed at the observation site is uniform. In addition, the physical aperture element array device or the array element is provided with at least one position or angle sensor for sensing the element position or a device having the same function, and the sensed position data can be used alone or with high accuracy. In some cases, they are used together in the same manner. (i) between the physical aperture element array and the object to be observed, a reference having elasticity and wave scattering properties (scattering properties) that deforms with the deformation of the array, and the thickness of the reference that occurs with the deformation of the array; Beam forming (transmission and / or reception focusing, steering, and superimposition) of changes, distribution of thickness direction displacement, distribution of vertical distortion component, displacement of horizontal or elevation direction, distribution of vertical distortion component, distribution of shear distortion component, etc. There is a case where observation (measurement of displacement and strain) is performed using a wave signal without alignment or with beam forming, deformation of a reference object is measured, and the shape of the physical aperture element array or the position of the array element is measured. (ii) In the case where the reference object has an elastic property and has a property of being transparent to waves, the displacement of the reflector (for example, a sphere or the like) distributed at a known interval in the reference object or a change in the interval. May be observed using the same wave to measure the shape of the physical aperture element array or the position of the array element. (iii) As a reflector in (ii), extendable strings are run at equal intervals in the form of a grid (grid) and run inside the reference object (there may be at least one in the horizontal or elevation direction only). The shape of the physical aperture element array or the position of the array element may be measured by measuring the deformation of the grid (expansion or contraction of the string) or the displacement of the node position. (iv) Also, in (ii) or (iii), if the medium is not transparent to the wave and consists of a scattering medium as in (i), and a reflector or string exists in it, In some cases, i) and (ii) or (iii) are simultaneously measured to measure the shape of the physical aperture element array or the position of the array element. It is desirable that the reference object be relatively thin so that its deformation reflects the shape of the physical aperture element array, and it is preferable that the reference object be provided as close to the element as possible. It may be built into the body of the sensor, or it may be used as needed. In some cases, the shape of the contact surface of the shape of the observation target and / or the physical aperture element array may be reflected to some extent. In such a case, the initial shape of the physical aperture element array or the initial position of the element may be reflected. Observe the changes in the same way. As described above, it is effective to use a reference provided with a marker regarding an element position, and may take various other aspects. The reference may also serve other functions, such as matching layers and lenses. The scatterers, reflectors, and grids in (i) to (iv) can also be used as virtual sources (the same can be used when the shape of the physical aperture element array is not deformed). If necessary, the beam aperture (transmission and / or reception focus or deflection, etc.) shall be used to determine the position and orientation of the effective aperture width at that time, and to be used for beamforming, etc. There is also. The position referred to here represents a representative position in an opening having a finite size. For example, the physical center of the opening, the directivity of transmission and / or reception, the strength of a reception signal, or the like is used as a weight. The center of gravity of the opening and the like.
Further, after generating a wave signal group (wave signal frame) in which the inhomogeneity of the sound velocity of the observation target is corrected by the above-described phase aberration correction, Fourier beam forming may be performed (described in the specification of the present application). Can be implemented in any opening shape.
Note that a device (body) including a physical aperture element array group arranged with respect to an observation target is not limited to an integrated type such as an array sensor. For example, as described in paragraph 0007, a device corresponding to an array element May be scattered, and as necessary, devices may be added, removed, activated, or deactivated, and may take various forms. The physical aperture or physical aperture array element may move or deform, either actively or under control, in which case dynamic data about the set or observed position and the orientation of the aperture is used. May be done.
Further, when signals having different wave parameters or beam forming parameters of transmission or reception overlap, phase aberration estimation or phase aberration correction may be performed on the signal as it is. Or by other processing, and then the phase aberration estimation or the phase aberration correction may be performed on each of the separated signals (for example, the processing can be performed on the signals at each steering angle). . Similarly, the spectrum may be divided in the frequency domain for the overlapping signal and the non-overlapping signal to generate a new wave, and then the phase aberration may be estimated or the phase aberration may be corrected. When the signals are separated in the frequency domain, wave parameters and beamforming parameters can be realized, for example, waves that are pseudo-steered in various directions and new waves and beam shapes can be generated. ). In each case, signals subjected to phase aberration correction may be superimposed.
It has been confirmed that the contrast and the spatial resolution of the image are higher in the processing of the frame alone than in the image without the phase aberration correction, and the processing is performed on a plurality of frames as described above to perform compounding (overlapping). It has been confirmed that it is more effective. This compounding performs coherent processing on the raw signal, but reduces the speckle by performing detection (envelope detection, square detection, absolute value detection, etc.) and then superimposing (incoherent compounding) Then, it is also effective when an image with enhanced contrast and CNR (Contrast-to-noise ratio) is generated by emphasizing a deterministic signal such as a specular reflection signal or a strong scattering signal. In such coherent or incoherent signals, the distribution of reflectance or specific impedance (specific electromagnetic impedance, specific acoustic impedance, related physical properties, attenuation rate, etc.) can be reconstructed with high accuracy (high resolution and high contrast). In order to obtain an effective aperture width as wide as possible, the array sensor may surround the observation target from the surroundings and perform processing in various directions (for example, completely surround the observation target like a sphere, , CT, etc., and steering may be performed). The waveform and distribution shape (sometimes estimated by the autocorrelation method) of the known transmission wave (which may be superimposed as described above) at each position in the region of interest and the unknown reflectance or wave at each position A plurality of observation signals (raw reception signals of a plurality of reception sensors) are fitted to a time-series signal model of a signal superimposed by multiplication or convolution integration with an unknown reflectance distribution in such an area to obtain an unknown reflectance. Sometimes the spatial distribution of is calculated. At the time of transmission, beamforming (eg, focusing or steering) may be performed, or beamforming may not be performed. It may be a superposition of them. In addition, the observation signal may be a signal subjected to reception beamforming (focusing, steering, superposition, etc.). In this case, the waveform and distribution shape of the corresponding transmission / reception wave (directly estimated by the autocorrelation method) May be estimated by convolution of transmission and reception). When the speckle is reduced, the reflectance distribution of specular reflection can be effectively captured, and when the speckle is not reduced, the scattering phenomenon can be also captured as a reflectance distribution at the same time. At this time, a known CT algorithm (propagation speed, attenuation rate, etc.) may be used in advance, and the observation result may be used. In addition, the reconstruction results of the specific impedance and the reflectance may be used together. Of course, in some cases, a known CT may only be performed.
When other methods such as (multidimensional) autocorrelation method and (multidimensional) Doppler method are used, the cross correlation method can be used for coarse estimation and they can be used for fine estimation without phase unwrapping processing. Like the cross-spectral phase gradient method, it may be used alone or may be unwrapped. The effective aperture width and phase aberration estimated as described above are obtained by minimum variance beamforming, independent component analysis, principal component analysis, super-resolution by nonlinear processing (addition processing by performing nonlinear processing, The method can be used for various applications including the above-mentioned application such as performing a non-linear processing after the application. It is also possible to make a database of the average effective aperture width at each distance position based on the method (i) or (ii) and use the database without phase aberration correction. The above processing is the same in the passive second embodiment.

  The signal separation is performed by increasing the frequency and widening (when the order is larger than 1) or lowering the frequency and narrowing the band (when the order is smaller than 1) by the exponentiation operation, and then performing the frequency domain processing. May be performed with high accuracy. Restoration of the signal after separation may be performed by simply raising the reciprocal of the power order using the power.

The above-described phase aberration correction is effective in various other cases. Phase aberration correction for various observation data (between), such as when the observed quantities (physical quantities, chemical quantities, etc.) are different, or when the same observed quantities have different conditions or parameters that may affect the observed quantities. Or after performing phase aberration correction, various processes described in this specification may be performed. For example, in integrating and integrating ultrasonic waves (echoes) and OCTs themselves and observation data obtained using them, a characteristic position accuracy is obtained from the OCT data, and phase aberration correction of the ultrasonic waves (echoes) is performed. (Even though the physical properties of light and sound are different, the positions where they change and the positions where scattering occurs can be used in common, and the matching process itself may be performed between coherent signals. Incoherent signals or image data obtained from the same). After the matching, the coherent signal or incoherent signal (or image data) is subjected to opportunity learning, deep learning, neural network (back-propagation type, Hopfield type, or the like, or Other models such as a model modified based on these) or other processing may be performed.
The inventor of the present application is mainly engaged in medical imaging and remote sensing (mounted on various types of radar, ground radar, extraterrestrial radar, stars and satellites, airplanes, meteorological observation, various earth observations, environment and resource exploration, space and astronomical objects Innovative multi-dimensional digital signal processing technology developed in various wave applications in fields such as observation, sonar, etc., non-destructive inspection (including structural science, material research, physical properties and functions, and life) Based on information processing including electronics (including electronics), inverse analysis and inverse problems, and statistical processing (based on mathematics), we are working on the fusion of measurement technology and advanced information processing. In particular, it can be applied comprehensively in the fields of human biological tissues (including microscopes), biotechnology, materials, structures, environment, etc., and creates innovative science and technology that will bring about social and economic changes. It becomes possible. For example, numerical results, graphs, imaging, and visualization of observation results, medical and life sciences (promotion of human health, human tissue examination, generation, treatment, processing, application, (small) animals, Development of tissues (cells, drugs, etc.), materials (electric, thermal, elasticity, composite materials, etc.), environmental observation (gas, liquid, solid), energy development, security (monitoring and monitoring, observation of moving objects) , A variety of high-precision observations (large and small, short and long-term phenomena, objects located at long distances and short distances), and the world's first in silico measurement standard And other phenomena (such as biology, chemistry, biochemistry, etc.) that can be applied to a very wide range of applications such as electromagnetism, mechanics, and heat. In addition, it is possible to realize innovative non-destructive inspection techniques for physical quantities, stoichiometry and physical properties of various phenomena), measurement (inspection and diagnosis), repair (repair, treatment, regeneration), manufacturing ( It enables material growth and tissue three-dimensional culture) and applications (including creation of new functions and physical properties). As a result, in-situ measurement of the spatio-temporal distribution of basic physical quantities, chemical quantities, and physical properties in an object that could not be observed until now can be performed, or observation can be performed without adjusting conditions for observation. For example, it becomes possible to observe operating devices, living things and cells under natural conditions, and to observe the process under the conditions of the material growth process. Furthermore, through the advanced fusion of these various simultaneous observation and analysis technologies with the latest information science and statistical mathematics, various latent factors (mechanisms), new phenomena, new principles, etc. are elucidated in detail, and new physical properties and It can contribute to the creation, synthesis, and restoration of functions. Rather than simply over-determined systematization (averaging or least-squares) to overcome the accuracy limitations of a single observation, for example, the following intelligent integration and fusion technologies (multiplexing of highly accurate common information, Precise digital signal processing can be achieved dramatically by separating independent information and separating independent signal sources (multiplexing of common information and increasing the accuracy of separating independent information and independent signal sources) ICA with new applications, machine learning and deep learning, and new applications of neural networks such as integrated learning and integrated recognition). Needless to say, if necessary, disassemble or, in humans, use craniotomy and laparotomy, laparoscopic, endoscope, oral and nasal (camera), capsule (type camera), and puncture needles to monitor the sensor. It may be observed in preparation for the vicinity. Further, phase aberration correction may not be performed at all or may not be performed precisely (for example, when a cross-correlation method is used, but a shorter sampling interval is better). The signal source referred to here may be a physical signal source (which may be treated as a diffraction source) itself, or may be a reflection source, a scattering source, or a diffraction source. Especially when the signal to be observed is considered to be included at a different position or time, such as when the received signal includes a signal of multiple reflection or multiple scattering, the signal at a different position (time) is positively transferred directly to ICA or the like It is effective to perform the processing of (1) and (2), such processing may be performed while shifting the position, and such processing may also serve as signal detection processing (correlation values can be used as indices of accuracy and reliability of detected signals) . Thereby, multiple reflection and multiple scattering signals can be separated.

For example, as described in paragraph 0380, the in-situ imaging by the wave sensing (including the inverse analysis) of the distribution of the physical quantity in the electromagnetism, the dynamics, and the thermodynamics in the observation target is realized, and the related observation is performed based on the observation. Reconstruction (inverse analysis) of physical property distribution can be realized. The source of the phenomenon can also be reconstructed. Further, another physical quantity can be obtained by using one physical quantity and their reconfiguration. You can also observe for energy. In order to realize high-precision observation, three-dimensional or two-dimensional multidimensional observation may be desirable. For example,
(1) <Patent Literature 8> Distribution of electrical properties (both or one of conductivity and / or permittivity) based on current density (vector) distribution measurement, distribution of current source or voltage source, and re-distribution of potential distribution Configuration (imaging) or electrical properties and current density (vector) based on potential distribution measurement, reconstruction of current source, etc. (2) <Patent Document 9> Distribution of displacement (velocity, acceleration) vector and strain (rate) tensor Reconstruction (imaging) of distribution of force and distribution of force source based on measurement (shear modulus, shear modulus, compressibility (Poisson's ratio), incompressibility, viscosity, density, etc.), average normal stress (internal pressure) distribution Simultaneous or separate observation, observation of inertial force vector and stress tensor distribution, etc. (3) Distribution of acoustic properties (bulk elasticity, viscoelasticity, density, static pressure, specific heat, etc.), sound source distribution, sound pressure based on sound wave propagation measurement Reconstruction of particle displacement and velocity distribution (Imaging) etc. (4) <Patent Document 10, Non-patent Document 44> Reconstruction of thermophysical property (thermal conductivity and heat capacity, thermal diffusivity, perfusion, convection) distribution, heat source distribution and heat flux distribution based on temperature distribution measurement (Imaging) and the like. These observations in the observation object that is the medium of each wave are analyzed by nuclear magnetic resonance imaging (MRI: Magnetic Resonance Imaging), SQUID (Superconducting Quantum Interference Device) (observation wave is a magnetic field), terahertz (electric field), DC ( (Not wave motion), power, radio wave, microwave, infrared, visible light, ultraviolet, radiation, electromagnetic waves such as cosmic rays, sound pressure distribution observation by Doppler effect using light pulse or laser, OCT (Optical Coherent Tomography) , An optical microphone (inventor: Yoshito Sonoda), an ultrasonic echo (sound wave) device (modality), and others (many patents of the present inventor). The reconstruction of the physical property distribution in (1) to (4) is to reconstruct the relative physical property distribution from the distribution of one physical quantity, and many inverse analyzes (X-ray CT, electric impedance CT, etc.) are observed. To solve the integral equation to observe the inside of the object from the physical quantity observed at the boundary position of the object, the partial differential equation or the ordinary differential equation (substituting the constitutive equations into the governing equations such as wave equation and diffusion equation) This is called the inverse problem / inverse analysis of the differential type with respect to the integral type. If a reference value (measured value, typical value, or the like) of the physical property is given to an appropriate position (reference region) in the region of interest, an absolute distribution can be obtained. When a region whose value is considered to be constant is set as a reference region and a value of unit size is set as a reference value, a relative value distribution is obtained. Of course, the integral inverse problem may be used.
In any case, the equation Ax = b holds for the unknown distribution (vector x) (the unknown number may be equal to the number of equations, or may be over-determined or fewer-determined). The unknown distribution x is often the distribution itself to be obtained in the case of a linear equation, and in the case of a non-linear problem, the estimation result is often updated by repeatedly estimating. Distribution Δx in many cases. Of course, that is not the case. In the case of a nonlinear problem, the matrix A or the vector b depends on the unknown distribution x, and A (x) or b (x ) Is used to determine Δx at that step. Then, x is updated by Δx. If the magnitude (norm) of Δx becomes smaller than a predetermined value, it is determined that the convergence has been reached, and the estimation is repeated.

In addition, the integration and integration of the electromagnetic wave and acoustic wave sensing and the inverse problem can be performed. For medical images, fusion devices of X-ray CT (morphological information), MRI (morphological and functional information), and PET (functional information) have been put to practical use. Under such circumstances, in addition to ultrasonic waves (longitudinal waves) and shearing phenomena (transverse waves), utilizing the characteristics of various waves, for example, MRI and ultrasonic waves, ultrasonic waves and terahertz, OCT, laser, etc. Electromagnetic waves and mechanical waves can be fused with heat waves.
For example, the application of the fusion and integration of (1) to (4) (hereinafter referred to as (5)) is various as described in paragraph 0380. For example, in the field of life science, based on new measurements of functions and physical properties, it can contribute to highly efficient culture (especially three-dimensional culture), its control, and elucidation of the pathogenesis of lesions (simultaneous observation of organic and inorganic substances, etc.) ). While iPs cells are attracting attention, for example, activity can be observed at the same time as kinetic and electrical phenomena in the in situ state in which cultured cardiomyocytes are naturally active (multiplexing and fusion of new observations are also possible). In addition, operating electrical and electronic circuits can be observed in situ (inspection of device functions and bonding). Also, in the growth and operation processes of various functional materials and in the development of various devices, physical quantities and physical properties are observed in situ (for example, in an ultrasonic element such as a piezoelectric PZT element or a polymer film PVDF, At the same time, we can observe the energy conversion efficiency, electrical impedance, vibration modes, and thermal phenomena of electric machines, and also contribute to miniaturization, speeding up, energy efficiency (energy saving), creation of new functions, and synthesis (electricity). Material, elastic body, thermal material, etc.) In addition, effective observation in various fields is performed as described in paragraph 0380.
Information science and statistical mathematics are effective in their inverse analysis and fusion. As described in paragraph 0381, various optimizations performed in signal processing, maximum likelihood estimation, MAP estimation, Bayesian estimation, EM (Expectation-Maximization), and unbiased regularization using partial differential operators as regularization terms (In the past, the world's first spatio-temporal variant regularization was performed. In absolute or relative physical property reconstruction for a homogeneous material, the regularization parameter was set to a large value and stabilized as much as possible. May be able to realize the world's first in silico standard if is reduced), singular value decomposition, equalizer and sparse modeling, signal (source) separation and feature analysis by ICA and MUSIC, new super-resolution (in silico harmonics) A patent is filed for imaging, etc.), and a displacement (vector) measurement error is evaluated using a stationary process or using Cramer-Rao Lower Bound (CRLB) or Ziv-Zakai Lower Bound (ZZLB). It came or (a priori and a posteriori that also applied to the regularization). It is also possible to establish an error model for each observation object and apply it to them. In addition, the integration and fusion of heterogeneous information (including the above-mentioned different observables and observables under different conditions and parameters) include KL information, maximum likelihood method, mutual information minimum / maximization, and entropy minimization. In addition to the use of ICA, the application of a new ICA with the above-mentioned precise digital signal processing to improve the multiplexing of common information and the separation ability of independent information (exact space-time precise matching of multiple digital signals (digital If the signal is processed after analog phase rotation without approximation processing), the extraction of common information will exceed the averaging and the separation of independent components will improve.) Integrated learning and integrated judgment (recognition, approaches to integrate and analyze multiple neural networks of three or more layers, differential diagnosis and recognition of lesions, etc. Coding, not only medical coding, but also various recognition targets), mapping between images and other clinical data, mapping to desired objectives / targets, new functions, etc. are not limited to medical applications as well) . It is also effective to integrate and fuse phenomena with different stochastic processes (for example, multiplex or separate a noise according to a normal distribution and an ultrasonic scattered signal according to a Rayleigh distribution, or mix a plurality of events of different stochastic processes). Terahertz signals, SQUID signals, optical signals, and optical ultrasonic signals have low S / N ratios. Similarly, signal processing using ICA (exceeds averaging) or MUSIC is also effective in improving accuracy (also useful during beam forming). And also useful for data after beamforming). Also, when the sensing data in the three-dimensional space or the spatiotemporal space is big data, the real-time property (high-speed operation) is pursued, and precise and high-speed Fourier beam forming (including data compression) and parallel processing are performed at the time of sensing. Processing may be performed. Of course, so-called data mining is also effective. Of course, various ordinary compression techniques are also effective.

  The new observation technology developed in parallel or integrated and integrated will establish itself as an innovative non-destructive inspection technique for each observation object in the future, and will provide new perspectives (new engineering) in various fields. Etc.) to advance scientific development. It can also contribute to international measurement standards for basic physical properties (particularly distribution constants) (it has the potential to become the first in silico international standard using regularization, etc.) Bring effect (achieving accuracy on the order of the number of significant digits of a computer). The above-mentioned in situ remote sensing application (approach) is not limited to these, and its ripple effect on other fields is immeasurable, and can be returned to various fields, fusion / integration fields, and society as described above.

Examples of applications realized by the above (1) to (4) are listed below in a bulleted list. Applications are not limited to these. In addition, it is sometimes possible to observe the distribution of changes in the thickness of the observation target with high precision from the reconstruction of the distribution of the physical property values (thermal conductivity and electric conductivity), so that apparent observation is sometimes effective, and it is not always necessary. Instead of a distribution, at least one value may be observed.
(1) <Patent Literature 8> Distribution of electrical properties (both or one of conductivity and / or permittivity) based on current density (vector) distribution measurement, distribution of current source or voltage source, and re-distribution of potential distribution Configuration (imaging), electrical properties and current density (vector) based on potential distribution measurement, reconstruction of current source distribution, etc.
Platform: MRI, terahertz, SQUID, electrode array (eg electroencephalogram / electrocardiograph etc.), electrostatic potential sensor array etc.
Observation target: MRI, electrode array, electrostatic potential sensor array are human and animal (mouse, etc.) neural networks, electrical networks, electrical materials (resistors and dielectrics), current and electric fields, potential fields; Terahertz refers to electrical circuits and electrical materials (resistors and dielectrics), piezoelectric elements (PZT, PVDF), etc .; SQUID refers to all of them. When MRI or SQUID is used, the distribution of the current density vector can be obtained by solving the inverse problem of Biot-Sabert's law (integral inverse problem).
(2) <Patent Document 9> Mechanical properties (shear modulus, shear modulus, compressibility (Poisson's ratio, etc.), incompressibility, etc.) based on measurement of distribution of displacement (velocity, acceleration) vector and strain (rate) tensor (Viscosity, density, etc.) distribution and force source distribution reconstruction (imaging), mean vertical stress (internal pressure) distribution simultaneously or separately, observation of inertial force vector and stress tensor distribution, etc.
Platform: MRI, terahertz, ultrasonic, OCT, laser, light pulse, etc.
Observation target: Soft tissues of humans and animals (such as mice) (brain tumors, cancer lesions such as liver cancer and breast cancer, vascular disease models such as sclerosis, hemodynamics including heart, blood vessels, and blood flow. Intracranial cancer lesion model that is difficult to observe with OCT); Terahertz is also a model of animal lesions, diseases of teeth and bones, piezoelectric materials of inorganic solids (PZT, PVDF, etc.), deformation of PVDF, rubber, etc. Fluids (including blood) and gases containing viscoelasticity, powders (tracers) such as drugs and metals (conductors and magnetic materials), gases and waste liquids containing dusts.
(3) Reconstruction imaging of acoustic physical property (bulk modulus, viscoelastic modulus, density, static pressure, specific heat, etc.) distribution, sound source distribution, sound pressure, particle displacement / velocity distribution, etc. based on sound wave propagation measurement.
Platform: light pulse, optical microphone, laser, MRI, ultrasonic, OCT, etc.
Observation target: In addition to the above organic observation targets, gases (helium, oxygen, air, etc.) and liquids (pure liquids, mixed liquids, water, saline, liquids containing drugs, blood, etc.), and solids (inorganic Including). Special environment (indoor, outdoor, altitude, mountain, depth, sea, narrow place, etc.) etc.
(4) <Patent Document 10, Non-Patent Document 44> Reconstruction imaging of thermophysical property (thermal conductivity and heat capacity, thermal diffusivity, perfusion, convection) distribution, heat source distribution, heat flux distribution, etc. based on temperature distribution measurement.
Platform: MRI, terahertz, ultrasonic, optical fiber, pyroelectric sensor, etc.
Observation target: Perfusion effect, metabolism, above-mentioned cancer lesions and inflammation, heart and blood vessels, blood (perfusion) model, piezoelectric element, such as thermal material, inorganic solid piezoelectric body (terahertz), etc. in animal (mouse etc.) neural network And PVDF, convection of gas and liquid.
In addition to (1) to (4), as (5), those obtained by fusing / integrating (1) to (4) and other inverse analysis or data mining. For example, the following applies.
(I) Simultaneous or multilateral observation of the same object, simultaneous or multilateral observation of a plurality of objects related to the same event (phenomenon) by (1) to (4) using the same or different devices.
-In situ observation in medical treatment (in health examinations and medical examinations, human dogs, diagnosis of diseases, and monitoring in various treatments, the same organs, tissues, and lesions are observed simultaneously or from multiple angles; one disease or concurrent diseases, or Simultaneous or multilateral observation of multiple independent diseases and related organs and tissues, which can be performed with a small number of devices (hardware)).
・ In situ observations in regenerative medicine and life sciences (high-efficiency culture, especially three-dimensional culture and its control, elucidation of lesion generation mechanisms; simultaneous observation of organic and inorganic substances, etc.).
-Observation (activity, etc.) of kinetic and electrical phenomena simultaneously in the in situ state in which cultured cardiomyocytes (iPs cells, etc.) are naturally active, and new observations can be multiplexed, highly accurate, and fused.
・ Human and mouse lesions (brain tumor, liver cancer, breast cancer) models and the (visco) elasticity (including hemodynamics) and thermal characteristics (and temperature) of blood (including drugs) in the heart muscle, blood vessels, heart chambers and blood vessels Simultaneous observation.
-Ultrasound and terahertz observation of drug delivery by dynamics and electromagnetic induction, development of new drugs.
-Simultaneous observation of electrical activity, heat generation (temperature), and blood perfusion effects on human and animal neural networks and metabolism.
・ In minimally invasive hyperthermia treatment (heating or heating using HIFU: High Intensity Focus Ultrasound etc.) for human cancer lesions and Parkinson's disease, the therapeutic effect of the affected area by MRI or ultrasound (such as temperature rise and change in viscoelasticity etc.) Degeneration) and perfusion itself, and neural network control of perfusion are simultaneously observed, and treatment is monitored in multiple ways in real time to improve the therapeutic ability: In medical treatment, it is safe not only to diagnose but also to affect normal parts In addition, only the abnormal part is efficiently treated (repaired).
・ Integrated medicine (general diagnosis, treatment, surgery, physio / chemotherapy, medication, etc.), Theranosis (the inventor of the present application has developed a reconstruction method of tissue shear modulus based on ultrasonic echo method in the past, and Diagnosis and before and after the heat treatment were consistently monitored under the same index, which is considered to be one successful case of Theranosis), and the viscoelastic modulus was changed by inflammation after the treatment ( Simultaneous observation of blood flow).
-Confirm Wiedemann-Franz's law regarding electrical conductivity and thermal conductivity and provide high-precision or inexpensive techniques (for example, use an infrared camera without using a SQUID meter).
・ Optimization of materials, structures, generation processes, etc., targeting desired properties in synthesis problems (composite materials, etc.)
-Observe energy conversion efficiency, electrical impedance, vibration mode, and thermal phenomena of electromechanical devices at the same time from various aspects of ultrasonic elements such as piezoelectric PZT elements and polymer membrane PVDF, and contribute to the creation and synthesis of new functions. (Electric materials, elastic materials such as rubber, thermal materials, etc.).
・ Spontaneous movement of the robot based on integrated judgment of In silico.
-A new measurement that has not been realized even in a conventional large-scale facility at a relatively low cost (for example, a single device or the like can be used frequently).
-For example, in medical treatment, using ultrasonic echo method, MRI, OCT, laser, or optical pulse, observe the distribution of displacement (vector) and deformation of the observed tissue, etc. (viscous) Distribution of physical properties such as shear modulus The original image and their observations are merged to diagnose and discriminate the lesion (in addition to various fusion and integration processes, the images are simply watermarked and superimposed to simultaneously In some cases, if any treatment (surgery or physio / chemotherapy) is performed, even the therapeutic effect (mainly, degeneration) is diagnosed using the same index (observed physical properties), that is, It is effective to diagnose, monitor, and monitor the progress before, during, and after the treatment, and in particular, in heating and heating treatment, use the sound speed of ultrasound and the temperature dependence of volume change. Nuclear The chemical shift of the air resonance frequency (Larmor frequency) is used. When light such as OCT is used, the temperature dependency of light (refractive index etc.) is used. The temperature (change) distribution can be observed by using properties, etc., and the therapeutic effect can be monitored. In addition, the thermophysical properties (distribution) can be reconstructed from the observed temperature (distribution) data, Estimation (Determine the heat source based on the inverse problem, or observe the heating and heating waves by sensing and find the autocorrelation function to understand the shape of the heat source and estimate the power of the heat source in consideration of the transmission power and tissue properties Or the shape data can be used for the inverse problem, and the distribution of the wavelength and the propagation velocity of the wave can be observed using the above autocorrelation function) (Patent Document 11). Jill becomes a temperature distribution estimation and predictable, integrated decision with their observations, sequentially make a heat-warming plan, it can be realized minimum-invasive therapy. If the receiver can also receive at the time of HIFU transmission, the receiver can process and use the echo signal generated by the HIFU transmission, and if reception is impossible, transmit the ultrasonic wave for observation to obtain the reception signal. It can be. Either can be used for imaging. Calculate phase aberration (caused by temperature dependence of sound speed, inhomogeneity of sound speed, wave directivity, etc.) using at least one of the received signals, and correct phase aberration for HIFU treatment or observation imaging May be performed to improve the positioning accuracy of the treatment position. HIFU beam and treatment parameters may be determined sequentially by optimization based on observation results and prediction results (a variety of linear and non-linear optimization methods can be used. In Patent Documents 45 and 46, an apodization function is optimized in order to achieve a desired sound pressure shape (point spread function) and its distribution. Linear or non-linear programming is also valid. In some cases, the temperature distribution and the amount of exposure, or the tissue properties such as the (viscosity) elasticity and the tissue pressure are optimized for optimization. At that time, typical data, measured values, or models of the heat receiving characteristics and denaturing characteristics of the treated tissue may be used. The present invention provides an HIFU irradiation power, irradiation intensity, continuous irradiation time, irradiation interval, irradiation position (focus position) based on the above observation, prediction, or optimization realized by making full use of the signal processing described in the present application. Regarding the position), the irradiation shape (apodization), or the HIFU administration interval, this includes electronically or mechanically controlling the HIFU treatment to realize the minimum-invasive treatment. Therapy control itself may be controlled manually by the clinician based on observations, predictions, or optimization results for lesions marked by the clinician or lesions diagnosed mechanically. Yes, it may be controlled automatically mechanically, but in the latter case it is necessary to always allow the clinician to change the course of treatment and switch to manual control mode We need to be able to do that. Switching from manual mode to automatic mode may also be effective. In each case, lesion tracking is important. (It is clear that cross-correlation-based processes such as cross-correlation and cross-spectral phase gradient methods are robust to changes in ultrasound images (noise sources) caused by heating. It is). The interface may be realized mainly by a PC and peripheral devices, or may be realized as a dedicated device.
This is one of the means to realize Theranosis, has extremely high spatial resolution not only for treatment but also for diagnosis, and minimizes invasiveness under the differentiation of diseased tissue, nerve, blood (tube), lymph, and niche. Achieve optimal treatment that is limited to Application to microsurgery is also important. In addition to early detailed diagnosis, one device can simultaneously diagnose multiple or multiple organs (brain, liver, kidney, breast, prostate, uterus, heart, eyes, thyroid, blood vessels, skin, etc.) in multiples Integrated diagnostic imaging that allows for early and precise HIFU treatment, even under the same parameters (mechanical and thermophysical quantities, tissue viscoelasticity and thermophysical properties, or markers, etc.) Diagnostic imaging and monitoring of therapeutic effects, as well as follow-up after treatment are possible, making diagnosis and treatment both minimally invasive, simple and fast, and therefore cheaper than other techniques. Medical services that can be performed can be realized. With the development of medical technology adapted to the super-aging society, it is a medical technology that will open up new clinical styles (diagnosis and treatment in a short time, medical examination, etc.) and will be useful for a long time in the future. These means are effective not only in HIFU but also in radiation therapy, heavy ion beam therapy, and optical therapy. It is also effective to use drugs (including those that respond to irradiation waves) and contrast agents in combination. Further, the waves for observation are not limited to ultrasonic waves, and various sensing waves such as MRI, OCT, and X-ray can be used (many other waves are described). In these waves, the wave parameters and beam forming parameters may be similarly optimized in order to realize a desired point spread function (wave shape) and its distribution (for example, Patent Document 12, Non-Patent Document 45). And 46 etc.). A point spread function with high spatial resolution and small side lobe (high contrast can be realized), a point spread function that can realize high-precision displacement measurement, their distribution, and the like can be realized. These waves are sometimes fused and integrated. Similar observations may be effective not only in medical applications but also in cases where diagnosis, restoration, creation, etc. are performed in material engineering.
-Elucidation of the function of human and animal brain tissue: In the cultured neural network, the learning and recognition processes, the effects of drug administration, etc. are observed in situ, heart and brain blood vessels (viscoelasticity), blood flow ( High-precision simultaneous observation of fluids and microflows can be performed. In addition, in conjunction with this, it becomes possible to develop external stimulation tools and processing techniques for those tissues and cells.
(Ii) Application to environment and industrial biotechnology, energy saving and environmental conservation (recycling, observation of air, soil, water, etc.). Acoustic properties of various gases (optical pulse, optical microphone), gases containing various dusts (flow observation by terahertz), etc.
(Iii) Development of new synthetic theories such as equivalent media and function substitution (material engineering).

Next, the above-mentioned (1) to (4) [Patent Documents 8 to 10 and the like], other inverse analysis, and the means of fusion / integration of (5) are listed. Technology related to information science and statistical mathematics, including back analysis. Basically, it aims to exceed the normal measurement limit. For example, the following processing is effective.
(A) Inverse analysis: In wave sensing,
・ Uses equalizers and sparse modeling of the system including the observation target (identification, reduction of dimensions, generation of coarse sampling data based on downsampling (the effect of regularization in inverse analysis), band compression in Fourier beam forming, etc.) Faster and more stable, data compression.
When performing inverse in measurement / reconstruction by optimization (weighted least squares, Bayesian estimation, maximum likelihood estimation (with or without MAP), singular value decomposition, linear / nonlinear programming, convex projection, etc.)・ Inverse analysis of Sabatt's law, such as integration type inverse problem such as obtaining current density (vector distribution) data and current (distribution) from magnetic field (vector distribution) data, and physical property reconstruction (linear or nonlinear differential inverse) Problem: Stabilization of the solution by optimizing the reference area (initial value) and the integral inverse problem (nonlinear inverse problem similar to impedance CT etc.) in the initial value problem using partial differential equations.
・ Unique existence and adaptive stabilization of the solution by unbiased regularization when performing inverse analysis (The inventors of the present application were the world's first time-variant regularizations that depended on the accuracy of measurement data in the past. By using parameters and setting large regularization parameters to stabilize the observation target as much as possible and reduce the variance, the world's first in silico standard may be realized. In the past, displacement (vector) observation and (viscosity) Implemented by reconstructing shear modulus).
・ Establish an error model (variation and variance) of the sensing signal directly observed in addition to each observation target (strain tensor, temperature, current density vector, each physical property, etc.) and improve the accuracy (displacement (vector) in the past) When estimating a measurement error, a stationary process is assumed locally in space and time, and Cramer-Rao Lower Bound (CRLB) and Ziv-Zakai Lower Bound (ZZLB) are used. For a priori or a posteriori, the regularization parameter is used in proportion to the variance (thus, it may be spatiotemporally variable). For each equation, the reciprocal of the variation or the reciprocal of the variance is used to weight the reliability (weighted least squares), and regularization and weighting may be performed simultaneously.
・ Super resolution (high resolution, world's first in silico harmonic generation imaging and instantaneous phase imaging, known inverse synthetic aperture and inverse filtering), new minimum variance beamforming (phase aberration correction is effective), and the above signals (source ) High resolution. The maximum likelihood estimation and the like have been used for a long time in image processing. For example, a point spread function that can be variously estimated by, for example, obtaining an autocorrelation function is used (for example, Non-Patent Documents 31 to 34). There are various other methods.
-Analog or digital linear or nonlinear processing of wave signals, generation and utilization of new waves due to linear or non-linear phenomena in the propagation process (within or outside the observation target), multiple waves with single or different parameters, Includes cases where objects with different observed quantities (physical quantities or chemical quantities) are targets.
・ Signal (source) separation and feature analysis (Independent Component Analysis ICA, Principal Component Analysis PCA, MUSIC, application of the above regularization, singular value decomposition, machine learning, neural network, deep learning, etc.)
It is not limited to these.
Also,
(B) Integration and fusion of heterogeneous information, multiplexing of the same information and separation of independent information (rather than simply exceeding the limit of accuracy by a single observation by simply over-determined systemization (addition averaging or least squares), Exceed by high-precision multiplexing of common information and separation of independent information: In signal processing and image processing, in particular, MRI (electromagnetic wave) and ultrasonic wave (mechanical wave), ultrasonic wave and terahertz (simultaneous observation of organic and inorganic), ultra In addition to using KL information, maximum likelihood estimation, mutual information minimization / maximization, entropy minimization, etc. for multiplexing and demultiplexing by new integration and fusion of sound waves (longitudinal waves) and shear waves (horizontal waves), In order to dramatically improve accuracy,
-ICA (In the past, if the ultrasonic echo signal (random signal) of human tissue was processed and subjected to precise spatio-temporal matching of multiple data (phase rotation without approximation processing in digital signal) and then processed, common information Extraction ability exceeds the averaging and separation of independent components is improved.
・ Neural network (deep integrated learning and integrated judgment / recognition): An approach for integrated learning / integrated recognition of multiple neural networks of three or more layers with heterogeneous feature vectors (information) as input (beyond the third layer of the recognition layer) Connect multiple neural networks with each other, train each neural network to a certain extent without learning deeply with the closed data of each feature vector (information), combine them, and use the closed data of all feature vectors (information) Learning speed is much faster than learning from closed data of all feature vectors (information) using a connection network from the beginning, and the learning rate is dramatically improved.) Applied to handwritten digit recognition, the recognition rate is dramatically improved compared to the case where only a single feature vector (information) is used In the integrated analysis, the weight distribution of the newly trained single neural network, the weight distribution of the network in the case of using the connected network from the beginning of learning and the network weight distribution in the case of deep learning by being connected after some learning as described above For example, it is effective to visualize the weight distribution or to perform ICA or PCA processing on the weight distribution to interpret the common component and the independent component. The recognition target is encoded and learned by encoding the type of (e.g., using an independent code), or the same or different observation data related to the recognition target, the related observation data, or the related recognition target (for example, Diseases and lesions), desired objectives and goals, new physical properties and functions (creation and synthesis by in silico and their use, and cases where it is difficult to make devices and comparisons) In the case of simple, inexpensive, etc., it may be operated in conjunction with other dedicated devices). In addition to back projection type, Hopfield type (learning and recognition of associative memory) can be implemented in the same way The same can be used when performing optimization or processing (in silico processing) described in this specification in addition to other models and neural networks.
-For phenomena with different stochastic processes (for example, ultrasonic Rayleigh scattering and normal distribution of observation noise, etc.), multiplex common components and separate independent components, transition to stochastic processes with different stochastic processes (stochastic models, Changes in random variables, etc.).
Also,
(C) Big data processing:
・ When handling big data such as a lot of sensing data (spatio-temporal), high-speed and high-precision Fourier beam forming and parallel processing are performed at the time of sensing in order to realize high-speed calculation in pursuit of real time.
Data mining (including the above-described statistical processing and correlation processing, extraction of feature amounts by ICA, PCA, neural network, etc.).
Also,
(D) Improvement of observed signal SN ratio: For example, generally observed terahertz signals, SQUID signals, light, etc. have a low SN ratio, and can be learned from analog processing of correlation in OCT, digitized, and processed by ICA. High-precision technology based on signal processing (signals are real-time signals or complex signals) such as MUSIC, Wiener filter, matched filter, correlation processing, and signal detection.
In the present invention, the above processing and the like are performed, but the purpose and processing means of the present invention are not limited to these.

  (1) to (4) of measurement / inverse analysis (imaging) performed using hardware (equipment, platform) and computers, and (5) fusion / integration (information science, statistical mathematics, etc.) using them Innovative technology that integrates and integrates non-destructive inspection of physical quantities, stoichiometric quantities and physical properties in physics, chemistry, and biochemistry in real time in an integrated and integrated manner (Measurement / analysis method), innovative measurement (inspection and diagnosis), repair (repair, treatment, regeneration), manufacturing (material growth and three-dimensional culture of tissue), and application (synthesis, etc.) in various fields. Creation of functions and physical properties). This research concept enables the detection of physical quantities and material states, their changes, latent factors, etc., which were not captured until now, and also enables various observations of the actual operation and functioning of the measurement target. Is the promotion of human health through medical and life sciences, the development of new technologies through the development of materials (including synthetics), food engineering (such as control of freshness and quality), highly efficient energy development and resource exploration, energy saving, Assessment and environmental protection (Earth and celestial bodies), weather forecasts (weather forecasts, rainfall, gas convection, ocean currents, etc.), security, satellites, radar, sonar, international standards (may be the first standard in silico) It has a tremendous ripple effect both economically and socially, including in the industrial world and social infrastructure. The techniques developed will always be basic technologies that contribute to the creation of science and technology innovation, new industries, and social contributions.

On the other hand, in the methods (1) to (6) relating to beamforming, the received signal stored in a memory or a storage device (storage medium) in order to generate a one-frame image signal by frequency-dividing the spectrum, In some cases, a plurality of processed waves are obtained in a situation where the spectrum is divided in the frequency domain represented after the matching. In some cases, the image is divided into angular spectra and each is processed. In any case, the processing may be performed by limiting the band of the signal component. Even when a plurality of waves overlap, the spectrum may be frequency-divided similarly. The frequency division of these spectra corresponds to the generation of physically simulated waves having new wave parameters (frequency, band, propagation direction, etc.). The divided spectra may be processed in parallel. The superposition process is also a process for generating a new wave parameter, but may be a process in which angular spectra are superimposed in the spatial domain and overlapped, or a spectrum may be superimposed before inverse Fourier transform. However, if necessary, the angular spectra after Fourier transform may be superimposed, or the signals after inverse Fourier transform may be superimposed. By applying the reversibility of the Fourier transform (Fourier transform and inverse Fourier transform), the generated signal is returned to the signal before receiving beamforming (or before transmitting and receiving beamforming in the case of aperture plane synthesis), and the other beamforming is performed. (For example, different steering angles for transmission or reception, a plurality of waves having different steering angles for one transmission, etc.).
As super-resolution processing, spectrum weighting processing (not so-called mere inverse filtering or deconvolution, but processing of performing such processing and filtering to have a desired point spread function can be performed collectively) , Non-linear processing, and imaging of the instantaneous phase excluding phase rotation are described. In addition to the Fourier beam forming, the processing may be performed under DAS processing. For example, when transmitting a wave that spreads widely in the horizontal direction, such as a plane wave, a circular wave, a cylindrical wave, and a spherical wave, it is possible to perform high-speed imaging as described above. It is effective to generate a plurality of waves with different steering angles for transmission or reception, superimpose them, and apply a super-resolution process to them after widening the bandwidth in the lateral direction, because these effects can be enhanced. It is. Superposition of plane waves, etc., realizes a case where uniform focusing is performed regardless of the depth position with respect to the phase, and based on the above-mentioned spectrum weighting processing, for example, when performing apodization using a Gaussian function. It is effective to compensate for the spectral intensity by targeting high-resolution imaging using aperture plane synthesis based on apodization using a square wave or a power function. In other words, the superposition corresponds to calculating the inverse of the calculation of the Angular spectrum based on plane wave separation in Fourier imaging. In some cases, the object subjected to the focusing and the synthesis of the aperture surface is subjected to the overlapping process. It is important to adjust the steering angle to be superimposed. When the angle difference is small, the band is not widened by merely looking at the spectrum intensity relatively in the lateral direction (the band is not broadened because the spectrum intensity is relatively low). However, if there is a certain SN ratio in the band, especially at the time of the aperture plane synthesis processing), if a certain degree of angular difference is provided, the band is broadened in a situation where the spectrum intensity is high. For a band having a relatively low spectrum intensity when the angle difference is small, for example, the spectrum weighting process is effective. Since the signal strength is low due to the superposition of those having different phases, it is necessary to perform double-precision calculation processing (such as beamforming and super-resolution processing) as necessary. On the other hand, when there is a certain angle difference, a wideband signal can be easily obtained with a small number of waves or beams. In those cases, it is also effective to normalize the wave energy and superimpose them. Similarly, the other two super-resolutions are also effective. Of course, a superposition process in which waves having different focus positions and ultrasonic frequencies are superposed is also effective as a super-resolution method. The results obtained by applying super-resolution to each wave can also be superimposed, but the processing performed by superimposition is less processing and more effective. Phase compensation in the superposition (compensating for inhomogeneities in wave propagation velocity) is important.
The inventor of the present application has proposed a method of observing a displacement vector (strain tensor) of an observation target based on an ultrasonic echo method (that is, a reflection method) or a transmission method, such as a cross-spectral phase gradient method or a multidimensional autocorrelation method. (And many others). It can also be used when using waves other than ultrasonic waves. In order to improve the measurement accuracy when using these techniques, it is effective to realize an over-determined system by extending the lateral modulation method to use more waves or using spectral frequency division. The regularization (a priori or a posteriori, cross-validation method) and the weighted least squares method (a priori or a posteriori) are effective. Maximum likelihood estimation (for example, Non-Patent Document 37) is also effective (with or without MAP). It is also effective to combine, integrate and mix them. When the variation is used, a local stationary process can be assumed, or Cramer-Rao Lower Bound (CRLB) or Ziv-Zakai Lower Bound (ZZLB) can be used. It has been found that the estimated variation can also be used (discussed below). Furthermore, by applying the displacement vector (strain tensor) observation, it is possible to increase the resolution of an image (for example, an ultrasonic echo image or the like) obtained from a wave signal obtained by a reflection method or a transmission method. For example, a plurality of wave signal frames that are continuous in time (for example, an ultrasonic rf echo data frame) or an image frame obtained therefrom may be subjected to the phase matching implemented in the present invention, or a motion based on a Markov model. And the use of signal separation such as the superposition processing and ICA processing of the present invention, and fusing statistically (multiplexing and separation, etc.), and various super-resolution (for example, Patent Document 38) can be effectively applied. Fusion processing after super-resolution is also possible. As the phase matching performed in these, block matching is also effective, but as described above, particularly, highly accurate phase matching based on phase rotation is effective.
Also, so-called Compressed sensing may be performed. Similarly, it may be performed in the DAS processing. Like the three super-resolutions described above, the super-resolution may be applied to the superposition of a plurality of waves. Although the above three super-resolutions require less computation, a combination of them, including compressed sensing, may be processed.

Here, some examples of DAS processing that may be performed in the present invention will be summarized. The method DII of the present invention and the like are also included. In addition, although processing of a real-time signal and an analysis signal is described below, other processing may be performed on a signal that has been subjected to various processing described in this specification.
-DAS processing performed by a normal digital diagnostic device (method D1)
In order to perform reception dynamic focusing, in reading out a reception signal stored in the memory of each channel after AD (Analog-to-Digital) conversion processing, it is determined by a distance between each reception element position of each channel and each point of interest. The stored signal is read from the memory at the address indicating the time of digital reception (ie, Delay). Then, those signals within the effective aperture width are added (Summation). According to this method, an error is determined in the delay depending on the sampling frequency of the received signal. Therefore, it is natural that sampling is performed based on the Nyquist theorem, but sampling is performed at as high a frequency as possible. It has the feature of being fast. The signal to be processed may be an analysis signal other than the digital actual signal after the AD conversion processing. In addition, the calculation may be performed using a general-purpose CPU in addition to the dedicated circuit, and an embodiment of a calculation protocol will be described below. The sampled time or space coordinates (integer value) may be considered as an index of an array in which a digital signal is stored in a program, or may be considered as an address of a memory in which a digital signal is stored. ).
For example, in the DAS processing at the interest point A or at the sampling position i = I closest to the interest point A and represented by an integer value, the real signal or the analysis signal
r (I) (DAS1)
If the signal from the point of interest A received by another receiving element that is added to the received signal r ′ is present at a position where the propagation distance is longer by Δx in the received signal r ′ (in the case of the reflection method, an outgoing Alternatively, when performing beamforming for transmission, the difference in propagation distance at that time is included), and when the sampling interval is represented as sampx by distance, Δi = nint (Δx / sampx) (where nint ( x) represents a rounded integer function), or Δi = inta (Δx / sampx) (where inta (x) represents a rounded-up integer function), or Δi = intd (Δx / sampx) (where, a real signal or an analytic signal represented using an integer value Δi calculated using a function or calculation for converting an argument x to an integer (eg, intd (x) represents a round-down integer function).
r '(I + Δi) (DAS1')
Is added. It is desirable that the integer value Δi is such that Δi × sampx is closest to the analog value Δx (nint is good in the above), and the calculation method is not limited to these. The digital signal received by the receiving element within the effective aperture width at each position is subjected to this processing and added. The same description can be made using time instead of distance under the assumption that the propagation speed is constant.
Alternatively, there are various interpolation processing methods for digital signal values, and using these, the signal value at the position of Δx may be obtained by interpolation approximation (bilinear interpolation, higher-order interpolation, Lagrange's method, spline interpolation, etc. However, not limited to these, various interpolation approximations can be performed).
DAS processing with high accuracy of method D1 (method D2)
In performing the DAS processing based on the method D1, in order to improve the delay processing accuracy, the analysis signal a (t) of the reception signal calculated based on the Hilbert transform is multiplied by a complex exponential function, and the phase rotation is performed. applying a Delay to perform by, with the accuracy of the short time in t ₀ than the sampling time interval Sampt, adds processing.
a (t + t ₀ ) = a (t) exp [jω ₀ (t) t ₀ ] (DAS2)
Here, j is an imaginary unit, and a relationship of t = i × sampt (i is an integer value of ₀ to N−1) is established, and ω ₀ (t) is a nominal angular frequency at a sampling time (position) t. , The center-of-gravity (center) angular frequency, or the instantaneous angular frequency. The expression (DAS2) approximates the signal at the time (position) moved by the analog amount t ₀ in the positive direction of the sampling coordinate system with respect to the sampling time (position) t. In the DAS processing at the sampling position i = I, which is the nearest integer to the point of interest A and is represented by an integer value, for the sampling time (position) t, for the sampling time (position) t, the analog value Delay value Δt (reflection method In such a case, when performing beam forming of the forward path or transmission, such as synthesis of an aperture surface, using Δi (for example, Δi = nint (Δt / sampt)) calculated based on the delay at that time (including the delay). It is desirable to use the analytic signal a (t) (= a ((I + Δi) × sampt)) of the represented sampling time (position) I + Δi. That is, it is desirable to use the signal of the sampling time (position) t closest to the ideal analog time (position) T = I × sampt + Δt. Therefore, when T> t, the formula uses the positive value t ₀ = Tt = Δt−Δi × sampt, and when T <t, the formula uses the negative value t ₀ = Tt. The digital signal received by the receiving element within the effective aperture width at each position is subjected to this processing and added.
Although the accuracy is higher than that of the method D1, the approximation process is performed using the frequency ω ₀ (t) of the sampled time (position). Affected by frequency modulation such as attenuation and scattering. As in the method D1, the higher the sampling frequency, the better. It has high speed.
By the way, when the sampling signal is represented not by time but by discrete positions x (= i × sampx, i is an integer of 0 to N−1), the equation (DAS2) expresses the wave number k ₀ (= ω ₀ / c = 2πf ₀ / c = 2π / λ) (where c is the propagation speed of the wave, f ₀ is one of the nominal frequency, the center of gravity (center) frequency, and the instantaneous frequency, and λ is the wavelength)
a (x + x ₀ ) = a (x) exp [jk ₀ (x) x ₀ ] (DAS2 ')
It is expressed as Similarly, in the DAS process at the sampling point i = I, which is the nearest point to the point of interest A or the point of interest A, the distance difference Δx of the analog amount to be applied to the discrete position x (in the case of the reflection method, When performing beam forming of the forward path or transmission, such as synthesis of an aperture plane, a Δi (for example, Δi = nint (Δx / sampx)) calculated based on the propagation distance difference at that time is used. It is desirable to use the analytic signal a (x) (= a ((I + Δi) × sampx)) of the sampling position I + Δi expressed as That is, it is desirable to use the signal at the sampling position x closest to the ideal analog position X = I × sampx + Δx. Therefore, when X> x, the formula uses a positive value x ₀ = X−x = Δx−Δi × sampx, and when X <x, the formula uses a negative value x ₀ = X−x.
Alternatively, in each of the expressions (DAS2) and (DAS2 ′), the phase rotation is performed on the digital signal at the sampling time (position) t and the position x that are closest to the ideal analog time (position) T and the ideal analog position X. Rather than multiplying, each receiving element position within an effective aperture width when each sampling position i (i representing x = i × sampx) of each beam or each wave to be generated is considered as each point of interest A, The delay Δt and the distance difference Δx with respect to the point A are used as discrete (digital) data Δt (i) and Δx (i) represented for each point of interest i, and reception within the effective aperture width of each position is performed. The analysis signal a (i) of each digital reception signal received by the element is multiplied by a complex exponential function as follows,
a (i) exp [jω ₀ (i) Δt (i)] (DAS2 '')
a (i) exp [jk ₀ (i) Δx (i)] (DAS2 ''')
to add.
-DAS processing which improved method D2 (method DII)
Although the method D2 is an approximation process using the frequency and the wave number of the sampling position in the analysis signal, the method DII of the present invention similarly enables high-speed calculation without using the frequency and the wave number of the sampling position.
Center-of-gravity (center) frequency also obtained as the center of gravity of the amplitude spectrum S (i) (the spectrum of the non-positive frequency is zero) in the frequency domain (analog value obtained at the frequency coordinate i represented by an integer value in the discrete Fourier transform)
M ₀ = ΣiS (i) / ΣS (i) (DASII1)
However, the amplitude spectrum S (i) (where i = 0 to N−1) is the product of the product of the Fourier transform of the digital spatial signal r (x) (where the sampling position is x = i × sampx) and its conjugate. Calculated by square root. The addition range of Σ in the equation is i = 0 to N / 2.
Therefore, the wave number k ₀ is
k ₀ = (2πM ₀ ) / (N × sampx) (DASII2)
It is. Here, the analysis signal a (x) is
a (x) = A (x) exp {jk ₀ (x) x}
= A (x) exp {jk ₀ (x) × (i × sampx)} (DASII3)
Try to express.
Based on this, when each sampling position i (i representing x = i × sampx) of each beam or each wave to be generated is considered as each point of interest A, each receiving element position within the effective aperture width becomes each point of interest. The distance difference Δx with respect to A is used as discrete (digital) data Δx (i) represented for each point of interest i, and the digital reception signal of each digital reception signal received by the receiving element within the effective aperture width at each position is used. Multiply the analytic signal a (i) by a complex exponential function as follows,
a (i) exp {j (2πΔx (i) / sampx) / (N × sampx) × (i × sampx)}
= a (i) exp {j (2πΔx (i)) / (N × sampx) × i} (DASII4)
Is calculated. As the DAS-processed signal advances in the positive direction of x, an effect is obtained in which the direction orthogonal thereto is strongly increased in bandwidth (higher resolution). Note that i (= 0 to N) in the expression (DASII4) is replaced by
Ni (i = 0 to N-1) (DASII5)
May be used for calculation. In this case, as the DAS-processed signal returns to the negative direction of x, an effect is obtained in which a direction orthogonal to the direction is strongly increased in bandwidth (higher resolution). If Δx is made constant without depending on the point of interest i, it means that invariant frequency modulation is applied in the i direction. In other words, this process applies frequency modulation to the received signal at each receiving element position within the effective aperture width for each point of interest i.
M ₀ + Δx (i) / sampx (DASII6)
Is multiplied and added. Similarly, when the signal is represented as a digital time signal r (t) instead of a digital spatial signal, the analytic signal a (i) represented using the instantaneous frequency ω ₀ (i) is also as follows. Multiplied by the complex exponential function,
a (i) exp {j (2πΔt (i) / sampt) / (N × sampt) × (i × sampt)}
= a (i) exp {j (2πΔt (i)) / (N × sampt) × i} (DASII4 ')
Is calculated. Others are the same.
It is also effective to apply a desired frequency modulation to a specific position or to apply a spatially uniform frequency modulation. When the modulation wavelength applied to the signal at the position x and the time t is k ₀ ′ and the modulation frequency is ω ₀ ′,
a '(x) = a (x) exp [jk ₀ ' (x) x] (DASII7)
a '(t) = a (t) exp [jω ₀ ' (t) t] (DASII7 ')
Is obtained. Similarly, it can be applied to discrete signals.
The superposition of unmodulated waves and modulated waves is also effective in increasing the bandwidth (improving the resolution) and increasing the accuracy of observations using phase (such as displacement observation).
・ Theoretically most accurate DAS processing (Method D3)
In the method invented in the past by the inventor of the present application (Patent Document 6, Non-Patent Document 15), the spectrum A (ω) of the local signal including the signal at the point of interest is multiplied by a complex exponential function in the frequency domain. Delay is performed by rotating the phase of the local signal.
A '(ω) = A (ω) exp [jωt ₀ ]
This is an interpolation process that satisfies the sampling theorem, and has the highest accuracy in theory, but requires calculation time.
・ Fourier beam forming (Method D4)
This is beamforming which is the basis of the present invention. This is a method for performing digital wave number mapping in a multidimensional frequency domain of a received signal, and performs a fast Fourier transform to calculate an accuracy equivalent to that of the method D3 at a much higher speed. As a feature different from other reported Fourier imaging methods, an interpolation approximation process is not required in the digital wave number mapping, but it is also possible to perform an interpolation approximation process in order to further increase the speed. However, in that case, it is required to increase the sampling frequency in order to reduce artifacts and decrease in accuracy.
In these beamforming processes, the analytic signal is not always processed, and the calculation time for reducing the received signal to the analytic signal may be omitted to shorten the calculation time. However, in the process of multiplying the complex exponential function in space-time, although it is not theoretically correct and includes errors, imaging of the ultrasonic signal itself and various types of imaging (elastic imaging, etc. And many others) may be practical.
In addition, the respective delay processes in these DAS processes (methods D1 to D3) are performed not only in the DAS process but also in other beamforming such as Fourier beamforming, adaptive beamforming, and minimum variance, and the signal described in the present application. This is useful when shifting signals such as phase aberration correction, motion compensation, phase matching, positioning, and position correction in time coordinates, space coordinates, and space-time coordinates. Further, the present invention is not limited to those described in the present application. As in the case of the one-dimensional analysis signal, the multi-dimensional analysis signal at the position (x, y, z) or the time (t1, t2, t3) can be processed. For example, in method D2,
In the case of two dimensions,
a (t1 + t1 ₀ , t2 + t2 ₀ ) = a (t1, t2) exp [j {ω1 ₀ (t1, t2) t1 ₀ + ω2 ₀ (t1, t2) t2 ₀ }]
(2DAS2)
a (x + x ₀ , y + y ₀ ) = a (x, y) exp [j {kx ₀ (x, y) x ₀ + ky ₀ (x, y) y ₀ }] (2DAS2 ′)
In the case of three dimensions,
a (t1 + t1 ₀ , t2 + t2 ₀ , t3 + t3 ₀ ) = a (t1, t2, t3)
× exp [j {ω1 ₀ (t1, t2, t3) t1 ₀ + ω2 ₀ (t1, t2, t3) t2 ₀ + ω3 ₀ (t1, t2, t3) t3 ₀ }]
(3DAS2)
a (x + x ₀ , y + y ₀ , z + z ₀ ) = a (x, y, z)
× exp [j {kx ₀ (x, y, z) x ₀ + ky ₀ (x, y, z) y ₀ + kz ₀ (x, y, z) z ₀ }] (3DAS2 ′)
Can be calculated. Here, (ω1 ₀ , ω2 ₀ , ω3 ₀ ) is the nominal angular frequency, the center of gravity (center) angular frequency, and the instantaneous angular frequency in each time direction at each time (t1, t2, t3), and (kx ₀ , ky ₀ , kz ₀ ) is the wave number in each direction at each position (x, y, z). Shifting can be similarly performed on a multidimensional signal of a combination of the position (x, y, z) or the time (t1, t2, t3). In other words, in the digital signal, discrete coordinates (which require high precision) are used by using the nominal angular frequency in each time direction at each time, the center-of-gravity (center) angular frequency, and the instantaneous angular frequency or the wave number in each direction at each position. In this case, a high sampling frequency is desirable), and analog shifting can be performed. As in the case of the one-dimensional case, the accuracy can be improved as compared with the method D1 (corresponding to signal block matching or fragment matching in the spatiotemporal domain), and other methods (phase matching based on phase rotation in the frequency domain of the method D3) And the calculation speed is high as compared with the method (Fourier beam forming of method D4). It is suitable when a high calculation speed is required.
The modulation in the method DII can be applied to the multidimensional analysis signal at the position (x, y, z) or the time (t1, t2, t3) as in the case of the one-dimensional analysis signal.
For example, in the case of two dimensions,
a '(x, y) = a (x, y) exp [j {kx 0' (x, y) x + ky 0 '(x, y) y}] (2DASII7)
a '(t1, t2) = a (t1, t2) exp [j {ω1 ₀ ' (t1, t2) t1 + ω2 ₀ '(t1, t2) t2}] (2DASII7')
In the case of three dimensions,
a '(x, y, z) = a (x, y, z) exp [j {kx ₀ ' (x, y, z) x + ky ₀ '(x, y, z) y + kz ₀ ' (x, y, z) z}]
(3DASII7)
a '(t1, t2, t3) = a (t1, t2, t3) exp [j {ω1 ₀ ' (t1, t2, t3) t1 + ω2 ₀ '(t1, t2, t3) t2 + ω3 ₀ ' ( t1, t2, t3) t3}]
(3DASII7 ')
Is obtained. Here, (kx ₀ ′, ky ₀ ′, kz ₀ ′) is a modulation wavelength in each direction applied to the multidimensional signal at each position (x, y, z), and is (ω1 ₀ ′, ω2 ₀ ′, ω3 _0). ') Is a modulation frequency in each time direction applied to the multidimensional signal at each time (t1, t2, t3). The same applies to multidimensional signals having spatial and temporal coordinates. The application is not limited to the DAS processing including the one-dimensional case.
Other delay processing can also be performed on multidimensional signals, and can be performed on multidimensional signals.

In the wave signal, the Fourier transform including not only the axial direction (the front direction of the physical aperture) but also the transverse direction and / or the elevation direction orthogonal thereto is known as a two-dimensional and three-dimensional angular spectrum, respectively. (See the illustration of the two-dimensional spectrum in FIG. 20). Applying this angular spectrum, the present invention makes it possible to evaluate the diffraction phenomena (characteristics) and the diffraction limit of the aperture element used in the sensor as described below. One physical aperture may be targeted, various shapes composed of at least two or more apertures, or a one-dimensional array may be targeted, and the physical apertures themselves may also have various shapes.
First, in the case where reception is performed by the same aperture element or at least two or more aperture elements (array element group) around the aperture element under transmission from one aperture element, diffraction phenomena (characteristics) of the transmission aperture element and The diffraction limit can be confirmed (in general, it is considered that the same aperture element has the same diffraction characteristics and the same diffraction limit for transmission and reception). A process of transmitting the receiving aperture element or the group of the receiving aperture elements mechanically and stepwise or continuously while scanning the object to be measured may be repeated to realize two or more aperture elements in a pseudo manner ( The received signal may be obtained by moving at a smaller interval (step) than the size of the receiving aperture element or the physical element pitch of the receiving aperture element group). The array shape and dimensions of the receiving aperture element itself and the group of receiving aperture elements are also various and are not limited, but generally, those having a flat array shape are used. When the transmission aperture elements form an array composed of transmission aperture element groups, the same shape may be used in some cases. In consideration of the spatial spread of the wave transmitted from the one-aperture element, it is necessary to receive the transmitted wave or the reflected wave without leaking as much as possible. Therefore, the reception aperture element (group) and the transmission aperture element (group) It is desirable that the front directions of the antennas face each other in a parallel direction, and that the number of receiving aperture elements at that time is as large as possible, or that the effective receiving aperture width is as wide as possible. The diffraction phenomenon (characteristics) can be evaluated well. When a transmitted wave is used, it is desirable to use a medium having little disturbance such as reflection, scattering, and attenuation as a medium between a transmission source and a reception source. When a reflected wave (scatterer) is used, one or more reflectors (scatterers) whose size is as small as possible within a range where a reflected signal can be obtained, or a random number of reflectors (scatterers) are used. The distribution can be used as a propagation medium. The scatterer is not limited to a sphere or a sphere, and may have a random shape when probabilistically evaluated. In these cases, the deterioration of a signal during propagation may be corrected for a received signal based on attenuation characteristic data of a medium as necessary. In addition, non-uniformity of the propagation speed of the medium may be dealt with by performing the phase aberration correction described in the present application. The aperture element for reception may be the same as the aperture element for transmission (the diffraction phenomena (characteristics) of transmission and reception may be considered to be the same), or may be compared in each direction. In some cases, a high-bandwidth and highly sensitive one is used (the band of the diffraction phenomenon (characteristic) of the observable transmission aperture element is determined by the reception aperture element or the group of the reception aperture element and the circuit). A dedicated hydrophone may be used. When a transmitted wave or a reflected wave is used, a diffraction phenomenon (characteristic) and a diffraction limit for transmission and reception are directly observed. Under the assumption of a linear system, if the aperture elements for transmission and reception are different (diffraction phenomena (characteristics are different)), the diffraction phenomena (characteristics) for transmission and reception are the diffraction phenomena (characteristics) for each of transmission and reception. ) Can be modeled as the product (AC−BD + jAD + jBC) of the frequency response (the spectrum (A + jB) and (C + jD) of the reciprocal of each frequency or wavelength) or the convolution of the diffraction phenomena (characteristics). In this case, the diffraction phenomenon (characteristics) (C + jD) of the receiving aperture element or the group of receiving aperture elements is divided by deconvolution or inverse filtering (frequency response (C + jD) in the frequency domain) as described in the present application in the frequency domain or the spatiotemporal domain. Or solve simultaneous equations in the spatio-temporal domain, or perform optimization or super-resolution on them) to separate them and evaluate the diffraction phenomena (characteristics) and diffraction limit of the transmitting aperture element. Can be. For convenience, or when the bandwidth is wider than the transmission aperture element, or particularly when the bandwidth characteristics of the reception aperture element or the group of reception aperture elements are flat, the diffraction phenomenon (characteristic) corresponding to the transmission / reception directly observed. May be used as a diffraction phenomenon (characteristics) of the transmission aperture element, or the diffraction limit of the transmission aperture element may be evaluated based on this. If the transmitting and receiving aperture elements are the same, under the assumption of a linear system, the diffraction phenomena (characteristics) for transmission and reception are the same as the frequency response (A + jB) of the same diffraction phenomena (characteristics) for transmission and reception. It can be observed as the product (A ² −B ² + 2jAB) or its convolution integral, and further, it solves simultaneous equations in the frequency domain or the spatio-temporal domain (similarly, optimization and super-resolution may be applied) and transmission It is also possible to evaluate the diffraction phenomena (characteristics) and diffraction limit of only the minute (or the amount of reception). Strictly speaking, the diffraction phenomena (characteristics) and the diffraction limit change depending on the intensity of the transmitted wave and the intensity of the received wave, so that observation depending on those intensities is required. It is not always treated as a linear system, and another model may be used. Under these processes, in the horizontal and / or elevation direction spectrum or in the multi-dimensional spectrum including the axial direction, the frequency coordinate axis in the angular direction as viewed from the direct current (origin of the frequency domain) where the spectrum exists. Shows that a wave in the same angular direction in space-time has a spectral distribution (superposition of signals of that frequency) confirmed on its frequency axis (the proof is in Non-Patent Document 30). Through transformation (spectral analysis), it is possible to evaluate the diffraction phenomenon (characteristics) and the diffraction limit (particularly, the spread of the spectrum in the lateral or elevation direction), including the spread of spatiotemporal wave propagation (multi-dimensional signal (See FIG. 20 for a two-dimensional signal.) In the present invention, there may be a case where the diffraction phenomenon (characteristics) is predicted and used through simulation, and the operation is performed in conjunction with the design of the element aperture (including the selection of the material as well as the shape and structure) (trial operation). It may be performed by mistake, but of course, by logic, it may be determined based on an optimization method together with sensor array parameters, beamforming parameters, wave parameters, etc.).
Further, the diffraction phenomena (characteristics) and the diffraction limit of the reception may be directly evaluated. The same applies to the case where it is necessary to observe the diffraction phenomenon (characteristics) of reception strictly separately from the diffraction phenomenon (characteristics) of transmission, and vice versa. The transmission and reception in the above process may be performed in reverse, and a plurality of transmission aperture elements are used for one reception aperture element, and the received signal is transmitted in the horizontal direction and / or the elevation direction according to the transmission position. It is sufficient to arrange them, generate a multidimensional signal, and perform the same processing. In this case, it is desirable that the transmission aperture element has as wide a band as possible in each direction, and a transmission aperture element having an aperture area as small as possible may be used. The received signal may be obtained by moving at intervals (steps) shorter than the physical element pitch.) An apparatus and a method for evaluating a diffraction phenomenon (characteristics) and a diffraction limit of the present invention using Fourier transform (spectral analysis) have not been disclosed so far.
Further, the device pitch in the lateral direction or the elevation direction can be determined by using this apparatus or method. For example, in the field of ultrasonic waves, in recent years, the bandwidth has been dramatically increased in each direction, including single crystal, composite PZT, PVDF, and CMUT (Capacitive Micro-machined Ultrasound Transducer). In digital devices, the sampling interval in the axial direction is determined by the Nyquist theorem, but there is no method for determining the element pitch in the horizontal direction. The received signal obtained by performing reception or transmission at a sufficiently short interval in the horizontal direction or the elevation direction is multidimensional Fourier transform including the axial direction, or when focusing on the spatiotemporal position in a certain axial direction, its position , A Fourier transform in the horizontal direction and / or the elevation direction may be performed to obtain the maximum value (± fm) of the reciprocal of the maximum frequency or wavelength in the horizontal direction of the multidimensional signal. Based on the Nyquist theorem, a short element pitch of not more than twice the reciprocal of fm or not more than 1/2 the reciprocal of fm may be realized. As described above, in the spectrum in the lateral direction and / or the elevation direction, or in the multi-dimensional spectrum including the axial direction, the frequency coordinate axis in the angular direction when the direction in which the spectrum exists is viewed from the direct current (origin of the frequency domain). It shows that waves in the same angular direction in space have a spectral distribution (superposition of signals of that frequency) confirmed on its frequency axis (the proof is in Non-Patent Document 30), and the Fourier transform (spectrum) Analysis), it is possible to evaluate diffraction phenomena (characteristics) and diffraction limits, including the spread of spatiotemporal wave propagation. Similar to the above, it may be performed by trial and error, and of course, it is not performed logically, based on the optimization method, together with other sensors and sensor array parameters, beamforming parameters, wave parameters, etc. May be determined. Although the array may be used with an integrated sensor, mechanical scanning is useful if it becomes apparent that a smaller element pitch is required than the element size. Techniques for processing array elements into smaller ones and mounting them are also important.
For example, in the current ultrasonic diagnostic imaging apparatus, the processing of the axial wave is emphasized and the horizontal aliasing (when exceeding ± fm) is ignored, and the processing may be performed. In this case, at each position in the imaged area, a signal that is inverted in the horizontal direction with respect to the aliasing is imaged. Recently, compounding and displaying the steering wave after detecting it has been performed in many cases, and the problem is further increased when steering is performed (although the problem is reduced in some sense by superposition). . At present, Doppler calculates and applies velocity and displacement only in the axial direction where aliasing does not occur. As described in the present application, in the next-generation lateral displacement observation and the observation of the displacement vector, etc., the horizontal aliasing of the raw signal generated by each transmitting or receiving aperture element or aperture element group (array) is performed. In addition to avoiding and making full use of the aperture element's wide bandwidth, high frequency (high precision) and high spatial resolution can be achieved, as well as imaging, in all directions without artifacts in the horizontal direction and elevation direction. Performing broadband imaging is important for the future. Even if other waves are targeted, the diffraction characteristics of the transmitting or receiving aperture element or the aperture element group (array) are inverse-filtered or super-resolution and beam-formed, and dynamics such as imaging and displacement are performed. Sometimes used for observation.
The angular spectrum is applied to the wave after the beam forming, and is frequently used in the present invention, including the invention described below. In particular, in Fourier beamforming without interpolation approximation and in DAS processing using an analytic signal multiplied by a complex exponential function described in the present application, it is also important to improve the resolution of AD conversion (currently, 12 bits is the mainstream).
In addition, the beam forming method according to another aspect of the present invention provides an array type aperture element in all beam forming, such as Fourier beam forming and DAS processing described in (1) to (6) and (7) above. In groups (each element is independently driven and has independent transmit or receive channels that can independently receive signals) in adjacent or distant locations (not necessarily at equal intervals) At least two or more elements are subjected to the same transmission or reception delay or transmission or reception apodization and used as one aperture to transmit or transmit a wave having a greater strength than transmission or reception using one element. Includes use for reception beamforming. For example, in the one-dimensional array type transducer, when the element width and the element interval are shortened in order to improve the spatial resolution in the axial direction and the lateral direction, the intensity of the wave of transmission and reception becomes weak. This is also the case when a two-dimensional array or a higher-dimensional array is used (the element width and the element interval in the direction of the number of dimensions are reduced). Even when the frequency is increased by reducing the element thickness, for example, in the case of using ultrasonic waves such as PVDF having a lower transmission intensity than PZT or the like, the strength of the wave is weakened. It is effective in such a case. That is, it is possible to increase the intensity of the transmission or reception wave, and to improve the SN ratio of the reception signal received by the reception transducer. For example, it is effective when performing classical aperture synthesis (monostatic or multistatic). In the scanning in this case, the effective aperture width can be shifted by the distance of the physical element interval (one element at a time), or can be shifted by the distance of an arbitrary number of elements. Yes, and the distance to be shifted during scanning may be variable. In a multi-dimensional array transducer, scanning may be performed at different numbers of elements or at different distance intervals in each dimension direction. The combination of adjacent or distant elements considered as one aperture may change during the scan. Further, there is a case where the effective aperture width is changed during scanning as is performed by ordinary beam forming. The process itself can be performed in various types of array type transducers, and the processing itself is not limited to digital devices, but also a fusion device with analog devices and digital devices (for example, a transmission circuit including a transmission delay and transmission apodization is an analog circuit). In some cases. In this processing, the number of elements regarded as one element for transmission or reception, their positions (combinations), the effective aperture width for transmission or reception, and the distance for shifting the effective aperture width for transmission or reception are added to the above beamforming parameters. If necessary, the above wave parameters are used, and if necessary, a plurality of waves or beams are generated by using a plurality of effective apertures together (simultaneous transmission or different objects at the same time phase). (Transmitted at time), and various applications described in the present invention may be similarly performed. In transmission or reception in classical aperture synthesis or ordinary beam forming, a plurality of aperture elements regarded as one aperture may be simultaneously used at a plurality of locations within at least one effective aperture width. When an object to be observed is mechanically scanned with a strong intensity wave using an array element having a large physical aperture or a transducer having a single aperture (the position of transmission or reception changes digitally or analogly), In some cases, beamforming is performed on what is transmitted or received spatially densely or sparsely compared to the width of the opening.

  In the simultaneous driving of a plurality of elements, the same effect may be obtained by adding the reception signals of those elements even during reception by one element or a plurality of elements in one element driving. Also, the same effect may be obtained by performing the same processing when receiving by one element or a plurality of elements in simultaneous driving of a plurality of elements. Also, when performing transmission beam forming by driving the element group within the effective aperture width, transmission may be simultaneously performed from a plurality of elements in various combinations existing within the effective aperture width. Transmission may be performed simultaneously from a plurality of effective aperture widths.

Performing simultaneous transmission of a plurality of elements in various modes as described above is equivalent to increasing the width of the transmission elements and the pitch of the transmission elements, and a grating lobe occurs. As described above, the width of the transmitting element may be large, and the pitch of the transmitting element may be smaller than the element width. In some cases, the element width or pitch is physically large (signals may be collected more densely than the width or pitch distance of the element by mechanical scanning). These depend on the carrier frequency of the wave and the steering angle (including 0 °) (the direction in which the grating lobe occurs can also be estimated by geometric calculation). In addition, side lobes are generated from the aperture element in the first place. Usually, beamforming is performed by optimizing the width and pitch of the element, the element shape, the carrier frequency of the wave, the steering angle, the apodization, and the like so as to reduce these artifacts (artifacts). In practice, the transmission and reception sensitivities are different, but often considered the same. Grating lobes and side lobes also occur in reception alone, and may occur in both transmission and reception.However, what is generated in transmission and reception may differ by using different elements or combinations of different elements. is there.
As disclosed in Patent Literature 7 and Non-Patent Literature 19 by the inventor of the present application, it is possible to separate waves having different steering angles in the frequency domain (see also paragraph 0623). From the center of gravity of the spectrum and the instantaneous frequency of the analysis signal corresponding to the spectrum, the propagation direction of the wave and the steering angle actually generated can be estimated. It is also possible to evaluate the wave refraction. This method can also be used to separate or remove these grating lobes and side lobes from the main lobe. Normally, the spectra of grating lobes and side lobes are separated in the frequency space, and it is easy to specify or separate them (extract only the spectrum of interest or reduce the spectrum of other bands to zero). Good).

  As a matter of fact, these grating lobes and side lobes can be used as they are or processed positively to realize lateral modulation, and can be applied to various applications such as wave imaging and displacement (vector) observation. it can. Normally, the lateral modulation refers to the situation where the waves intersect, but it may be applied separately (and simultaneously weighted) to each steered wave. In these, for example, it is possible to detect the separated wave and convert it into an incoherent signal for imaging, or to superimpose (compound) these incoherent signals for imaging to reduce speckle. Also, a new coherent signal may be synthesized by dividing (or weighting) a spectrum into a certain band while keeping the coherent signal. It is also possible to generate one or more waves having different parameters such as a steering angle, and detect and image each wave, or to superimpose and image each wave. In addition, each of the coherent signals generated by these processes is used for displacement observation, or used simultaneously to solve simultaneous equations and over-determined systems for the same displacement and displacement vector components. Sometimes. Some waves corresponding to grating lobes and side lobes have a steering angle larger than the steering angle set by beamforming, in which case, if the horizontal frequency does not cause grating or side lobes, As compared with the above, the measurement accuracy of the lateral displacement (Non-Patent Document 19) and the displacement vector is improved. Some steering wheels have a steering angle larger than or substantially equal to the steering angle set by beamforming, and may be used in combination with them. A plurality of grating lobes and side lobes are generated, but the higher the frequency in the horizontal direction, the weaker the signal strength is. Instead, it is used as a wave component together with a low frequency component in the horizontal direction. As in the case of normal steering beamforming, the higher the frequency in the lateral direction, the lower the frequency in the frontal direction. In addition, the accuracy of measuring the displacement in the front direction may be improved.

  Using a plurality of waves generated in these processes, a displacement vector moving in an arbitrary direction in a digital signal unit (a displacement vector using a multidimensional autocorrelation method, a multidimensional auto Doppler method, etc. (Non-patent Document 13)). In the method of solving simultaneous equations relating to the components, the displacement in one direction is measured with high accuracy in the past invention of the inventor of the present application) (more equations are derived than the number of required displacement components, and overdetermined. In an (over-determined) type system, a highly accurate result is obtained in a state of high frequency and wide band due to the least squares method, the average value of the calculation result, and the overlap of the waves (Patent Document 5). From each generated wave, an equation is derived one by one. The normal Doppler method may be applied to one wave. Each individual wave may be an overlap of the waves, or the spectrum may be a frequency-divided or processed spectrum. It is preferable that each wave has a high frequency, a wave from which a low-frequency spectrum is removed is used, and if a high spatial resolution is also required, it is preferable that the wave has a wide band (Non-patent document). Reference 14). A window that can weight the spectrum may be used for the division and processing. From the displacement (vector), a strain (tensor), a strain rate (tensor), a speed (vector), and an acceleration (vector) can be obtained by partial differential processing using a differential filter relating to space or time. These can be used to determine the (viscosity) shear modulus, viscosity, average normal stress, density, and the like. In addition, as a method of measuring a displacement (vector), a multidimensional cross-spectral phase gradient method (one of block matching methods, Patent Document 6, Non-Patent Document 15, etc.) Reference) and a digital demodulation method (Patent Document 7), and similarly, measurement of distortion and the like is possible. Further, by using these, it is also possible to measure the propagation of shear waves and low-frequency vibration waves. (Viscous) Shear modulus, shear wave propagation speed, propagation direction, shear wave displacement, frequency, phase, vibration amplitude, vibration speed, vibration acceleration, etc. can be measured. These can also be obtained as distributions.

  To improve the accuracy of the displacement measurement, the inventor of the present application invented regularization in the past. In order to determine the regularization parameter of the punishment term, for example, a posteriori estimates and uses the variation of the measured displacement (vector) under a (local) stationary process (Patent Document 6). The inventors have invented the use of Ziv-Zakai Lower Bound (ZZLB, for example, the variation shown in Non-Patent Document 16) using the characteristics of waves or beams (for example, Non-Patent Documents 17 and 18). It is also possible to apply the variation derived by the one-dimensional autocorrelation method (Non-Patent Document 20) which is a one-way velocity measurement method (used in power Doppler).

  In the present invention, these variations and ZZLB can be used for weighting in order to adjust the reliability of each of the equations when the Doppler equations derived as described above are to be simultaneously established. , And those with low reliability are set low). That is, at each position in the region of interest, the values thereof are obtained from each of the above-mentioned waves or beams, and the Doppler equations derived from each of the corresponding waves or beams at each position are weighted to calculate the simultaneous equations. solve. Weighted Least Squares Solusion (WLSQS) can be determined a posteriori or a priori using the least squares method.

The system of Doppler equations derived above is
Here, u is an unknown displacement vector of an interest point or a local area including the interest point or its distribution, b is a vector representing the phase change of the interest point or the local area related to the interest point generated between frames or its distribution, and A is a corresponding vector. It is a matrix composed of frequency components or distributions of the interest points or local regions related to the interest points arranged in a row, and the components of A and b may be subjected to moving average processing in the time direction or the spatial direction. In the case where demodulation is performed, the Doppler equations in a state where only displacement components in two directions or one direction having a carrier frequency are unknown are in a simultaneous state.
Is expressed by using the variation itself or the reciprocal of ZZLB, weighting the matrix itself, or its power, or the matrix W representing its distribution, to solve.

In particular, focusing on one point of interest or local region, one Doppler equation (or multiple, ie, cross-spectral phase gradient method) derived from one of the waves or beams p (= 1-N) Is used, the number of simultaneous equations for the phase spectrum in the signal band with respect to the cross spectrum obtained in the local region is calculated, and the block is based on the multidimensional autocorrelation method and the multidimensional Doppler method. When matching is performed, the reciprocal value Wp of the ZZLB calculated at the point of interest or the local region is given by the number of simultaneous equations that hold at the position in the local region. Since it is the reciprocal of the ZZLB of the displacement in the beam direction, for example, when the unknown displacement of the point of interest or the local region is a three-dimensional vector u = (Ux, Uy, Uz) ^T ,
Here, Axp, Ayp, and Azp (p = 1 to N) are frequency components in the x, y, and z directions, are components of the matrix A of the formula (A1) or (A2), and bp (p = 1 to N) is a phase change between frames and is a component of the vector b of the same formula, and Wp is a diagonal component of the matrix W of the formula (A2). In the case where the cross-spectral phase gradient method (one of the block matching methods) is used and the case where block matching is performed based on the multidimensional autocorrelation method or the multidimensional Doppler method, Wp is applied to all of the simultaneous equations. (I.e., in one p, a plurality of equations are systematized, and all of them are multiplied by Wp).

For example, when Cramer-Rao Lower Bound (CRLB) holds according to ZZLB described in Non-Patent Document 16, the variance that is the square of the Cramer-Rao Lower Bound is:
Here, T is a moving average width for obtaining a frequency or a phase change in the case of the multidimensional autocorrelation method or the multidimensional Doppler method. When performing block matching, it is the length of the local area of the displacement measurement in the beam direction. (If T is the same in simultaneous beams or equations, it is not necessary to use the variable T and use an arbitrary constant such as 1. F _0b is the ultrasonic frequency in the beam direction, B _b is the rectangular bandwidth in the beam direction, and SNRc is SNRe, which is the SN ratio of the echo, and SNRρ, which is the correlation SN ratio (for displacement and deformation of the object). The signal ratio to the noise component caused by the decrease in the correlation due to the accompanying waveform distortion)
Here, ρ is a correlation value obtained when a local cross spectrum is obtained between frames, or a correlation value obtained locally using the length of the moving average width.
S / N ratio with Combined
It is.

Therefore, the variation may be estimated by measuring and using T, f _0b , B _b , SNRc, SNRe, SNRρ, and ρ as described in Patent Document 17, for example. Arbitrary constants or typical values may be used without measurement. As described in Non-Patent Document 19, f _0b may be obtained by calculating the instantaneous frequency or the first moment (centroid, that is, a weighted average value), and B _b is the second central moment. It can be estimated by finding the square root.
S (fb) in the equations (S1) and (S2) is obtained by dividing the raw spectrum by using the raw spectrum and the total energy calculated using fb = 1 in the equation (S1). It is normalized so as to be 1. Alternatively, in Expressions (S1) and (S2), a raw spectrum may be used as S (fb), and each calculation result may be divided by the total energy, and the latter has a smaller amount of calculation. B _b obtained by the equation (S2) may be used after being converted so as to represent a Rectangular bandwidth based on an actual transmitted or received pulse shape or spectrum shape (the following second-order central moment is expressed as follows). The same applies to the case where it is used.) In the case of a multidimensional reception signal, the calculation may include two axes orthogonal to the frequency axis in the beam direction (ie, three dimensions) or one axis direction (two dimensions). In this case, the following equation is used.

Similarly, the spectra in the expressions (S1 ′) and (S2 ′) are normalized so that the energy becomes 1. Alternatively, similarly, a raw spectrum may be used in the equations (S1 ′) and (S2 ′), and each calculation result may be divided by the total energy, and the latter has a smaller amount of calculation. B _b obtained by the equation (S2 ′) may be used after being converted to represent a rectangular bandwidth based on the actual transmitted or received pulse shape or spectrum shape (the following second-order central moment). The same applies to the case of using.
On the other hand, the SN ratio SNRe of an echo can be statistically estimated by repeatedly collecting echoes for an object or a calibration phantom. In some cases, a typical value is determined a priori based on the target, its state, measurement experience, and the like. On the other hand, the correlation SN ratio SNRρ can be estimated using the correlation value ρ locally evaluated at each point of interest. These methods are not limited to these. In addition, when any of the values is missing and the variation cannot be estimated absolutely, a typical value can be used.However, when a regularization parameter is set, it is expressed in a possible range. Multiplied by the undetermined proportionality constant, and the result obtained while changing the proportionality constant may provide the best situation result (for regularization, for example, Patent Document 6, Non-Patent Document 17, 18).

When the variation (used in power Doppler) derived by the one-dimensional autocorrelation method (Non-Patent Document 20), which is a one-way velocity measurement method, is applied, the autocorrelation function is slow. At -time-axis τ,
Where the mean and variance of the Doppler angular frequency ω are
When the speed in the beam direction is constant within the pulse repetition period I, approximately
If the pulse repetition period I is short, approximately
Is required. Incidentally, R (0) may be obtained from the integral of the energy or power spectrum of the signal based on the Wiener-Khinchine theorem.
Although the above autocorrelation function was not represented using spatial coordinates, it was processed using signals of a one-dimensional local region in the beam direction at the point of interest, a two-dimensional local region including the point of interest, or a three-dimensional local region. (One-dimensional, two-dimensional, or three-dimensional moving average processing may be included, for example, see Non-Patent Documents 13 and 19 in detail.) In the two-dimensional or three-dimensional local area, the beam direction does not need to be on the orthogonal coordinate axes (including not only the Cartesian coordinate system but also the curvilinear coordinate system) of the local area, and the average and dispersion obtained are calculated based on the local area. Are the average and dispersion of the speed in the beam direction.
Therefore, each of the average and the variance of the displacement in the beam direction can be obtained by multiplying each of the formulas (AUTO2) or (AUTO2 ') and (AUTO3) or (AUTO3') by I and I square. Here, the weighted measurement of the displacement using the variation of the displacement has been described. However, the Doppler equations of the velocity and the acceleration may be derived, and each of the variations may be weighted and measured.

Here, when the first moment and the second center moment in the beam direction are not directly estimated but are estimated in each direction (for example, when the signal is three-dimensional), the x-axis direction The first moment f _0x and the second center moment Bx are
Alternatively, when a method different from ZZLB is used and the variation of each component of the displacement vector is estimated without directly estimating the variation of the beam direction displacement, the following estimation can be performed. In other words, propagation of the error to the beam direction displacement may be considered under the assumption that the stochastic process of the measurement error of those displacement components is independent. For example, when the average value and the variation of the displacement of the three-dimensional displacement vector are estimated to be (mx, σx), (my, σy), (mz, σz), the average value m _beam of the displacement in the beam direction and Each of the variations σ _beam can be estimated as follows.

Further, parameters described in equation (A4) ~ formula _{(A6) (T, f 0b} , B b, SNRc, SNRe, SNRρ) is given for each of a plurality of directions, the average f _0x in each direction of displacement, f _0y , f _0z and variation σ _CRLBx, σ _CRLBy, σ _CRLBz are each when estimation variance sigma _CRLB beam direction of displacement, according to equation (A8),
Can be estimated.

The case where the unknown displacement of the position of interest is a two-dimensional vector u = (Ux, Uy) is derived in the same manner (when the unknown displacement is one and the displacement U in one direction or the displacement U in the beam direction). Is used as the estimated value itself).

  When a displacement is to be obtained for each point of interest or a local region related to the point of interest, the equation (A2) that is established by simultaneously establishing the weighted Doppler equations (A3) (p = 1 to N) established at that position is solved. The number N of waves or beams (ie, the number of equations) must be equal to or greater than the number of unknown displacement components. However, when performing the above block matching, as described above, a plurality of equations (A3) are satisfied from one wave or beam p. Therefore, the measurement may be performed with a smaller number of waves or beams as compared with the case where another displacement measurement method is used.

At the same time, when regularization is also performed, all equations (A3) that are satisfied in a plurality of points of interest in the region of interest or a local region related to the point of interest are simultaneously established, and the unknown vector u is a displacement component distribution. Equation (A2) is obtained, and a regularized weighted least squares solution may be obtained (RWLSQS). At this time, variation or ZZLB may be used as a regularization parameter (a value proportional to the variation, a value proportional to a power, etc.). The regularization is described in detail in, for example, Patent Document 6. The variation in the displacement in the propagation direction or the beam direction of each wave described above may be used as a regularization parameter of the displacement in all directions, and the variation in the displacement in each direction estimated for each wave or beam may be different. May be used as a regularization parameter for displacement in the direction of. For example, as a distribution of unknown three-dimensional displacement vectors (Ux, Uy, Uz) ^T , an unknown vector having Ux, Uy, Uz, which are distributions of displacement components Ux, Uy, Uz in the x, y, and z directions, as partial vectors. When u = (Ux, Uy, Uz) ^T is determined, a matrix W having a beam direction displacement Wp (p = 1 to N) as a diagonal component, or a displacement Wpx, Wpy, in each direction. When matrices Wx, Wy, and Wz each having Wpz (p = 1 to N) as a diagonal component are used, the least squared error energy E (u) and its solution u are expressed as follows.

In addition, the variation or ZZLB may be subjected to an averaging process with respect to the measurement result of the displacement component obtained by simultaneously selecting the selected Doppler equations, and may be used for weighting in that case. The weighted average is calculated by using the reciprocal Wp (p = 1 to N) of the variation in the beam direction or the reciprocal (Wpx, Wpy, Wpz) (p = 1 to N) of the variation in the displacement in each direction. May be required.

  The variation may be obtained based on an ensemble average under a non-stationary process other than the steady process or ZZLB, may be obtained using a calibration phantom, or may be obtained from the measurement target itself. As described above, the regularization parameter and the weighted matrix can be determined. However, there may be a case where a typical value is determined a priori based on an object, its state, measurement experience, and the like. Also, this is not a limitation.

As described above, the weight value and the regularization parameter can be set with high accuracy in a state having a spatial resolution. However, when the deformation is small or the amount of calculation is reduced, an area wider than the point of interest or the local area ( For example, the entire region of interest or, for example, a partial region in the region of interest such as a partial region provided for each of the distances in the propagation direction and the depth of the observation target) is estimated, and the variation is estimated. It may be set globally and processed. The phase matching method (Patent Literature 6, Non-Patent Literature 15) invented in the past by the inventor of the present application is required to enable the measurement itself and to increase the measurement accuracy. For the conversion, the stretching method reported elsewhere is useful.
FIG. 21 shows motion compensation (phase matching) performed in the two-dimensional case by moving a search area provided in the next frame to be processed using an estimated value of a displacement vector of a point of interest or a local area including the point of interest. 21A is a schematic diagram of FIG. 21A. FIG. 21A illustrates translational motion compensation, and FIG. 21B illustrates motion compensation including rotation. In the case of three dimensions, the same processing is performed using a three-dimensional or two-dimensional local area or search area in a three-dimensional space.
When performing a translation process in phase matching (Non-Patent Documents 13 and 15), for example, each interest point or each interest point is determined in an arbitrary orthogonal coordinate system such as a Cartesian coordinate system using a linear array probe. For each included local region, use the signal of the search region or region of interest (see FIG. 21 (a)) that includes the location of that point of interest or the local region containing the point of interest in the next frame (referred to as frame Ne). . Similarly to the phase rotation of the one-dimensional signal in the method D3 in paragraph 0384, the spectrum is multiplied by a complex exponential function. For example, in the case of two-dimensional, the displacement vector of the local signal is (Δ ₁ , Δ ₂ ) (1 and 2 are two-dimensional When it is estimated to represent the axis of the Cartesian Cartesian coordinate system), the complex exponential function exp {i (k ₁ Δ ₁ + k ₂ Δ) is added to the two-dimensional spectrum A (k ₁ , k ₂ ) of the wave signal in the search area. ₂ )} to shift the search area in the direction opposite to the displacement vector by (−Δ ₁ , −Δ ₂ ), and in the three-dimensional case, the displacement vector of the local signal is (Δ ₁ , Δ ₂ , Δ ₃ ) (Where 1, 2 and 3 represent axes of a three-dimensional Cartesian coordinate system), a complex three-dimensional spectrum A (k ₁ , k ₂ , k ₃ ) of the wave signal in the search area is obtained. Multiply the exponential function exp {i (k ₁ Δ ₁ + k ₂ Δ ₂ + k ₃ Δ ₃ )} to shift the search area by (−Δ ₁ , −Δ ₂ , −Δ ₃ ) in the direction opposite to the displacement vector (Patent Document 6, Non-patent Document 15 etc.). That is, when the spectrum after the multiplication is subjected to the inverse Fourier transform, a local (spatio-temporal) spatial signal represented by a Cartesian coordinate system phase-matched (shifted) at the same position is obtained. Incidentally, when the local region is shifted in the direction of the displacement vector, exp {−i (k ₁ Δ ₁ + k ₂ Δ ₂ )} or exp {−i in which the sign of the core of the complex exponential function is inverted in each case. (k ₁ Δ ₁ + k ₂ Δ ₂ + k ₃ Δ ₃ )}. However, in digital signal processing, as described later, the cyclicity of the digital signal becomes a problem, Should be shifted.
When rotation processing is performed in phase matching, similar to translational phase matching (see Non-Patent Documents 13 and 15, FIG. 21A), for example, a Cartesian coordinate system using a linear array probe Search for each point of interest or each local region containing each point of interest in any orthogonal coordinate system, such as the frame of interest, including the position of that point of interest or the local region containing the point of interest in the next frame (referred to as frame Ne) The Fourier transform (ie, spectrum) of the signal of the region or region of interest (see FIG. 21 (b)) in the polar coordinate system (the center of the polar coordinate system is at each point of interest or a position within or outside the region of interest) is described herein. It is obtained directly without approximation through the Jacobi operation implemented in the book.
That is, in the two-dimensional case, for example, when x = rsinθ and y = rcosθ, the Jacobian matrix becomes the inverse of the Fourier transform expressed by the equation (22) (the inverse function theorem).
In the three-dimensional case, for example, when x = rsinθcosφ, y = rcosθ, and z = rsinθsinφ, the Jacobian matrix is the inverse of the Fourier transform expressed by the equation (27) (the inverse function theorem).
(The origin of the polar coordinate system is a singular point), and the Fourier transform (spectrum) of the polar coordinate system is also calculated directly by the signal of the interest point or the local area including the interest point and the signal of the same position in the frame Ne. Displacement of the radial direction, polar angle, elevation angle, and azimuth angle estimated from the displacement vector measurement method such as the gradient of the phase of the local cross spectrum (cross spectrum phase gradient method, Non-Patent Document 15) or multidimensional autocorrelation method obtained from The motion compensation is performed by performing a phase rotation of multiplying the Fourier transform (spectrum) of the signal of the search region or the region of interest in the frame Ne by a complex exponential function in the Fourier space of the frame Ne in the polar coordinate system using the vector component. What is necessary is just to perform phase matching. For example, when the displacement vector of the local signal is estimated to be (Δ _r , Δ _θ ) in the two-dimensional case, a complex exponential function exp is added to the two-dimensional spectrum F (k _r , k _θ ) of the wave signal in the search area. _{{i (k r Δ r +} k θ Δ θ)} obtained by multiplying by search area displacement vector in the opposite direction to (-Δ _r, -Δ _θ) is moved by the displacement vector of the local signal in the case of a three-dimensional There _{(Δ r, Δ θ, Δ} φ) when it is estimated that the 3-dimensional spectrum F of the wave signal of the search area _{(k r, k θ, k} φ) to a complex exponential function exp {i (k _{r Δ r + k θ Δ θ +} k φ Δ φ)} obtained by multiplying by search area displacement vector in the opposite direction to _{(-Δ r, -Δ θ, -Δ} φ) is moved by. That is, a local signal represented by a Cartesian coordinate system or a polar coordinate system which is phase-matched at the same position is obtained from the result of inverse Fourier transform of the signal. That is, in the case of two dimensions, because it is k _x = k _r sinθ 'and _{k y} = _{k r cosθ',} respectively,
And in the case of three _{dimensions, k x = k r sinθ'cosφ '} , k y = k r cosθ' because it is and _{k z} = _{k r sinθ'sinφ} ', respectively,
It is.
The local area and the search area are often set at the center of interest, but the latter can efficiently provide the search area in the direction of tissue displacement when the direction is given a priori. The same is true for the purpose of phase aberration correction and motion compensation. In the case of using a multidimensional autocorrelation method other than the cross spectrum phase gradient method, for example, the (analysis) signal of each frame may be obtained in a polar coordinate system, and similarly, a Fourier transform using a Jacobi operation may be performed. good. In this way, rotational phase matching can be performed with high accuracy, as with translational phase matching. By the above-mentioned Fourier transform using the Jacobi operation, a digital signal or a discrete Fourier transform (discrete spectrum) represented in an arbitrary rectangular coordinate system, such as when a sector scan or a convex type probe is used, is not approximated. Directly to another arbitrary Cartesian coordinate system (even if it is a different Cartesian coordinate system such as Cartesian Cartesian coordinate system or various curved Cartesian coordinate systems, the origin is different or rotated, or the same Cartesian coordinate system It is possible to re-express the expression by using the phase rotation described in paragraphs 0026, 0132, 0214, etc., which has high accuracy. It takes time to calculate). FIG. 22 is a flowchart showing an example of signal processing by Fourier transform using Jacobi operation, but the above signal processing is not limited to this.
In the phase matching, first, translation phase matching is performed on a signal represented by each rectangular coordinate system, and then rotation phase matching is often performed, but this is not a limitation. It may be performed alternately or in reverse order. Further, as described in Non-Patent Documents 13 and 15, each phase matching may be repeatedly performed (the repetition is terminated when the corrected displacement becomes smaller than a preset threshold). In some cases, expansion and contraction processing is performed.
Note that the local region and the search region are not necessarily rectangular, but may have another shape such as a circle (data is stored in a rectangular array, for example, a square or rectangle, a cube or a rectangular parallelepiped array). In such a case, the array of positions corresponding to the area outside the area such as a real circle or a sphere may be padded with zeros). The search area must be appropriately larger than the local area so that the signal circulating in the search area does not appear in the region of interest due to the phase rotation by multiplying by the complex exponential function in the frequency domain. Only the amount increases, and it is appropriately determined a priori from the magnitude of the displacement vector of the observation target). Incidentally, when there is no displacement in the radial direction and only the displacement in the rotational direction is observed, the size of the search area may be the same as the local area. The displacement in the radial direction may be set to zero, and only the displacement in the rotation direction may be obtained as an unknown variable. When the displacement in the radial direction is minute, it may be ignored and assumed to be zero, and only the displacement in the rotation direction may be estimated. Also, the search area may be provided in the previous frame. Further, in order to shorten the processing time, phase matching may be performed by discrete shifting of a digital signal, instead of phase matching multiplied by a complex exponential function. In this case, it is not always necessary to perform motion compensation on the search area, and phase matching may be performed by directly searching (block matching) the local area in the search area of another frame.
The phase matching is performed by a DAS process described in paragraph 0384 (an interpolation process of the method D1 or a process of performing a phase rotation on the analytic signal in the spatiotemporal domain of the method D2) in addition to the phase rotation process in the frequency domain of the polar coordinate system. As in the case of shifting a multi-dimensional signal based on the delay processing of shifting through a multi-dimensional analysis, a multi-dimensional analysis signal represented by a polar coordinate system is processed to perform phase matching (shifting or rotation in a radial direction). Processing). The phase rotation processing in the frequency domain of the polar coordinate system is based on the delay processing of the method D3. These processes can also be used for the DAS process in the polar coordinate system, and can be performed at the time of other beam forming such as Fourier beam forming, adaptive beam forming, and minimum variance in the polar coordinate system. This is useful when signals such as motion compensation, phase matching (including a new processing method), positioning, and position correction are shifted or rotated in the radial direction in time coordinates, space coordinates, or space-time coordinates.
For example, in the case of two dimensions,
f (r + r ₀ , θ + θ ₀ ) = f (r, θ) exp [j {k _r (r, θ) r ₀ + k _θ (r, θ) θ ₀ }] (2DASr)
In the case of three dimensions,
f (r + r ₀ , θ + θ ₀ , φ + φ ₀ ) = f (r, θ, φ)
× exp [j {k _r (r, θ, φ) r ₀ + k _θ (r, θ, φ) θ ₀ + k _φ (r, θ, φ) φ ₀ }] (3DASr)
Can be calculated. Here, (k _r , k _θ , k _φ ) is the wave number in each direction at each position (r, θ, φ). That is, in a digital signal, analog shifting can be performed in a discrete polar coordinate system (preferably a high sampling frequency when high accuracy is required) by using a wave number in each direction at each position. . As in the case of the one-dimensional case, the accuracy can be higher than that of the method D1 (corresponding to signal block matching or fragment matching in the spatiotemporal domain), and the accuracy is lower than the other methods (methods D3 and D4). But the calculation speed is fast. It is suitable when a high calculation speed is required.
It should be noted that in these processes, the point spread function is simultaneously shifted in the radial and rotational directions together with the observation target itself (it can be a source of error in phase matching). Further, these processes may be performed on a signal having no carrier frequency (for example, image processing).
In addition, as described above, there are various ways to change the orthogonal coordinate system between the space domain and the frequency domain or to change the coordinate system in the same domain without the interpolation approximation process by the Fourier transform or the inverse Fourier transform through the Jacobi operation. It is useful in accurate measurement imaging (high accuracy). For example, as a method of measuring a displacement vector and a displacement, a multidimensional cross-spectral phase gradient method, a multidimensional cross-correlation method, a multidimensional autocorrelation method, a multidimensional Doppler method, and a method of making them one-dimensional are useful. When using a method other than the cross-correlation method, it is possible to obtain a measurement result by changing the coordinate system through a Jacobi operation in Fourier transform when obtaining a spectrum or inverse Fourier transform when obtaining an analytic signal, When the cross-correlation method is used, a measurement result can be obtained by changing the coordinate system by the above-described method using the Jacobi operation in the spatial domain. It is useful for temperature observation and observation of various physical properties.

Further, a Wiener filter can be applied as Wp. In the spatio-temporal domain, after directly weighting the signal itself, imaging or displacement measurement of the signal is performed. The signal is a signal r (x, y, z) before or after detection.

  The noise signal n (x, y, z) can be statistically estimated by repeatedly collecting echoes for an object or a calibration phantom. For example, a variation can be used, and the estimation may be performed locally using an averaging or as an ensemble average, assuming a steady process. In some cases, a typical value is determined a priori based on the target, its state, measurement experience, and the like. Also, this is not a limitation. In addition, when performing envelope detection, square detection, and absolute value detection to detect the signal r (x, y, z) for imaging, Expression (A12) and Expression (A13) are multiplied at each position. Sometimes. Also, weighting can be performed in the same manner when a self spectrum is obtained by obtaining a power spectrum by multiplying a conjugate of the analysis signal by the analysis signal. The pre-processing of the signal before using the auto-correlation method or the Doppler method, which is a displacement measurement method using the analysis signal, or the cross-spectral phase gradient method or the cross-correlation method (the analysis signal may not be used), etc. Can be used.

  Even when the signal is two-dimensional or one-dimensional, instead of r (x, y, z) and n (x, y, z) in the equations (A12) and (A13), r (x, y) respectively And n (x, y), and r (x) and n (x). Further, in each beam or a region of interest obtained by scanning with each beam, Expression (A12) or Expression (A13) may be obtained and used globally. Similarly to Expressions (A12) and (A13), Expressions (A4) to (A6) may also be used directly for echo weighting.

In particular, when the multidimensional cross-spectral phase gradient method (Patent Document 6, Non-Patent Document 15) is used, the Wiener filter can be applied not only in the spatio-temporal domain but also in the frequency domain. As described above, for each wave or beam, the frequency domain (ωx) of the cross spectrum Hp (ωx, ωy, ωz) (p = 1 to N) between the signals before and after the deformation or displacement acquired under the same conditions. , ωy, ωz), the gradient (three-dimensional unknown displacement vector) of the phase spectrum θ (ωx, ωy, ωz) is obtained using the least squares method.
However, PWpn (ωx, ωy, ωz) and PWps (ωx, ωy, ωz) are noise and signal power spectra, respectively, and PWps (ωx, ωy, ωz) is replaced by The square (|| Hp (ωx, ωy, ωz) || ² ) may be used. q is an arbitrary positive value.
Is performed, and the least squares are applied. For example, expressions (1) to (14 ′) of Patent Document 6 describe a case where the square of the magnitude of the cross spectrum (|| Hp (ωx, ωy, ωz) || ² ) itself is used for weighting. However, Wp (ωx, ωy, ωz) may be used in place of the weight (as described above, the dispersion in the beam direction and ZZLB may be used separately). is there). Note that the least squares are evaluated for each of the N waves or beams for p = 1 to N and are least squared at each point of interest at once.

  The noise power spectrum PWpn (ωx, ωy, ωz) can be statistically estimated by repeatedly collecting echoes for the target object or the calibration phantom. In some cases, a typical value is determined a priori based on the target, its state, measurement experience, and the like. Also, this is not a limitation.

  In addition, n (x, y, z) / r (x, y, z) represented in the formulas (A12) and (A13), and the formulas (A12 ′) and (A13 ′) PWpn (ωx, ωy, ωz) / PWps (ωx, ωy, ωz) is the reciprocal of the SN ratio SNRe of the above-mentioned echo, or the combination of SNRe and SNRρ which is the correlation SN ratio (Combined) SN. It may be set based on the reciprocal of the ratio. Further, in a state where there is a spatial resolution, or in a region of interest obtained by scanning each beam or each beam, Expressions (A12 ′) and (A13 ′) are obtained globally, and Expressions (A12) and (A12) are obtained. Like Expressions (A13) and (A4) to (A6), they may be used directly for echo weighting (imaging or displacement measurement). When detecting the signal r (x, y, z) for imaging (envelope detection, square detection, absolute value detection, etc.), Expression (A12) or Expression (A13) may be used. However, in that case, the square norm of the first spectrum Hp (ωx, ωy, ωz) in the equation (however, the spectrum of the local signal or the signal covering the region of interest) may not be used. The same applies to the case where the conjugate of the local spectrum Hp (ωx, ωy, ωz) is multiplied by the spectrum Hp (ωx, ωy, ωz) to obtain a power spectrum to obtain an autocorrelation function signal.

  When the unknown displacement is a two-dimensional vector u = (Ux, Uy) or the unknown displacement is U (one) in the beam direction, H (ωx, ωy, ωz) in the equations (A12 ′) and (A13 ′). ), Weights similarly expressed using respective Wiener filters for the cross spectrums H (ωx, ωy) and H (ωx) between the signals before and after the deformation or displacement can be used.

  Furthermore, when regularization is performed, similarly, the regularization parameter may be set using the above-described variation or the like in accordance with Equations (10) and (10 ′).

  When the cross-spectrum phase gradient method or other block matching method is used, displacement vectors in two or more directions can be obtained using one wave or beam alone, and one wave or beam can be used alone. Even so, an over-determined system can be configured.

  In any of the above displacement measurements, it is possible to perform the measurement without using an over-determined system. In such a case, the above-described weighting and regularization may be performed.

The displacement is obtained from at least two signals. When the displacement is large in the displacement (displacement of the point of interest or a local area including the point of interest), the instantaneous phase (multidimensional or One-dimensional auto-correlation method, multi-dimensional or one-dimensional Doppler method, Non-Patent Document 13) and local phase (multi-dimensional or one-dimensional cross-spectral phase gradient method, Non-Patent Document 15) may be inverted. As described above, phase matching (spatial shifting or phase rotation multiplied by a complex exponential function) may be performed instead of unwrapping the phase of the object. (C. Sumi et al, World Congress of Ultrasound in Medicine and Biology, Sapporo, 1994). In paragraph 0405, the shifting process in the radial direction and the rotation direction in the polar coordinate system by the same process has also been described. Also, various shifting processes that can be used for the delay process of the DAS process described in paragraphs 0384 and 0405 are effective. A cross-correlation-based multi-dimensional or one-dimensional cross-correlation method (in which case block matching is effective) or a cross-spectral phase gradient method (processing with a coarse sampling interval) that enables estimation of a large displacement. Perform coarse estimation to perform phase matching (it may be iteratively processed), and then perform Fine estimation using those methods (it may be iteratively processed as well, In the cross-spectral phase gradient method, the sampling interval may be returned to the original value for processing. As described above, it may be used for phase aberration correction.
Various processes can be performed by modifying these as a base (for example, the demodulation method described in Patent Document 7). Basically, the autocorrelation method uses the phase of the complex autocorrelation function, and in order to stabilize its estimation, it is obtained by multiplying the imaginary part / real part of the complex autofunction by the inverse tangent function based on Euler's formula. Whether the instantaneous phase is subjected to moving average processing in time or space (method Ai), or the moving average is similarly applied to the complex self-function, and the imaginary part / real part is similarly multiplied by the inverse tangent function to calculate the phase. Can be used (method Aii). In the case of the Doppler method, the instantaneous phase or the difference obtained by multiplying the imaginary part / real part of the analytic signal by the inverse tangent function is used to stabilize the estimation using the instantaneous phase difference of the analytic signal itself. Similarly, moving average processing can be performed (method D). The cross spectrum phase gradient method uses the phase of the cross spectrum of the local signal (method C).
Of these, coarse displacement is estimated using the cross-correlation method and phase matching (spatial shifting) is performed. When processing is performed based on method Ai and method D, spatial displacement is not considered. Because the moving average of time or space is applied to the instantaneous phase that may have a continuous distribution, the displacement is not obtained correctly (errors occur, and the final result of phase matching is a discontinuous displacement distribution turn into). Therefore, after phase matching (spatial shifting), for example, in three-dimensional observation, the instantaneous frequency is (fx, fy, fz), and the unknown displacement to be updated for the coarse estimation result (dx0, dy0, dz0) Is (ux, uy, uz), and the instantaneous phase that may have a spatially discontinuous distribution before moving average processing is θ, the equation was expressed as fx ux + fy uy + fz uz = θ In this case, using the coarse estimation result (dx0, dy0, dz0) for the phase θ, calculate θ ′ = θ + fx dx0 + fy dy0 + fz dz0 to obtain the coarse estimation result (dx0, dy0, After applying phase matching (corresponding to phase rotation) to add the phase of dz0) and performing moving average processing to obtain θ '', solve fx dx + fy dy + fz dz = θ '' The estimation result of the unknown displacement (dx, dy, dz) can be obtained directly (a new phase matching). In these calculations, the instantaneous frequency (fx, fy, fz) may be subjected to moving average processing or may not be moving averaged. By this phase matching, it is possible to avoid adding an estimated value (ux, uy, uz) that cannot be obtained correctly to a coarse estimation result (dx0, dy0, dz0). In addition, the moving average of the instantaneous phase θ ′ after phase matching is not used, and the estimation result of the unknown displacement (dx, dy, dz) can be directly obtained by solving the equation using θ ′ instead of θ ″. Yes, the same result as the result of adding the estimated value of the displacement (ux, uy, uz) to be updated to the coarse estimation result (dx0, dy0, dz0) is obtained. The same applies to two-dimensional observation and one-dimensional observation.
On the other hand, when the coarse displacement is similarly estimated using the cross-correlation method and phase matching (spatial shifting) is performed, when processing is performed based on the method Aii, a spatially discontinuous distribution is obtained. The moving average of the time or space is not applied to the instantaneous phase that may be performing, and there is no problem even if the moving averaged instantaneous phase has a spatially discontinuous distribution. . That is, for example, in the case of three-dimensional observation, when processing is performed based on the method Aii, a coarse estimation result is obtained for the moving averaged instantaneous phase θ ″ obtained after phase matching (spatial shifting). Phase matching that calculates θ '''=θ''+ fx dx0 + fy dy0 + fz dz0 using (dx0, dy0, dz0) and adds the phase of the coarse estimation result (dx0, dy0, dz0) (Corresponding to phase rotation) to obtain θ '''', and solve the fx dx + fy dy + fz dz = θ '''' to directly estimate the unknown displacement (dx, dy, dz). The displacement amount (ux to be updated by solving the equation fx ux + fy uy + fz uz = θ '' using θ '' instead of θ '''' as in the past (a new phase matching) , uy, uz), and adds it to the coarse estimation result (dx0, dy0, dz0), the estimation result is obtained. In these calculations, the frequency (fx, fy, fz) may be subjected to moving average processing or may not be subjected to moving average. The same applies to two-dimensional observation and one-dimensional observation.
Further, when processing is performed based on Method D, similarly, when coarse displacement is estimated using the cross-correlation method and phase matching (spatial shifting) is performed, the phase characteristic (frequency Characteristics) may have a spatially discontinuous distribution, but the moving average is not applied to the distribution, and this is not a problem. (In each local region, the phase frequency characteristics become discontinuous.) Is not). The equations relating to the displacement may typically be set up simultaneously at the center of gravity frequency or frequencies near the center of gravity (in the case of one-dimensional, two-dimensional, three-dimensional, at least one, two, three (It is necessary to set the frequency) and may be set to be over-determined in the signal band. Even in this case, after phase matching (spatial shifting), for example, in three-dimensional observation, the frequency in the signal band is (Fx, Fy, Fz) and the coarse estimation result (dx0, dy0, dz0) If the unknown displacement to be updated is (ux, uy, uz) and the phase of the cross spectrum of the same frequency is α, and the equation is expressed as Fx ux + Fy uy + Fz uz = α, the phase α On the other hand, using the coarse estimation result (dx0, dy0, dz0), calculate α '= α + Fx dx0 + Fy dy0 + Fz dz0, and add the phase of the coarse estimation result (dx0, dy0, dz0) By performing phase matching (corresponding to phase rotation) and obtaining α ′, the estimation result of the unknown displacement (dx, dy, dz) can be obtained directly by solving Fx dx + Fy dy + Fz dz = α ′. Estimated value of displacement (ux, uy, uz) to be updated by solving the equation Fx ux + Fy uy + Fz uz = α using α instead of α ′ (this is a new phase matching) And convert it to a coarse estimation result (dx0, dy0, dz0) Calculated to be estimated result is obtained. The same applies to two-dimensional observation and one-dimensional observation.
The calculation of this phase matching is processed using the same-dimensional frequency component in the signal dimension, but is not limited to the case where the unknown displacement has the same dimension (coarse estimation is performed with the same dimension). For example, a highly accurate one-way displacement based on calculating the generated beam direction at each point of interest and calculating the displacement in the same beam direction, disclosed in Patent Document 11 and Non-Patent Document 19 by the inventor of the present application. In the observation method or apparatus, for example, an equation (A) for calculating a generated beam direction at each point of interest and obtaining a displacement in the same beam direction, which is derived from the two-dimensional signal in FIG. Alternatively, in the equation (A ') for determining the direction of the unknown displacement by any method and calculating the displacement in that direction, the phase of the multidimensional coarse estimation result is similarly set to the frame in those equations. In some cases, an unknown displacement (one-direction displacement) in the beam direction or a specific direction is directly obtained by solving after performing phase matching to be added to the phase difference Δθ between them. This processing can be applied when calculating displacements in various specific directions. For example, in observing blood flow in a blood vessel such as a carotid artery or a jugular vein running in a direction parallel to the body surface, the blood flow direction is minimized. It has been disclosed that a polarized beam can be generated and applied in a direction close to that of a conventional Doppler, which required mechanical adjustment of the orientation of a physical aperture of a sensor (probe) to direct the beam in the direction of blood flow. It has been put into practical use as a measurement technique that is simpler than observation. (In extreme cases, the direction in which the array elements of the probes are lined up while looking at rf images of raw signals, B-mode images, images of other modalities, etc.) (It may be equipped with a special sensor that can determine the blood flow direction with respect to the physical aperture of the probe and the deflected beam, image processing, and signal processing.) . It is important that the probe can be broadened to generate a good deflection beam. Patent Document 11 also discloses a case of a three-dimensional signal. This processing is performed when a beam or a wave having one deflection angle (including a case where the deflection angle is 0 ° in the front direction of the opening surface) is generated (when the sensor having various physical opening shapes is used, the opening shape itself or (In some cases, the beam is focused through the beamforming calculation process, in other cases, the beam is not focused by using a plane wave, a divergent wave, a virtual source, or a sensor having various physical aperture shapes.) This is also effective when constructing an over-determined system for unknown displacement in a specified direction when a plurality of beams having different deflection angles are generated (that is, the equations corresponding to equation (A ′) are simultaneously established). Do). It is useful not only for medical applications of ultrasonic waves but also for various observations using various physical waves (such as electromagnetic waves and heat waves).

In observing the displacement vector and the displacement in one direction (not limited to the above-described apparatus and method), a plurality of waves having different wave forms and beam forming parameters generated at the same position (in addition to those physically generated, Derives one equation from each one of the following: a pseudo wave generated by superimposing waves having different waves and beamforming parameters, and a pseudo wave generated by frequency-dividing a spectrum. The same number of equations as the unknown displacement component may be combined, or more than the same number of equations may be combined to realize an over-determined system, or equations derived at different positions may be solved simultaneously, and those equations may be solved. May be processed by performing the above-described phase matching that makes the spatial distribution of the phases continuous.
In particular, when performing the optimization processing (paragraph 0402, paragraph 0403, etc.) and other optimization processing described in the present application in order to increase the accuracy and stabilization of displacement measurement (estimation), all displacement measurement methods are used. Should be processed after the above-described phase matching for making the spatial distribution of the phase continuous. First, assuming a local stationary process with respect to the phase of the complex autocorrelation function and the instantaneous phase difference of the analytic signal and the phase of the local cross spectrum, local or temporal local average or variance, or covariance is estimated. If the phase includes the above error, an error occurs. For example, the case where the maximum likelihood estimation is performed is applicable (may be performed together with the Maximum a posteriori (MAP)). Normal equations or over-determined equations at the point of interest
And the likelihood function is
Therefore, the log likelihood L is obtained by multiplying the equation (LM3) by the logarithm.
Get.
Incidentally, as the super-resolution, a matrix F representing a blur function (considered as a point spread function of a linear space-time invariant system or a linear space-time variable system), a vector O representing an original image (target), and a vector B representing a blur image, When FO = B is solved using and maximum likelihood estimation is performed, similarly,
When a direct current is not included in the wave signal, the calculation may be performed with the average value set to zero as in Expression (LM9 ′) instead of Expression (LM9). It should be noted that the restoration of the blurred image and the super-resolution often require time to calculate the covariance matrix.
The processing in the spatio-temporal domain is effective in the case of a spatio-temporal variant. The point spread function at each position at a distance from the physical aperture plane is averaged over a plurality of point spread functions (one-dimensional autocorrelation function or multidimensional autocorrelation function in the depth direction or the horizontal direction) estimated at the same distance position. It is effective to perform estimation (see Non-Patent Documents 35 and 36). A point spread function estimated at a position of interest without averaging may be used. For processing in these spatiotemporal domains, for example, a conjugate gradient method or the like can be used. When the maximum likelihood estimation is performed, a MAP (Maximum a posteriori described later, for example, Non-Patent Document 42) is effective, but a method using the EM algorithm (Non-Patent Document 31) has also been reported. For these processing results, it is also effective to convolve a point spread function desired as shaping filtering in the spatiotemporal domain or to multiply its frequency response in the frequency domain.
In the case of processing in the spatio-temporal domain, if the spatio-temporal invariant of the point spread function (spatially invariant) can be assumed, devolution will be performed, but considering the calculation speed, the processing is described in the present application. It is better to perform an inverse filtering process in the frequency domain. In that case, the point spread function may be averaged and used in a region considered to be space-time invariant. This applies to the case of classical aperture synthesis where the spatial resolution is almost uniform, or the case where dynamic reception is performed by performing plane wave transmission.However, even when the spatio-temporal variation occurs when the focus beam is generated, the spatio-temporal invariance is assumed. The same processing may be performed in the frequency domain. Similarly, for the processing result, it is effective to convolve a point spread function desired as shaping filtering in the spatio-temporal domain or to multiply its frequency response in the frequency domain.
Further, a variance is estimated from a displacement measurement result in a posteiori, and a regularization parameter is determined so as to be proportional to the variance (regularization, Non-Patent Document 18). When the least squares method is performed, an error occurs when the displacement measurement result includes an error due to the phase error.
Further, those statistics are implemented in an equation relating to the displacement (ux, uy, uz) to be updated for the coarse estimation result (dx0, dy0, dz0). Therefore, the variation (used in the power Doppler) derived by the one-dimensional auto-correlation method (Non-patent document 20) which is a one-way velocity measurement method, and the multi-dimensional auto Variations derived for the correlation method and Ziv-Zakai Lower Bound (ZZLB) are a priori and do not assume a steady process for displacement measurement, but also cause errors. When performing this type of optimization processing, it is necessary to perform the above-described phase matching that makes the spatial distribution of phases continuous in all displacement measurement methods. During the phase matching, the moving average processing or optimization must not be performed on the displacement (residual displacement) itself to be updated or the corresponding phase data. In addition, even if this new phase matching is not necessary, there are cases where a plurality of estimation results are obtained by using several types of optimization methods, or a final result is obtained by integrating or judging them. There are some good things to do if you do.
Here, MAP estimation that is effective in maximum likelihood estimation will be described, and further, similarity with regularization will be described (Non-Patent Document 42).
The MAP estimation of D in equation (LM1) is a posteriori probability density function of D
Here, p (θ | D) is an equation (LM3) of the a posteriori probability density function (maximum likelihood estimation) of θ,
Is the probability density function of D (prior: pre-established).
Can be maximized. When D represents the distribution of the displacement vector, D consists of the distribution of displacement components in multiple directions, similar to the case where the distribution of the displacement components in each direction is regularized simultaneously using different regularization parameters in regularization. Next, _CD and E [D] components are obtained and used in the distribution of displacement components in each direction. This MAP estimation is performed using a cost function as a weighted least squares method.
Is equivalent to minimizing and the solution is
Where P is a regularization operator and λ is a hyper regularization parameter.
Will be solved. A unit matrix can be used as the regularization operator P. In this case, the regularization parameter λ can be used spatially variable (Non-Patent Document 17). Since this regularization operator is a full band pass filter, the result of D may be smaller than the true value. As another regularization operator P, a high-pass filter or a differential filter (a Laplacian operator G ^T G using a gradient operator G or its even n-th norm) or the like may be used. The band frequency error is effectively suppressed, but high frequency components may be lost (but can also be used for blurred image restoration and super-resolution). Multiple regularization operators may be used simultaneously. Instead of the derived equation (REG1), for convenience, a typical value is used as λ as a regularization parameter, the variance of θ at the time of new phase matching, the variance of the difference between the left side and the right side of equation (LM1), In some cases, it is determined to be proportional to the variance (the effect of regularization increases when the regularization parameter is increased). Furthermore, weighted least squares method using the weight matrix W of the formula (A2) is the W ^T W is obtained using the inverse of the variance of D (variation is small precision high expression of D is emphasized weight To increase).
Due to the similarity between the formula (MAP2) and the formula (REG1), it is also effective to use a mixture of both formulas. Alternatively, in the (MAP02) equation, PD may be used in place of D and used as a pre-established prior (p (PD)) for PD. Here, P is a said G or G ^T G or their even-n th power norm, (covariance matrix of the PD) C _PD instead of C _D is sometimes is used is determined in the same manner. In these, even if E [D] and E [PD] are not zero vectors, they may be calculated as zero vectors for convenience (the amount of calculation can be reduced).
In addition, in the restoration and super-resolution of the blurred image, when the maximum likelihood estimation is performed in the above-described system FO = B, the equations (LM7) to (LM9) are solved, and similarly to the above displacement measurement, MAP estimation (If O is random, the calculation amount can be reduced by setting E [O] = 0. Even if it is not a zero vector theoretically, it can be calculated as a zero vector for the same purpose for convenience. Yes), it is also possible to use the EM algorithm, and it is also effective to perform processing in the frequency domain as a space-time invariant system. The gradient operator G may be used in the prior establishment similarly. As in the case of the above displacement measurement, it is also effective to regularize and stabilize the system in the spatio-temporal domain and solve it (Non-Patent Document 43). Is possible.
Here, * represents conjugate, and here, the frequency response of the spatial distribution represented by each matrix or vector is represented using the same character. The document reports that regularization is more effective than a normal Wiener filter. In the present invention, application (including anomalous type) of the Wiener filter described in the present application and spatio-temporal variant regularization (regularization parameter is spatio-temporal variant) are performed. Also, a shaping filter may be applied as described above.
This regularization is at the cost of lowering the spatial resolution when the SN ratio of the received signal is low, between signals with different ultrasonic parameters or beamforming parameters, or between sensing signals that are physically different. Also, such a smoothing process may be useful.
Other than that, for example, optimization can be similarly performed in the inverse analysis shown in paragraph 0377 and various other inverse analysis (when the system is represented by Ax = b). In addition to maximum likelihood estimation, MAP, and regularization, Bayesian estimation can be similarly performed, and various other effective methods can be applied. By the way, when a vector such as a displacement vector or a current density vector is to be observed, another regularization parameter or another regularization operator may be used for each direction component (Non-Patent Document 17).

The new phase matching process includes different waves generated at the same position and a plurality of waves themselves having beamforming parameters (including physically generated waves and pseudo waves generated by frequency-dividing a spectrum). ) And pseudo waves generated by superimposing those waves (broadband and high resolution by coherent addition), or phase aberration correction at the time of their beam forming process (high accuracy by applying displacement measurement method) It is also effective in high-precision phase matching based on phase aberration measurement), in which signal separation by ICA (Independent Component Analysis) processing (which has a multiplexing effect more effective than averaging) and super-resolution by non-linear processing It is also effective for etc. If there is tissue displacement in the phase aberration correction, motion compensation can be performed at the same time, and the received signal in a single frame received when the observation target is clearly displaced or continuously acquired It is also effective to correct the phase aberration during and after beamforming and to perform super-resolution during and after beamforming on received signals in a plurality of frames that are frequently performed (super-resolution due to superimposed waves). Image processing, superimposition of super-resolution results, etc.). It is also effective to process these between different sensing signals such as MRI, ultrasound, X-ray CT, OCT, and terahertz. In such a process using a plurality of frame data, a large displacement or deformation of the observation target, particularly a signal loss due to spontaneous displacement of the observation target under non-control (for example, when the observation target is one-dimensional or two-dimensional or three-dimensional) Since the accuracy of phase matching between a plurality of frame data is reduced due to a physical action such as departure from the dimensional region of interest) or heating (treatment) or a chemical action such as chemotherapy, the displacement measurement (shifting) described in the present application is performed. Although optimization such as regularization and maximum likelihood estimation in (including processing) is effective, the new phase matching is also useful in those cases. Speckle signals may be processed, or specular signals may be processed. Edge extraction, enhancement, and feature points (for example, tissue structure such as blood vessel bifurcation position when viewing a human) may be performed as necessary. Obtained displacement tracking and the like are effective. Alternatively, depending on the signal, it may be effective to perform smoothing in the above regularization or to perform processing after performing envelope detection.
As described above, in addition to the phase matching in displacement measurement and the like, the new main phase matching processing includes the DAS processing (methods D1 to D3) described in paragraph 0384, and other phase matching such as Fourier beam forming, adaptive beam forming, and minimum variance. Estimation of Delay in beamforming (phase aberration correction), and shifting of signals in time coordinates, space coordinates, and space-time coordinates such as phase aberration correction, motion compensation, alignment, and position correction during beamforming described in paragraph 0372 Useful for estimating quantities.

In addition, there are various techniques for detecting and imaging the movement of the target based on the observed wave motion.For example, in the field of medical ultrasound, regarding the displacement and deformation of blood flow and tissue, based on the average velocity and dispersion, etc. , Speed information, presence / absence of motion, complexity, and the like. In some cases, measurement imaging is performed in a state in which a contrast medium (microbubble) is actively used and the intensity of wave from blood in a blood vessel or a heart cavity is enhanced. It may be useful not only for morphological observation but also for functional measurement. A typical example of the self-emanating type contrast agent is a radioisotope used in PET (positron emission tomography), and observation is performed based on a count of the number of occurrences. This is a passive device of the second embodiment, which is of a target type. For example, a magnetic substance (which may have an affinity for a target such as a cancer lesion) is injected intravenously, and a dynamic substance is added thereto. A magnetic field may be generated by applying vibration. Therefore, it is stimulated dynamically by the transmitting transducer as the transmitting means, and the electromagnetic wave is observed as the response by the receiving transducer as the receiving means. Further, the photoacoustic and the like described above are also possible. For example, a typical PET imaging agents in which ¹⁸ FDG ⁽¹⁸ F- fluorodeoxyglucose, labeled positron glucose) ingests the glucose more than cancer cells are normal cells (3 to 20 fold) It is used for the early detection of cancer targeting the whole body by applying its properties. By applying Photoacoustics (photoacoustics) to this, it is possible to detect the cancer early by receiving ultrasound (the integration mechanism by metabolic trapping Yes, like glucose, it is taken into the cell membrane via the glucose transporter of the cell membrane and metabolized by the enzyme hexokinase, but, unlike glucose, stays in the cell without entering the glycolysis system.) Sometimes it is used together with PET, but sometimes the ultrasound examination is done separately from PET. The processing itself is based on receiving beamforming for incoming ultrasonic waves (transmitted waves) using a trigger based on the timing of laser irradiation. The positron is released from the positron-emitting nuclide (positron nuclide) by β-decay, attracts the electron, couples with it after moving a few mm, and disappears. At that time, two photons ( Although the spatial resolution is low by observing γ-rays (that is, annihilation radiation), there is an advantage that, in a part where the generated ultrasonic waves can be observed, high-resolution observation can be performed. It is also suitable for early detection, and it is also possible to observe the presence or absence of disease by the presence or absence of accumulation, and to observe the degree from the intensity of the photoacoustic signal to judge the degree of malignancy or progression ( In malignant tumor cells, glucose metabolism is enhanced and highly accumulated). In addition to the D-type glucose present in the body, "Integrated function physiology course at Hirosaki University Graduate School of Medicine outside the field of photo-ultrasonics that applies the characteristic of cancer lesions specifically taking up L-type to fluorescent L-glucose One course) The use of L-type glucose is also effective after learning the results of Katsuya Yamada's research group (oral or ingestion). In addition, for example, the brain has the highest glucose metabolism in the human body, and Alzheimer's disease has metabolic abnormalities from an early stage. In the myocardium, glucose metabolism is enhanced (positive) when ischemia progresses, but glucose metabolism is not performed when necrosis occurs. Photoacoustic can also be used for those observations. In the case of the brain, the head may be cranulated. When targeting diseases of deep organs in the abdomen, laser irradiation or laser irradiation near the disease may be performed, such as by laparotomy or using a laparoscopic (laparoscopic) catheter. Ultrasonic detection may be performed. In many of these applications, the light absorption frequency characteristics of the contrast agent have been clarified and known, and the frequency dispersion of the irradiation laser and the generated ultrasonic signal may be actively used (ie, Observe the ultrasonic waves generated at the time of laser irradiation in a wide band or a specific band in a wide band as described below, or sometimes pay attention to a specific ultrasonic frequency band, or the ultrasonic waves generated at the time of laser irradiation in a different band. Observing sound waves in a wide band, focusing on a specific ultrasonic frequency band at that time, or superimposing the observed ultrasonic signals to artificially realize broadband laser irradiation, Ultrasonic sensors having the same characteristics in a wide band or a specific band may be arranged in a one-dimensional, two-dimensional, or three-dimensional array, or may have different band characteristics. May be similarly arranged in an array (eg, locally continuous, alternately, or periodically), or the light source and the ultrasonic sensor may have separate bodies. (In some cases, light sources and ultrasonic sensors are replaced and they are installed at the same location for observation.) In addition, imaging is not always performed, and quantification based on numerical values is performed. In some cases, only general observations are made. As described above, the glucose concentration is used as an observation target, and the present invention can be applied to blood sugar level observation and imaging. Further, the PET imaging agent, in addition to sugar, oxygen, water, those labeled amino acids, nucleic acids, a positron-emitting nuclide to neurotransmitters such as ⁽¹¹ C-methionine, ¹¹ C-acetate, ¹¹ C-choline, ¹¹ C-methyl spiperone, ¹³ N-ammonia, ¹⁵ O-water, ¹⁵ O-oxygen gas, ¹⁸ F-fluorodover, etc.) have been put into practical use, and they have been developed separately such as those developed for Photoacoustics. It can also be used for various contrast agents. In these photoacoustics, Doppler measurement (including vector measurement) may be performed on blood, urine, and body fluid, depending on whether a contrast agent is used or not, and soft tissue or hard tissue may be used. In some cases, the displacement and deformation of organs, viscoelasticity, and thermodynamic properties may be observed (including not only diagnosis and examination but also various treatments). The usefulness of indocyanine green (ICG) fluorescence imaging is well known, and is widely used for angiography and observation of blood flow, microcirculation, vascularity, lymph vessels, lymph flow, sentinel lymph nodes, liver segment, etc. However, it has strong light absorption and can be used as a contrast agent for Photoacoustics, and can be used for their observation as well. In the case of exposure to radiation, it is necessary to prevent the exposure and to reduce the exposure to a safe value or less, as usual. Contrast agents may also have a therapeutic effect. Conversely, a therapeutic agent may have the effect of a contrast agent.
Various contrast agents may be used at the same time, but they may not be used at the same time. Ultrasonic sensors with broadband reception characteristics are actively used, and the broadband Photoacoustics signal can be used at one time. In some cases, a frequency band is selected by filtering (analog or digital) and used for the above application (including imaging of a photoacoustics signal itself). The observation result of the above application using the Photoacoustics signal of each frequency or frequency band may be superimposed or averaged and used. In the case of imaging, a color may be assigned to the numerical value of the observation data to be displayed, or the same color may be displayed with shading to give a resolution. Further, an observation result at each observed frequency or frequency band may be imaged and displayed in a superimposed manner. In this case, different colors may be assigned to the observed results of the respective frequencies or frequency bands, or the numerical value of the observation data to be displayed with shading may be given a resolution. Understand which contrast agent or observation target substance is responsible for the Photoacoustics signal in each frequency band. (It is also important to actually measure the dispersion of optical ultrasonic waves. Absorbance data from 400 nm to 25 μm of related substances are abundant and helpful), Photoacoustics signals in the frequency band matching their targets may be used positively, but not necessarily. It is useful (that is, a case where a plurality of markers are mixed, such as a case where at least one originally exists in the observation target, a case where at least one is taken from outside the observation target, and a case where both exist together, For example, when there is no marker without being conscious of the marker, light having a bandwidth in which a Photoacoustics signal is generated is emitted in those cases). Images may be formed as described above, and displacement and temperature observations (including heating and heat treatment, as well as temperature rise due to light irradiation in Photoacoustics) described in this application, and other inverse analysis (observation) ) May be used. Furthermore, as described in the present application, spectrum analysis (analog or digital filtering), signal processing such as ICA (including cases where phase aberration correction is performed and not performed), and other image processing (eg, deterministic or probability statistics) Using a specific image pattern as an index) to separate signals from different markers. It is also effective to use the difference in signal strength or spectrum size (effective value) itself. This can be the marker analysis itself. In that case, the signals when the contrast agent is used and when it is not used may be targeted. Similarly, an image may be formed as described above, or the separated signal may be used for observation of displacement and temperature described in the present application, or for inverse analysis (observation) using them. In addition, for example, when imaging a fluid in a medium having a stationary or slow displacement such as a blood flow or observing the movement thereof, a photoacoustics signal itself or an ultrasonic wave (echo) which may be used in combination. Direct separation using Doppler observations in signals, using clutter rejection filters and differences in signal strength used in normal blood flow Doppler observations, or specifying and separating blood flow positions (regions) Is also useful. Of course, this processing is also effective in the case where the frequency and band of the irradiation light are set appropriately for the target fluid for observation, and the OCT or other frequency or band with or without frequency or band is matched. It is also useful to perform the processing in combination with Doppler observation using an optical device (light pulse or electromagnetic wave pulse). Importantly, a detailed evaluation of the medium surrounding the separated fluid is also possible (displacement, temperature, back analysis, etc.). These are also useful methods for cognitive analysis / analysis and synthesis (theory).
For these Photoacoustics signals (received signals), in addition to a known beamforming method, various beamforming methods and signal processing described in this specification are used. Thus, applications include imaging of the Photoacoustics signal itself, as described above. As the detection processing, a method described in this specification is used in addition to a known method. For example, as a simple beamforming process, as described in paragraph 0098 and the like, the conjugate is applied to the frequency response of the observed wave (for example, the frequency response S (ω1 of each of the three-dimensional, two-dimensional, and one-dimensional signals) , ω2, ω3), S (ω1, ω2) and S (ω1), the self-spectrum in the frequency domain S (ω1, ω2, ω3) S ^* (ω1, ω2, ω3) and S (ω1, ω2) S ^* (ω1, ω2) and S (ω1) S ^* (ω1)), and the autocorrelation function in the spatio-temporal domain obtained by inverse Fourier transform is obtained. A correlation function may be obtained, but it is effective only when the signal length is short. That is, if the normal auto-correlation signal is normalized and calculated without setting the maximum value to 1, a point spread function (sound pressure shape) at each point of interest in the region of interest is obtained, and these are superimposed in the region of interest. Thus, beamforming in the region of interest can be achieved. This conjugate product has the effect of a matched filter in signal detection, and gives a highly accurate result. Optical ultrasonic waves often have lower intensity and a lower SN ratio than ultrasonic waves received at the time of ultrasonic transmission. When the ultrasonic array is a multidimensional array (two-dimensional or three-dimensional), the intensity of the transmitted wave and the received signal is small, and the SN ratio is low. It is also effective in other various waves. Processing may be performed on a beam that has been subjected to various beamforming (including aperture synthesis), or may be performed before or after receiving beamforming (a transmission / reception signal for aperture synthesis). Processing may be applied. Incidentally, Patent Literature 11 discloses that it is possible to estimate a point spread function of an arbitrary wave such as an ultrasonic wave, a shear wave, and a heat wave at a point of interest and a source thereof. The wavelength can be estimated from the estimated point spread function (estimated in the spatial coordinate system including the fast-time-axis in the wave propagation direction and the spatial coordinate in the lateral direction), and the signal processing in the slow-time-axis direction It is disclosed that the propagation speed of various waves can be estimated.
In displacement measurement, temperature measurement, and the like, a multidimensional cross-spectral phase gradient method, a multidimensional cross-correlation method, a multidimensional autocorrelation method, a multidimensional Doppler method, a one-dimensional method thereof, a demodulation method, and the like are used. In some cases, the beamforming (including aperture synthesis) may be processed, or the beamforming may be performed before or after receiving beamforming (transmission / reception signal for aperture synthesis). May be processed. These displacement measurement methods are highly accurate and effective because they also have the above-mentioned beam forming process. The present invention is effective not only for optical ultrasonic waves but also for ordinary transmitted or echo ultrasonic waves and other waves. An optical ultrasonic signal tends to have a lower SN ratio than an ordinary transmitted or echo ultrasonic signal, and the intensity of the optical ultrasonic signal or the ultrasonic signal is extremely large compared to the surrounding signal intensity. In some cases, sudden measurement errors may occur in coarse measurement results using the multi-dimensional spectral phase gradient method or multi-dimensional Doppler method, including cases in which a median filter or low-pass It is effective to perform fine matching by performing phase matching after removing or reducing by applying a type filter. The same applies to other waves. Average processing is performed on the observation results obtained using each of the transmitted or echo ultrasonic signal and the optical ultrasonic signal, and the reliability evaluated by the method described in the present invention or which one is to be emphasized, etc. Or the result may be displayed by performing weighted averaging using. In addition, the equations derived from each of the ultrasonic signal and the optical ultrasonic signal are simultaneously obtained by the least square method, or the weighted least square method is performed using the reliability or which one is more important, It may be obtained by performing optimization such as regularization, maximum likelihood estimation, Bayesian estimation, and the method described in the present invention. A priori or a posteriori optimization is possible. In addition, the transmission or echo ultrasonic signal and the optical ultrasonic signal may be processed in a superimposed state. Similarly, the strength (or amplification degree) of each signal is determined by using the reliability or which one is important. ) May be obtained while adjusting the image (the display of the apparatus may have a graphical interface, or the console may have a hardware adjustment device such as a knob). In these processes, the signal may be processed on hardware after the signal is digitized, or may be processed by software in the calculation process. Analog processing may be performed using an analog delay (delay line or the like) or an amplifier.
Various signal processing methods such as the ICA described in this specification can be used for signal separation. For example, the spectrum can be divided, divided after beamforming, and the angular spectrum before beamforming can be used. May be divided. When dividing the angular spectrum, various beamforming such as DAS processing can be performed in addition to Fourier beamforming. In superposition, coherent addition or incoherent addition is performed. In particular, by using the beam forming method or the signal processing described in this specification, a weak signal can be processed without leaking, and detailed observation can be performed with high accuracy. Basically, the Photoacousics signal has a wide band, so it can not only realize high-resolution observation (including the above applications etc.), but also can be applied as a microscope. The ultrasonic sensor unit uses a handy type Photoacoustics microscope. It can also be achieved. In this case, the above-described application and the like are performed. The light may be irradiated to a wide area such as a plane wave, a spherical wave, or a cylindrical wave at one time, or may be scanned by a light beam (mechanical scanning or electronic scanning). The latter is better than the former. High resolution observation is possible.
In addition, when the reception characteristics of the ultrasonic sensor are narrow bands, each Photoacoustics signal received using a plurality of ultrasonic sensors having different reception bands may be used as described above, and may be used in combination. Sometimes.
These observed photoacoustic signals are similarly processed instead of ultrasonic echoes, subjected to various signal processing (including inverse analysis) described herein, and applied in various ways. For example, it is not limited to these, such as Doppler observation, mechanical reconstruction, and thermodynamic reconstruction based on temperature observation. As described above, the optical ultrasonic device realized by further providing the ultrasonic device with the light source has various applications. Various images obtained through optical ultrasound are displayed superimposed on the transmission or echo ultrasound image (one is colored and displayed simultaneously on the other grayscale image, and both are displayed simultaneously through the transparency) Sometimes). Therefore, at least the ultrasonic irradiation and the light irradiation are alternately and repeatedly performed, and each receives and processes the ultrasonic waves. Optical ultrasonic waves often have lower intensity and a lower SN ratio than ultrasonic waves received at the time of ultrasonic transmission. When the ultrasonic array is a multidimensional array (two-dimensional or three-dimensional), the intensity of the transmitted wave and the received signal is small, and the SN ratio is low. In these cases, it is effective to perform averaging after receiving a plurality of ultrasonic waves or optical ultrasonic waves in the target simultaneous phase in order to improve the SN ratio. In these cases, the ultrasonic irradiation and the light irradiation may be performed simply and alternately repeatedly, may be repeatedly performed while continuously performing each of them, or may be performed under the simultaneous phase of the object. , Or under the assumption, they may be digitally digitized and then averaged on hardware, or they may be arithmetically averaged by software in the calculation process. Analog processing may be performed using an analog delay (delay line or the like). In some cases, imaging of only optical ultrasonic waves is performed, and in other cases, the ultrasonic apparatus does not include a transmitter.
For example, the transmitting unit 31 and the receiving unit 32 shown in FIG. 2 calculate a local autocorrelation function that does not normalize the magnitude at each point of interest in the region of interest with respect to the received signal in each time phase, and To generate a wave data signal, and the digital signal processing unit 33 images the wave data signal in each time phase or calculates a displacement vector or a displacement component. Here, the received signal in each time phase for obtaining the autocorrelation signal may be a superposition of a plurality of received signals in each time phase.

  In addition, the wave is separated and detected before the last inverse Fourier transform (square detection, envelope detection, etc.), separated and analyzed after the last inverse Fourier transform, or separated from the original. Can be detected before and after Fourier transform (Non-Patent Document 1), and an image representing the intensity distribution of each wave is formed, or an incoherent signal obtained by the detection is superimposed. Emphasizing deterministic signals (eg, reflected and specular signals) and reducing stochastic signals (eg, scattered and speckle signals) The effective change is effectively depicted (past invention of the present inventor).

  In some cases, a coherent signal having overlapping waves is detected and its intensity distribution is imaged. In addition, a coherent signal that has not been detected may be imaged to undulate itself, or an image of a phase distribution obtained together with an image of the signal intensity (amplitude) may be presented. A single wave may be similarly imaged.

  The display method is generally grayscale image or color image (popular). In this case, if quantitativeness is required, numerical values corresponding to the displayed brightness and color are displayed as bars. There is also. In addition, it may be displayed in a bird's eye view or the like, or may be displayed in combination with CG. They may be displayed as still images or video, videos may be displayed frozen, they may be displayed in real time, or processed offline and displayed There is also. The wave data or image data stored in the storage device (or storage medium) may be read and displayed. The change over time of an arbitrary numerical value may be displayed as a graph.

  In addition, for example, it is also possible to observe the temperature distribution of the measurement target using microwaves, infrared rays, or signals in the terahertz band. The wave transmitted to the radiating object is modulated and detected (the passive type device according to the second embodiment also measures the target temperature distribution from the radiated wave itself). May be done). As with other waves, spatial resolution can be obtained by using pulse waves, burst waves, and beam forming instead of continuous waves. Infrared rays are mainly used to observe the temperature distribution on the surface of an object ( In some cases, it is considered that the temperature is restricted only by the surface of the object.) If microwaves or terahertz are used, the temperature distribution inside the object can be observed. Based on these observed physical and chemical quantities, higher-order processing such as an inverse problem approach is performed, and the viscoelasticity, elasticity, viscosity (Patent Document 9), and thermophysical properties (Patent Document 10) , Electrical properties (conductivity and dielectric constant, Patent Document 8), magnetic permeability, wave propagation speed (light speed, sound speed, etc.), attenuation, scattering (forward scattering, back scattering, etc.), transmission, reflection, refraction, diffraction waves, A surface wave, a wave source (sometimes treated as a diffraction source), or the like may be obtained including frequency dispersion. Patent Literatures 8 to 10 disclose a method capable of reconstructing a physical property distribution related to a physical quantity from one physical quantity (observed quantity) in a region of interest (differential inverse problem). In addition, the physical property distribution may be directly evaluated from the wave itself directly sensed by the sensor. In medical applications, including the use of ultrasound and MRI, observation of the viscoelastic modulus, as well as the temperature and thermophysical properties of inflamed areas during cancer lesions and heating / heating treatment, and after such treatment and surgery. And monitoring may be performed. In addition, body temperature observation (morning, noon, night, metabolism, growth, aging, before and after eating, before and after smoking, load on the peripheral system, including electrophysiological nerve control), exercise load on various organs, etc. Then, it may be observed. It is not limited to medical applications, and other organic and inorganic substances, as well as those composed of a mixture of substances, may be observed, and various observations and monitoring are linked in diagnosis, restoration, application, etc. May be implemented. Terahertz can be used not only for measurement but also for imaging of transmitted waves, reflected waves, refracted waves, diffracted waves, etc., as well as other waves, and can be applied to Doppler measurement and the like. Characteristically, it can be applied to observation of inorganic substances as well as X-rays. Other waves may be used for observing organic and inorganic substances, but can be used simultaneously with other waves to perform fusion.

  The measured physical quantities such as displacement and temperature may be displayed as an image in the same manner, but may also be displayed while being superimposed on a morphological image obtained at the same time. Images representing these distributions are often required to be quantitative, and numerical values corresponding to the displayed luminance and color may be displayed as bars. In addition, it may be displayed in a bird's eye view or the like, or may be displayed in combination with CG. They may be displayed as still images or video, videos may be displayed frozen, they may be displayed in real time, or processed offline and displayed There is also. The wave data or image data stored in the storage device (or storage medium) may be read and displayed. The change over time of an arbitrary numerical value may be displayed as a graph.

  Further, from another device, additional information about the wave to be observed may be provided through the input device, and observation data of other physical quantities or chemical quantities may be provided. In the digital signal processing unit, , Data mining, independent signal separation (independent component analysis), principal component analysis, code, multidimensional spectrum analysis, signal separation by MIMO, SIMO, MUSIC, signal separation based on object identification by parametric method, Super-resolution or a higher-order processing such as ISAR (Inverse synthetic aperture) that may use these methods in combination may be performed. In other words, super-resolution may be applied to the beam-formed (including the aperture synthesis), or to the beam-forming (or aperture-synthesis transmission / reception signal) before or after the reception beam-forming at all. Beam forming may be performed after performing super-resolution processing, and in each case, these methods may be used in combination.

  These processes are also performed in the passive-type device according to the second embodiment, and will be described in detail. However, unlike the passive device, the active-type device according to the present embodiment has It is very different to be able to specify the position of interest in the received signal to transmit and scan, and if transmission focus or multi-focus is performed, the state and function of those focus positions, the wave source If there is any information on the wave source, it modulates and demodulates the wave with high resolution and understands it. Also, plane wave (flat array), cylindrical wave (ring array), spherical wave (spherical shell array) By using waves similar to the above, it is also possible to capture them at a high frame rate and at high speed.

  In performing communication, the position of the communication destination can be narrowed down from the transmitting transducer, and energy saving and communication security can be improved. In performing observation, there is a high degree of freedom in configuring a measurement system. Further, in the processing based on such a system theory, it is easy to identify a point spread function to be generated and to adjust it according to the purpose. It is possible to use a plurality of transmitting transducers and receiving transducers (which may also serve as transmitting transducers), and the waves to be transmitted and received may be of the same type or different, In some cases, a plurality of device bodies dedicated to a plurality of transducers operating in synchronization may be used in plurality, or a passive type device according to the second embodiment may be used in combination. May be connected to another device including a device for controlling the network through a dedicated or ordinary network, or the device body may have a network control function.

  Based on various observation data, devices such as devices for manufacturing materials and structures, devices for treatment and restoration, and devices to be applied (robots, etc.) may operate in conjunction with each other, but are not limited to them. . Note that the measurement and higher-order calculation processing using these waves may be performed by another device using wave data stored in a removable storage device (storage medium). Data may be stored in the same type of storage device (storage medium) and used by another device.

  When a received signal received and stored in a memory or a storage device (storage medium) includes a harmonic component generated in an object or a medium, a fundamental wave or a harmonic wave may be generated before performing beamforming processing. In some cases, a wave (only the second harmonic or a plurality of higher harmonics may be handled without ignoring higher-order components) may be separated and subjected to beamforming processing (ordinary phasing addition). However, separation may occur after beamforming is performed. Some of the separation methods separate the spectrum in the frequency domain, but the bands may overlap, and so-called pulse inversion method in medical ultrasound generates waves with opposite polarities in the simultaneous phase. In the measurement imaging apparatus according to the present embodiment, when the received signals for each transmission are superimposed before or after beamforming, the second harmonic component can be extracted and the fundamental wave can be obtained.

  In addition, a separation method using a polynomial is also known. In the measurement imaging apparatus according to the present embodiment, one-dimensional processing of the wave propagation direction, or when the wave is modulated in the lateral direction or the wave propagation direction is strictly determined. Can be subjected to multidimensional processing in consideration of the change at each position, and can be performed before or after beamforming. However, when performing beamforming after separation, when performing beamforming for each of a fundamental wave and a harmonic, each beamforming process is performed, so that calculation time is required. Processing may be performed, but separation after beamforming is faster.

  On the other hand, when the wave transmitted from each transmission aperture is encoded, when performing beamforming, the wave generated and transmitted from any transmission aperture element with respect to the reception signal received by each reception aperture element. Components are separated by signal detection based on a matched filter to perform not only dynamic focusing of reception but also dynamic focusing of transmission, which is widely known. This is effective in high-speed transmission by plane wave transmission, and is also effective in the case of performing a focus beam or steering.

  In the case of transmitting a plurality of waves or beams at the same time, for example, the waves having the plurality of different frequencies and the plurality of different propagation directions are transmitted as coded, and the received signal is transmitted. May be similarly decoded to separate them into received signals generated by their respective waves and transmitted beams, thereby improving the separation performance. This is effective, for example, in the case where the propagation directions are the same due to waves, refraction, reflection, transmission, scattering, diffraction, etc., whose bands overlap. It is based on the basic idea of encoding the waves to be separated with another code. In some cases, encoding is simply performed under the same physical parameters.

  In these, simultaneous equations can be solved, but the processing is fast and the effect of a matched filter can be obtained. Codes suitable for the target and medium are also being developed. However, as the number of elements used increases, the code length increases, the energy of the signal increases, and it is important to use this effectively, but on the other hand, if the target or medium is deformed, for example, the accuracy will increase. Is known to be unsuitable due to a decrease in the chirp signal, and a similar problem occurs in chirp signal compression.

  In communication, a wave transmitted from each transmitting aperture element is encoded with information and coded, and then transmitted (for beam forming, for example, a plane wave, a cylindrical wave, or a spherical wave is used). Focusing may be spread over multiple locations or multiple locations may be used to ensure accuracy at those locations, as well as secure or communicate with local or specific objects and save energy. ), The received signal is subjected to beamforming and then decoded. The application of the coding in the measurement imaging apparatus according to the present embodiment is not limited to them, but these processes are performed in a digital signal processing unit (there is also a built-in memory type), a memory, and a storage device (storage medium). Done. A new application in the near future is a home delivery service by autonomous driving. As the population ages and the population declines, it is expected that home delivery services will be unmanned. Article management using tags is well known and has a wide range of applications and is a deep field, but similarly, tags are used to carry goods out of goods transport vehicles at the time of receipt, and to transport goods to goods transport vehicles at the time of collection. It is necessary to automate the loading. For security (including not only physical security but also confidentiality regarding personal information, etc.), tags and passwords from a courier company or a sender via a network at the time of unloading and / or loading of goods are provided. Issuing a number is valid. In these readings, automated beamforming may be performed. It is also desirable to automate the movement of the articles in the vehicle to the exit and the movement from the entrance to an appropriate storage location. Transportation and collection routes also need to be considered. During this time, automated beam forming is performed, and the situation inside the goods transport vehicle may be monitored. Delivery items requiring an appropriate storage location include, for example, raw items, precision machines, drugs, and the like. In that case, to check the contents of the goods written on the transport tag or the contents of the goods registered in advance, the packed goods are judged by remote sensing, and after safety is confirmed, the goods are properly unloaded. Or it is desirable to carry in. The determination may be automatically performed based on a computer mounted on the vehicle, or may be performed automatically by sending observation data (images and the like) to a determination center or the like through communication. However, when high safety and reliability are required, human judgment is performed. A function to refuse to transport explosives and dangerous drugs is also required. In addition, although the amount of transportation at one time is reduced, a mobile body such as an unmanned airplane, an unmanned helicopter, a small helicopter, or a drone may be used instead of a car. At the time of collection, inform the current location and required time before arriving at the collection location, or automatically notify the arrival via telephone, e-mail, Internet, etc. when arriving at the collection location It is desirable to have a function. Normally, all information about a mobile is managed in a discrimination center or a central office. A system in which a mobile body is managed and controlled based on the results of environmental observation, weather observation, congestion status, and the like, which are provided by the own or external communication, or in cooperation with IoT or smart communication (society). It is sometimes incorporated into. The above-mentioned discrimination center or central office may be independent or may be incorporated together. In some cases, the mobile body spontaneously determines an action pattern, and the discrimination center or the central office plays a central role in managing and monitoring the action. In some cases, such management and monitoring are performed by sensing (or receiving) a signal (information) emitted by the mobile unit, but various sensing mechanisms provided outside the mobile unit provide the signal (information) by communication. There are also (eg, satellites and other mobiles, fixed sensors in the path, etc.). The transport target may be a human (healthy, elderly, child, sick, disabled, etc.). The transport destination may be a special institution (a hospital or the like). If the hospital's emergency reception system is managed in real time, the efficiency and reliability of emergency transportation will be improved (including manned cases). In this case, it is effective that the basic diagnosis based on the automatic or human sensing during transportation is performed and the hospital can grasp the situation at an early stage. Instead of manpower, robots can be active. Full automation is required for loading and unloading goods and people, but manpower may be required due to ethical or technological limitations. It is desirable that a home delivery service request or the like can be made in a short time through telephone, e-mail, or the Internet. Various beam forming and sensing according to the present invention can be utilized in various other forms.

  Physical quantity (displacement, velocity, acceleration, strain, strain rate, etc., size, direction, temperature, etc.), chemical quantity, or additional information observed by the measurement imaging apparatus according to the present embodiment or provided by another source In addition, data relating to waves and viscoelastic modulus and elastic modulus, viscosity, thermophysical properties, Electrical properties (conductivity and dielectric constant), magnetic permeability, wave propagation speed (light speed, sound speed, etc.), attenuation, scattering, transmission, reflection, refraction, diffraction, surface waves, wave sources, materials, structures, or their The above wave parameters (frequency, bandwidth, etc.), beamforming and sensor parameters (transmission intensity, transmission and reception apodization, transmission and reception, etc.) based on frequency dispersion, etc., constantly, appropriately, or at fixed time intervals. of Array, steering angle, transmission and reception time intervals (scan rate), frame rate, number of scanning lines, number, shape, size, direction and position of effective apertures, shape, size and orientation of aperture elements, physical aperture The orientation or the polarization mode may be optimized (for example, Patent Document 12 and Non-Patent Documents 45 and 46). It has, for example, a spatially uniform quality (spatial resolution, contrast, scan rate, etc.) and a certain target (based on shape, material, structure, motion characteristics, temperature, humidity, etc.) Scattered waves (forward or backward scattered waves), transmitted waves, and reflections with high quality (spatial resolution, contrast, scan rate, etc.) at the specified position and related positions according to the movement, composition, and structure of the target Optimized beamforming is performed, such as appropriately capturing waves, refracted waves, diffracted waves, or surface waves, or primarily observing from a wide direction.

  The propagation speed of a wave is determined by the physical properties of the medium, but the physical properties vary depending on environmental conditions such as pressure, temperature, and humidity.In addition, the physical properties are often inhomogeneous in the medium. It is. The propagation speed may be measured in real time, and the propagation speed may be obtained from the observed environmental conditions based on calibration data for the environmental conditions. The measurement imaging apparatus according to the present embodiment further includes a phase aberration correction unit that corrects the inhomogeneity of the propagation velocity, and substantially adjusts the transmission delay itself of each channel or the delay dedicated to correction during transmission. Thus, the phase aberration can be corrected. After reception, the digital signal unit can be corrected by multiplication of a complex exponential function in the frequency domain in order to correct the inhomogeneity of the propagation speed in the transmission and / or reception propagation path. Alternatively, in the calculation of the above-mentioned Fourier transform and inverse Fourier transform, it is also possible to directly make a correction. The reliability of the measured propagation velocity is based on the fact that an imaging signal is generated for the measurement object itself, a reference object that exists in the vicinity of the measurement object, or a reference object that is installed, and the imaging state, spatial resolution, signal intensity, contrast, etc. It can be confirmed as an index, and it may be adjusted further based on this. In the second embodiment, which is a passive mode described later, phase correction of transmission and / or reception may be performed after reception.

  A wave propagates and spreads under the influence of attenuation, scattering, transmission, reflection, diffraction, refraction, and the like. Basically, the strength of the wave decreases with the propagation distance. Therefore, in the measurement imaging apparatus according to the present embodiment, for example, based on Lambert's law, a function of performing attenuation correction on a signal before or after beam forming is mounted, or an operator receives a signal from an input device. A function that can adjust the attenuation correction at each position and each distance may be provided, but as described above, it may be provided with a function of performing an optimal correction before or after the beam forming process according to the target. is there. In these processes, although the degree of freedom is low, an emphasis is placed on high-speed processing, and instead of digital processing, analog processing by analog devices or circuits may be performed.

  In the above processing, the superposition and the spectral frequency division are linear processing. However, after generating or after generating the wave by the beam forming in the above methods (1) to (6), a non-linear processing is performed, and another processing is performed. Generating a signal having wave parameters is performed. In the process of beamforming, when the received signal is an analog signal, it is based on analog signal processing using an analog circuit (diode, transistor, amplifier, dedicated nonlinear circuit, etc.), and when the received signal is a digital signal, it is digital using a digital signal processing unit. A power operation, a multiplication operation, or other non-linear processing may be performed on the received signal based on the signal processing. In the frequency domain, the spectrum may be subjected to non-linear processing.

  In addition, as a modification of DAS, DAM (Delay and Multiplication) processing, which is the invention of the present inventor, may be performed in the frequency domain in the measurement imaging apparatus of the present invention. Calculation of a product such as exponentiation or multiplication in the spatiotemporal domain can be calculated by convolution in the frequency domain. For signals that have been made higher in frequency, wider in frequency, simulated higher harmonics, and steered waves, it is possible to obtain signals detected in at least all directions from at least one arbitrary direction. Image can be generated, and the displacement vector can be measured using a normal one-way displacement measurement method.

  It is also possible to generate an imaging signal using a virtual source. As for the virtual source, it has been reported in the past that a virtual source was installed before the physical aperture and that a virtual source was installed at the transmission focal position. It has been reported that can be installed at an arbitrary position, that a physical source of wave motion and a detector can be installed at an arbitrary position of an appropriate scatterer or diffraction grating (Patent Document 7 and Non-Patent Document 8). The invention can also be implemented in those virtual sources and virtual detectors, as described above. It is possible to increase the spatial resolution and widen the field of view (FOV). Also, when performing transmission or reception, or transmission / reception beamforming on a reception signal obtained by transmission using one or more apertures (when beamforming is not performed, transmission / reception for aperture synthesis). , A plurality of wave parameters, a plurality of beamforming parameters, and a plurality of transducer parameters (element shape, size, arrangement, number, effective aperture width, element material, and the like). By doing so, a plurality of beams or waves having different characteristics can be generated (including obtaining a plurality of beams or waves from the same received signal), and an over-determined system can be configured. Similarly, an over-determined system can be configured by changing the position and distribution (shape, size, etc.) Kill. Also in this case, a plurality of beams or waves having different characteristics may be generated from the same received signal. The features of the over-determining system, such as high SN ratio and high resolution by their coherent superposition and speckle reduction by incoherent superposition through their detection, may be effective for imaging. In addition, the effect of improving the accuracy of various measurements such as displacement measurement and temperature measurement can be obtained. Along with the virtual source and the virtual receiver, at least one of the plurality of wave parameters, the plurality of beamforming parameters, and the plurality of transducer parameters may be different (e.g., electro-electronic or mechanical). Change the steering angle physically or softly). In addition, in order to generate a desired wave (point spread function and its distribution), the parameters, positions, shapes, sizes, and distributions of virtual sources and virtual receivers (scatterers, diffraction gratings, and the like) are linearly or non-linearly. (The diffraction characteristics, directivity, scattering characteristics, etc. of the virtual sound source and the virtual receiver are obtained through experiments, simulations, or theories, and their positions, shapes, and so on are realized in order to realize the desired point spread function.) The size and distribution can be optimized).

By an arbitrary wave source, a wave is generated by rotating a coordinate system determined by a receiving aperture element array around an arbitrary position, or by spatially shifting a coordinate system (for example, the axis and the horizontal coordinate of the transmitting aperture). , And is different from that determined by the receiving aperture), beamforming may be performed after correcting the coordinates of the received signal. For example, when it is desired to directly generate an imaging signal in a state where the above-described two-dimensional Cartesian coordinate system (x, y) is rotated by θ around the origin, an analysis signal obtained by the first time-direction Fourier transform Is calculated by multiplying by the equation (29), and the rotation of the wave vector (kx, √ (k ² -kx ² )) and the coordinates (x, y) and the calculation of the Jacobian The image signal can be generated at high speed without losing the high speed achieved by the present invention.

However, in the case of a reflected wave, s = 2, and in the case of a transmitted wave, s = 1. Substantially, correction for transmission may be performed with s = 1. Spatial shifting can also be performed in the frequency domain by multiplying by a complex exponential function. Additional wave vector ^{(kx, √ (k 2 -kx} 2)) and the coordinate (x, y) method of performing the calculation of rotation and Jacobian of the transmission beam forming with the conversion of the coordinate system determined by the receive aperture array (S = 1), and under that condition, reception beamforming (s = 1) is performed and the speed is low.

  In the active device according to the present embodiment, the same applies to the passive device according to the second embodiment described later, but as an analog device, in addition, it may be incorporated in a transducer or a device body. Lenses and reflectors (mirrors), scatterers, deflectors, polarizers, polarizers, absorbers (attenuators), multipliers, conjugators, phase delay devices, adders, differentiators, integrators, matching devices, A special device such as a filter (space or time, frequency), a diffraction grating (hole), a spectroscope, a collimator, a splitter, a directional coupler, or a nonlinear medium or a wave amplifier may be used in combination. In addition, in the case of light, polarization filters, ND filters, shields, optical waveguides, optical fibers, optical Kerr effect devices, nonlinear optical fibers, optical mixing optical fibers, modulation optical fibers, optical confinement devices, optical memories, dispersion shifts Optical node technology, optical cross-connect (OXC), optical coding, etc. using optical fibers, bandpass filters, time inverters, optical masks, etc. An optical add-drop multiplexer (OADM), an optical multiplexing / demultiplexing device, or an optical switch element is used, and the device itself may be an optical transmission network or an optical network. This is not the case. In beamforming, they are controlled either with the device, either artificially or spontaneously, or equally optimally under the above-mentioned scheme. In the frequency domain, the spectrum may be subjected to non-linear processing.

  Further, under such a combination, the measurement imaging apparatus according to the present invention is also used in an ordinary apparatus using waves. Examples of medical devices include an ultrasonic diagnostic device (reflection / echo method and transmission type), X-ray CT (contrast agent that enhances the attenuation effect is sometimes used), X-ray radiography, Angiography, mammography, MRI (Magnetic resonance Imaging, a contrast agent is sometimes used), OCT (Optical Coherent Tomography), PET (Positron Emission Tomography, corresponding to the second embodiment), SPECT (Single Photon Emission Computed) Tomography), endoscope (also available in capsule type), laparoscope, catheter equipped with various sensing functions, terahertz imaging device, various microscopes, various radiation therapy devices (chemotherapy may be used in combination to enhance the therapeutic effect ), SQUID meter, electroencephalograph, electrocardiograph, HIFU (High Intensity Focus Ultrasound) and the like. Above all, a nuclear magnetic resonance imaging apparatus is a digital apparatus from the beginning, and its application range is extremely wide, including its capabilities. For example, using the electromagnetic wave observation and the inverse problem that the inventor of the present application is working on, the current distribution and the reconstruction of electrical properties (measurement), the observation of the propagation of displacement and mechanical waves, the reconstruction of mechanical characteristics (measurement), The present invention can be applied to all of observation of a temperature distribution and a heat wave, and reconstruction (measurement) of thermophysical properties (Patent Documents 8 to 10). Patent Documents 8 to 10 disclose a method capable of reconstructing a distribution of physical properties related to a physical quantity from one physical quantity (observed quantity) in a one-dimensional, two-dimensional, or three-dimensional region of interest. Observed physical quantities are surface waves (electromagnetic waves, elastic waves, heat waves, etc.) and physical quantities at boundaries, and their physical properties may be similarly reconstructed based on the observations. When terahertz is used, the electric field can be observed, and the current density, electrical properties, and the like can be observed. Doppler observations using terahertz are also important. In addition, the physical property distribution may be directly evaluated from the wave itself directly sensed by the sensor. Regarding these, in addition to the nuclear magnetic resonance imaging apparatus, approaches using ultrasonic waves or the like are also being performed, and the same is true. As another approach, for example, in OCT, it is possible to measure the absorption spectrum and perform imaging of, for example, basal cell carcinoma of the skin, oxygen and glucose concentrations in blood based on infrared spectroscopy. become. Although application to ordinary Near InfraRed (NIR) is also possible, its distribution can be grasped with higher spatial resolution as compared with so-called NIR-based reconstruction. In these, photoacoustic imaging may be performed by using an ultrasonic sensor device (a microscope is also possible) in combination with the OCT or laser device, and the application is not limited thereto. In some cases, laser and OCT devices are used to capture and image tissue fluctuations with high sensitivity without mechanical stimulation (observation of surface waves such as Doppler observation and its application). There is also). In addition, the response to any (mechanical) stimulus including the one caused by laser light may be an object of imaging (including observation using dynamic light generated by using light, etc.). In other imaging, a chemical sensor or the like may be used. The combination of the waves is not limited to these, and another sensor such as a chemical sensor may be used in addition to the physical sensor. Further, the measurement and imaging apparatus according to the present invention is also used in various radars, sonars, optical systems, and the like. The wave is not limited to a pulse wave or a burst wave, and a continuous wave may be used. Further, digital processing having a high degree of freedom may be realized and used by a dedicated analog circuit having a fast operation time, and vice versa. Various devices exist in each field such as the field of resource exploration, nondestructive inspection, and communication, and the device according to the present invention is used in those fields. The measurement and imaging apparatus of the present invention can be used as an apparatus and in an operation mode (for example, an imaging mode, a Doppler mode, a measurement mode, a communication mode, and the like) in an ordinary apparatus. It is not limited to things.

In the case where a plurality of fixed focusing beams, multi-focusing, and other arbitrary beams and waves, such as plane waves, are simultaneously transmitted physically at the same time, a high frame rate can be obtained if the beam can be transmitted to a region of interest at a time in a wide range. realizable. The same effective aperture may be transmitted simultaneously in a plurality of directions, or different effective apertures may be simultaneously transmitted in the same direction or different directions. In addition to cases where such steering angles and focus positions are the same or different, ultrasonic frequencies and bandwidths (beam directions and propagation directions of waves, directions orthogonal to them), pulse shapes, wave numbers, aperture shapes and apodizations. The beamforming parameters such as the beam shape due to the above, and the same or different transducer parameters such as the element shape, size, and arrangement status may be transmitted simultaneously.
In physical multiple transmission, when those parameters are different, the following can be considered as a typical case.
(A1) A case where the same soft steering is applied to all.
(A2) A case where a plurality of different soft steerings are performed (for example, a case where the same steering is softly performed for each different transmission steering angle).
When the parameters are the same, the following can be considered as a typical case.
(B1) When soft steering is performed.
(B2) When a plurality of soft steerings are performed.
However, they may be implemented in combination. So-called adaptive beamforming may be performed due to obstacles in the propagation process and the effects of scattering and attenuation (including those depending on frequency). At that time, if the same combination of soft transmission and reception steering and apodization is implemented, they are processed at once in a state where they are superimposed. When the combinations include different ones, each of the combinations to be performed is processed at once in a state where the same combination is superimposed on each other, and is superimposed before the final inverse Fourier transform.
In the cases of (A1) and (B1), one soft process can be performed on the received echo signal received as a superposition of the echo signals for each transmission ultrasonic wave.
In the case of (A2), the signals are classified into echo signals to be subjected to the same processing in software, are superimposed on those to which the same soft steering is performed, and the software processing is performed once for each. Superimpose them before the inverse Fourier transform of. It should be noted that the above-described various methods may be used for signal separation, and the present invention is not limited to these methods.
In the case of (B2), a plurality of different soft processes are performed on all the superimposed angular spectra, and the superimposed angular spectra are superimposed before the final inverse Fourier transform.
In the case where the beams and waves are not transmitted physically at the same time, if the time phase of the object is the same, or if a plurality of transmissions and receptions are performed under the assumption, It may be processed according to the case of transmission. Also, when the same combination of soft transmission and reception steering and apodization is performed, they are superimposed and processed at once, and when the combination includes different ones, it is performed. Combinations are superimposed on each other, each processed at once, and superimposed before the final inverse Fourier transform. Simultaneously transmitted and not simultaneously transmitted may be processed similarly under the same conditions or assumptions described above. These parameters in physical transmission may be known in advance, or beams and waves may be analyzed and used. This also applies to a passive type described later.
By performing simultaneous or non-simultaneous transmission of multiple beams and waves, high frame rate and focusing of the same or multiple locations can be realized.Based on the same processing including superposition processing, beams and waves with new parameters can be created. In addition, it is possible to generate a beam or wave having a new parameter with the frequency division processing of the spectrum. May be used separately (for example, measurement of a displacement in a generated beam direction or a propagation direction of a wave or measurement of a displacement vector). The superimposed state, the spectrum-frequency-divided state, and the separated state may be subjected to broadband based on non-linear or linear processing described later. In addition, superposition or spectral frequency division, separation, non-linear or linear processing, or the like may be used for displacement measurement or the like. Each of them may be detected and imaged, or the detected ones may be superimposed and imaged (eg, speckle can be reduced). The application is not limited to these, but is various as described above, and is not limited to them.

<Simulation result>
Hereinafter, a result of confirming the feasibility of the above beam forming methods (1) to (7) by simulation mainly when the wave is an ultrasonic wave (monostatic aperture during plane wave transmission or steering) will be described. Surface synthesis, multi-static aperture synthesis, image signal generation by fixed focusing, image signal generation in Cartesian coordinate system during transmission / reception in polar coordinate system, and result of migration method).

  FIG. 23 is a diagram illustrating a numerical phantom used in the simulation. Here, a numerical phantom including five point scatterers that are present at an interval of 2.5 mm at a depth of 30 mm in an anechoic and unattenuated medium is used. Field II (see Non-Patent Document 21) was used to generate the echo signal. Here, the depth direction is the z-axis, and the horizontal direction is the x-axis.

  In the plane wave transmission, the migration method, and the monostatic aperture synthesis, a one-dimensional linear array transducer (128 elements, element width 0.1 mm, gap 0.025 mm, thickness in the slice direction 5 mm) was used. For fixed focusing and multi-static aperture synthesis, a one-dimensional linear array transducer (256 elements, element width 0.1 mm, gap 0.025 mm, slice direction thickness 5 mm, effective aperture width 33 to 129 elements) was used. For transmission and reception in the polar coordinate system, a convex transducer (128 elements, element width 0.1 mm, gap 0.025 mm, thickness in the slice direction 5 mm, radius of curvature 30 mm) was used. The center frequency of the emitted ultrasonic pulse is 3 MHz, and the sound pressure waveform is shown in FIG. The deflection angle is defined with respect to the depth direction of the front surface, and is hereinafter represented as “θ”.

(1) Transmission of Deflected Plane Wave FIG. 25A (respectively (a) to (d)) shows a simulation result when a deflection plane wave having a deflection angle θ = 0 °, 5 °, 10 °, and 15 ° is transmitted. . FIG. 25B shows a simulation result when interpolation approximation is performed in wave number matching when the deflection angle is θ = 0 °. These are the results of receiving at the same angle. 25A and 25B, the horizontal axis represents the position [mm] in the horizontal direction (Lateral x), and the vertical axis represents the depth (Depth) z [mm]. As shown in FIG. 25A, a formed echo image is obtained, and it can be confirmed that the image is deflected. In each case, in the frequency domain, downsampling is performed from 100 MHz to 10 MHz (paragraphs 0208 and 0209), and image signals are generated at intervals corresponding to the sampling frequency of 25 MHz (the same applies to other cases).
On the other hand, when the deflection angle is θ = 0 °, interpolation approximation is performed in wave number matching, and FIG. 25B (e) shows that the sampling frequencies are 100 MHz (left) and 25 MHz (right) when the spectrum is replaced with a nearby spectrum. FIG. 25B (f) shows the results when the sampling frequency is 100 MHz (left) and 25 MHz (right) when the linear interpolation approximation is applied to the spectrum. Although the image was more stable when the sampling frequency was high and the linear interpolation approximation was performed, it did not reach the level in FIG. 25A (a) where the interpolation approximation was not performed. A non-zero deflection angle resulted in a more unstable result.

  FIGS. 26 and 27 show the results of calculating the obtained deflection angle from the spectrum of the generated image signal. For this evaluation, the number of scatterers in the numerical phantom was increased, and 300 scatterers were randomly arranged at a depth of 0 to 40 mm. The reflection coefficient of each scatterer was a random value of -1 to 1. Regardless of the set deflection angle, an error of 0.5 to 0.8 degrees was confirmed. The error is dependent on the position of the scatterer with respect to the generated waves. Increasing the number of scatterers improves accuracy (abbreviated).

  FIG. 28 shows the result of superimposing a plurality of images obtained at different deflection angles. The deflection angle is set at 1 ° intervals, and 1 wave (0 °), 11 waves (−5 ° to 5 °), 21 waves (−10 ° to 10 °), and 41 waves (−20 ° to 20 °) Each was superimposed. FIG. 29 is a diagram in which the horizontal distribution of the point spread function estimated from the generated image signal is plotted. In FIG. 29, the horizontal axis represents a position [mm] in the horizontal direction (Lateral x), and the vertical axis represents a relative value of brightness. As shown in FIG. 29, it can be confirmed that the resolution increases as the number of superpositions increases.

Migration method (method (6) is applied to beam forming when transmitting the same plane wave)
FIG. 30 shows a result of generating an image signal by the migration method according to the present invention. The deflection angles were θ = 0 °, 5 °, 10 °, and 15 ° as in FIG. 25A. In the wave number matching, the result of the interpolation approximation is omitted, but the image is unstable.

(2) Deflection monostatic aperture synthesis The simulation result at the time of deflection by the monostatic aperture synthesis of the method (2) is shown in FIG. As in FIG. 25A, the deflection angles were set to θ = 0 °, 5 °, 10 °, and 15 °. As shown in FIG. 31, it can be confirmed that the image is formed and deflected.

(3) Multi-Static Aperture Synthesis The simulation result by the multi-static aperture synthesis of method (3) is shown in FIG. FIG. 32 (a) shows a low-resolution image generated using only received signals (ie, one set) with the receiving element equal to the transmitting element (ie, the same as the monostatic type). FIG. 32B shows a result obtained by superimposing a total of 33 sets of results obtained by using 16 elements on the left and right in addition to the element at the transmission position. 32 (c) and (d) show the result of overlapping 65 sets (32 elements on the left and right sides of the transmitting element) and the result of overlapping 129 sets (64 elements on the left and right sides of the transmitting element), respectively. As shown in FIG. 32, it can be confirmed that an image has been formed. FIG. 33 shows the results of plotting the point spread functions. 32 and 33, it can be confirmed that the side lobes are suppressed as the number of superimpositions increases, and that the resolution is high.

(4) Fixed Focusing The result of fixed focusing transmission is shown in FIG. Here, the method (1) was used. FIG. 34A shows the result of superimposing the echo signals received at the respective effective transmission apertures and performing a single echo signal generation process. FIG. 34B shows the result of generating and superimposing low-resolution echo signals for each effective aperture width. FIG. 34 (c) shows the result of generating and superimposing echo signals with sets having the same positional relationship in transmission and reception as in the multi-static aperture plane synthesis. As shown in FIG. 34, an image is formed in each case, and there is no particular difference. Method (1) is faster and more effective than the other two methods. In addition, the result of the method (1) indicates that the reception beam forming is possible even if the reception signal obtained when the plural or all the beams are ideally transmitted at the same time is used (for the transmission beam having the interference). It can also process received signals and achieve high frame rates). This processing is not limited to the fixed focusing transmission, and can be performed at the time of transmitting a plurality of waves of all types (including a combination of different waves). In other words, the plurality of waves may include those subjected to different transmission beamforming, include the case with and without beamforming, or include different types of waves (electromagnetic wave, mechanical wave, heat wave, etc.). However, there may be cases in which processing such as non-linear processing or detection processing, super-resolution or adaptive beam forming, minimum variance processing, or signal separation is performed. These processes may be performed during beamforming. Of course, the received signals for each transmission may be superimposed. Interpolation approximation processing may be performed also in wave number matching in these cases.

(5) Generation of image signal in Cartesian coordinate system for transmission and reception in polar coordinate system (5-1) Cylindrical wave transmission The echo signal when cylindrical waves are transmitted by simultaneously radiating ultrasonic waves from all elements of the convex array is referred to as frequency. FIG. 35A shows the result of processing in the region. As a matter of fact, as described in (5-1 ′), a plane wave or a virtual linear array is generated at a position with a depth of 30 mm in transmission and reception. As shown in FIG. 35A, it can be confirmed that the scatterer is imaged.
(5-1 ') Cylindrical Wave Transmission Using Linear Array Next, an echo signal when a cylindrical wave is transmitted using the linear array and a virtual sound source (FIG. 8A (a)) set at a position behind the linear array. The result of generating is shown. FIG. 35 (b) shows the result of using the method (1) described in the method (5-1 ′) with the virtual sound source positioned at a position 30 mm behind, and FIG. The results obtained by using the method (2) described in the method (5-1 ′) with the position 60 mm behind are shown. It can be confirmed that the scatterer is imaged.
In addition, when a linear array transducer is used, the method (1) described in the method (5-1 ′) is used, and a case where a cylindrical wave is generated using a virtual source at a position 30 mm behind the physical aperture is applied. FIG. 35 (d) shows the result of a case where a plane wave or virtually a linear array type transducer is generated at a distance position of 30 mm (FIG. 8B (g)).

(5-2) Fixed Focusing FIGS. 36 (a) and 36 (b) show the results of processing the received signal when the fixed focusing is performed at a distance of 30 mm from each element using the convex array (FIG. 14 (a)). FIG. 36 (a) shows the result of superimposing the received signals obtained at each effective transmission aperture and performing one echo signal generation process, and FIG. 36 (b) shows the low resolution for each transmission. It shows the result of generating and superimposing images. Similar to the multi-static aperture synthesis, the result of generating and superimposing echo signals with the same positional relationship in transmission and reception as a set is omitted, but these three operations are almost the same as in (4). Results. FIG. 36 (c) shows the result of performing one echo signal generation process on the reception signal when the fixed focusing is performed at the depth of 30 mm (FIG. 14 (b)). The scatterer was well imaged.
These results are obtained in the same manner as in (4), and show that reception beamforming is possible even with the use of reception signals when multiple or all beams are ideally transmitted simultaneously. (It can also process received signals for transmitting beams with interference, and achieve high frame rates). This processing is not limited to the fixed focusing transmission, and can be performed at the time of transmitting a plurality of waves of all types (including a combination of different waves). In other words, a plurality of waves may include those subjected to different transmission beamforming, include cases with and without beamforming, or include different types of waves (electromagnetic waves, mechanical waves, heat waves, etc.). In some cases, processed data such as nonlinear processing or detection processing, super-resolution or adaptive beamforming, minimum variance processing, or signal separation may be included. These processes may be performed during beamforming. Of course, the received signals for each transmission may be superimposed. Interpolation approximation processing may be performed also in wave number matching in these cases.

  The beamforming using the digital Fourier transform according to the present invention performed in the above simulation is based on the use of the complex exponential function multiplication and the Jacobi operation, and is based on the arbitrary beamforming process in the arbitrary orthogonal coordinate system. It has been demonstrated that it can be realized with high accuracy without interpolation approximation. Although any beamforming can be realized by using the DAS (Delay and Summation) method, the beamforming according to the present invention is accelerated by a difference between wave number matching and a transverse Fourier transform. When a PC is used, the computation time is significantly faster by a factor of 100 or more. When the aperture elements form a two-dimensional or three-dimensional distribution, a two-dimensional or three-dimensional array, the above method may be further multi-dimensional, and more processing may be performed than in the one-dimensional case. It solves the problem of cost, and its high speed is more effective. In addition, an embodiment has been described in which superposition and the like at the time of plane wave transmission with different deflection angles are effective. It is possible to obtain a high resolution and an effect of suppressing side lobes and increasing a contrast at a high speed.

  In the above example, it has been confirmed that arbitrary focus (including no focus) and steering can be performed in an arbitrary array-type aperture surface shape. It was confirmed that it could be realized with high accuracy. The time for obtaining a higher-order measurement result such as displacement measurement based on the generated image signal is also shortened, and the effect of improving the measurement accuracy is obtained. In the present invention, as described in the methods (1) to (7), interpolation approximation processing may be performed in arbitrary beamforming wave number matching, and beamforming may be performed at higher speed. In order to perform approximate approximate wave number matching, it is necessary to appropriately oversample a received signal at the cost of an increase in the amount of calculation. In such a case, it is necessary to pay attention to an increase in the number of data of the Fourier transform, unlike a case where a signal at an arbitrary position can be selectively generated without performing the interpolation approximation processing.

  The example using the representative transducer, the reception sensor, the transmission unit and the reception unit, the control unit, the output device, the external storage device, and the like in the first embodiment has been described above. The fact that the beamforming of the methods (1) to (7) was possible proves that arbitrary beamforming based on focusing and steering can be performed in an arbitrary orthogonal coordinate system, and the apparatus of the present invention is used. The beamforming and applications that can be realized by using are not limited to those described above.

<< Second Embodiment >>
Next, a configuration of a measurement imaging apparatus according to a second embodiment of the present invention will be described. FIG. 1 is a typical block diagram showing a configuration example when the measurement and imaging apparatus according to the first embodiment is of an active type, and FIG. 2 is a typical block diagram showing a configuration example of the apparatus main body in detail. Although FIG. 1 is a diagram, in the second embodiment, a passive-type device is used. Therefore, the measurement and imaging device according to the second embodiment does not include at least a transmitting transducer in FIG. It does not have a wired or wireless path for sending a drive signal from the control unit to the transmitting transducer.

  In the case of the active-type device according to the first embodiment, a detailed configuration example of the device and the unit has been described with reference to FIGS. 1 and 2 as a representative configuration. The passive-type devices, in which the transmitting and receiving transducer array devices (the transducers may be used for both transmitting and receiving), need to be used. Do not use

  That is, the basic configuration of the measurement imaging apparatus according to the second embodiment includes a receiving transducer (or receiving sensor) 20 as a receiving unit, an apparatus main body 30, an input device 40, and an output device (or display device) 50. , An external storage device 60. The device main body 30 mainly includes a receiving unit 32, a digital signal processing unit 33, a control unit 34, and a storage unit (memory or storage device or storage medium) not shown. Further, the device main body 30 may include a transmission unit 31. The description of these components in the first embodiment also applies to the second embodiment.

  As in the first embodiment, each of these devices and each unit in the device main body 30 can be installed at a remote place. The apparatus main body 30 is composed of a plurality of such units, and is referred to as such for convenience. Further, similarly to the first embodiment, reception may be performed by mechanically scanning the reception transducer 20. Generally, the same processing may be performed even when not called an array type.

  However, the measurement imaging apparatus according to the second embodiment is different from the measurement imaging apparatus according to the first embodiment in that, as described in detail below, an arbitrary The control unit senses the timing signal generated by receiving the wave of the observation target arriving from the wave source itself or through another process through wired or wireless communication, and captures the data of the receiving unit. (AD conversion in each reception channel and writing to the memory) may be used as a trigger signal for starting.

  As a method in which the control unit senses a timing signal indicating the timing at which the wave is generated, when the wave itself coming from the wave source is used as the timing signal, the receiving transducer (or the receiving transducer) of the measurement imaging apparatus according to the present embodiment is used. The received signal itself received by the receiving aperture element 20a of the sensor 20 is used, or a timing signal received by a dedicated receiving device that may be provided in the device main body 30 is used.

  In this case, the receiving aperture element 20a (there may be all elements, but the element at the end or the center may be used sparsely in the physical aperture) or a dedicated receiving device (at least a plurality of receiving channels). Is detected continuously over time, and, for example, through various input means as described above, information on the signal strength, frequency, band, code, etc. of the received signal is obtained. Is set in the control unit 34 itself (built-in memory) or in an analog determination circuit (in this case, it is not variable either in software or hardware, but is fixed in hardware). Alternatively, the sensing of the timing at which the wave is generated is performed by converting the signal received by the receiving aperture element 20a or the dedicated receiving device into a threshold value, a value, or a characteristic of the wave to be observed recorded in a memory or a storage device (storage medium). Based on collation with discrimination data in a database or the like.

  When the received signal is determined in an analog manner, the signal is determined by a dedicated analog circuit provided, and only when the signal is determined to be an observation target signal, a trigger signal for capturing data is generated. The data is converted and stored in a memory or a storage device (storage medium), and may be subjected to a beamforming process.

  When the received signal is digitally determined, the received signal is continuously and temporally A / D converted and stored in a memory or a storage device (storage medium). ), At a predetermined time interval (set through an input device or the like), the stored signal is read out by the digital signal processing unit 33 and discriminated based on the comparison with the same discrimination data to determine that the signal is an observation target signal. Only when it is performed, the beam forming process may be performed.

  Since the storage capacity of the memory or the storage device (storage medium) is finite, the signal of the wave to be observed was not observed within a predetermined time (set through an input device or the like) when digitally discriminating. In such a case, the address of the memory is initialized. Although it is not efficient in terms of energy saving, beam forming may be performed at any time, and a wave signal may be determined using the same determination data based on an image signal of which accuracy has been increased by the beam forming. The processing is the same when the normal communication wave is the observation target.

  In addition, the dedicated receiving device may be installed at a different position from a unit of another device, for example, a position near a wave source to be measured, or a position having a good reception environment for the timing signal. Yes, a wave that propagates faster than a wave received at the receiving aperture (a wave that becomes a timing signal) is used, and the timing signal may be transmitted to a control unit in the device main body via the dedicated receiving device. . A dedicated line (wired or wireless) that may use a relay station may be used. In this case, using the timing signal as a trigger signal, reception of a received signal (AD conversion and storage in a memory, a storage device, or a storage medium) and beamforming are performed.

  Further, after the measurement imaging apparatus of the present invention receives a wave, a timing signal at which the wave is generated may arrive. That is, the propagation speed may be slow or such a mechanism may be used, but as a result it may be. In order to cope with such a case, the reception signal is always taken in continuously, the reception signal stored in the memory or the storage device (storage medium) is read back in time, and the beam forming is performed. . In this case, information on the wave obtained by another observer or an observation device is added as additional information to the timing signal at a relay station or the like, and the timing signal to which the additional information is added is transmitted to the dedicated reception signal. The information including the additional information is read by the device, and may be used not only in the measurement and imaging device of the present invention but also in other devices. The line used is not limited to a dedicated line, and an ordinary network may be used. Similar timing signals may be used even when a normal communication wave is an observation target. The additional information may be transmitted in a wave or a signal different from the timing signal.

  In addition to the generation of the wave to be observed, a wave that propagates at a higher or lower speed than the wave received by the receiving aperture element (wave serving as a timing signal) before, during, or after the generation is generated. The dedicated receiving device and the dedicated line may be similarly installed and used. In this case, information about the wave to be observed may be added to the wave serving as the timing signal, and information about the wave obtained by another observer or an observation device may be added and transmitted by a relay station or the like. Then, the information including the additional information is read by the dedicated receiving device, and may be used by the measurement imaging device of the present invention or another device. The line used is not limited to a dedicated line, and an ordinary network may be used. Similar timing signals may be used even when a normal communication wave is an observation target. The additional information may be transmitted in a wave or a signal different from the timing signal.

  As these dedicated receiving devices, dedicated sensing devices capable of sensing a timing signal or reading additional information are used. However, any observer or any observation device (observation target) can be used. Any active or passive observation device or similar observation device related to a wave, such as a sign that the wave is generated, generated simultaneously with the wave, or generated after the generation of the wave Any active or passive observation device or similar observation device relating to the above phenomenon or wave motion) is used. In an irregular manner, only the dedicated receiving device receives the timing signal, and the reading of the additional information itself may be performed by the digital signal processing unit via the dedicated device or a control unit in the device main body.

  Even when the active or passive device of the present invention itself is used as a sensing device, the additional information may be similarly read by the digital signal processing unit 33. The timing signal may be generated by the provided sensing device. When and when, or where, or when and where, the wave is not known, the efficiency of the data capturing operation and the beam forming process, power saving, memory and storage devices It is important for saving (storage media). Data acquisition and beamforming are performed based on the clock signal of the control unit 34. If the wave source is digital, it is better to synchronize and the device may operate at a high clock frequency and high sampling frequency based on digital reception of the wave to be observed. The same applies to the case where the timing signal is an analog signal. However, when the timing signal is a digital signal, synchronization may be established in the apparatus body.

  The observation target is the wave itself generated by the self-emanating wave source, and the characteristics (strength, type of source, etc.) and position of the wave source, time when the wave source was activated, etc. May be observed. It may be treated as a diffraction source as in the case of active. Further, similarly to the case where the device is of the active type, the distribution of the target temperature (distribution), displacement, velocity, acceleration, strain, strain rate, or the like may be obtained from the spectrum of the wave. In addition, the characteristics of the medium during the propagation process (propagation velocity, physical properties related to waves, attenuation, scattering, transmission, reflection, refraction, diffraction, etc., or their frequency dispersion, etc.) are observed, and the structure of the observation target and the medium, The composition etc. may be clarified. For example, radioactive materials (such as isotopes in PET), materials with non-zero thermodynamic temperatures, seismic sources, neural activity, astronomical observations, weather, incoming objects, moving objects, telecommunications equipment including mobile communication equipment, physical Alternatively, an object that responds to a chemical stimulus, an electric source, a magnetic source, a radiation source, various energy sources, or the like is observed, and the observation target is not limited to these.

Fusion and data mining of measurement results may be performed through multiphysics or multichemistry using a plurality of different types of wave receiving transducers and sensors. Of course, they may be observed by a single transducer or sensor (e.g., in medical ultrasound imaging, the strain and blood flow that represent tissue deformation, and the related tissue properties may be selectively observed). Simultaneously, images are superimposed using different colors, etc. on the echo image, or optical ultrasonic waves of different markers are simultaneously imaged using different colors, etc. in a wide band, depending on the magnitude of physical quantities and physical property values and the direction of physical quantities. To display images in different colors, or to change the color depth for imaging, etc.). Multi-functional and multi-physical functions, or those that affect the surroundings in a different way, etc. In addition, the behavior of the whole (in the case of humans, the whole body) or local behavior of the object is also newly or in detail understood. For example, various neural controls (such as body temperature, blood flow, metabolism, etc.) that are performed in a living body for a short time or a long time, and effects that are given to a living body for a short time or a long time (radiation Observation of radiation exposure, nutrition intake, etc. can be used to develop artificial organs and cultured tissues, their hybrids, drugs, or supplements, etc. that contribute to prolonging life and extending life, and to monitor their operation.
It is important for advanced nations, including Japan, to enter an aging society. Therefore, it is important to improve QOL and reduce medical expenses. Increasing numbers of cancerous lesions such as human liver cancer, pancreatic cancer, kidney cancer, thyroid cancer, prostate cancer, and breast cancer (more than 1.5 million people in Japan, one in two people and one in three people die) And uterine fibroids, brain disease (brain tumor and bleeding, cerebral infarction, about 1.3 million or more), ischemic heart disease (myocardial infarction and angina, more than 1.7 million), arteriosclerosis and thrombosis (one in four) For many diseases of adult diseases such as deaths), dyslipidemia (more than 2.06 million), diabetes (more than 10 million), attention is paid to nerve, blood flow, and lymph networks in the connection of these organs and diseases. However, the present invention opens up innovative integrated diagnostic imaging systems and techniques and clinical styles (including screening) that can perform early non-invasive differential diagnosis with high accuracy, convenience, and low cost.
Most cancer metastases are spread to lymph nodes where lymph flow collects (lymphatic metastasis), as well as to places where blood flow is abundant, such as the lungs, liver, brain, and bones (hematological metastasis). . At present, when a swelling or lumps are diagnosed, the spread (stage) and general condition of the lymphatic species are diagnosed. Also, through the bloodstream, for example, pancreatic cancer is in the liver, peritoneum, etc., breast cancer is in the liver, lung, brain, etc., gastric cancer is in the lungs, liver, kidney, pancreas, etc., and lung cancer is in the liver, kidney, brain, etc. Colorectal cancer is known to metastasize to organs such as the liver, lungs, and brain. Since metastatic cancer has characteristics of a primary cancer, it is important to identify the primary cancer in order to perform appropriate treatment. Of course, for example, it is also important to catch the hepatitis, viral chronic hepatitis, cirrhosis, and the like (the mechanism of occurrence itself), as in the case of primary hepatocellular carcinoma. In addition, there is much blood flow in the nutritional arteries and advanced cancer tumors around early cancer tumors, and poor blood flow increases the possibility of prostate disease or uterine fibroids.High blood pressure increases the possibility of arteriosclerosis. And hyperlipidemia, high blood sugar viscosity, 1.2 to 1.3 times the probability of getting cancer with or without a history of diabetes, and the risk of developing ischemic heart disease in the diabetic group is 3 times, Dyslipidemia (20-50% of diabetes mellitus) and their acceleration of arteriosclerosis, increase in blood flow due to temperature rise by heating (perfusion), kidney regulates the number of red blood cells (oxygen amount) and blood pressure It is important that the present invention to simultaneously observe the pathological state, neural control, and hemodynamics of various tissues in situ with high precision in real time with high accuracy. It is also desirable for blood clots to have improved measurement accuracy of hemodynamics after surgery and in a normal life of a cardiac pacemaker user (welfare).
For example, under the above approach focusing on the network of nerves, blood flow, and lymph, specifically, MRI (nuclear magnetic resonance imaging), SQUID (superconducting quantum interference device), (optical) ultrasonic device, OCT (optical interference A new high-precision and simple real-time three-dimensional device based on the mathematical inverse problem of three basic physics (electromagnetics, mechanics, and heat) (described in paragraph 0377 etc.) using a single device or a fusion device Using in vivo diagnostic imaging techniques, early integrated imaging techniques (related simultaneous observation and fusion imaging by simultaneous multiple observations of the same or multiple organs) of the properties of related organs and tissues can be performed, and cancer and brain -Highly focused ultrasound (HIFU), electromagnetic coagulation, chemotherapy, pharmacy, and various types of radiation therapy as a means of minimally invasive treatment of heart disease Breakthrough fusion with can be performed early treatment of highly accurate and inexpensive early differential diagnosis and minimally invasive. Innovative clinical styles that allow for short-term early diagnosis followed by heat treatment in the shortest time are pioneered.
(1) <Electromagnetics-based, Patent Literature 8> Imaging of current density vector and electrical properties using MRI and SQUID: Three-dimensional distribution of current density vector and electrical properties (conductivity and dielectric constant) based on magnetic field measurement Visualize the cranial nerve network by imaging (superimposed and displayed on diffusion imaging of MRI). Inverse problems of Biot-Savart's law and differential inverse problems using observed current density vectors, respectively. For example, perfusion (blood flow) control can be monitored in fusion with the HIFU heat treatment described in (6) below.
(2) <Mechanical base, Patent Document 9> Imaging of blood flow vector, blood pressure, and shear viscosity using MRI, (optical) ultrasound, and OCT: MRI is based on distribution imaging of hydrogen, carbon, phosphorus, and the like. In addition, in the case of ultrasound echo method and optical ultrasound (under the discrimination between arteries and veins, or when using D-type glucose or L-type glucose that is specifically taken up in a recently reported cancer as a contrast agent, In the case of using LDL, HDL cholesterol and triglyceride as markers as sugars due to diabetes or dyslipidemia as markers), a three-dimensional flow velocity vector of blood flow and a three-dimensional distribution of a strain rate tensor are imaged using a multi-dimensional Doppler method ( Unlike ordinary Doppler, it is possible to observe vectors in any direction just by pointing the sensor at the target), and based on the differential inverse problem based on the observed velocity data Pressure and heart cavity pressure and shear viscosity, the 3-dimensional distribution of density imaging. MRI is for intracranial blood flow, ultrasound echo is for intracardiac and abdominal organs (liver, pancreas, kidney, prostate, uterus), and body tissue (breast, thyroid, eyes, skin) Blood flow, optical ultrasound, and OCT are used to monitor blood flow in open organs, eyes, and skin (observe the eye in connection with diabetes). Finally observed the blood flow network. Diagnosis of ischemic heart disease (myocardial infarction and angina pectoris), cerebral disease (brain tumor, cerebral hemorrhage, cerebral infarction), arteriosclerosis, thrombosis with a focus on dyslipidemia and blood sugar by quantifying blood pressure, chamber pressure and viscosity. Simultaneous observation of soft tissue in (3) was performed in integrated imaging in (5). Alternatively, perfusion (blood flow) in the HIFU heat treatment in (6) is monitored.
(3) <Mechanical base, Patent Document 9> Imaging of mechanical dynamics and shear (visco) elasticity of soft tissue using MRI, (optical) ultrasound, and OCT: Ultrasonic echo method and optical ultrasonic (focusing on soft tissue components) Or the novel observation of broadband observation of irradiation light and optical ultrasonic waves without a contrast agent or marker)), using the same multidimensional Doppler method as in (2), the three-dimensional displacement vector and strain tensor of soft tissue. Of the internal pressure (tissue pressure and intraocular pressure), shear (visco) elasticity (hardness), density, and force source (radiation pressure, etc.) based on the differential inverse problem from the observed displacement data. In situ imaging of three-dimensional distribution of HIFU). MRI is for intracranial brain tissue and lymph network, ultrasonic echo is for heart tissue (heart muscle and valves) and abdominal organs (liver, pancreas, kidney, prostate, uterus), and body surface tissue (breast, thyroid, eyes, skin) , Lymph network, optical ultrasound and OCT diagnose the pathology (tissue properties) of open organs, eyes and skin. Simultaneous observation of blood flow in (2) was performed in integrated imaging in (5). Alternatively, the effect (degeneration such as tissue coagulation) of the HIFU heat treatment of (6) is monitored.
(4) <Thermobase, Patent Document 10> Imaging of temperature and thermophysical properties of soft tissue using MRI, (optical) ultrasound, and OCT: To monitor metabolism and (6) HIFU heat treatment, so-called MRI In addition to the observation using the chemical shift of the Larmor frequency and the temperature dependence of the sound speed and volume of (optical) ultrasonic waves, the three-dimensional temperature distribution using the temperature dependence of the shear (viscosity) elasticity using (3) Conducted in situ observations and conducted practical observations that were robust to tissue displacement. Further, based on the differential inverse problem, imaging the thermophysical properties (thermal conductivity, heat capacity, thermal diffusivity), perfusion (the blood flow observation of (2) can be applied), and the three-dimensional distribution of the heat source (HIFU) , (6) applied to heat treatment planning in HIFU heat treatment.
(5) <Integrated imaging> Simultaneous multi-observation of multiple organs by (1) to (4): Based on three-dimensional imaging of tissue properties of electromagnetism, mechanics, and thermology, focusing on networks of nerves, blood flow and perfusion Integrated imaging diagnosis for simultaneous observation of multiple organs from multiple angles. Simple and quick diagnosis.
(6) <Integration of integrated imaging and treatment> (5) HIFU heating treatment control using integrated imaging (automatic treatment): In order to complete treatment in a short time with minimal invasiveness, blood flow data of (2) and ( Using the temperature and thermophysical observation data in 4) and the HIFU heat source database in a temperature distribution calculation simulator to predict the temperature distribution, and (3) using the monitoring data of the therapeutic effect (denaturation) by shear (visco) elasticity imaging. Controls the focus (heating) position, beam shape, beam intensity, irradiation time, and irradiation interval of the HIFU beam under phase aberration correction using an updated automatic heating treatment plan. The accuracy, reliability and safety of the treatment are improved, and the HIFU applicator can be installed in the vicinity without obstacles such as bones, so that it is possible to treat organ cancers other than prostate cancer and uterine fibroids which are widely spread.
It is desirable that the therapeutic means be minimally invasive, and is not limited to these as described above. The present invention is a technique which is simple, inexpensive and provides a high QOL to an aging society, thereby widespread medical examinations leading to prevention and early detection, and also implements a short-term treatment means (ideally at the same time). It is a promising candidate for a possible technology (Theranosis). The above-mentioned imaging and treatment are performed from the surface of the body, during surgery (directly or through an organ during opening), during laparoscopic surgery, during oral and nasal passages, portal, and vaginal Can also be implemented.
It also includes alternatives to various sensors of living things, supplements to them, or cases where new sensors are provided. When targeting living things, there are occasions where it is required to be small and wearable, or to be in a form or material that is easily adapted to living things. The processing content is also various.For example, when multiple compression waves and shear waves arrive at the same time as a dynamic wave, an analog dedicated device is used using the mode, frequency, band, code, propagation direction, etc. Alternatively, beamforming may be performed after separating waves using a digital signal processing unit as in the first embodiment. When there are a plurality of wave sources of electromagnetic waves, a plurality of electromagnetic waves having different characteristics may be superimposed on each other, and may be separated similarly. Alternatively, even when a plurality of waves arrive due to the phasing addition effect by beamforming, a highly accurate image signal may be generated (for example, when the medium is a scattering medium).

  Of course, after beamforming is performed, signals may be separated based on the same processing. In order to obtain the effect of the phasing addition, it is necessary to determine the arrival direction of the wave and the position of the wave source. Steering may be performed in that direction and focusing may be performed on the position. In reception, in addition to dynamic focusing, fixed focusing is also useful. To find them, the center of gravity (center) frequency, instantaneous frequency, and band of the multidimensional spectrum of the wave received by the receiving aperture element array, so-called MIMO, SIMO, MUSIC, independent component analysis, code, or various parametric methods, etc. Is sometimes used. The same processing may be performed after performing beamforming, but in addition, waves may be observed using geometric information, especially after performing beamforming at multiple positions. . The processing method is not limited to these, and may be performed under an inverse problem approach, for example.

  For example, the propagation direction of the arriving wave is obtained based on a multidimensional spectrum analysis of the received signal (the past work of the inventor of the present application). Further, in the measurement and imaging apparatus of the present invention, a plurality of When information on the propagation time cannot be obtained using the transducer or the receiving effective aperture of the wave (usually, the position or distance of the wave source is determined from the time when the wave is observed at a plurality of positions), It is possible to determine the location and distance of the source. Waves can be observed not only as pulse waves or burst waves but also as continuous waves. Through any processing, when the arrival direction of the wave is known, the received beam can be steered and focused in that direction (monostatic or multistatic aperture plane synthesis) to observe in detail. If necessary, transmission beamforming may be performed by using the active type according to the first embodiment. In those processes, always, with emphasis on the likely direction, perform reception beamforming while changing the steering angle, and observe the obtained image or image, spatial resolution, contrast, signal strength, or Through multi-dimensional spectral analysis, the direction of the wave source can also be specified. It may be automatically controlled.

  In some cases, the resolution of an image signal is increased by super-resolution. Also described in paragraphs 0009 and 0425. In some cases, it is easy to measure the size, strength, position, and the like of a wave source, a scattering object in a measurement object or a medium, and a reflector. Although the band is always limited by the physically generated wave field, a typical super-resolution is to widen the band by inverse filtering and restore them as an original signal source or signal. is there. Also, waves are usually affected by frequency-dependent attenuation, may be out of focus, the source of the wave may be a moving object, and disturbance may occur in the intervening medium. . In order to correct these, super-resolution may be performed. As described in paragraph 0383, it is sometimes useful not only to broaden the bandwidth but also to apply a further filtering so as to have a desired point spread function. Implementation in the domain or spatiotemporal domain is one of the features of the present invention.

  In addition, the measurement target or the like may move while performing transmission and / or reception required to generate one image signal, and may need to perform motion compensation. In many cases, the point spread function is unknown, and in such a case, blind deconvolution may be performed including the case where the above-described signal separation processing (particularly, blind separation) is used together. The method described in paragraph 0425 is known. In addition, there are various other methods such as the maximum likelihood method (for example, Non-Patent Documents 39-41). It is desirable to evaluate the point spread function by some method such as finding an autocorrelation function, and ideally to obtain a coherent point spread function.However, the spectrum distribution shape and bandwidth including those obtained from incoherent signals are desirable. Even if is obtained, inverse filtering is possible. Even in such a case, it is useful to perform filtering together so as to have a desired point spread function.

  If the point spread function cannot be obtained when observation is desired, for example, it is preferable to evaluate the point spread function and store it as a database when observation is possible. One effective method of performing inverse filtering is to weight the observed spectrum so that it is the same as the spectral distribution (of course, the spectral intensity distribution) of the signal distribution such as the desired point spread function or echo distribution. Is possible. The desired point spread function and the spectral distribution of the signal distribution such as the echo distribution may be set through analysis, simulation, optimization, etc., and perform beamforming under ideal parameters for the measurement target. , It can be done with a single measurement, ensemble averaging can be performed under multiple measurements, or averaging under the assumption of local stationary processes ( For example, it may be obtained in a similar manner using a phantom (calibration phantom) of an object to be measured, which has been performed for a long time, for example, non-patent documents 35 and 36). In some cases, the one-dimensional point spread function in the direction of wave propagation or in the direction perpendicular to the wave is estimated by obtaining a one-dimensional autocorrelation function. However, the multidimensional point spread function is estimated by obtaining a multidimensional autocorrelation function. (See Non-Patent Documents 8 and 14). Each is equivalent to a one-dimensional spectrum or a multidimensional spectrum in the propagation direction or the orthogonal direction (that is, self-spectrum). These are used when evaluating the wavelength of a wave, the shape of a force source, and the spatial resolution of a wave (Patent Document 11 and the like), and are used for super-resolution. For example, fixed focusing or aperture plane synthesis (Non-Patent Document 15) is performed using a power function type apodization to obtain a desired high-resolution point spread function or a signal distribution such as an echo distribution, and a plane wave capable of high-speed transmission and reception. The resolution of a low-resolution signal (Non-Patent Document 15) obtained by performing transmission using Gaussian apodization may be increased. The latter is suitable for high-precision measurement of high-speed motion and shear wave propagation, and can simultaneously realize the measurement and high-resolution ultrasonic imaging. Alternatively, inversion can be performed using the power spectrum of the signal itself. These processes can be performed on the angular spectrum before wave number matching or the spectrum after wave number matching. That is, super-resolution can be performed using an angular spectrum or spectrum of a signal distribution such as a desired point spread function or an echo distribution or an angular spectrum or spectrum of a received signal. In the weighting, care must be taken when dividing by a zero value or a small spectrum, and in particular, it is not effective to amplify various noises included in the received signal. ), Singular value decomposition (discard small singular values and spectra, and do not use signal components of the corresponding frequency). Likelihood estimation (with or without MAP) is effective.

  In the process of the methods (1) to (7) in the digital wave signal processing, inverse filtering can be performed. The resolution of an image signal is increased, and an effect may be obtained also in terms of quantitativeness (numerical value). However, the same effect may be obtained when displayed as an image. The effect of restoring a blurred image or focusing can be obtained. Inverse filtering is sometimes performed on an incoherent signal, and is effective when performed in the state of a coherent signal. In particular, spatial change of a physical property distribution can be understood. Super-resolution may be applied to the superimposed one or the one whose spectrum is frequency-divided. Applications of super-resolution are not limited to these.

  Also, a new super-resolution can be implemented. One is based on the non-linear processing described later, and the other is an imaging of the instantaneous phase described here.

Now, the signal of the position coordinate s in the propagation direction (coordinate axis t) in the region of interest obtained using a single wave or beam is
Where t = 0 represents a reference position in the t-axis direction, that is, the position of the wave source (t = 0), and δθ (t) represents a phase change caused by reflection or scattering at the position coordinate t.
Then, the instantaneous angular frequency ω (t) in the propagation direction t, the instantaneous phase θ (t), and the like are obtained, and imaging is performed. The propagation direction t may be directed to the front without steering, or may have a deflection angle by steering. When the region of interest is three-dimensional, it is two-dimensional or one-dimensional. Sometimes. As described in Non-Patent Document 19, the propagation direction of a wave or a beam can be measured with a spatial resolution (using the center of gravity or the instantaneous frequency of the spectrum), and at the same time, the frequency in that direction can also be measured. The frequency in the direction of the integration path (tangential direction) set in the spatial integration process can be obtained and calculated with high accuracy. For example, the integration path is linearly set in the steering direction (angle) of the wave or beam set at the time of transmission or in the generated wave or beam, but similarly, in the steering direction (angle) estimated globally. Can be taken. In order to simplify the processing, a nominal frequency or a frequency in that direction which is simultaneously estimated globally can be used. Performing integration in the propagation direction estimated in a state having spatial resolution involves interpolation processing of a frequency distribution and is not impossible but not practical.

Incidentally, A (s) is the amplitude, and represents the reflection intensity and the scattering intensity at the position coordinate t = s. For example, it is obtained by envelope detection (square root of the sum of squares of IQ signals) through quadrature detection of Expression (30-1). Alternatively, through the Hilbert transform using the Fourier transform,
Is also obtained by the square root of the sum of the squares of the equations (30-1) and (31) (Patent Document 7 and Non-Patent Document 14). The latter is particularly suitable for digital signal processing.

Using Equation (30) and Equation (31), a complex analysis signal (Patent Document 6 or Non-Patent Document 7) is displayed,
Can be expressed as

First, to find the instantaneous phase θ (s), an instantaneous angular frequency is found. As a conventional means, it is assumed that the instantaneous frequency at the next sampling position coordinate t = s + Δs is equal and the instantaneous phase is not equal at the position coordinate t = s by the method described in Patent Document 6 or Non-Patent Document 7 ( δθ (t) is a phase change (that is, random) determined by random scattering intensity and reflectance, and greatly changes randomly with respect to t);
Assuming that the signal at the position coordinate t = s + Δs is
When the conjugate product of Expression (32) and Expression (35) is obtained, under the assumption of Expression (33) and Expression (34),
Thus, the instantaneous frequency at the position coordinate t = s is
It is estimated to be.

As described in Patent Literature 6 and Non-Patent Literature 7, noise is actually mixed into the signal r (s), and the signal r (s) is estimated under the assumptions of Expressions (33) and (34). , S-axis direction or two or one direction orthogonal to the s-axis direction, the moving average processing is performed, and the accuracy may be improved. This moving average processing is performed on equation (36) and is obtained according to equation (37).
Is applied to equation (37) itself
Equation (38-1) has been confirmed to have higher accuracy in displacement (vector) measurement.

The instantaneous frequency at which the moving average has been applied may be used to detect the instantaneous frequency at each coordinate. The estimated value of the instantaneous frequency is unbiased, and in the case of digital signal processing,
Is multiplied by the assumption that the instantaneous phase θ (s) is an integrated value of phase change determined by random scattering intensity and reflectance (that is, random),
Is obtained.

  The center of gravity obtained from the first moment of the spectrum (center of gravity, that is, a weighted average value) instead of performing the moving average on the instantaneous frequencies obtained by the equations (38-1) and (38-2). The frequency (× 2π) may be used. The equation is shown in equation (S1).

  In the expression representing the observation signal, t = 0 represents a reference position in the t-axis direction, that is, a wave source position. On the other hand, the reference position t = t ′ in the equation (39) may be set to t ′ = 0 (wave source position). In this case, θ ′ (s) obtained as a distribution of the position coordinates t = s Is an estimated value of the instantaneous phase (Equation (30-2)) itself represented by an integral value of a phase change caused by reflection or scattering. The instantaneous frequency is averaged, and the obtained θ ′ (s) is an estimated value obtained in that situation.

Further, due to the influence of the moving average processing and the influence of the window length when obtaining the spectrum, the instantaneous frequency is obtained from the wave source position (t = 0) to t = s ′ (non-zero, not equal to s). Otherwise, assuming that t ′ = 0, using the nominal angular frequency or the previously measured / estimated angular frequency ω ₀ ,
Equation (39) is used as Alternatively, equation (39) may be used as t ′ = s ′ (non-zero, but not equal to s), in which case the estimated value θ ′ (s) has the following bias error: Will occur.

However, when estimating Δθ (s), which is the amount of change in the instantaneous phase at sampling Δs intervals, based on Expressions (30-2) and (34), the bias does not pose a problem. The estimation result is
Is obtained as The conjugate product of Expression (36) and a complex exponential function having ω (s) Δs as a core may be obtained. In the above equations (34), (36), (43) and the like, the case where the subtraction of the phase is obtained by using the forward difference is described, but instead, the backward difference can be performed. In Expressions (37), (38-1), and (38-2), the calculation of the phase differential was performed by approximation of dividing the above-described phase difference by the sampling interval. Differentiation processing may be performed using a differentiation filter. For integration of the estimated value of the instantaneous frequency in Expression (39), various well-known integration operations including a trapezoidal rule can be performed.
In order to obtain the estimation result of the instantaneous phase (Equation (30-2)) not including the phase rotation represented by Equation (40), the imaginary number of the analytic signal represented by Equation (32) is obtained regardless of the above. Arctan (inverse tangent function) is applied to the part / real part to obtain the cosine angle (ie, instantaneous phase including phase rotation) in equation (30-1). In equation (42), s ′ = s The subtraction can also be made directly using the moving average of the instantaneous frequency or the phase rotation determined by the integral operation of the first moment of the spectrum. However, since the direct operation result of arctan is a result of -π to π, it is necessary to perform a subtraction process after unwrapping the result. Since the instantaneous phase including the phase rotation is monotonically increasing, unwrapping may be performed by adding 2π to an integer m when the arctan result is negative. Here, m is the number of times that the result of arctan observed in the beam direction or wave propagation direction is negative. As in the above case, the equation (41) may be used, or a bias error represented by the equation (42) may occur. Also, in order to estimate Δθ (s), which is the amount of change in the instantaneous phase of the sampling interval Δs that does not include the bias error, the phase rotation estimated at a position separated by Δs is not included separately from Expression (43). The difference between the instantaneous phase and the estimated value can be calculated directly by subtraction.
The image related to the phase represented using Expression (40) or Expression (43) has a wide band, and is a type of super-resolution. The phases themselves can be displayed, can be displayed by multiplying by a cosine or sine function, or can be displayed by weighting with an envelope. Incidentally, the square root of the sum of the squares of the real part and the imaginary part of the complex analytic signal for which the phase of equation (40) is obtained is the same as that of the envelope signal. Therefore, square detection or absolute value detection, ideally, it is desirable to form an image as it is without destroying the undulation (sign and phase of the signal value) (a grayscale image or a color image can be displayed). The image mainly represents the signal intensity, phase, and phase change determined by reflection and scattering. On the other hand, when the obtained instantaneous frequency is imaged, it becomes an image showing the influence of frequency modulation due to attenuation and scattering (similarly, gray and color display is possible).

Although the above-mentioned Hilbert transform is described as being performed based on a (high-speed) Fourier transform (Non-Patent Document 13), it is needless to say that the original Hilbert transform may be calculated. When noise is mixed in the signal, the accuracy is reduced. However, a differential process is performed on the target real-time signal to generate a signal whose phase is advanced by 90 °, and the signal is multiplied by −1 to obtain an imaginary number. It is also possible to calculate the component (for the part multiplied by the angular frequency by the differential processing, the phase obtained by applying the inverse function of the cosine or sine signal to the original real-time signal is used to calculate the phase at the neighboring position (phase ) (The forward difference, the backward difference, the center difference, etc., multiplied by 1 and −1, or added or subtracted) and divided by the distance between those positions (difference approximation). And a differential filter may be applied instead of the difference approximation).
For example, when differentiating the arbitrary signal represented by the equation (30-1), the spatial differential (spatial (s) -like change) of the amplitude A (s) is compared with the instantaneous frequency ω (s). By making a moving average in the multidimensional including the partial differential direction or in the partial differential direction with respect to the expression (30-1) or its differential result, Approximates
In some cases, the moving average processing is not performed on the signals themselves. ω (s) can be estimated as follows in addition to the above calculation. Expression (30-1 ′) is further differentiated, and under the above conditions, assumptions, and processing, and when the spatial differentiation of ω (s) is small or assumed, the approximation is as follows.
At that time, the moving average processing may not be performed on the signals themselves. By dividing equation (30-1 ″) by equation (30-1) and multiplying by −1, ω ² (s) can be estimated. However, the estimation result of ω ² (s) may be a negative value, and it is replaced with a positive value in the multidimensional including the partial differential direction s, or in the vicinity of the partial differential direction s, or a positive value in the vicinity. Interpolation approximation using only values, median filtering, moving average processing, or a combination thereof may be performed. The median filter is particularly effective in removing a sudden large estimation error. Further, ω (s) obtained by applying a square root to a positive value may be subjected to a median filter or a moving average process. Through these processes, ω (s) may be obtained. By dividing equation (30-1 ′) by ω (s) and multiplying by −1, the imaginary component of the analysis signal of equation (30-1) is obtained (that is, the analysis signal is obtained). The second-order differentiation may be obtained by applying a differential filter or a difference approximation twice to Equation (30-1), or a second-order differential filter or a second-order difference approximation (using a so-called central difference, -2, which is multiplied and added and divided by the square of the distance between those positions). In addition, for the differentiation, for example, a differential filter using an operational amplifier in an analog circuit may be used, or in a digital circuit or digital signal processing, differential calculation based on a differential filter or difference approximation may be performed. Since these differentiating processes are a kind of high-pass filtering, processing may be performed by providing a high-frequency cutoff frequency, or moving average processing may be performed on the result of the differentiating process. In addition, for the above-mentioned instantaneous frequency ω (s), a nominal frequency or a globally estimated frequency (such as the first moment of the spectrum) can be used instead for simplifying the calculation. This detection processing is much faster than other detection processing. This processing can also be used for envelope imaging of r (s) (the magnitude of an analysis signal may be obtained) and measurement of displacement, velocity, acceleration, strain, strain rate, temperature, and the like. Although the measurement accuracy of the displacement is almost the same as that obtained by performing the (high-speed) Fourier transform, the echo image is experienced to have a higher intensity in a deep part. The Hilbert transform method is faster than the Hilbert transform using Fourier transform (Non-Patent Document 13), and a plurality of beams and waves having different wave parameters and beam forming parameters are generated in each time phase. In such a case, the number of reception signals received by the reception transducer increases and the number of times of performing beam forming or Hilbert transform increases, which is effective in such a case. The Hilbert transform may be performed at once by regarding a signal obtained by superimposing a plurality of beamformed signals as one beamformed signal. In this case, the present invention is also effective (the instantaneous frequency obtained by differentiation is: This is the composite frequency in the differential direction of the superposition of those beams and waves.) The instantaneous phase imaging described above may also be performed on superimposed composite waves. When performing these measurements, multiple Doppler equations derived from each of them are used by using multiple waves and beams, or using multiple pseudo waves and beams obtained through frequency division of spectrum. (Which may be an over-determined system), in which case equation (30-1) describes each of those waves or beams, or pseudo waves or beams. , And each analysis signal is obtained and used in the same manner. Also, when the received signal is a multidimensional received signal and the carrier frequency exists in a plurality of orthogonal coordinate axis directions (when lateral modulation or steering is performed), the instantaneous phase can be similarly estimated (the details will be described later). Do).

FIG. 37 is a diagram illustrating an example of two steering beams in a two-dimensional case and a lateral modulation of their superposition. FIG. 38 is a diagram illustrating an example of four steering beams in a three-dimensional case and a lateral modulation of their superposition (in the case of three steering beams, one of the steering beams shown in FIG. 38). It is possible to use three steering beams among the above, and it is also possible to generate three steering beams which are all symmetrical with respect to the axial direction, but the drawing is omitted). Although FIGS. 37 and 38 show linear one-dimensional and two-dimensional array apertures, array apertures of other arbitrary shapes can be used, and the coordinate system is also arbitrary rectangular coordinates. The system can be used. Whatever the shape of the array aperture type or rectangular coordinate system is used, in the two-dimensional or three-dimensional lateral modulation, respectively, the axial direction of the rectangular coordinate system in which observation is performed or the horizontal axis orthogonal thereto. (Waves are symmetrical with respect to the axis coordinate axis and the abscissa axis, respectively) or with respect to the plane including the axis coordinate axis and the transverse direction orthogonal thereto (that is, all waves are symmetrical with respect to the axial direction). Deflection (steering) intersects (if not symmetric, the coordinate system may be translated or rotated to make it symmetrical, or may be processed asymmetrically as described elsewhere). Here, although referred to as a steering beam, it can be applied to any wave that has been steered (the steering beam may include an unsteered one, that is, a steering beam having a steering angle of 0 ° with respect to the front direction of the opening). In the case of lateral modulation, for example, in the case of two-dimensional modulation, as shown in FIG. 37, processing is performed in a state where two cross waves generated by steering are superimposed and a state where they are not superimposed. Similarly, in the three-dimensional case, as shown in FIG. 38, processing is performed in a state where three or four cross waves generated by steering are superimposed and in a state where they are not superimposed. The same applies when steering is performed and processing is performed as a multidimensional received signal. As described in Non-Patent Document 19, the propagation direction of a wave or a beam can be measured with a spatial resolution (using the center of gravity or the instantaneous frequency of the spectrum), and at the same time, the frequency in that direction can also be measured. The frequency in the direction of the integration path (tangential direction) set in the spatial integration process can be obtained and calculated with high accuracy. In the case of the above-mentioned one-dimensional signal, as an example, the integration path is estimated in the steering direction (angle) of the wave or beam set at the time of transmission, or the generated wave or beam, similarly, but globally. Although it is described that the steering direction (angle) to be taken is linear, the integration path can be theoretically arbitrarily taken in that dimensional space in this multidimensional case. However, when actually calculating the integral, it is important to set the integration path in a state suitable for the coordinate system in which the beamforming is performed, such as those that draw straight lines and arcs and those that connect them. Often used. In addition, in order to simplify the processing, a nominal frequency or a frequency that is simultaneously estimated globally can be used (projected onto an integration path). Performing integration in the propagation direction estimated in a state having spatial resolution involves interpolation processing of a frequency distribution and is not impossible but not practical. Now, the signal in the region of interest
From this, the instantaneous angular frequencies (ω ₁ (t ₁ , t ₂ , t ₃ ), ω ₂ (t ₁ , t ₂ , t ₃ ), ω in each direction (t ₁ , t ₂ , t ₃ ) ₃ (t ₁ , t ₂ , t ₃ )) and the instantaneous phase θ (t ₁ , t ₂ , t ₃ ) are obtained and imaging is performed. When the region of interest is two-dimensional,
It is expressed as Processing is performed in the same manner as in the following three-dimensional case.

Incidentally, A (s ₁ , s ₂ , s ₃ ) is an amplitude, and represents the reflection intensity or the scattering intensity at the position coordinates (s ₁ , s ₂ , s ₃ ). For example, it is obtained by envelope detection (square root of the sum of squares of the IQ signal) through quadrature detection of Expression (30′-1). Alternatively, through the Hilbert transform using the Fourier transform,
Is also obtained by the square root of the sum of the squares of the equations (30′-1) and (31 ′) (Patent Document 7 and Non-Patent Document 14). The latter is particularly suitable for digital signal processing.

Using Equation (30 ′) and Equation (31 ′), a complex analytic signal (Patent Document 6 or Non-Patent Document 7) is displayed,
Can be expressed as

First, an instantaneous angular frequency is obtained to obtain the instantaneous phase θ (s ₁ , s ₂ , s ₃ ). The usual practice, the method described in Patent Document 6 and Non-Patent Document 7, in the position coordinates _{(s 1, s 2, s} 3), for example, t ₁ the direction of the next sampling position coordinates (s ₁ + Δs _1, Assuming that the instantaneous frequencies at s ₂ , s ₃ ) are equal and the instantaneous phases are not equal (δθ (t ₁ , t ₂ , t ₃ ) is a phase change determined by random scattering intensity or reflectance (ie, random ), And randomly changes greatly with respect to (t ₁ , t ₂ , t ₃ )),
, The signal at that location coordinate (s ₁ + Δs ₁ , s ₂ , s ₃ ) is
When the conjugate product of Expression (32 ′) and Expression (35 ′) is obtained, under the assumption of Expression (33 ′) and Expression (34 ′),
Is expressed as, Accordingly, the position coordinates _{(s 1, s 2, s} 3) s 1 direction instantaneous frequency omega ₁ in _{(s 1, s 2, s} 3) are
It is estimated to be.

As described in Patent Literature 6 and Non-Patent Literature 7, noise is actually mixed in the signal r (s ₁ , s ₂ , s ₃ ), and Equation (33 ′) and Equation (34 ′) Assuming that the moving average process is performed in the s ₁ axis direction and in two directions or one direction orthogonal to the s ₁ axis direction, the accuracy may be improved. This moving average processing is performed on equation (36 ′) and is obtained according to equation (37 ′).
And ω ₁ (s ₁ , s ₂ , s ₃ ) itself
However, it has been confirmed that Equation (38′-1) has higher accuracy in displacement (vector) measurement. direction of the instantaneous frequency of s ₂ and s ₃ are also determined in the same manner through obtaining the _{R 2 (s 1, s 2} , s 3) and _{R 3 (s 1, s 2} , s 3).

The instantaneous frequency at which the moving average has been applied may be used to detect the instantaneous frequency at each coordinate. The instantaneous frequency estimate is unbiased, and in the case of digital signal processing,
Is multiplied by the assumption that the instantaneous phase θ (s ₁ , s ₂ , s ₃ ) is an integrated value of phase change determined by random scattering intensity and reflectance (ie, random),
Is obtained.

  It should be noted that instead of performing a moving average on the instantaneous frequencies obtained by Expressions (38′-1) and (38′-2), the first moment (centroid, that is, a weighted average value) of the spectrum is used. The obtained center-of-gravity frequency (× 2π) may be used. The equation of the center of gravity in the x-axis direction on one axis of the three-dimensional orthogonal coordinate system is shown in equation (S1 ″). The other directions are obtained in the same manner, and are obtained in two dimensions.

The integration path c in the expression representing the observation signal is an arbitrary line from the starting point 0 where the position where the instantaneous phase is zero is regarded as the reference position to the point of interest (s ₁ , s ₂ , s ₃ ). 0 represents the position of the wave source. On the other hand, the starting point of the integration path c ′ in the equation (39 ′) may be set to 0 (wave source position). In this case, the position coordinates (t ₁ , t ₂ , t ₃ ) = (s ₁ , s _2, s ₃ obtained theta 'as _{distribution) (s 1, s 2,} s 3) is the instantaneous phase represented by the integral value of the phase change caused by reflection or scattering (formula (30'-2)) itself Is the estimated value of The instantaneous frequency is averaged, and the obtained θ ′ (s ₁ , s ₂ , s ₃ ) is an estimated value obtained in that situation.

Also, due to the influence of the moving average processing and the influence of the window length when obtaining the spectrum, the instantaneous frequency is shifted from the wave source position 0 by (t ₁ , t ₂ , t ₃ ) = (s ₁ ′, s ₂ ′, s ₃ ′) ) (Not the wave source position, but not equal to (s ₁ , s ₂ , s ₃ )), the starting point of the integration path c ′ is set to 0 and the nominal angular frequency or measured / estimated in advance. Using angular frequencies (ω ₀₁ , ω ₀₂ , ω ₀₃ ) in each direction,
Equation (39 ′) is used as Alternatively, the starting point of the integration path c ′ is (t ₁ , t ₂ , t ₃ ) = (s ₁ ′, s ₂ ′, s ₃ ′) (not the wave source position 0 but (s ₁ , s ₂ , s ₃₎ ) Is also used), there is a case where equation (39 ′) is used. In this case, the following bias error occurs in the estimated value θ ′ (s ₁ , s ₂ , s ₃ ).

However, for example, based on the equation (30'-2) and equation (34 '), [Delta] [theta] ₁ is a variation of the instantaneous phase of t ₁ axially sampling Delta] s ₁ interval _{(s 1, s 2, s} 3) The bias does not matter when estimating. The estimation result is
Is obtained as The conjugate product of Expression (36 ′) and a complex exponential function having ω ₁ (s ₁ , s ₂ , s ₃ ) Δs ₁ as a core may be obtained. In addition, the estimated value of the phase change Δθ ₂ ′ (s ₁ , s ₂ , s ₃ ) Δθ ₃ ′ (s ₁ , s ₂ , s ₃ ) in the direction of t ₂ or t ₃ is also the sampling interval Δs _{2 in} each direction. Δs ₃ can be obtained. In the above formulas (34 '), (36'), (43 '), etc., the case where the subtraction of the phase is obtained by using the forward difference is described, but instead, the backward difference may be performed. is there. In Expressions (37 '), (38'-1), and (38'-2), the differential of the phase was calculated by the above-mentioned approximation of dividing the phase difference by the sampling interval. Differentiation processing may be performed using a differential filter having a frequency. For integration of the estimated value of the instantaneous frequency in Expression (39 ′), various known integration operations including a trapezoidal rule can be performed. In order to obtain the estimation result of the instantaneous phase (Equation (30′-2)) not including the phase rotation expressed by Equation (40 ′), the analysis expressed by Equation (32 ′) is performed regardless of the above. Arctan (inverse tangent function) is applied to the imaginary part / real part of the signal to obtain the cosine nucleus (ie, the instantaneous phase including the phase rotation) in equation (30′-1). (s ₁ ′, s ₂ ′, s ₃ ′) = (s ₁ , s ₂ , s ₃ ) and directly using the phase rotation obtained by the moving average of the instantaneous frequency or the integral operation of the first moment of the spectrum It can also be subtracted. However, since the direct operation result of arctan is a result of -π to π, it is necessary to perform a subtraction process after unwrapping the result. Since the instantaneous phase including the phase rotation is monotonically increasing, unwrapping may be performed by adding 2π to an integer m when the arctan result is negative. Here, m is the number of times that the result of arctan observed in the beam direction or wave propagation direction is negative. As in the above case, the equation (41 ′) may be used, or a bias error represented by the equation (42 ′) may occur. Further, in order to estimate Δθ ₁ (s ₁ , s ₂ , s ₃ ), which is the instantaneous phase change amount of the sampling interval Δs _{1 in} the t ₁ direction, which does not include the bias error, separately from the equation (43 ′), the difference between the estimated value of the instantaneous phase without the estimated phase rotation at t ₁ direction Delta] s ₁ only separated position can also be calculated by directly subtraction. Similarly, the estimated value Δθ ₂ ′ (s ₁ , s ₂ , s ₃ ) Δθ ₃ ′ (s ₁ , s ₂ ) of the instantaneous phase change amount of the sampling intervals Δs ₂ and Δs ₃ in the directions of t ₂ and t _3. , s ₃ ) can also be obtained.
The image related to the phase represented using Expression (40 ′) or Expression (43 ′) has a wide band, and is a type of super-resolution. The phases themselves can be displayed, can be displayed by multiplying by a cosine or sine function, or can be displayed by weighting with an envelope. Incidentally, the square root of the sum of the squares of each of the real part and the imaginary part of the complex analytic signal for which the phase of the equation (40 ') is obtained is the same as that of the envelope signal. Therefore, square detection or absolute value detection, ideally, it is desirable to form an image as it is without destroying the undulation (sign and phase of the signal value) (a grayscale image or a color image can be displayed).

Note that the above Hilbert transform is performed based on a multidimensional (high-speed) Fourier transform (Non-Patent Document 13, even if cross beams and cross waves overlap in space, they are not overlapped and are separated. However, as will be confirmed later, the former process can perform a Fourier transform on all the received signals at once, reducing the amount of calculation, and processing the separated signals positively after superimposing them. However, the calculation of the original Hilbert transform may be applied similarly to the one-dimensional case.
Also, if noise is mixed in the signal, the accuracy is reduced. However, similar to the one-dimensional case, the differential processing is performed on the target real-time signal to generate a signal whose phase is advanced by 90 °. It is also possible to calculate the imaginary component by multiplying by -1 (the part multiplied by the angular frequency by the differential processing is calculated by applying the inverse function of the cosine or sine signal to the original real-time signal, It is sufficient to calculate the difference (so-called forward difference, backward difference, center difference, etc.) with the same calculation result (phase) at the position of, and correct by dividing by the distance of those positions (difference approximation). Instead, a differential filter may be applied). However, the method described in this paragraph is limited to the case where the lateral modulation is performed and the steered waves do not overlap as shown in FIG. 37 and FIG. It is also possible to process a single steered wave independently (this paragraph). One processing method in the case of overlapping is described at the end of this paragraph, and the other two processing methods are described in the following paragraphs.
For example, when performing the partial differential processing with respect to any signal expressed by formula (30'-1), etc., subjected to partial differentiation with respect to one direction of the s ₁ of s _3. The spatial partial derivative (spatial change) of the amplitude A (s ₁ , s ₂ , s ₃ ) is the instantaneous frequency ω ₁ (s ₁ , s ₂ , s ₃ ) or ω ₂ (s ₁ , s ₂ , s ₃ ) and ω ₃ (s ₁ , s ₂ , s ₃ ), and make assumptions about them. By performing a moving average in the multidimensional including or in the partial differential direction, the following approximation is obtained. For example, when the partial differentiation in s ₁ direction is as follows.
In some cases, the moving average processing is not performed on the signals themselves. For example, in the case of lateral modulation, the instantaneous frequency in that direction may be lower than the instantaneous frequency in other directions depending on the direction. In such a case, the direction of partial differentiation is taken in that direction. However, if the steering direction is used, the sampling interval of the signal may be coarse, so that caution is required in performing the approximate calculation. ω ₁ (s ₁ , s ₂ , s ₃ ) can be estimated as follows in addition to the above calculation. The equation (30′-1 ′) is further partially differentiated in the same direction, and under the above conditions, assumptions, and processing, furthermore, when the spatial differentiation of ω ₁ (s ₁ , s ₂ , s ₃ ) is small, Given that assumption, we approximate as follows:
At that time, the moving average processing may not be performed on the signals themselves. Equation (30'-1 '') divided by formula (30'-1), be multiplied by -1, can be estimated ^{_{ω 1 2 (s 1, s}} 2, s 3). However, the estimation result of ω ₁ ² (s ₁ , s ₂ , s ₃ ) may be a negative value, and a positive value in multidimensional including the partial differential direction or in the vicinity of the partial differential direction s ₁ , Interpolation approximation using only nearby positive values, median filtering, moving average processing, or a combination of these. The median filter is particularly effective in removing a sudden large estimation error. A median filter or a moving average process may be applied to ω ₁ (s ₁ , s ₂ , s ₃ ) obtained by applying a square root to a positive value. Through these processes, ω ₁ (s ₁ , s ₂ , s ₃ ) may be obtained. By dividing equation (30′-1 ′) by ω ₁ (s ₁ , s ₂ , s ₃ ) and multiplying by −1, the imaginary component of the analytic signal of equation (30′−1) is obtained (that is, , An analysis signal is obtained). The second derivative may be obtained by applying a differential filter or difference approximation twice to equation (30′-1), or by applying a second order differential filter or second order difference approximation (so-called central difference). May be. Similarly, when partial differentiation is performed in each direction of s ₂ and s ₃ other than s ₁ , ω ₂ (s ₁ , s ₂ , s ₃ ) and ω ₃ (s ₁ , s ₂ , s ₃ ) are As a result, it is desirable to appropriately select the direction of the partial differentiation, as described above. For example, in the case of a two-dimensional case, when a steering beam with a steering angle of ± 20 ° is used, there is no significant difference between the case where the direction of the partial differentiation processing is set to the depth direction and the case where the direction is set to the horizontal direction. Although we have experienced the case, in imaging, unlike the Hilbert transform (Non-Patent Document 13) through a multidimensional (fast) Fourier transform (Non-Patent Document 13), the echo intensity in the deep part is strongly obtained compared with the use of this approximation processing Sometimes. On the other hand, even in such a case, we have experienced that the accuracy of displacement vector measurement is almost the same. In addition, for the differentiation, for example, a differential filter using an operational amplifier in an analog circuit may be used, or in a digital circuit or digital signal processing, differential calculation based on a differential filter or difference approximation may be performed. Since these differentiating processes are a kind of high-pass filtering, processing may be performed by providing a high-frequency cutoff frequency, or moving average processing may be performed on the result of the differentiating process. In order to simplify the calculation, the instantaneous frequency such as ω ₁ (s ₁ , s ₂ , s ₃ ) is replaced with a nominal frequency or a frequency estimated globally (first moment of spectrum). Etc.) can also be used. This detection processing is much faster than other detection processing. This processing includes the envelope imaging of r (s ₁ , s ₂ , s ₃ ) (the magnitude of the analysis signal may be obtained), displacement (vector), velocity (vector), acceleration (vector), and distortion (tensor). ), Distortion rate (tensor) and the like. When measuring vectors and tensors, use multiple waves and beams, or use multiple pseudo waves and beams obtained through frequency division of the spectrum, and combine Doppler equations derived from each of them. (Which may be a lateral modulation or an over-determined system), in which case equation (30'-1) describes each of those waves and beams, and the simulated waves and beams. And each analysis signal is determined and used in a similar manner. In addition, it may be used for measuring temperature and the like in the same manner.
This Hilbert transform method is faster than the Hilbert transform using multidimensional Fourier transform (Non-Patent Document 13), and generates a plurality of beams and waves having different wave parameters and beam forming parameters in each time phase. (However, if the steering direction is the same or the steering direction is not necessarily symmetrical with respect to the axis), the number of reception signals received by the reception transducer increases, and beam forming or Hilbert transform is performed. This is effective in such a case because the number of times of execution increases. The Hilbert transform may be performed at once by regarding a signal obtained by superimposing a plurality of beam-formed signals as one beam-formed signal (Equation (30′-1)). (The instantaneous frequency obtained by partial differentiation is a composite frequency in the partial differential direction of the superposition of those beams and waves.) The instantaneous phase imaging described above may also be performed on superimposed composite waves. In the case where the physical aperture elements form a two-dimensional or three-dimensional distribution or a multidimensional array, the problem that a large amount of processing time is required is more effectively solved, and the high-speed Hilbert transform is effective.

In addition, the echo signal itself that is subjected to lateral modulation by superimposing cross beams or crossing waves can be directly processed as follows (FIG. 37 in the case of two dimensions and FIG. 37 in the case of three dimensions). 38). In the following, at the time of two-dimensional or three-dimensional lateral modulation, respectively, with respect to the axial direction of the orthogonal coordinate system for performing observation or the horizontal axis (or the horizontal coordinate axis and the horizontal coordinate axis, respectively) orthogonal thereto, or The processing when the waves are deflected (steered) and crossed so as to be symmetrical with respect to the plane including the axis coordinate axis and the transverse direction orthogonal thereto (ie, all the waves are symmetrical with respect to the axial direction) is shown.
In the two-dimensional case, the echo signal itself that has been subjected to lateral modulation by superimposing two cross waves can be directly processed as follows. The echo signal is
When the first and second partial derivatives of s ₁ are obtained,
From (30A-1) and (30A-3), the instantaneous angular frequency ω ₁ (s ₁ , s ₂ ) is obtained in the same manner as described above, and from (30A-2),
Is found. Here, it is omitted (30A-1) in the initial value of the cosine function of the direction of the s ₁ and s _2. Further, when partial differentiation with respect to s ₂ a (30A-2),
And the instantaneous angular frequency ω ₂ (s ₁ , s ₂ ) obtained by calculating the first-order partial derivative and the second-order partial derivative of (30A-1) with respect to s _{2 in} the same manner, and the instantaneous angular frequency obtained above Using ω ₁ (s ₁ , s ₂ ),
Is found. To determine the (30A-6) may be partially differentiated by s ₁ the (30A-1) in the next s _2, in this case, instead of (30A-4),
Is also found. The analysis signal is obtained by adding or subtracting (30A-1), (30A-4), (30A-6), and (30A-7).
Or
When,
Or
And the two independent analysis signals are subjected to a displacement measurement method such as a multidimensional autocorrelation method, a multidimensional Doppler method (Non-Patent Document 13), a demodulation method (Patent Document 7), or the like to obtain a displacement vector. And each of the envelope detections may also be obtained, each of which may be imaged. A plurality of envelope detection results obtained may be superimposed and used for imaging (there is an effect of reducing speckle). Detection is not limited to envelope detection, it is possible to perform other detection processing such as square detection, can use the real component and / or imaginary component of the analysis signal, each of them can be used for imaging, A plurality of detection results obtained may be superimposed and used for imaging (there is a speckle reduction effect).
Since the actual calculation result of (30A-6) is different when the order of partial differentiation is reversed, two (30A-6) are obtained in such a manner, and (30A-8), (30A-8 ′) , (30A-9) and (30A-9 ′), the analysis signals represented by the same equation may be superimposed and averaged (displacement measurement or imaging). Further, an over-determined system for unknown displacement vector components may be realized (displacement measurement and imaging). A plurality of envelope detection results obtained may be superimposed and used for imaging (there is an effect of reducing speckle).
In addition, the echo signal itself subjected to lateral modulation by overlapping the cross beams is as follows:
In some cases, an analysis signal or an over-determined system can be obtained and used according to the same procedure performed in (30A-1). Incidentally, in (30A-1 ′), (30A-1 ″), and (30A-1 ″), similarly to (30A-1), the cosine function and the sine function in the directions of s ₁ and s ₂ are used. The initial value of is omitted.
In the three-dimensional case, the echo signal itself subjected to lateral modulation by superimposing three or four cross waves is:
, The analytic signal is obtained through partial differentiation as in the two-dimensional case.
And the analytic signal independent of this, the total number of crossing waves (3 or 4) can be obtained, and at least 3 of them are simultaneously set, or all are 3 An over-determined system can be obtained simultaneously. Here it is omitted the initial value of the cosine function of the direction of the s ₁ and s ₂ and s ₃ in (30B-1). As in the two-dimensional case, three-dimensional echo imaging is also possible. Each signal may be imaged through detection such as envelope detection or square detection. Further, an image may be formed by superimposition (there is also an effect of reducing speckle). It is also possible to change the order of partial differential directions for multiple detection signals in the same way as in the two-dimensional case, to obtain multiple analysis signals represented by the same equation, and use them to realize an over-determined system. In some cases, displacement measurement or imaging may be performed (there is also an effect of reducing speckle).
In addition, the echo signal itself subjected to lateral modulation by overlapping the cross beams is as follows:
Similarly, three or four analytic signals, and signals obtained by changing the order of the directions in which partial differential processing is performed can be obtained and used. However, (30B-1 '), (30B-1''),(30B-1''''),(30B-1''''),(30B-1'''''), (30B- 1 '''''') , (30B-1 ' in the''''''), (30B-1) and similarly, the cosine function and sine function in the direction of the s ₁ and s ₂ and s ₃ Initial values are omitted.
However, when each wave has a different carrier frequency (when using a sensor with a different carrier frequency or a different driving frequency, etc.) or when it is not actually generated symmetrically due to frequency modulation during propagation, etc. (In other words, when the wave is not precisely generated because it is not generated symmetrically), the coordinate systems (s ₁ , s ₂ ) and (s ₁ , s ₂ , s ₃ ) in the rectangular coordinate system, the instantaneous frequency of all waves themselves, or the local or global center of gravity frequency of all waves themselves (that is, √ ( ω ₁ (s ₁ , s ₂ , s ₃ ) ² + ω ₂ (s ₁ , s ₂ , s ₃ ) ² + ω ₃ (s ₁ , s ₂ , s ₃ ) ² ) 、 ２ (ω ₁ (s ₁ , s ₂ ) ² + ω ₂ (s ₁ , s ₂ ) ² ) can be calculated to be equal to any other wave signal so as to be equal to the frequency of any one wave signal. The instantaneous phase (that is, θ = ω ₁ (s ₁ , s ₂ , s ₃ ) s ₁ + ω ₂ (s ₁ , s ₂ , s ₃ ) s ₂ + ω ₃ (s ₁ , s ₂ , s ₃ ) s ₃ , and in the case of two dimensions θ = ω ₁ (s ₁ , s ₂ ) s ₁ + ω ₂ (s ₁ , s ₂ ) s ₂ ) and their coordinate systems need to be implemented as Cartesian coordinate systems (in order to achieve strictly lateral modulation, this is necessary in paragraph 0640). Can be confirmed). There are various methods for normalization, and the method is not limited to this. However, the phase information of one wave signal targeted for normalization must not be destroyed.
The subsequent one processing method, to process the coordinate axes s ₁ and s ₂ and s ₃ or more axes of symmetry and the plane of symmetry of the wave that is actually generated a surface including at least one of those axes The observed wave signals are interpolated and represented in their Cartesian coordinate system (translation and rotation of the coordinate system in order to make the wave symmetric), the calculation based on the above partial differentiation is performed, and the analytic signal is produced in those Cartesian coordinate systems. Finally, it is conceivable to re-interpolate to the orthogonal coordinate system where the observation was made, but when approximation is performed by interpolation, the calculation is fast but the accuracy decreases, and the complex exponential function without approximation , The accuracy is obtained but the processing takes time. Therefore, as another method, an approximate calculation based on the above-described partial differentiation may be performed on the observed coordinate axes of the orthogonal coordinate system without performing the interpolation processing. However, the frequency approximately calculated through partial differentiation during that time is not the frequency in the coordinate axis direction of the observed rectangular coordinate system, but the coordinate axis of the rectangular coordinate system consisting of the actually generated symmetry axis and the symmetry axis representing the plane of symmetry. This is the projection of the approximate value of the frequency in the direction onto the corresponding coordinate axis of the observed rectangular coordinate system. Since the angle (rotation angle) between these rectangular coordinate systems is obtained, it is possible to correct those approximate values to approximate frequency values in the observed rectangular coordinate system. In addition, when the directivity of the sensor has a bias or there is an obstacle or the like, even if the wave is intentionally not generated symmetrically in the front direction of the opening surface, the same processing can be performed, and in this case, accuracy can be obtained. In such a case, the above-described normalization processing (processing of the instantaneous phase) regarding the instantaneous frequency or the center-of-gravity frequency is effective to realize the orthogonal coordinate system in the lateral modulation.
However, when performing the above-described normalization, a Fourier transform is performed to obtain the frequency of the wave, so that the spectrum of a single quadrant or a single actant is subjected to an inverse Fourier transform by zero-filling the spectrum. It is desirable to directly generate an analysis signal of each wave.

Further, in the lateral modulation by superposition of cross waves (FIG. 37 in the case of two dimensions, FIG. 38 in the case of three dimensions), a Hilbert transform using a multidimensional (fast) Fourier transform (Non-patent Document 13) Unlike the partial differential processing described in the preceding paragraph, it is also possible to realize a Hilbert transform by performing a one-dimensional (high-speed) Fourier transform.
In the case of 2-dimensional and a two-dimensional echo signal crossing wave are overlapped is represented as (30A-1), performs a one-dimensional (Fast) Fourier transform for each of s ₁ and s _2, each half-band After the (negative band) spectrum is zero-filled, one-dimensional inverse Fourier transform is performed,
as well as,
The obtained, further, (30C-1) or relative (30C-2), subjected to the same processing with respect to the cos function of the imaginary term coordinates (i.e., s ₂ and s _1),
Get. From these real terms (30C-1), (30C-2), and (30C-3) real terms (common to them) and imaginary terms, analytic signals (30A-8), (30A-8 '), (30A -9) and (30A-9 ') can be obtained, and as described above, two independent ones of these four equations are obtained to obtain a multidimensional autocorrelation method or a multidimensional Doppler method (Non-patent Document 13). , The displacement vector can be obtained using the demodulation method (Patent Document 7). Further, detection results such as envelope detection and square detection of each of the two independent equations can be obtained (there is also an effect of reducing speckle). Regarding the amount of calculation, the total number of times of one-dimensional Fourier transform or one-dimensional inverse Fourier transform is the same as the number of times of performing the two-dimensional Fourier transform reported in Non-Patent Document 13 (total number of times in six directions).
Also, in the three-dimensional case, if the echo signal of the lateral modulation in which three or four cross waves are overlapped is expressed as (30B-1), the one-dimensional Fourier transform is performed similarly to the two-dimensional case. Through the one-dimensional inverse Fourier transform, the analytic signal (30B-2) and the analytic signal independent of the analytic signal (30B-2) can be combined to determine the total number (three or four) of the crossing waves, and at least three of them are simultaneous. Or, since there are three unknown displacement components, all of them are simultaneously obtained to obtain an over-determined system. As in the two-dimensional case, three-dimensional echo imaging is also possible. The same number of one-dimensional Fourier transforms and one-dimensional inverse Fourier transforms as in the method using the three-dimensional Fourier transform reported in Non-Patent Document 13 will be performed. When there are four waves, the number of times is 15 directions).
In these cases, the displacement vector is measured in the same manner. Further, each signal may be imaged through detection such as envelope detection or square detection. Further, an image may be formed by superimposition (there is also an effect of reducing speckle). Even in the case of an over-determined system, displacement measurement and imaging may be performed similarly (there is also an effect of reducing speckle).
As described above, a new high-speed Hilbert transform method relating to the signal itself in which the cross waves are overlapped and subjected to the lateral modulation has been described.The overlapped cross waves are the case where the waves are transmitted at the same time or the received signal for each transmission. It is a stack. On the other hand, when the cross waves described above are separated (that is, a signal obtained by processing a received signal when each is transmitted or a received signal that is simultaneously transmitted and separated), For example, in the case of two dimensions, when two crossing waves do not overlap, two independent wave signals ((30A-8) or (30A-8 ') and (30A-9) or (30A-9') Real signal)
as well as,
In this case, the one-dimensional Fourier transform and the one-dimensional inverse Fourier transform are applied to each of the two times (i.e., the two-dimensional Fourier transform and the two-dimensional inverse Fourier transform are performed once each). A conversion process for the number of directions is required. As described in Non-Patent Document 13 and above, the amount of calculation is smaller when the separated reception signals are superimposed and a plurality of waves are received simultaneously. The same applies to the case of three-dimensional conversion (the one-dimensional conversion processing is performed in a total of 18 directions when three cross waves are used, and in a total of 24 directions when four cross waves are used). 6 and 8 times).

  When this method is used, an image mainly representing a signal intensity, a phase, and a phase change determined by reflection and scattering is obtained. On the other hand, when the obtained instantaneous frequency is imaged, it becomes an image representing the influence of frequency modulation due to attenuation and scattering (similarly, gray and color display can be performed). In addition, the existence of the instantaneous phase degrades any measurement accuracy, even if it is a minute displacement, when the above-described tissue displacement measurement method based on the Doppler method or the classical measurement method is independently performed. However, the inventor of the present application has developed a phase matching method between frames to overcome this (for example, Non-Patent Document 15). Other methods of expanding and contracting the signal representing tissue deformation that are reported may be effective, but the former phase matching method is intended for high intensity and random signals in measurement of tissue displacement and strain. Indispensable for measurement (translation and rotation are possible). Normally, blood flow is measured using a narrow-band signal. However, according to this method, high-resolution measurement can be performed, and high-precision viscosity measurement and the like are developed. Measurement of multidimensional vectors and tensors is also possible. Also in the blood flow measurement, a detailed examination can be performed by performing a process of performing phase matching.

  In addition, the above-mentioned envelope detection is a routine means to be performed on the generated image signal.However, in the frequency domain, an operation based on an angular spectrum or a conjugate product of the spectra, These calculations on wavenumber (frequency) components are also useful (one of the non-linear processes in the present invention). In addition, in addition to the above, square detection, absolute value detection, and the like may be performed for amplitude detection. It is to be noted that the spectrum obtained from the image signal obtained by performing the beam forming (i.e., focusing and deflection realized by applying delay and apodization) is a spectrum, but the beam forming is further performed. If so, what has been Fourier transformed in the axial direction and in at least one lateral direction is an angular spectrum. That is, after the image signal is generated, the beam forming process may be further performed. In addition, those that have undergone super-resolution processing, including this processing and other processing (spectral weighting processing, nonlinear processing on signals, inverse filtering, etc., described in detail later), are used for the above coherent addition. Or may be used for the incoherent addition described above. The target of addition is a signal obtained by subjecting different or identical signals (before or after beamforming) to other processing, or raw signals thereof. Coherent addition is suitable for widening the band (higher resolution) and increasing the SN ratio, while incoherent addition is suitable for reducing speckle and increasing the SN ratio. The reduction of speckles may be accompanied by a decrease in spatial resolution, but processing with super-resolution may bring about a result with high spatial resolution without any problem. Basically, incoherent addition is performed on a signal that has been subjected to some kind of detection (including power detection) to a positive value. However, detection processing other than the above-described envelope detection is performed by detection. This is a process in which coherence remains in the signal (at least, the vibration of the wave is known). Although envelope detection is also useful, such detection with remaining coherence is particularly useful as detection processing that does not impair spatial resolution. In contrast, according to the envelope detection, the spatial resolution may be easily reduced.

  The operating mode may be determined by a command (signal) input to the device. In addition, the wave (type and characteristics of wave, intensity, frequency, bandwidth, or code, wave source (diffraction), etc.) of the observation target and a medium that propagates (propagation speed, physical property values related to the wave, attenuation, scattering, transmission, etc.) , Reflection, refraction, diffraction, or their frequency dispersion), and the received signal may be appropriately processed in an analog or digital manner. The characteristics (intensity, frequency, bandwidth, sign, etc.) of the generated image signal may be analyzed. The data obtained by the measurement imaging apparatus according to the present embodiment may be used in another apparatus. The measurement imaging apparatus according to the present embodiment may be used as one of network devices, may be controlled by a control device of a network system, and may be used as a control device for controlling a network device. In some cases, it may be a control device for controlling a locally configured network.

  When the passive type device according to the present embodiment is used as an active type device, the transmitting transducer (or applicator) 10 is connected to the transmitting unit 31 of the device main body 30, and the transmitter 31a is a trigger signal by an analog device. In this case, the control unit 34 generates and applies a trigger signal. Alternatively, if there is a mode in which the transmitter 31a operates in a digital device according to an external clock signal, any one of the devices in the device main body 30 is used. A mechanism may be provided to either supply a clock signal from the control unit 34 or to operate the apparatus main body 30 with the clock signal of the transmitter 31a. When the transmitter 31a is a digital device, the transmission and reception clock signals are synchronized by any of these mechanisms. This is important when one image signal is generated based on a plurality of transmissions. If synchronization cannot be achieved, errors may be reduced in situations where the clock frequency and sampling frequency are high.

  As described above, arbitrary beamforming can be realized by digital processing without performing interpolation approximation at high speed through fast Fourier transform. Virtually any focusing and any steering (deflection) can be performed using a transducer array device of any aperture shape. In the present invention, as described in the methods (1) to (7), interpolation approximation processing may be performed in arbitrary beamforming wave number matching, and beamforming may be performed at higher speed. In order to perform approximate approximate wave number matching, it is necessary to appropriately oversample a received signal at the cost of an increase in the amount of calculation. In such a case, it is necessary to pay attention to an increase in the number of data of the Fourier transform, unlike a case where a signal at an arbitrary position can be selectively generated without performing the interpolation approximation processing. The second embodiment can be used as a device and with respect to operation modes (eg, imaging mode, Doppler mode, measurement mode, communication mode, etc.) in a normal device, It is not limited to.

  In the first and second embodiments, vibration waves (mechanical waves) including electromagnetic waves, sound waves (compression waves), shear waves, shock waves, surface waves, and the like, or waves (heat waves, (Including Guided waves), the transmission / reception focusing system, transmission / reception steering, transmission / reception apodization, and the coordinate system for transmission / reception are different from the coordinate system for generating the beamformed signal. In any case, any beam forming can be performed with high accuracy and high speed without performing interpolation approximation based on digital processing. Not only the frame rate when displaying the image of the beamformed signal is improved, but also a high spatial resolution and high contrast can be obtained with respect to the image quality, and further, the displacement and deformation using the beamformed signal, or If the temperature or the like is measured, the measurement accuracy is improved. In the present invention, as described in the methods (1) to (7), interpolation approximation processing may be performed in arbitrary beamforming wave number matching, and beamforming may be performed at higher speed. In order to perform approximate approximate wave number matching, it is necessary to appropriately oversample a received signal at the cost of an increase in the amount of calculation. In such a case, it is necessary to pay attention to an increase in the number of data of the Fourier transform, unlike a case where a signal at an arbitrary position can be selectively generated without performing the interpolation approximation processing. High-speed beamforming in the situation where superposition of waves or beams subjected to high-speed beamforming and spectral frequency division, and where received signals of unreceived beamforming are superimposed or spectral frequency division are used, realizes various applications. I do. The application of the present invention is not limited to this. The high processing speed has a great effect in multidimensional imaging using a multidimensional array. It is desirable that the Fourier transform or the inverse Fourier transform process performed in the above-described calculation algorithm includes a dedicated fast Fourier transform or a fast inverse Fourier transform, and that the fast Fourier transform be performed. In addition, the present invention is not limited to the above embodiments, and many modifications can be made by those having ordinary knowledge in the technical field within the technical idea of the present invention.

The object to be measured is various, such as an organic substance, an inorganic substance, a solid, a liquid, a gas, a substance that follows rheology, a living thing, a celestial body, the earth, the environment, and the like. Non-destructive inspection (as a recent topic, inspection of metals and plastics (especially Fiber-Reinforced Plastics using carbon fiber or glass fiber, etc.) by ultrasonic waves which is cheap and simple is active. Has proposed ultrasonic observation of rubber, which is conventionally considered to have strong ultrasonic attenuation), diagnostics, resource exploration, creation and manufacture of materials and structures, and various physical and chemical repairs and treatments. It contributes to monitoring, application of clarified functions and physical properties, etc., in which non-invasive, minimally invasive, non-invasive conditions that do not cause significant disturbance to the measured object are imposed. Accuracy may be required in the air. In some cases, an object can be ideally observed in situ. For example, when a three-dimensional wave can be observed, a three-dimensional displacement vector can be Doppler-observed. In the case of a normal Doppler, it is necessary to direct the wave propagation direction to the displacement direction of the observation target, but the sensor is directed to the observation target. The movement in any direction can be observed only by using (e.g., ultrasonic echo method). The measurement procedure is also simplified. For example, when the eyelids are open, the ultrasonic echo method is used when passing through or closing the water, and when the eyelids are open, the eyeball distortion tensor, distortion rate tensor, shear wave using OCT are used. By observing the propagation, the viscoelasticity distribution and intraocular pressure of the eyeball can be reconstructed by the mathematical inverse problem. It is also possible to reconstruct blood viscosity, heart cavity pressure, blood pressure, etc. by ultrasonic Doppler observation of blood flow vectors in the heart cavity, blood vessels, fundus and retina. In addition, not only light but also ultrasound can be applied to various biometrics including fingerprint identification (authentication) and iris authentication (including functional observations such as dynamics and temperature, and various physical properties observations). In some cases, observation can be performed in situ while the observation target is operating. For example, the distribution of electrical properties such as conductivity and dielectric constant of a neural network or an electric / electronic circuit operating using the mathematical inverse problem can be reconstructed by observing the current density vector distribution based on the magnetic field distribution observation. Observing the temperature distribution to reconstruct the distribution of thermophysical properties, or the internal strain tensors and strains of the tires of running cars, rubber pipes of flowing fluid, and rubber of electric wires carrying current Reconstruction of the distribution of viscoelastic modulus and internal pressure by ultrasonic Doppler observation of the rate tensor, reconstructing the distribution of thermophysical properties, heat generation and perfusion by observing the temperature inside them, The viscoelasticity and the tissue pressure can be reconstructed by observing the muscle motion vector in the same manner. Further, during the generation and growth of the material, the generation and growth process can be monitored without changing the physical conditions and the like for observation. Paragraph 0094 describes a method of observing elastic waves for observing anisotropy of elastic modulus (ultrasonic waves, MRI, OCT, etc. can be used for the observation), Isotropy can also be observed by observing waves (various electromagnetic waves, mechanical waves, heat waves, etc.) related to each physical property. In other words, the position and number of sources, the directivity, etc. are adjusted to observe the overlap of waves to be observed (electromagnetic waves, light, radiation, audible sound waves, ultrasonic waves, elastic waves, heat waves), and to observe each wave Can be observed and superimposed to control the propagation direction. Alternatively, it is also possible to generate and observe a plurality of purely independent waves by adjusting the position, number, directivity, etc. of the source to improve the accuracy of reconstruction of physical properties (an over-determined system can be generated) ). For example, it can be applied to the design of a device (medium, source, etc.) that realizes various surface waves and guided waves. Here, the observation target is described as a wave, but a static or pseudo-static field (strain tensor distribution, potential distribution, current density vector distribution, temperature distribution, etc.) may be the observation target. In some cases, we observe static fields and reconstruct static physical properties.
When the S / N ratio of a wave directly sensed for observing the wave or the field is low, the superposition and the averaging of the waves are effective. For example, when observing the current density vector by observing the brain magnetic field of a human or animal (it is very weak and often buried in the surrounding magnetic field) with a SQUID meter, visual, auditory, somatosensory In some cases, the distribution of the current density vector is reconstructed by superimposing (averaging) the evoked brain magnetic fields, thereby obtaining the accuracy and reconstructing the distribution of the electrical properties. The distribution of electrical properties may be reconstructed by observing the current density vector distribution for each trigger and superimposing them (by averaging). Also, when targeting suddenly occurring ones such as epilepsy, they may be reconstructed after superimposing observation magnetic fields or integrating observation time series. In addition, in the terahertz observation (electric field observation), averaging is performed to improve the SN ratio, but the electrical properties may be reconstructed based on the superimposed ones. When signal components of a plurality of events are included in superposition (averaging) and integration, their accumulation can be observed simultaneously, and random signal components are suppressed. It is also possible to carry out their reconstruction on such superimposed signals, for example by visualizing the running structure of the neural network used during observation by means of current density vectors and distribution reconstruction of electrical properties. Or be done.
The frequency dispersion of physical properties may be reconstructed by changing the frequency of a wave or realizing and observing a broadband wave.
In addition, the treatment or repair may be performed on the target by the action of the wave itself, and the situation may be observed by performing beam forming on the response from the target at that time. Also, beamforming is performed in satellite communication, radar, sonar, etc., thereby realizing an informationally safe environment while saving energy, and enabling accurate communication. The present invention is also effective in ordinary communication including an ad hoc communication device and mobile. It can also be applied to sensor networks. When the target is dynamic, real-time performance is required. However, according to the present invention, digital beamforming can be completed in a short time, at high speed, and with high accuracy.

<< Third Embodiment >>
2. Description of the Related Art Waves such as electromagnetic waves, light, mechanical vibrations, sound waves, and heat waves have different behaviors depending on the frequency, bandwidth, intensity, or mode. Many transducers for various waves have been developed so far, and imaging using these waves (diffraction waves) themselves, transmitted waves, reflected waves, refracted waves, diffracted waves, or scattered waves has been performed. I have. For example, it is well known that non-destructive inspection, medical treatment, and sonar use ultrasonic waves having a high frequency among sound waves. In addition, an electromagnetic wave (microwave, terahertz wave, infrared ray, visible light, radiation such as X-ray, or the like) having an appropriate frequency according to the observation target is also used in the radar. The same applies to other waves.

  In imaging using such waves, distribution of amplitude data obtained through orthogonal detection, envelope detection, or square detection is usually displayed in one-dimensional, two-dimensional, or three-dimensional as a grayscale image or a color image. You. In Doppler measurement using those waves, a raw coherent signal is processed (ultrasonic Doppler, radar Doppler, laser Doppler, etc.). Further, in the field of image measurement, it is well known that motion is observed using a signal made incoherent through detection (cross-correlation processing, optical flow, etc.). In medical ultrasound and sonar, imaging using physically generated harmonics, chords, and difference sounds is also performed.

  Under such circumstances, the inventor of the present application has developed an ultrasonic imaging technique for differentially diagnosing cancerous lesions and sclerosis in human tissues. The inventor of the present application has performed high resolution and high efficiency of HIFU (High Intensity Focus Ultrasound) treatment, together with high resolution of echo imaging and high precision measurement imaging of tissue displacement, and the like. Their imaging is also based on the reception of echoes during intense ultrasonic radiation. Such imaging is based on performing appropriate beamforming, and requires an appropriate detection method and a tissue displacement measurement method.

  For example, the inventor of the present application has proposed beamforming methods such as a transverse modulation method using cross beams, a spectrum frequency division method, a method using many cross beams, and an over-determined system method. In addition, in particular, quadrature detection and envelope detection, as well as square detection, etc., as a method for detecting a multidimensional received signal, and multidimensional autocorrelation, multidimensional Doppler, multidimensional cross spectrum phase gradient as a displacement vector measuring method. And a technique for reconstructing and imaging (viscosity) shear modulus distribution and thermophysical property distribution based on displacement and strain measurement (Non-patent Documents 13 and 30). See). Some of them are already in clinical use. A recent report by the inventor of the present application is ITEC (International Tissue Elasticity Conference), IEEE Trans. on UFFC, Ultrasound Study Group, and Acoustic Imaging Study Group.

  In this regard, the inventors of the present application have focused on non-linear imaging. In medical ultrasound, nonlinear imaging (so-called harmonic imaging) based on the result of a physical action in the propagation process of ultrasound is currently performed. In the following, the application of non-linear ultrasound to diagnosis and treatment will be particularly described.

  Harmonic imaging is based on harmonics generated during propagation due to a high propagation velocity of a wave component having a high sound pressure intensity (usually explained as having a large bulk modulus for a high sound pressure). This is to image wave components. In this harmonic imaging, a contrast agent (ultrasonic contrast agent) may be used to enhance a nonlinear effect in ultrasonic wave propagation.

  Its effectiveness has been recognized in clinical practice, such as the ability to perform blood flow imaging of capillaries, and has a long history (see Non-Patent Document 22). Doppler measurement using a non-linear component (harmonic component) is also possible, and in such a case, a report will be made on multidimensional vector measurement realized by the inventor of the present application in such a case. In Non-Patent Document 23, a so-called pulse inversion method is used, and separation from a fundamental wave is performed.

  Tissue imaging has a history of preceding blood flow imaging. At first, harmonics were separated by filtering (see Non-Patent Document 24). Separated by version method. When the transmission signal has a wide band, the band of the fundamental wave and the harmonic wave is covered, so that the filtering method has a limit. In addition, there is a report that a multidimensional polynomial composed of a power term is separated into a fundamental wave and a harmonic represented by each dimension term based on the least square method (see Non-Patent Document 25).

  Recently, there have been reports of applying harmonic components and chords to ultrasonic microscopes (see Non-Patent Document 26) and radiation pressure imaging (see Non-Patent Document 27). Further, the nonlinear propagation and the heat absorption are closely related to each other, and the HIFU is used by focusing high-intensity ultrasonic waves at a focal position including a case where cavitation occurs (Non-Patent Document 28). Etc.). Also, when energy (or mode) is converted from an ultrasonic wave to a shear wave (for example, when a sound wave is obliquely incident on a boundary where the acoustic impedance between soft tissue and bone greatly changes or when shear occurs due to scattering). In (2), the generated high-frequency shear wave is easily absorbed by tissue during propagation in the vicinity of the generation position (Girke).

  Contrast agents used for enhancing non-linear effects in HIFU treatment (see Non-Patent Document 29, etc.) are also considered effective in these respects. The inventor of the present application first described the effect of coagulating blood to occlude the feeding artery 17 years ago in the world regarding the treatment of cancer lesions. I have. Recently, an applicator having a frequency band similar to that of a probe for clinical diagnosis has become available at low cost, but the inventors of the present application have thought that it is necessary to develop a dedicated contrast agent I have. The inventor of the present application considers at least both the fragile property and the fragile property as attractive properties. It is.

  A wave is affected by attenuation during its propagation, and thus the energy of the wave decreases as the propagation distance increases. In addition, the spreading wave is also affected by the spreading. In such a situation, transmitted, reflected, refracted, scattered, or diffracted waves reflect changes in impedance, the presence of reflectors or scatterers, and are used for their imaging and Doppler measurements. You. In such maging, it is desirable that the signal contains high-frequency components and has a wide band as much as possible or within a required range, and the same is true for Doppler measurement.

  However, usually, high frequency signal components are strongly affected by attenuation, and as the propagation distance increases, their energy is lost, the signal is reduced in frequency, and the band becomes narrower. That is, imaging at a position far from the signal source is affected by a decrease in signal-to-noise ratio (SN ratio) and a decrease in spatial resolution. In Doppler measurement, the accuracy decreases. Reducing their effects due to damping is extremely important in the engineering sense.

  In addition, if a high-frequency signal that cannot be realized by a single signal source can be generated, higher-resolution imaging and more accurate Doppler measurement can be performed. A high-frequency signal may simply be generated. Normally, the effect of attenuation is strong against high-frequency components. For example, in a microscope that is easily affected by attenuation, it is preferable that observation can be performed at a high frequency as deep as possible. In addition, low frequency imaging or measurement using low frequency signals may be possible. Further, a low-frequency signal that cannot be realized by a single signal source may be generated. For example, a deep part of the object can be deformed at a low frequency. In medical ultrasound imaging, nuclear magnetic resonance imaging, OCT, and laser applications, multiple sources are used to deform deep tissue at low frequencies (Tissue Elasticity).

  For example, vibration is applied from multiple directions to generate a vibration wave with a frequency lower than that frequency, or a plurality of ultrasonic beams are crossed at their focal positions, etc., and a low-frequency force source is realized there. To generate low-frequency vibration waves, the generated vibration waves may be ultrasonic waves (longitudinal waves), and the generated vibration waves may be shear waves (transverse waves). In some cases, it may be observed by ultrasonic waves. It may be possible to adjust the propagation direction of the generated waves. If these signals can be realized theoretically or on the basis of calculation, the generated waves may also be controlled. Furthermore, a detection method that can be easily implemented in a short time is also important in place of the normal orthogonal detection, envelope detection, and square detection.

  In view of the above, a second object of the present invention is to enhance a high-frequency component having a relatively weak intensity or a high-frequency component which is generally lost in an arbitrary wave propagating from within a measurement target. It is an object of the present invention to provide a measurement imaging apparatus capable of improving spatial resolution and measurement accuracy by performing measurement or newly generating the measurement resolution. In addition, the measurement imaging device enhances or simulates a non-linear effect in the measurement target, newly generates the non-linear effect when there is no non-linear effect in the measurement target, or virtually realizes imaging by realizing the non-linear effect. You may go. A third object of the present invention is to generate a high-frequency signal that cannot be realized by a single wave source. Further, a fourth object of the present invention is to realize a detection method that can be easily performed in a short time.

  In order to solve the above-mentioned problems, a measurement imaging apparatus according to one aspect of the present invention performs (i) non-linear processing using a non-linear device at an arbitrary position on a propagation path for an arbitrary wave propagating from within a measurement target. (Ii) receiving the transducer to generate a received signal, generating an analog received signal by the transducer, and performing analog non-linear processing on the analog received signal; and (iii) A non-linear reception processing unit that performs at least one of processing for performing digital non-linear processing on a digital reception signal obtained by digitally sampling the analog reception signal, generating an analog reception signal received by the transducer, An image signal representing an image to be measured is generated based on a reception signal obtained by the non-linear reception processing unit. And an image signal generator for.

  According to one aspect of the present invention, by performing nonlinear processing on a signal having a frequency at which the influence of attenuation does not matter in an arbitrary wave propagating from the inside of a measurement target, the intensity is generally relatively low. By enhancing or newly generating a high-frequency component or a lost high-frequency component, it is possible to improve the spatial resolution and the measurement accuracy. In addition, electromagnetic waves, light, mechanical vibration, sound waves, or waves arriving from a signal source of an arbitrary wave such as a heat wave, the wave itself emitted from those signal sources, the transmitted wave of the wave, the reflected wave, A coherent signal obtained by detecting a refracted wave, a scattered wave, or a diffracted wave by a transducer is subjected to multiplication and exponentiation effects during wave propagation, and a process including an analog operation and a digital operation thereof. Non-linear effects can be enhanced. The same is true for the wave source (diffraction source) itself. Alternatively, a similar effect can be simulated, newly generated, or virtually realized. These can be imaged.

  For example, in imaging using coherent signals and Doppler measurement, high-resolution imaging using a wideband signal including high-frequency components is realized compared to imaging using the original signal. Measurement of displacement, velocity, acceleration, strain, or distortion rate with higher accuracy than Doppler measurement can be realized. Also, the same processing is performed on the incoherent signal for the same problem. An ordinary device can be used as hardware. Of course, analog processing (circuit) is faster than digital processing (circuit). A computer or a device having an arithmetic function (such as an FPGA or a DSP) can be used in the case of performing calculations including higher-order calculations and in that the degree of freedom is wide.

  In particular, it is possible to generate a high-frequency component that is robust to the influence of attenuation in the wave propagation process and cannot be realized by a single signal source, and enables high-resolution imaging and high-accuracy Doppler measurement. It is also possible to generate a high-frequency signal that cannot be physically realized with a single signal source. When a plurality of 100 MHz ultrasonic transducers are used, ultrasonic waves that are physically as many as the number of ultrasonic transducers can be generated, and a high frequency that cannot be generated by a normal transducer can be realized. Further, a signal of a high frequency may be simply generated. According to the present invention, such a high frequency can be realized by calculation. Therefore, high-frequency waves and signals that cannot be physically realized can be generated. Similarly, low-frequency imaging and measurement using low-frequency signals can be realized. It is also possible to generate a low-frequency signal that cannot be physically realized by a single signal source. These signals can also be realized theoretically or on an arithmetic basis to control the generated waves.

  For example, in an ultrasonic microscope, a high-frequency ultrasonic wave (signal) of several hundred MHz is applied to generate an ultrasonic wave having a frequency higher than a frequency determined by a sound source, and the ultrasonic wave is robust against attenuation. Therefore, it is possible to realize an ultrasonic microscope capable of performing higher-resolution imaging and higher-accuracy Doppler measurement than usual. In addition, low-frequency imaging and measurement using low-frequency signals can be performed. In the case of measuring the deformability of a tissue, for example, a deep part of a target can be deformed at a low frequency. In medical ultrasound images, nuclear magnetic resonance images, OCT, laser applications, and the like, a plurality of signal sources are used to deform deep tissue at a low frequency. The same applies to other imaging devices and Doppler devices. In addition, effects such as heating, heating, cooling, freezing, welding, heat treatment, cleaning, or restoration are also improved, and high resolution can be achieved at that time. Similar effects can be obtained for incoherent signals after various detections.

  Further, in the technical aspect of signal processing, the processing of quadrature detection and envelope detection can be facilitated. For example, when the present invention is applied to a deflected beam or a deflected wave, an IQ signal obtained by quadrature detection with respect to all coordinate axes is obtained, so that envelope detection becomes easy. Further, when the present invention is applied to the cross beam, an IQ signal orthogonally detected in each coordinate axis can be obtained. Therefore, only by performing normal Doppler signal processing in each direction, a displacement vector, a velocity vector, an acceleration vector, a strain tensor, Alternatively, the strain tensor can be measured. Of course, in imaging, square detection may be performed as the detection processing.

  Electromagnetic waves, light, mechanical vibrations, sound waves, or waves arriving from arbitrary wave signal sources such as heat waves, and transmitted waves, reflected waves, refracted waves, scattered waves, of waves emitted from those signal sources, Alternatively, imaging and Doppler measurement using coherent signals obtained by detecting diffracted waves with transducers are widely performed using appropriate frequencies for each medium in radar, sonar, nondestructive inspection, diagnosis, etc. Have been done. The wave generated from the signal source is also applied to heating, heating, cooling, freezing, welding, heat treatment, cleaning, restoration, and the like. Furthermore, recently, image measurement such as motion using an incoherent signal has been performed, and various imaging and measurement have been performed based on image processing and signal processing. The present invention is effective in all of these aspects, and the applicability and market potential of the present invention are very high.

  FIG. 39 is a block diagram illustrating a configuration example of a measurement imaging apparatus according to the third embodiment of the present invention. This measurement imaging apparatus captures an image of a measurement target based on an arbitrary wave such as an electromagnetic wave, light, mechanical vibration, sound wave, or heat wave arriving from the measurement target, or a physical quantity such as displacement in the measurement target. Is a non-destructive measurement device.

  As shown in FIG. 39, the measurement imaging apparatus includes at least one transducer 110 that is both a transmitting unit and a receiving unit, and an imaging device main body 120. The transducer 110 may be capable of generating and receiving an arbitrary wave such as an electromagnetic wave, light, a mechanical vibration, a sound wave, or a heat wave. In this case, the transducer 110 can transmit an arbitrary wave to the measurement target 1 and receive a reflected wave or a scattered wave reflected in the measurement target 1. For example, when the arbitrary wave is an ultrasonic wave, an ultrasonic transducer that transmits an ultrasonic wave according to a drive signal and receives the ultrasonic wave to generate a reception signal can be used. It is well known that ultrasonic elements (PZT, polymer piezoelectric elements, etc.) are different depending on the application, and the structure of the transducer is different.

  Historically, narrow-band ultrasonic waves have been used in blood flow measurement. However, the present inventor has proposed the use of soft tissue displacement and strain (including static cases) and shear which have been put into practical use in recent years. The use of broadband transducers for (echo) imaging, including the measurement of wave propagation (velocity), has been pioneered in the world. As with HIFU treatment, continuous waves may be used. However, the present inventor has been developing using a broadband device in order to achieve high-resolution treatment. When using high-intensity ultrasonic waves, a tissue is stimulated within a range that does not cause a heating effect, and a power source may be generated in the measurement target 1 as described above. Therefore, a transducer for (echo) imaging is used. Sometimes. Heat treatment, force source generation, and (echo) imaging may be performed simultaneously. The same is true for other wave sources and transducers. Transducers are classified into a contact type and a non-contact type, and impedance matching of each wave is appropriately performed before use.

  Alternatively, as the transducer 110, a transmitting transducer that generates an arbitrary wave and a receiving transducer (sensor) that receives the arbitrary wave may be used. In that case, the transmitting transducer transmits an arbitrary wave to the measurement target 1, and the sensor determines whether the reflected wave or refracted refracted wave or scattered scattered wave or diffracted diffraction wave is reflected in the measurement target 1. A wave or a transmitted wave transmitted through the measurement target 1 can be received.

  For example, when the arbitrary wave is a heat wave, a heat source that is not intentionally generated, such as sunlight, lighting, or metabolism in a living body, may be used, but an infrared heater, a heater, or the like may be used. An ultrasonic transducer (which may generate a force source in the measurement object 1), an electromagnetic transducer, a laser, etc. which transmit a comparatively stationary or heating ultrasonic wave which is often controlled according to a drive signal. Is also used. In addition, infrared sensors that receive heat waves and generate received signals, pyroelectric sensors, microwave and terahertz wave detectors, temperature sensors such as optical fibers, and ultrasonic transducers (temperature-dependent such as sound speed and volume change of ultrasonic waves) A nuclear magnetic resonance signal detector (detecting a temperature using a chemical shift of nuclear magnetic resonance) can be used. For each wave, an appropriately receivable transducer is used.

  When actively generating a wave according to the drive signal, the transducer 110 may actively generate a wave including a harmonic. For example, the transducer 110 generates a wave according to the nonlinear characteristics of the wave source or the circuit of the transmitter 121 driving the wave source. Further, the transducer 110 may have one transmitting surface or receiving surface, or may have a plurality of transmitting surfaces or receiving surfaces. A non-linear device 111 for performing non-linear processing on the generated arbitrary wave may be provided on the transmission surface of the transducer 110. A non-linear device 111 that performs non-linear processing on an arbitrary wave propagating from inside the measurement target 1 may be provided on the receiving surface of the transducer 110. The nonlinear device 111 does not necessarily need to be in contact with the transmission surface or the reception surface of the transducer 110, and may be provided at an arbitrary position on a propagation path of an arbitrary wave.

  Further, an action device 112 such as a filter (a spectroscope or the like), a shield, an amplifier, or an attenuator may be provided between the measurement target 1 and the transmission surface or the reception surface of the transducer 110. When the nonlinear device 111 is used, the action device 112 may be provided on both front and rear sides of the nonlinear device 111. The transducer 110, the non-linear device 111, and the working device 112 may be separated or integrated in a combination.

  FIG. 39 also shows a case in which a wave source is provided in the measurement target 1, or it may be directly controllable by the control unit 133. In addition, the wave generated by the transducer 110 may be concentrated using a lens or the like, or a focus may be transmitted using a plurality of transducers 110 to generate a wave source (such as a mechanical wave or the like). Using a heat wave source, or a mechanical wave or an electromagnetic wave, for example, to generate a new electromagnetic wave for a magnetic substance or the like that may be a contrast agent, or to create a physical action or physical property between waves. (Including the case where the wave intensity and the propagation direction are controlled by the stimulus).

  Of course, there may be a wave source in the measurement target 1 from the beginning (for example, the electrical activity of the brain and heart becomes a current source, and the heart becomes a power source). In addition, there are cases where the wave source can be controlled, cases where the wave source cannot be controlled, cases where the measurement target 1 is observed in situ, or those wave sources themselves which are the imaging target or the measurement target. Sometimes. Alternatively, such a wave source may exist outside of the measurement target 1 from the beginning, and may be treated in the same manner and become a measurement target. The nonlinear device 111 and the action device 112 may be appropriately provided between such a wave source and the measurement target 1.

  Furthermore, in order to obtain a non-linear effect in the measurement object 1 or to positively enhance the non-linear effect in the measurement object 1 at least in a part of the measurement object 1, a contrast agent such as a microbubble (non-linear enhancement) is used. Agent 1a may be injected. As the contrast medium 1a, a substance having an affinity for a lesion, a fluid, or the like in the measurement target 1, in particular, may be used. Thus, a wave generated by a plurality of wave sources may arrive at a transducer that receives a wave.

  The transducer 110 is supplied with a drive signal from the imaging apparatus main body 120 by wire or wirelessly, and / or outputs a reception signal to the imaging apparatus main body 120. In the case of wireless communication, a wireless receiver and / or a wireless transmitter is provided in the transducer 110, and a wireless transmitter and a wireless receiver are also provided in the imaging apparatus main body 120.

  In part A, the imaging apparatus main body 120 includes a transmitter 121, a receiver 122, a filter / gain adjustment unit 123, a nonlinear element 124, a filter / gain adjustment unit 125, a detector 126, and an AD (Analog- to-digital) converter 127 and storage device 128. In part B, the imaging apparatus main body 120 includes a reception beam former 129, an operation unit 130, an image signal generation unit 131, a measurement unit 132, a control unit 133, a display device 134, an analog display device 135, May be included. The control unit 133 controls each unit of the imaging apparatus main body 120.

  When a plurality of transducers 110 are used, part A having the same number of channels as the number of transducers 110 may be provided. A case where the transducers 110 form an array will be described later. As shown in FIG. 39, when a part A of a plurality of channels is provided, a reception signal output from the storage device 128 of the part A of a plurality of channels may be supplied to the reception beamformer 129 of the part B. . Alternatively, each part B may be connected to each part A in cascade and processed independently. In this case, the received signal output from the storage device 128 of the part A of each channel is Is supplied to the reception beamformer 129 of the part B of FIG. Note that the plurality of transducers 110 may relate to different different types of waves, and in that case, the non-linear effects of different types of waves may be observed at the same time. You may observe non-linear effects between different types of waves.

  In Part A, the transmitter 121 to the detector 126 may be configured by an analog circuit, or at least a part thereof may be configured by a digital circuit. In Part B, the reception beam former 129 to the control unit 133 may be constituted by digital circuits, or may record a central processing unit (CPU) and software for causing the CPU to perform various processes. It may be constituted by a recording medium. As the recording medium, a hard disk, a flexible disk, an MO, an MT, a CD-ROM, a DVD-ROM, or the like can be used. Note that at least a part of the reception beam former 129 to the control unit 133 may be configured by an analog circuit.

  The transmitter 121 includes a signal generator such as a pulser that generates a drive signal according to a trigger signal supplied from the control unit 133. The control unit 133 may control the frequency, carrier frequency, bandwidth, transmission signal strength (apodization), or the waveform or shape of a pulse wave, burst wave, or the like. The control unit 133 may set the timing or delay time of the trigger signal for each channel. Alternatively, the timing of the trigger signal output from the control unit 133 may be constant for all channels, and the transmitter 121 may further include a delay element that delays the trigger signal according to the delay time set by the control unit 133. .

  The transmitter 121 causes the transducer 110 to generate an arbitrary wave by applying the generated drive signal to the transducer 110. For example, the transmitter 121 includes a drive signal amplifier (which can also serve as apodization) in order to adjust the intensity of the transmitted wave and the intensity of the generated harmonic, and the control unit 133 sets the delay time. An element may be further included. A drive signal including harmonics may be generated and used. When performing apodization or forced vibration instead of resonance, various waves are generated and used, such as generating a chirp wave. When the drive signals generated by the transmitters 121 of a plurality of channels are applied to the plurality of transducers 110, focusing and steering of a transmission beam and transmission of a plane wave can be performed by setting a delay time by the control unit 133. (A plane wave is a wave having a narrow band in a direction orthogonal to the propagation direction, and is effective when the band is widened).

  The transmitter 121 may further include a non-linear element (an analog device such as a transistor, a diode, or a non-linear circuit, or a digital device such as a non-linear arithmetic unit) for which a non-linear effect is similarly set. In some cases, the frequency and the carrier frequency, the bandwidth, the apodization, the delay, and the non-linear effect prepared in advance are set, but they may be controlled by the operator via the control unit 133. They may be adaptively determined and controlled by the arithmetic unit 130 according to the observation situation.

  When driving a plurality of transducers 110, the transmitter frequency, carrier frequency, bandwidth, apodization, delay element, and nonlinear element of each channel are controlled, but are set to those patterns prepared in advance. In some cases, those patterns may be controlled by the operator via the control unit 133, and the arithmetic unit 130 may adaptively determine and set those patterns in accordance with the observation situation. is there.

  The receiver 122 includes, for example, an amplifier that amplifies the received signal or an attenuator that can attenuate the received signal (which can also serve as apodization and a filter), and may further include a delay element whose delay time is set by the control unit 133. The receiver 122 may further include a non-linear element (an analog device such as a transistor, a diode, or a non-linear circuit, or a digital device such as a non-linear arithmetic unit) that generates a non-linear effect. They may be configured similarly to those of the transmitter 121, including when waves are received by multiple transducers 110. The receiver 122 amplifies a reception signal generated by the transducer 110 that has received the arbitrary wave, and outputs the amplified reception signal to the filter / gain adjustment unit 123 and the AD converter 127.

  The filter / gain adjustment unit 123 includes a filter that limits the frequency band of the received signal, or an amplifier or an attenuator that adjusts the gain of the received signal. Filter / gain adjustment section 123 adjusts the frequency band or gain of the received signal, and outputs the received signal to nonlinear element 124.

  The nonlinear element 124 includes, for example, an analog device such as a transistor, a diode, or a nonlinear circuit, and performs an analog nonlinear process on a received signal. This non-linear processing may be a power operation for at least one frequency component signal included in the received signal, or may be a multiplication operation for a plurality of frequency component signals included in the received signal ( Hall effect elements can be used).

  Filter / gain adjustment section 125 includes a filter for limiting the frequency band of the received signal, or an amplifier or attenuator for adjusting the gain of the received signal. The filter / gain adjuster 125 adjusts the frequency band or gain of the received signal, and outputs the received signal to the detector 126 and the AD converter 127.

  The filter / gain adjustment units 123 and 125 and the non-linear element 124 may be set to those prepared in advance by the control unit 133, but they are controlled by the operator via the control unit 133. In some cases, these may be adaptively determined and controlled by the arithmetic unit 130 according to the observation situation. When a plurality of transducers 110 are driven, they are independently controlled in each channel. However, in some cases, the patterns are set in advance in a prepared pattern. May be controlled, and the arithmetic unit 130 may adaptively determine and set those patterns according to the observation situation.

  For example, when the reception beamforming is not performed, the detector 126 performs an envelope detection process or a square detection process on the received signal to generate an analog image signal. Also, displacement measurement may be performed through orthogonal detection. The analog display device 135 displays an image of the measurement target 1 or the wave source based on the image signal or the measurement result generated by the detector 126.

  The AD converter 127 selects the reception signal output from the filter / gain adjustment unit 125 when performing the analog nonlinear processing on the reception signal, and selects the receiver 122 when not performing the analog nonlinear processing on the reception signal. Select the received signal output from. The AD converter 127 converts an analog reception signal into a digital reception signal by digital sampling. The digital reception signal obtained by the AD converter 127 is output to the storage device 128. The storage device 128 is configured by a memory such as a RAM, for example, and stores a received signal.

  The reception signal stored in the storage device 128 is supplied to the reception beamformer 129. Note that while the signal is processed by the reception beamformer 129, the signal being processed may be temporarily stored in the storage device 128 or the external storage device 140, and these signals are read out as necessary. In the case where a single or a plurality of transducers 110 are used, the reception beamformer 129 may separate harmonics by a pulse inversion method, a polynomial fitting method, or the like (the same processing is performed in the calculation unit 130). May be done).

  When a plurality of transducers 110 are used, the reception beam former 129 performs a reception beam forming process on the reception signals supplied from the storage devices 128 of a plurality of channels. For example, the reception beamformer 129 delays the reception signals of a plurality of channels in accordance with the delay time set by the control unit 133, performs phasing processing, and then performs addition or multiplication operation to synthesize the reception signals, thereby obtaining a focus. To generate a new received signal.

  Alternatively, when the receiver 122 includes a delay element, the receivers 122 of a plurality of channels may delay each received signal according to a delay time set by the control unit 133. The reception beamformer 129 combines reception signals by performing addition or multiplication operation on reception signals of a plurality of channels. At the time of reception beamforming, the reception beamformer 129 may perform apodization.

  In addition, by mounting a (multidimensional) fast Fourier transformer on the imaging apparatus main body 120 to obtain the spectrum of the received signal, filtering and beam or wave characteristics (frequency, carrier frequency, bandwidth, etc.) can be performed based on the spectrum processing. , A frequency in any direction, a carrier frequency, a bandwidth in any direction, a waveform, a beam shape, a steering direction, a propagation direction, or the like. It is possible to obtain a plurality of received signals (corresponding to a plurality of different beamformings) from a single received signal by spectral frequency division (see Non-Patent Document 30), and to further perform nonlinear processing on these signals. is there. These processes may be performed on a signal that has been subjected to nonlinear processing.

  In this measurement imaging apparatus, the plurality of wave signals (ones subjected to the non-linear effect or not) which are generated using a single or a plurality of transducers are stored in the storage device 128 or the external storage device 140. In the reception beamformer 129 or the operation unit 130, the results are read out, and addition (superposition, linear processing) and multiplication (non-linear processing) are calculated, and this calculation is sometimes used for imaging and various measurements. In that case, the phasing process is appropriately performed.

  The calculation unit 130 mainly performs digital nonlinear processing on the digital reception signal output from the reception beam former 129. This nonlinear processing may be a power operation for at least one frequency component signal included in the received signal, or may be a multiplication operation for a plurality of frequency component signals included in the received signal. As described above, the calculation unit 130 may also serve as the reception beam former 129. Including that case, while the signals are being processed, the signals being processed may be temporarily stored in the storage device 128 or the external storage device 140, and those signals are read out as needed.

  Here, the transducer 110 to the action device 112 and the receiver 122 to the calculation unit 130 perform nonlinear processing on an arbitrary wave propagating from within the measurement target 1 or a received signal obtained by receiving the arbitrary wave. And a non-linear reception processing unit to be applied. In the non-linear reception processing unit, at least one of the non-linear device 111, the non-linear element 124, and the calculation unit 130 converts an arbitrary wave propagating from within the measurement target 1 or a received signal obtained by receiving the arbitrary wave. Non-linear processing is performed on the data. In other cases, a non-linear effect may be obtained as described above.

  That is, the non-linear reception processing unit performs (i) non-linear processing using the non-linear device 111 at an arbitrary position on the propagation path with respect to the arbitrary wave propagating from the inside of the measurement target 1 and receives the arbitrary wave by the transducer 110. Processing for generating a reception signal may be performed. In addition, the nonlinear reception processing unit generates (ii) an analog reception signal that is received by the transducer 110 for an arbitrary wave propagating from within the measurement target 1 and converts the arbitrary reception signal into, for example, an analog nonlinear signal. A process of performing an analog nonlinear process using the element 124 may be performed. Further, the nonlinear reception processing unit is obtained by (iii) generating an analog reception signal by receiving the arbitrary wave propagating from inside the measurement target 1 by the transducer 110 and digitally sampling the analog reception signal. The digital received signal may be subjected to digital non-linear processing using, for example, the digital operation unit 130. In other cases, a non-linear effect may be obtained as described above.

  The image signal generation unit 131 and the measurement unit 132 select the reception signal output from the calculation unit 130 when performing digital nonlinear processing on the reception signal, and perform reception when not performing digital nonlinear processing on the reception signal. A received signal output from the beamformer 129 is selected.

  The image signal generation unit 131 generates an image signal representing an image of the measurement target 1 based on a reception signal obtained by the non-linear reception processing unit. Alternatively, the image signal generation unit 131 may generate an image signal based on a reception signal that has not been subjected to the non-linear processing, together with a reception signal obtained by the non-linear processing. Further, the image signal generation unit 131 may generate an image signal representing an image of the measurement target 1 by selectively using a reception signal obtained when the non-linear processing is not performed. For example, the image signal generation unit 131 generates an image signal by performing an envelope detection process, a square detection process, or the like on the received signal. The display device 134 generates an image signal representing an image of the measurement target 1 based on the image signal generated by the image signal generation unit 131.

  The measurement unit 132 measures a displacement or the like in the measurement target 1 using at least one of a plurality of signals obtained by the non-linear processing. For example, when observing the propagation of a mechanical or electromagnetic wave, the measuring unit 132 measures a particle displacement or a particle velocity caused by an arbitrary wave propagation of its own wave or another wave based on the measured displacement. In that case, the image signal generation unit 131 generates an image signal representing the wave propagation based on the particle displacement or the particle velocity measured by the measurement unit 132. When a plurality of waves arrive, the measurement may be performed in advance by separating the waves, or through a process of separating the waves by analog processing or digital processing after reception.

  Alternatively, when observing the propagation of a thermodynamic wave, the measuring unit 132 may use an infrared sensor, a pyroelectric sensor, a microwave or terahertz wave detector, a temperature sensor such as an optical fiber, an ultrasonic transducer (ultrasonic) as the transducer 110. Measuring heat wave using temperature dependency such as sound speed and volume change of sound wave) or nuclear magnetic resonance signal detector (detecting temperature using chemical shift of nuclear magnetic resonance) You may. In that case, the image signal generation unit 131 generates an image signal representing the propagation of a thermodynamic wave based on the heat wave measured by the measurement unit 132. The image signal generated by the image signal generation unit 131 and the measurement data obtained by the measurement unit 132 can be stored in the external storage device 140.

  In the above, the non-linear reception processing unit obtains the result of the exponentiation operation by the non-linear processing on the arbitrary wave propagating from within the measurement target 1, or based on the arbitrary wave by the non-linear processing being the exponentiation operation As a result of the chord, the difference sound, and the overtone, a received signal whose frequency is increased or decreased as compared with the reception signal obtained when the non-linear processing is not performed may be obtained. Further, the non-linear processing may be a multiplication operation. The non-linear processing may be a higher-order non-linear processing, and from the effect thereof, mainly obtaining a result of a power operation or a multiplication operation may be performed.

  Accordingly, when the arbitrary wave has a plurality of different frequency components, the received signal has a wider band than the received signal obtained when the nonlinear processing is not performed. Or, a higher-frequency received signal becomes a higher-frequency, higher-spatial-resolution, lower-sidelobe, or higher-contrast harmonic signal compared to a received signal obtained when no nonlinear processing is performed. . Alternatively, the received signal whose frequency has been reduced becomes a signal in a band including direct current obtained by performing substantially orthogonal detection of the harmonic signal. The image signal generator 131 generates an image signal based on at least one signal obtained by the non-linear processing.

  Alternatively, a plurality of arbitrary waves propagating from the inside of the measurement target 1 are transmitted in the measurement target 1 in a propagation direction, a steering angle, a frequency, a carrier frequency, a pulse shape, a beam shape, a frequency or a carrier frequency in any direction, Alternatively, when at least one of the bandwidths is different, the non-linear reception processing unit performs at least one of the processes (i) to (iii) on a plurality of arbitrary waves arriving in an overlapping manner. Is also good. The image signal generation unit 131 generates an image signal based on a reception signal obtained by the non-linear reception processing unit.

  Here, before receiving the plurality of arbitrary waves, the non-linear reception processing unit allows the plurality of arbitrary waves to pass through at least one of the analog delay device and the analog storage device serving as the operation device 112, thereby providing a plurality of arbitrary waves. The waves may overlap at each position in the measurement target 1. This is a so-called aberration correction.

  Further, the nonlinear reception processing unit obtains a result of a power operation by a non-linear process with respect to a superposition of a plurality of arbitrary waves propagating from within the measurement target 1, or the non-linear process is a power operation, Based on a plurality of arbitrary waves, as a result of the chord, the difference sound, and the overtone, a reception signal whose frequency has been increased or decreased as compared with the reception signal obtained when the non-linear processing is not performed may be obtained. This also provides the same effect as described above. The image signal generation section 131 generates an image signal based on at least one signal obtained by the non-linear reception processing section.

  Alternatively, a plurality of arbitrary waves propagating from the inside of the measurement target 1 may cause the propagation direction, the steering angle, the frequency, the carrier frequency, the pulse shape, the beam shape, and the frequency or the carrier in any direction within the measurement target 1. When at least one of the frequency or the bandwidth is different, the nonlinear reception processing unit performs at least one of the processes (i) to (iii) for a plurality of arbitrary waves that overlap with each other. At the same time, the received signal may be separated into a plurality of signals using an analog or digital device or based on analog or digital signal processing at an arbitrary time after receiving a plurality of arbitrary waves. The image signal generator 131 generates an image signal representing the image of the measurement target based on at least one of the plurality of signals separated by the non-linear reception processing unit. In the non-linear operation, a multiplication effect is obtained. Also, after analog or digital aberration correction is performed, those signals may be added again to obtain a power-up effect.

  Alternatively, a plurality of arbitrary waves propagating from the inside of the measurement target 1 are transmitted in the measurement target 1 by a propagation direction, a steering angle, a frequency, a carrier frequency, a pulse shape, a beam shape, and a frequency or a carrier in any direction. Waves that arrive non-overlapping when at least one of the frequencies or bandwidths are different, waves that are shielded and non-overlapping using the working device 112, and devices (analog or digital) or The non-linear reception processing unit may perform at least one of the processes (i) to (iii) on at least one of the waves separated by using analog or digital signal processing. . The image signal generation unit 131 generates an image signal based on a reception signal obtained by the non-linear reception processing unit.

  Here, before receiving the plurality of arbitrary waves, the non-linear reception processing unit allows the plurality of arbitrary waves to pass through at least one of the analog delay device and the analog storage device serving as the operation device 112, thereby providing a plurality of arbitrary waves. The waves may overlap at each position in the measurement target 1. This is a so-called aberration correction.

  Alternatively, the non-linear reception processing section allows the analog reception signal to pass through at least one of the analog delay device and the analog storage device, or delays the digital reception signal by digital operation, or May be passed through a digital storage device so that a plurality of arbitrary waves overlap at each position in the measurement target 1.

  In addition, the nonlinear reception processing unit obtains a result of a power operation by nonlinear processing for each of a plurality of arbitrary waves propagating from within the measurement target 1, or the nonlinear processing is a power operation, Based on each of the arbitrary waves, a chord and a difference sound, and as a result of the overtone, a reception signal whose frequency has been increased or decreased as compared with the reception signal obtained when the non-linear processing is not performed may be obtained. . This also provides the same effect as described above. The image signal generation section 131 generates an image signal based on at least one signal obtained by the non-linear reception processing section.

  Alternatively, the nonlinear reception processing unit obtains a result of a multiplication operation by nonlinear processing for each of a plurality of arbitrary waves propagating from within the measurement target 1, or a plurality of arbitrary Based on the wave, a received signal having a higher frequency or a lower frequency than a received signal obtained when the non-linear processing is not performed may be obtained as a result of a chord and a difference sound or an overtone.

  Accordingly, when a plurality of arbitrary waves have a plurality of different frequency components, the received signal has a wider band than a received signal obtained when the nonlinear processing is not performed. Alternatively, the high-frequency or low-frequency reception signal has higher spatial resolution, lower side lobes, or higher contrast than the reception signal obtained when the non-linear processing is not performed. The signal is substantially orthogonally detected in the direction and includes a direct current, and becomes a signal in a band including a harmonic frequency in at least one other direction. The image signal generator 131 generates an image signal based on at least one signal obtained by the non-linear processing.

  In the above, the image signal generation unit 131 performs an arbitrary detection process on at least one of a plurality of signals obtained by the non-linear process, or performs an arbitrary detection process on a signal obtained by superimposing a plurality of signals. Alternatively, an image signal may be generated by performing an arbitrary detection process on a plurality of signals and superimposing the plurality of signals.

<< 4th Embodiment >>
Next, a fourth embodiment of the present invention will be described. FIG. 40 is a block diagram illustrating a configuration example of a measurement imaging apparatus according to the fourth embodiment of the present invention and its modification. The measurement imaging apparatus according to the fourth embodiment and its modification is an apparatus that drives a plurality of transducers 110 or a transducer array to generate a wave, or receives a wave from them to perform imaging (FIG. 40). Shows a transducer array). As the components, those having the same performance as the components in the third embodiment can be used.

  In the measurement imaging apparatus according to the fourth embodiment shown in FIG. 40A, as in the case where a plurality of transducers 110 or transducer arrays are used in the measurement imaging apparatus according to the third embodiment shown in FIG. A plurality of transducers 110 or elements are connected to a plurality of transmitters 121 or receivers 122, respectively. However, in the imaging apparatus main body 120a, a plurality of transmitters 121 or receivers 122 are provided in one part A ′.

  An addition processing unit adds (linear processing) to the analog received signal which is output from the plurality of transducers 110 or the transducer array and is phased using the delay element in the receiver 122 or is not phased. ), Or the multiplication processing section performs multiplication (non-linear processing, a Hall effect element or the like is used) analog processing. Thus, the reception beam forming is performed, so that the reception beam former 129 (FIG. 39) is unnecessary in the part B.

  Then, the digital reception signal obtained through the AD converter 127 is stored in the storage device 128. The part B of the imaging apparatus main body 120a controls each unit by the control unit 133 based on the received signal in order to obtain all the nonlinear effects that can be realized by the third embodiment. Similarly, imaging and measurement imaging are performed. In FIG. 40, wiring from the control unit 133 to the receiver 122 and the like is omitted.

  In the fourth embodiment as well, similarly to the transmitter and the receiver in the third embodiment, a delay can be given to the drive signal or the received signal of each transducer, and focusing or steering of transmission or reception can be performed. Processing can also be performed. In the fourth embodiment, compared with the third embodiment in which the same number of AD converters 127 and storage devices 128 as the number of channels are required, one AD converter 127 and one storage device 128 are used. The device can be simplified because it can be provided.

  On the other hand, in the measurement imaging apparatus according to the modification of the fourth embodiment shown in FIG. 40B, in the part A ″ of the imaging apparatus main body 120b, the transmission delay element 121a and the reception delay element 122a include the transmitter 121 and the transmission delay element 122a. It is provided outside the receiver 122. The measurement imaging apparatus shown in FIG. 40 (b) is different from the measurement imaging apparatus shown in FIG. 40 (a) in that the reception delay element 122a performs phasing or an unphased analog reception signal. Then, the addition processing unit performs analog processing of addition (linear processing), or the multiplication processing unit performs analog processing of multiplication (nonlinear processing), and then receives the data at the receiver 122. Therefore, since only one transmitter 121 and one receiver 122 need to be provided, the device can be significantly simplified, and the same non-linear effect as in the third embodiment can be obtained.

  The measurement imaging apparatus according to the third embodiment shown in FIG. 39, the measurement imaging apparatus according to the fourth embodiment shown in FIG. 40A, and the modifications of the fourth embodiment shown in FIG. Such metrology imaging devices, or other types of metrology imaging devices, and their components may be used simultaneously. For example, each of the coherent or incoherent image signals and measurement results obtained using a plurality of types of devices can be displayed, can be displayed side by side at the same time, or can be superimposed or multiplied. Things can also be displayed. Basically, signals obtained from received signals at the same time or the same phase can be targeted. Even in the same measurement imaging apparatus, the same processing may be performed when a plurality of image signals and measurement results are obtained using signals received at the same time or at the same time phase. The target signal is an analog signal or a digital signal after phasing, and the addition or multiplication is performed by analog processing (using a Hall effect element or the like) or digital processing (using a computer or a computing unit). .

  The measurement imaging apparatus according to the first or fourth embodiment of the present invention uses a non-linear analog signal, a digital computer, a computer, or a similar device (FPGA, DSP, etc.) of various devices to convert a signal into a nonlinear signal. Based on performing calculations. As will be described in detail later, the non-linear operation mainly focuses on obtaining the effects of exponentiation and multiplication, but the operation itself is not limited to this, and may be a higher-order calculation having other non-linear characteristics. These effects can be extracted and separated through polynomial fitting, spectral analysis, pulse inversion, numerical calculations, or signal processing. Non-linear operations may be performed not only on signals but also on waves, and before reception, waves are extracted using devices (time or space, or filters or spectrometers at those frequencies). And can be separated. Dedicated devices may be available.

  As described above, this measurement imaging apparatus includes the transducer 110 for arbitrary waves, the transmitter 121, and the receiver 122, and includes the nonlinear device 111, the nonlinear element 124, or the calculation unit 130, If necessary, a data storage device (memory, hard disk, photograph, CD-RW, or other recording medium), a display device, and the like are provided. The general-purpose devices can be assembled and configured, and the nonlinear processing of the present invention can be performed on an existing device that does not include the nonlinear device 111, the nonlinear element 124, the arithmetic unit 130, or another nonlinear device. Non-linear processing can also be performed by adding devices to perform.

  As a wave transmitted from the transmitter 121 or the transducer 110 serving as a wave source, a pulse wave, a burst wave, or a coded wave such as a phase modulation is used, and imaging or measurement having a spatial resolution can be performed. is there. However, when measurement is possible without requiring spatial resolution, the present invention is not limited to this, and a continuous wave may be used.

  The generated wave is determined by the conversion characteristic of the transducer 110 from the electric signal (drive signal) to the wave, and an appropriately designed device and drive signal are used. For example, in the case of light waves, various light sources (coherent or incoherent, light emitting diodes (LEDs), light mixing LEDs, (variable wavelength) lasers, optical oscillators, etc.) are used, and in the case of sound waves, electric sources are used as sound sources. An acoustic transducer, a vibrator or the like is used. In the case of a vibration wave, an actuator-based vibration source is used, and in the case of a heat wave, a heat source or the like is used. As described above, in the present embodiment, the transducer 110 that generates various waves can be used.

  The transducer 110 to be used includes a typical transducer when targeting the above-mentioned various waves, and a transducer which is not usually used because of having a nonlinear characteristic can be positively used. Normally, in an ultrasonic element, when a high pressure is applied, an ultrasonic wave including harmonics is generated by a non-linear phenomenon, but harmonic imaging is performed by a pulse inversion method to extract a non-linear component generated in the medium. In some cases, only the signal in the fundamental band is used without filtering out the harmonic components.

  Also in the present embodiment, the nonlinear wave may be actively generated and used. That is, when a non-linear characteristic appears at the time of transmission, the transmitted wave contains harmonics. In the present invention, this may be effectively applied. On the other hand, a wave that does not include a non-linear component is generated to search for a non-linear phenomenon in a measurement object.

  In addition, in a wave having a non-linear component, a non-linear phenomenon may also occur in a higher harmonic. When the transmitted wave originally contains harmonics or when there are a plurality of intersecting waves (frequency, carrier frequency, pulse shape, beam shape, or frequency or carrier frequency viewed in each direction, or bandwidth) May be different, that is, the wave parameters other than the propagation direction and the steering angle are different), as described later, including the pulse inversion method, the spatiotemporal filtering, the spectral filtering, or the polynomial fitting for the received signal. The present invention may be implemented after separation by analog processing or digital processing such as signal processing or the like, or the present invention may be implemented without separation. In the propagation process, a barrier such as an obstacle, a filter device, or a spectroscope (time or space or those frequencies) or a physical stimulus is applied to change the refractive index of the medium (optical Using a switch) or the like, the waves may be received in a state where the waves are separated in advance. If the source of each wave can be controlled, each wave may be generated independently and observed.

  In addition, after a wave is generated in the transducer 110 and before the wave propagates to the measurement target, the wave including a non-linear component can be measured by using a device that causes a nonlinear phenomenon directly to the wave. May be propagated. It is also possible to use a device that causes a non-linear phenomenon after or during propagation in the measurement object. Waves or signals may be combined or mixed to provide a multiplication effect.

  For example, regarding light, (i) a nonlinear optical element (for example, an optical harmonic generation device used for wavelength conversion of laser light into a short wavelength region, etc.), (ii) an optical mixing device, and (iii) optical parametric generation Devices that generate optical parametric effects such as stimulated Raman scattering, coherent Raman scattering, stimulated Brillouin scattering, stimulated Compton scattering, or four-wave mixing; (iv) multiphoton transitions such as ordinary Raman scattering (spontaneous emission Raman scattering) , A device that causes a nonlinear refractive index change, a device that causes an electric field-dependent refractive index change, and the like. Couplers and optical fibers can also be used effectively. It is suitable for multi-point observation (multi-channel) and for signal processing.

  The use of light relates to a wide range of fields, such as optoelectronics, non-linear optical effects, or laser engineering for generating, controlling, or measuring light. Normally used optical devices can be used as the working device 112 and the non-linear device 111, and those realized specifically may be used. These include optical amplifiers (such as photon multi-tubes), absorbers (attenuators), reflectors, mirrors, scatterers, diffraction gratings, collimators, (variable focus) lenses, deflectors, polarizers, polarizing filters, and ND filters. , Deflection beam splitter (separation), shield, optical waveguide (using photonics crystal, etc.), optical fiber, optical Kerr effect device, nonlinear optical fiber, optical mixing optical fiber, modulation optical fiber, optical confinement device, optical memory, coupler (Coupler), directional coupler, distributor, mixer / distributor, spectrometer, dispersion-shifted optical fiber, bandpass filter, phase conjugator (such as by degenerate four-wave mixing or photorefractive effect), and optical control of ferroelectric semiconductor Switches, phase delay devices, phase correction devices, time inverters, optical switches, or optical The coding due disk, etc., some when used alone, sometimes in combination. Also, this is not a limitation. Under optical control (wavelength conversion / switching / routing), optical node technology, optical cross connect (OXC), optical add / drop multiplexing (OADM), optical multiplexing / demultiplexing device, or optical switch element is used, and the device itself is used. May constitute an optical transmission network or an optical network, and optical signal processing may be performed.

  For detection, a CCD camera, a photodiode, a mixed photodiode, or a virtual source (also as a wave source) as described herein can be used. Optical signal processing includes temporal and spatial filters, correlation operations and matched filter processing, signal extraction, heterodyne and superheterodyne (AD can be obtained and demodulated by demodulating low-frequency signals), and homodyne. Vessels may be used.

  In particular, examples of non-linear media include carbon disulfide, sodium vapor, semiconductors such as silicon and gallium arsenide, quantum wells, and organic dyes such as fluorescein and erythrosine. In the case of a crystal such as barium titanate, there is a self-pump that performs four-wave mixing without supplying a pump wave from the outside.

  For other waves such as visible light, infrared light, microwave, terahertz wave, and radiation, each general-purpose device can be used, but a dedicated device may be realized and used. Not only SAW but also devices having a relationship between a vibration system and an electromagnetic system are useful. Also, non-linear devices can be used. Various materials exhibiting nonlinearity in heat conduction include alumina and zirconia synthesis, solder, and layered cobalt oxide. Heat acts on optical devices and can create non-linearities, making it possible to broadly consider their applications.

  The transducer 110 has a contact type and a non-contact type with respect to the measurement target, but an impedance matching device for each wave may be required as an action device. In a measurement space, a matching device may be used between devices in a measurement space, as is the case between devices in an apparatus or in an electric circuit. For example, when observing a living tissue by ultrasonic waves, gel or water is used as a matching material. In an ultrasonic microscope, a sample is often observed on a gantry, but an array type or a mechanical scan type (elements or element arrays move mechanically through a matching material such as water in a housing) Is often realized and used, and it can be easily installed on the sample (the direction can be freely determined, etc.). It is also possible to directly observe in situ or in vivo without cutting out (in vitro). Many ultrasonic microscopes have a fixed type in which the focal position is determined by a lens or the like. This is a particularly good method when such an element or an element array is used. Therefore, the mechanical scan is not limited to the horizontal direction or the elevation direction, and may be movable in the propagation direction. An antenna is used for RF waves, and an electrolyte gel and an electrode, or a SQUID meter or the like is used for observation of a biological tissue potential or a magnetic field, depending on the size of the measurement target. In some cases, a smaller one is used (such as a microscope). The weak signal may not have the nonlinearity, and in such a case, the nonlinearity may be generated in a pseudo manner or a virtual manner. If the nonlinear signal is too weak to be observed, the nonlinearity may be enhanced.

  The nonlinear device may be integrated with the transmitter 121 or the transducer 110, or the nonlinear device may be separately assembled and used. As described above, the nonlinear device can perform a nonlinear operation on a wave itself by using a nonlinear device at an arbitrary position, not only for a signal after reception, including performing a higher frequency or a wider band. it can.

  In addition, when passively observing a wave, the present invention may be applied to a case where a wave source cannot be controlled. The present invention may be applied by using various methods or devices to obtain the signal source position and arrival direction, the signal source intensity, the signal source size and distribution, or the present invention is applied to obtain the signal source and wave In some cases, the location and direction of arrival of the source may be required. At that time, they may be obtained by separating waves and signals, the source and the direction of arrival of the signals and waves may be obtained, and then the waves and signals may be separated, and both are obtained at the same time Sometimes. When the wave source and the direction of arrival are determined, the accuracy of reception beamforming is improved. The signal is subjected to signal processing such as analog processing or digital processing, and a time or space, or a filter or a spectroscope of those frequencies can be used for the wave.

  When receiving a wave transmitted through a medium including an object to be measured by a transducer, the transducer used for transmission may be used for reception (a reflected signal may be observed). On the other hand, a transducer different from the transducer used for transmission may be used for reception. In this case, when the transmitting transducer and the receiving transducer are located near each other (when a reflected signal is observed) or when the transmitting transducer and the receiving transducer are located at different positions (for example, a transmitted wave or a refracted wave is observed). In some cases.

  In addition, the transducer 110 may have a single aperture, or a plurality of transducers 110 may be used in a closely adjacent state in an array (one-dimensional array or two-dimensional array, three-dimensional array). In some cases, a sparse array or a sparse array is used at the same time. There are various types of openings (circular, rectangular, flat, concave, convex, etc.), and their directivities are various. Some elements are integrated with openings in a plurality of directions, and some have multi-directional directivity at the same position. In addition to scalar measurement such as electric potential, pressure, or temperature, there is also one that performs vector measurement such as electromagnetic wave or electric field vector. Some are polarized. Needless to say, even with respect to the same wave, the materials and structures of the elements are various. There are also various arrangements using them, and for example, there is one in which openings are oriented in multiple directions.

  FIG. 41 is a schematic diagram illustrating an example of the arrangement of a plurality of transducers. 41, (a1) shows a plurality of transducers 110 densely arranged in a one-dimensional array, and (b1) shows a plurality of transducers 110 sparsely arranged in a one-dimensional shape. . (A2) shows a plurality of transducers 110 densely arranged in a two-dimensional array, and (b2) shows a plurality of transducers 110 sparsely arranged in a two-dimensional shape. (A3) shows a plurality of transducers 110 densely arranged in a three-dimensional array, and (b3) shows a plurality of transducers 110 sparsely arranged in a three-dimensional shape.

  A beam may be generated or adjusted in an analog manner using a lens or the like at the aperture of the transducer, but may be adjusted by the above-described drive signal. Further, the measurement imaging apparatus according to the present embodiment includes a mechanical scanning device having a maximum of six degrees of freedom (three degrees of freedom in three directions of translation and three directions of rotation), and the mechanical scanning device includes at least one transducer 110 or at least one degree of freedom. By mechanically moving the transducer array in at least one direction, scanning of the measurement target 1, adjustment of the focus position, and steering may be performed.

  On the other hand, when a plurality of transducers 110 are used, transmitters 121 having the same number of channels as the number of transducers 110 are provided to generate as many drive signals as the number of transducers 110 to be driven. Alternatively, by using a group of delay elements to generate a plurality of drive signals from a limited number of generated signals, a desired beamforming (forming a focus at a desired position or steering in a desired direction) ) May be performed.

  Conventional analog or digital beamformers can also be used. In some cases, the above beamforming (including only at the time of reception) is performed in parallel to improve real-time performance when scanning the measurement target.

  At the same time, a plurality of transducers 110 may be driven to perform a plurality of beamformings simultaneously. Alternatively, the beamforming may be performed a plurality of times at different times using different transducers 110 within the time allowed to receive the signals in the same phase, including the case where the transmitter 121 is switched and used. In some cases, the same transducer is subjected to mechanical scanning to perform beamforming a plurality of times.

  In each beam forming, a classical aperture synthesis may be performed including a case where a mechanical scan is performed, and a normal delay-and-summation or a delay multiplication (Delay-multiplication) according to the present invention is performed. -and-Multiplication) (all are monostatic or multistatic). At the time of transmission, a plane wave may be generated without performing focusing, and in that case, a wide area can be observed at once in a short time. At that time, a plane wave may be steered. The wave may be received as a plane wave or may be dynamically focused (when steering during transmission, it is better to steer during reception). A plane wave is a wave of a narrow band in a direction orthogonal to the direction of propagation, and is effective when the band is widened.

  FIG. 42 is a diagram for explaining the form of a wave when a one-dimensional transducer array is used. In FIG. 42, (a) shows the focusing of a wave, and a wave beam narrowed to a focus position determined by the setting of a delay time is formed at the time of transmission or reception. (B) shows the steering of the wave, and a wave beam deflected in a direction determined by the setting of the delay time is formed at the time of transmission or reception. (C) shows transmission or reception of a plane wave, and a plane wave directed in a direction determined by the setting of the delay time is formed. A plane wave is a wave of a narrow band in a direction orthogonal to the direction of propagation, and is effective when the band is widened.

  Before the reception by the transducer 110, the waves are passed through at least one of the analog delay device and the analog storage device, so that a plurality of waves overlap at each position in the measurement target 1. is there. Also, passing an analog signal obtained after reception by the transducer 110 through at least one of an analog delay device and an analog storage device, or delaying a digitally sampled digital signal obtained after reception by digital operation, Alternatively, a plurality of waves may be caused to overlap at each position in the measurement target through passage through a digital storage device. The so-called phase aberration correction may be performed as described above, or may be performed in connection with the phasing of the beam forming. There are various devices. For example, in light, an optical fiber also serves as a delay line, and an optical confinement device also serves as a delay device or a storage device.

  On the other hand, a signal subject to a strong nonlinear phenomenon may be observed as a result of propagating through the measurement object, but a non-linear component may not be obtained. Generally, when the intensity of the wave is strong, the nonlinear phenomenon is easily observed, and when the intensity is weak, the nonlinear phenomenon is hard to be observed. In any case, the present invention can be implemented. The received signal may be separated into independent signals by performing appropriate signal processing or the like, and the present invention may be implemented.

  For separation of signals, analog devices of various waves (time or space, or filters or spectrometers of those frequencies, etc.) may be used, and based on signal processing, analog processing or digital processing ( Decoding process for the above coding, process of obtaining the center of gravity of spectrum through spectrum analysis, process of obtaining analysis signal to obtain instantaneous frequency, MIMO, SIMO, MUSIC, or independent signal separation process. is there. In the passive case, using various methods or devices, signal source position and direction of arrival, signal source intensity, signal source size and distribution may be processed, and the present invention has been implemented. Later, the signal source position and the direction of arrival may be determined. At the same time as beamforming, the position and arrival direction of the signal source, the intensity of the signal source, and the size and distribution of the signal source may be obtained. As will be described later in detail, the signal may be accurately separated in a situation represented by a harmonic by performing a non-linear process. Specifically, after performing a high frequency and wide band (when the order is greater than 1) by a power operation, or a low frequency and narrow band (when the order is less than 1) processing, in the frequency domain May be performed with high accuracy. Restoration of the signal after separation may be performed simply by raising it to the reciprocal power of the power order used.

FIG. 43 is a diagram showing angles of beam directions and wave arrival directions in the spatial domain and frequency domain in the case of two-dimensional measurement and the center of gravity of the spectrum. In FIG. 43, (a) shows the beam direction angles θ1 and θ2 of the beam 1 and the beam 2 at the point of interest (x, y) in the spatial domain. (B) shows the center of gravity of the spectrum of beam 1 and beam 2 and the instantaneous frequency (fx, fy) of beam 1 in the frequency domain. In the present invention, such an instantaneous frequency of the independent frequency coordinate axis or a vector having a center of gravity of a local or global spectrum as a component may be referred to as an instantaneous frequency vector or a center of gravity frequency vector. In this case, it is represented as (fx, fy, fz). In the spatial domain, the signal of the wave is represented in a two-dimensional or three-dimensional Cartesian rectangular coordinate system or a polar coordinate system or a rectangular curve coordinate system, and the spectrum obtained by the Fourier transform in each rectangular coordinate system is composed of frequency coordinates of the coordinate axes. It is represented by a two-dimensional or three-dimensional Cartesian or polar or orthogonal curve coordinate system in the frequency domain, in which an instantaneous frequency vector or a centroid frequency vector is used. In addition, it is not possible to change the rectangular coordinate system in the space domain and the frequency domain, or to change the coordinate system in the same domain without the interpolation approximation process by the Fourier transform or the inverse Fourier transform through the Jacobi operation described in paragraph 0405. Useful (high accuracy). As described elsewhere, in addition to the arrival direction of the wave, the direction and position of the wave source, the propagation direction of the generated wave and beam, the steering angle of transmission and / or reception, and the like can be obtained. . The beam 1 or the beam 2 may correspond to the wave of the grating lobe or the side lobe. As a method of measuring the displacement vector and the displacement, a multidimensional cross-spectral phase gradient method, a multidimensional cross-correlation method, a multidimensional autocorrelation method, a multidimensional Doppler method, and a method of making them one-dimensional are useful. When using other methods except the cross-correlation method, it is possible to obtain a measurement result by changing a coordinate system through a Jacobi operation in a Fourier transform for obtaining a spectrum or an inverse Fourier transform for obtaining an analysis signal. However, when the cross-correlation method is used, a measurement result can be obtained by changing the coordinate system in the spatial domain by the above-described method using the Jacobi operation.
By the way, if the element pitch in the array type sensor is coarse, beam forming is performed by receiving a signal in which aliasing has occurred in the element array direction (original digital space). In the signal, the signal in the folded band is removed by filtering. When the element width is reduced and the element pitch is shortened as described above, a wide band in the horizontal direction can be obtained as can be confirmed from the angular spectrum, and a signal having a wide band in the horizontal direction can be generated by beam forming, but the same applies when aliasing occurs. Need to be processed. These processes are required for all beamforming processes. Since a beamforming signal can be generated within the signal band of the angular spectrum of the received raw signal, a steering angle that can be realized using the element array can be confirmed.

  Basically, beamforming is performed in an analog manner with respect to a wave, or when a plurality of transducers 110 are used, beamforming (focusing or steering) is performed. As described above, beam forming may be performed after signal separation, but signal separation may be performed after beam forming.

  In addition, when performing aperture plane synthesis processing, it is possible to generate focusing signals at different positions and steering signals in different directions from the same received signal set (Delay-and-Summation or Delay based on the present invention). -and-Multiplication). Also, the present invention can be implemented on those generated signals. The transmitter 121 and the receiver 122 may be an integrated type or a separated type.

  There are various types of non-linear elements 124, and a diode or a transistor can be used for an electric analog signal after being received by the transducer 110. In addition, any non-linear element that applies a non-linear phenomenon to a signal by a circuit can be used, including one that applies a superconducting phenomenon. Also, a nonlinear element of a distributed constant system can be used. An appropriate one is used according to the frequency of the wave (signal). Waves or signals may be appropriately gain-adjusted using various amplifiers or attenuators.

  The non-linear operation may be performed using a non-linear device that causes non-linear phenomena directly on the wave before receiving at the transducer 110. For example, regarding light, the above-mentioned (i) nonlinear optical element, (ii) light mixing device, (iii) optical parametric effect, (iv) multi-photon transition such as ordinary Raman scattering (spontaneous emission Raman scattering), (v A) a non-linear refractive index change, or (vi) an electric field dependent refractive index change, etc. can be used. For other waves, non-linear devices can be used as well. The non-linear devices may be integrated with the transducer 110, or the non-linear devices may be separately assembled and used. Further, the nonlinear phenomenon itself at the time of converting a wave into an electric signal in the transducer 110 used at the time of reception may be used.

  In any of the above cases, there is a case where an analog operation (non-linear processing) is performed on the wave itself and a case where an analog operation is performed on a signal after reception. A signal may be subjected to a non-linear operation using a computer, a computer, or a similar device (eg, an FPGA or a DSP).

  Regarding the measurement imaging apparatus according to one embodiment of the present invention, when it is referred to as an analog type, it means that the operation is performed by analog processing as described above. For example, an analog signal subjected to a non-linear effect is converted into a CRT display or an oscilloscope (analog). Or digital) and recorded on a storage medium such as a photograph (analog or digital) or holography as necessary. Alternatively, the data may be digitized through AD conversion, recorded on a digital data storage medium such as a memory, a hard disk, or a CD-RW as necessary, and displayed using a display device.

  On the other hand, when it is referred to as a digital type, it includes a case where an analog signal is AD-converted after appropriate analog processing (gain adjustment and filtering) and the signal is stored in a memory or a hard disk as a recording medium. The data is stored in a data storage device (such as the above-mentioned photograph or digital recording medium) as necessary, and is displayed on a display device.

  In the above configuration, the received signal may include a non-linear phenomenon in the object to be measured.In such a case, the effect can be enhanced by using the above-described analog device or digital device. In a received signal that does not include a non-linear effect, it is possible to newly generate a non-linear effect, simulate the non-linear effect, or virtually realize the non-linear effect. In some cases, a nonlinear effect (harmonic component) generated in the measurement target and a nonlinear component (harmonic component) generated in the signal source are separated from the effect of the nonlinear operation. Exceptionally, the above devices and signal processing may be used to separate the former two non-linear effects (non-linear components), including cases where non-linear operations are not performed.

  In the above description of the measurement imaging apparatus, a case where a transducer (transducer) for a wave to be observed is used has been described. For example, propagation of an oscillating wave is optically performed based on laser Doppler or optical image processing. It can be observed, and the propagation of a shear wave that becomes dominant as a low-frequency vibration wave in human tissue can be observed using the Doppler effect of ultrasonic waves, which are also vibration waves.

  Further, it is also possible to optically capture the propagation of sound such as audible sound waves and ultrasonic waves. The optical process is a process for generally processing an electromagnetic wave, and includes radiation such as X-rays. Audible sound waves may be observed using ultrasonic waves. The heat wave can also be observed by using an infrared camera based on radiation, a change in sound speed of a microwave, a terahertz wave, or an ultrasonic wave, a change in a volume of an object, a chemical shift of nuclear magnetic resonance, or an optical fiber. This is based on coherent signal processing or incoherent processing such as image processing. The case where the behavior of the wave of interest can be observed using other waves is not limited to these, and in any case, the measurement result is an analog signal or a digital signal. Therefore, the present invention can be implemented also for those observed waves (signals). In addition to the Doppler effect, it may be interpreted that the physical property of the medium is modulated by the wave of the observation target, and the wave used for sensing is modulated. In these cases, a process of detecting a wave subjected to the Doppler effect or modulation is useful. In particular, electromagnetic waves can easily observe waves propagating in various directions by applying polarized waves, and can easily grasp structures having various directions. On the other hand, sound waves also allow various measurements based on divergence as described in the present specification. Radiation measurement is also important. Various remote sensings are performed using microwaves in addition to temperature distribution measurement. For example, scattering and attenuation are measured, and distributions of raindrops, moisture, air pressure, and the like are measured. Even in such a case, it is effective to obtain a high spatial resolution by various processes such as the beam forming described in the specification of the present application, and in particular, an effect that a desired position can be observed at high speed is obtained. It is possible to obtain an effect that any surface, area, and space can be observed directly and at high speed, without depending on image processing after generating the image.

  In the above description of the measurement imaging apparatus, the electromagnetic wave, the vibration including sound, the heat wave, or the nonlinear operation device of the signal corresponding thereto have been described, but the nonlinear effect between different types of physical energies is enhanced. Simulating or simulating a non-linear effect, or virtually realizing a non-linear effect (ie, producing a non-linear effect other than physically, chemically, or biologically). Is not possible), in which case the signals received at different times by simultaneously using the devices for the different types of waves used, or if they are in phase, The present invention can also be implemented on the basis of. That is, the present invention can handle a case where a plurality of types of waves are simultaneously generated and a case where one type of a wave is generated alone.

  In addition, in vibrations and heat waves including electromagnetic waves and sounds, if the frequency is different, the dominant behavior differs depending on each measurement object (medium), and the name is different (it may be considered that the type is different). For example, regarding electromagnetic waves, microwaves, terahertz waves, radiation such as X-rays and the like exist, and regarding vibration, when targeting human soft tissues, shear waves do not propagate as waves due to the effect of attenuation in the mega-Hz band. Ultrasonic waves are dominant, but at low frequencies such as 100 Hz, incompressible characteristics are strong, and shear waves are dominant.

  The present invention can enhance the non-linear effect between waves having different behaviors, simulate the non-linear effect, or virtually realize the non-linear effect. In this case, the present invention can be implemented based on signals received at different times when waves are received by using a plurality of types of wave-related devices at the same time. Of course, there is a limitation that phenomena such as attenuation, scattering, reflection, refraction, or diffraction of the waves have dispersion characteristics and must be appropriately used in consideration of the SN ratio of the received signal. However, the application range of the present invention is very wide, including the ability to physically generate high-frequency components and to generate high-frequency components that cannot be captured.

  In the case where the nonlinear effect in the measurement object is actively observed, and in the case where the nonlinear processing according to the present invention is actively performed, the two can be switched and used, or both can be used at the same time. In some cases, non-linear effects in the measurement object are clarified through the calculation.

  Next, an embodiment in which the present invention is applied to an ultrasonic echo signal using the configuration of the above measurement imaging apparatus will be described. Generation of harmonics in the ultrasonic wave propagation process is represented by multiplication or exponentiation. In particular, chords and difference tones are represented by multiplication of waves having different propagation directions or different frequencies (see Non-Patent Document 27), and harmonics are generally represented by powers of waves of the same frequency (see Non-Patent Document 27). See Non-Patent Document 25). As a physical phenomenon, it tends to occur when the intensity of the wave is large. The wave distortion has an effect of increasing with the propagation of the high-intensity component, but is more susceptible to attenuation during the propagation than the fundamental wave. On the other hand, when the intensity is not so strong, only superposition (sum or difference) is strongly observed as wave interference, and a lateral modulation method developed by the inventor of the present application is applied to this. (See Non-Patent Documents 13 and 30).

  FIG. 44 is a diagram showing two deflection beams used in the lateral modulation method in a two-dimensional space. In FIG. 44, the horizontal axis indicates the horizontal position y, and the vertical axis indicates the depth position x. Here, two typical examples are a case where beamforming is performed in an arbitrary direction (direction of the angle θ in the drawing) and a case where lateral modulation is performed using an arbitrary direction as an axis (X axis). For two cases, the effect of the non-linear operation after receiving beamforming is confirmed. This calculation can be easily extended to a three-dimensional space, and it can be confirmed that a similar effect can be obtained in a three-dimensional space. In the following, “λ” is a wavelength corresponding to the center frequency of the ultrasonic wave. Further, the distance x in the depth direction and the distance y in the lateral direction are represented by the time t until the ultrasonic wave transmitted from the origin is reflected at a certain point and returned to the origin, and the ultrasonic wave propagates at time t / 2. Represents distance.

<0> lateral modulation: superposition of two beams or waves (plane waves, etc.) in the angles θ ₁ and θ ₂ (simultaneous transmission / reception or superposition of each transmission / reception)
The superposition (addition, or sum) of two RF echo signals having the same carrier frequency or instantaneous frequency or local or global center of gravity frequency is represented by the following equation.
A (x, y) cos [2π (2 / λ) (xcosθ ₁ + ysinθ ₁ )]
+ A '(x, y) cos [2π (2 / λ) (xcosθ ₂ + ysinθ ₂ )] ・ ・ ・ (0 ′)

Here, assuming that the reflection or scattering is equal and A (x, y) = A ′ (x, y), the coordinates consisting of the X axis in the central direction of the propagation direction of the two waves and the Y axis orthogonal thereto. In (X, Y), the superposition of two RF echo signals is represented by the following equation.
A (x, y) cos {2π (2 / λ) cos [(1/2) (θ ₂ −θ ₁ )] X}
× cos {2π (2 / λ) sin [(1/2) (θ ₂ −θ ₁ )] Y} (0)
As described above, the lateral modulation is realized in the (X, Y) coordinate system. In order to generate a laterally modulated image signal having independent frequencies in the orthogonal X and Y directions, it is necessary to generate two waves having the same carrier frequency or instantaneous frequency of the wave itself or a local or global center of gravity frequency. Yes. However, in the displacement vector measurement, the two waves may have different frequencies. For example, in the following <2> and <3>, non-linear processing is performed on this. In the case of performing lateral modulation in a three-dimensional space, there are two directions for modulation, and therefore it is necessary to similarly generate at least three cross beams (see Non-Patent Documents 13 and 30).

<1> Calculation of the power of one beam or one wave in the θ direction The RF echo signal is represented by the following equation.
A (x, y) cos [2π (2 / λ) (xcosθ + ysinθ)]
In this case, for example, the square is represented by the following equation (51).
(1/2) A ² (x, y) × {1 + cos [2π (2 · 2 / λ) (xcosθ + ysinθ)]} (51)
In this way, the second harmonic component is generated at the same time as the DC component, and the baseband signal is obtained at the same time (the envelope signal is also directly obtained). The calculated squared echo signal has a wider bandwidth than the spectrum of the fundamental wave, a shorter pulse length and a shorter beam width, and a higher spatial resolution due to the effect of the product of different frequencies in the band.

As yet straightforward, for example, when having an RF echo signal frequencies f ₁ and f ₂ at the position in the depth direction x, the calculation of the square, the square echo signal is expressed by the following equation.
e _I (x; f ₁ , f ₂ ) ² = e _II (x; 0,2f ₁ , 2f ₂ , f ₁ + f ₂ , f ₁ -f ₂ )
Thus, squared echo signal includes a DC (frequency 0) will have a signal component of the frequency _{2f 1, 2f 2, f 1} + f 2, f 1 -f 2.

  That is, those signals generated by the exponentiation operation, when the wave has a plurality of signal components of different frequencies, the plurality of different frequency signal components compared to the wave received when the nonlinear operation is not performed. It has been broadened in the direction it has, and the harmonics are higher in frequency, higher in spatial resolution, or lower in side lobe, or higher than the waves received when the non-linear operation is not performed. A signal that has obtained at least one effect of contrast enhancement, and a signal (baseband signal) generated in a band including direct current is a signal obtained by substantially quadrature detection of a harmonic, and at least one of these signals obtained through a non-linear operation is obtained. Waves can be imaged based on one.

  When a higher power is calculated, a signal component having a frequency n times higher than the fundamental wave is obtained by the nth power, and the spatial resolution is further increased. Strictly speaking, the baseband signal is different from a signal obtained by quadrature detection of the second harmonic (ordinary baseband signal), and the calculation result includes a pure DC signal. A high-resolution image can be easily obtained as compared with the echo image. Note that the DC component generated by the non-linear operation is obtained from the intensity of a high frequency, a low frequency, a harmonic, and the like generated at the same time, and the DC component included in the baseband signal is basically excluded. Occasionally, the calculation may be simplified to remove all DC in the baseband signal. By this processing, it may be possible to perform imaging to a deeper portion than in the case where a direct current is included, without performing luminance adjustment depending on the depth.

  According to the theorem of multiplication or division, harmonic signals and low-frequency signals are represented in various forms (four arithmetic operations of sine and cosine waves), and when necessary, digital Hilbert transform (Non-patent Document 13) See). Measured harmonics can also be used. These are obtained by calculating a nonlinear signal at each position with respect to a wave of an arbitrary intensity. Unlike a nonlinear component that is physically accumulated in the propagation process and is affected by attenuation, a new harmonic or low-frequency signal is obtained. It realizes frequency imaging.

<2> Calculation of power of transverse modulation echo signal For example, the square of equation (0) is represented by the following equation (52).
A (x, y) ² × cos ² {2π (2 / λ) cos [(1/2) (θ ₂ −θ ₁ )] X}
× cos ² {2π (2 / λ) sin [(1/2) (θ ₂ −θ ₁ )] Y}
= A (x, y) ² × [1 + cos {2π (2 · 2 / λ) cos [(1/2) (θ ₂ −θ ₁ )] X}
+ Cos {2π (2 · 2 / λ) sin [(1/2) (θ ₂ −θ ₁ )] Y}
+ Cos {2π (2 · 2 / λ) cos [(1/2) (θ ₂ −θ ₁ )] X}
× cos {2π (2 · 2 / λ) sin [(1/2) (θ ₂ −θ ₁ )] Y}] (52)
In this way, a DC (the above-described baseband signal), two signals of the second harmonic detected in different directions, and a laterally modulated signal of the second harmonic are obtained. As in <1>, higher resolution is also performed. The baseband signal and other high-order harmonic signals can be calculated in the same manner as in <1>.

As an easy-to-understand example, the cross-echo signal at the position (x, y) is e ₁ ((x, y); (f ₀ , f ₁ )) and e ₂ ((x, y); (f ₀ , f ₂ )), and when symmetric in the y direction, the squared signal of the superimposed signal is represented by the following equation.
[e ₁ ((x, y); (f ₀ , f ₁ )) + e ₂ ((x, y); (f ₀ , f ₂ ))] ²
= E ₁ ((x, y); (f ₀ , f ₁ )) ² +2 e ₁ ((x, y); (f ₀ , f ₁ )) e ₂ ((x, y); (f ₀ , f ₂ )) + e ₂ ((x, y); (f ₀ , f ₂ )) ²
= E ₁ '((x, y); (0,0), (2f ₀ , 2f ₁ )) + e ₁₂ ' ((x, y); (2f ₀ , 0), (0,2f ₁ ), (0,2f ₂ ))
+ E ₂ '((x, y); (0,0), (2f ₀ , 2f ₂ ))
Thus, the squared signal of the superimposed signal has the frequencies (0,0), (2f ₀ , 2f ₁ ), (2f ₀ , 2f ₂ ), (2f ₀ , 0), (0,2f ₁ ), (0,2f ₁ ) 0,2f ₂ ).

  That is, those signals generated by the exponentiation operation are a harmonic signal of each of the linearly superimposed signals (a signal corresponding to the crossed waves) and a baseband signal (a band of at least one direction including DC). Signal), and when the wave has a plurality of different frequency signal components, the band is broadened in the direction having the plurality of different frequency signal components as compared with the received wave when the nonlinear operation is not performed. Yes, the harmonic is at least one effect of higher frequency, higher spatial resolution, lower side lobe, or higher contrast than the corresponding wave received when the non-linear operation is not performed. The baseband signal is a signal obtained by quadrature detection or substantially quadrature detection of harmonics in each direction or plural directions, and at least one of those signals is obtained. Based on, it is possible to image the wave. If the same processing is performed when the intersecting waves or beams have different frequencies or are not symmetrical with respect to the coordinate axes, chords and difference tones can be obtained in a multidimensional space. Used for They also work in situations where other parameters are different.

  In three-dimensional space, lateral modulation requires the generation of at least three crossed beams, as described above, in which case the resulting basebanded signal is similarly approximately harmonic of each beam. In addition to the orthogonally detected signal (a nearby signal including direct current), a signal that is orthogonally detected only in one arbitrary direction or arbitrary two directions is obtained. That is, since the polarity of the frequency in the symmetric direction is opposite to the axis (or plane) to be symmetric, the sum thereof is zero. All waves and beams may be generated symmetrically with respect to the coordinate axis, but not limited thereto. Also, the frequency and other parameters may be different.

<3> Multiplication of two waves of the transverse modulation echo signal For example, since the two waves in the expression (0 ′) can be handled separately, when considering the product, in order to show an easy-to-understand expression, the propagation direction is x If two directions are symmetrical with respect to the axis, θ ₁ = −θ ₂ , and the multiplication (product) of the two RF echo signals is represented by the following equation (53).
A (x, y) cos [2π (2 / λ) (xcosθ ₁ + ysinθ ₁ )]
× A '(x, y) cos [2π (2 / λ) (xcosθ ₁ −ysinθ ₁ )]
= A (x, y) A '(x, y) × {cos [2π (2 · 2 / λ) cosθ ₁ x]
+ Cos [2π (2 · 2 / λ) sin θ ₁ y]}
As a result, two signals of the second harmonic detected in different directions are obtained. These are the signal components obtained also in the equation (52).

As an easy-to-understand example, the cross-echo signal at the position (x, y) is e ₁ ((x, y); (f ₀ , f ₁ )) and e ₂ ((x, y); (f ₀ , f ₂ )) and when symmetric in the y-direction, the signal multiplication is represented by the following equation:
e ₁ ((x, y); (f ₀ , f ₁ )) × e ₂ ((x, y); (f ₀ , f ₂ ))
= E ₁₂ '((x, y); (2f ₀ , 0), (0,2f ₁ ), (0,2f ₂ ))
Thus, it can be seen that the multiplication of the signals has signal components of the frequencies (2f ₀ , 0), (0,2f ₁ ), (0,2f ₂ ).

  That is, the signal generated by the multiplication operation is a baseband signal (a signal in a band including DC in at least one direction) with respect to each of the linearly superposed signals (signals corresponding to crossed waves), If the wave has a plurality of different frequency signal components, the band is broadened in the direction having the plurality of different frequency signal components compared to the wave received when the nonlinear operation is not performed, and the baseband signal Are higher harmonics, higher spatial resolution, or lower side lobes, or higher harmonics that have at least one effect of higher contrast than the corresponding waves received when no nonlinear operation is performed. It is a signal obtained by orthogonally detecting a wave signal in each direction or a plurality of directions, and a wave can be imaged based on at least one of the signals. If the same processing is performed when the intersecting waves or beams have different frequencies or are not symmetrical with respect to the coordinate axes, chords and difference tones can be obtained in a multidimensional space. Used for They also work in situations where other parameters are different.

  In three-dimensional space, the transverse modulation needs to generate at least three intersecting beams, as described above, in which case the resulting base banded signal is only in any one direction or any two A signal orthogonally detected in the direction is obtained. That is, since the polarity of the frequency in the symmetric direction is opposite to the axis (or plane) to be symmetric, the sum is zero. All waves and beams may be generated symmetrically with respect to the coordinate axis, but not limited thereto. Also, the frequency and other parameters may be different.

  In addition, in addition to the case where the propagation direction and steering angle of each beam and wave are different as in the above-mentioned cross beam, other parameters are different, for example, frequency, carrier frequency, pulse shape, beam shape, frequency viewed in each direction Or carrier frequency or bandwidth may be different. In addition, unlike in the case of generating two (two or three) intersecting waves or beams in the two-dimensional case and three (three) in the lateral modulation, in each dimension, , More waves or beams may be used. In particular, when a plane wave, a cylindrical wave, or a spherical wave is transmitted, high-speed transmission / reception is possible. Even when a plurality of waves are used, the speed is higher than that of beam forming in normal imaging. Also, when using a focusing beam, high-speed beamforming using the fast Fourier transform can be performed on the superimposed received signal. High-speed processing (interpolation approximation may be performed in wave number matching as described above). It is also effective to perform transmission and reception a plurality of times with the same parameters and to superimpose them (addition averaging) in order to stabilize the nonlinear processing. In addition, the same processing as described above can be performed on a signal received when so-called pulse inversion transmission is performed, and harmonics obtained by superimposing received signals at the time of pulse transmission with different polarities are obtained. And the same processing can be performed before superimposing. When these superpositions (that is, addition) are performed, a harmonic having a frequency that is an even multiple of the frequency of the fundamental wave is obtained. It is also important to use them for imaging (just subtraction of the pulse inversion received signal will mainly yield the third harmonic). When superposition of a harmonic signal is determined using the present invention with respect to a signal which is band-limited by a transducer band or aggressively applying an analog or digital filter during reception, filtering (analog or digital) is performed. ), Or by performing signal processing (analog or digital) with various superpositions or fundamental waves, harmonics can be separated. Further, instead of pulse inversion, a signal having a phase difference other than 180 ° may be transmitted. However, the present invention can be applied to such a case. In other words, even in a beam or wave in which at least one of the parameters is different, the same non-linear effect can be obtained in a superimposed state, a separated state, a non-superimposed state, etc., and is effectively used. Sometimes. It can be understood from the theory or calculation that waves and beams generated by not only linear effects but also non-linear effects can be designed (wave and beam parameters such as the propagation direction) and controlled.

  Harmonic signals, chords, difference tones, overtones, and the like generated by these non-linear operations have the above characteristics and improve the image quality of echo imaging. There is no influence of attenuation that occurs in normal harmonic imaging. The present invention is also effective for interpreting a physically generated nonlinear signal that virtually generates a nonlinear component at each position. Further, the present invention is also effective when observation is not possible due to weakness. Furthermore, in displacement measurement, higher frequency is welcomed and phase rotation is faster, so it is expected that high-precision measurement will be possible. However, when high spatial resolution was measured as it was, noise tended to increase.

  In such a case, the regularization (for example, see Non-Patent Document 18), the weighted least square method through the above-described statistical evaluation, the averaging process, and the like are effective. For example, two signals of the second harmonic detected in different directions obtained in <2> and <3> may be used for displacement measurement in each direction using a normal one-way displacement measurement method. Can be. In order to measure a displacement or a displacement vector generated between different time phases, for a signal having a carrier frequency in only one arbitrary direction, at each point of interest, the change in the instantaneous phase generated between the time phases is determined by the instantaneous frequency and the center-of-gravity frequency. Alternatively, the displacement in that direction can be measured by dividing by a nominal frequency or the like, and further, a displacement vector can be synthesized based on the measurements in different directions. In the past, although the calculation amount required was larger than that of the multidimensional autocorrelation method (see Non-Patent Document 13), the digitalization of the transverse modulation echo signal was performed to realize the displacement vector measurement using the normal one-way displacement measurement method. A demodulation method was devised and reported (a product of a analytic signal and a conjugate product are calculated: see Non-Patent Document 30, etc.). According to the present invention, the transverse modulation echo signal can be demodulated with a small amount of memory and a small amount of calculation at each stage, and the obtained signal is a harmonic signal. In addition, when a plurality of the same waves can be obtained in the same condition, the noise can be averaged after performing the received raw signal or the non-linear processing after the reception, and the received raw signal or It is effective to reduce by performing integration processing after performing non-linear processing after reception. In addition, instead of exponentiation or multiplication, a square norm or inner product can be calculated. In this case, the spatial resolution is determined by the signal length in the calculation. These methods may be effective in imaging other than displacement measurement.

The digital demodulation method described in Non-Patent Document 30 invented by the inventor of the present application specifically derives a phase determined only by a displacement component in each direction, and obtains a displacement component in each direction. As described below, for example, when measuring a two-dimensional displacement vector (dx, dy), the instantaneous phase difference (change) between two different time phases at a certain point in the two-dimensional region of interest is determined by two cross beams. Alternatively, the complex autocorrelation signals exp [j (fxdx + fydy)] and exp [j (fxdx-fydy)] (Non-Patent Document 13) using the spectra of two independent single quadrants generated by waves. Multi-dimensional complex auto-correlation signal in the case of using the auto-correlation method of, or a corresponding multi-dimensional complex signal in the multi-dimensional Doppler method of Non-Patent Document 13 may be, in the following, "complex auto-correlation signal", Or simply "complex signal") Since they are expressed as phases, their products and conjugate products are calculated to obtain exp [j (2fxdx)] and exp [j (2fydy)], and the instantaneous phase difference 2fxdx and 2fydy in each direction is calculated as The unknown displacement vector (dx, dy) is obtained by dividing by the instantaneous frequencies 2fx and 2fy in the direction (as shown in FIG. 8B of Patent Document 7, the combination of the spectra of two independent single quadrants is There are others). When measuring the three-dimensional displacement vector (dx, dy, dz), exp [j (fxdx + fydy + fzdz)], exp [j () of the complex autocorrelation signal obtained from four or at least three cross beams or waves. fxdx + fydy-fzdz)], exp [j (fxdx-fydy + fzdz)], exp [j (fxdx-fydy-fzdz)] (a multidimensional complex autocorrelation signal when using the autocorrelation method of Non-Patent Document 13, Alternatively, the corresponding multi-dimensional complex signal in the multi-dimensional Doppler method of Non-Patent Document 13 may be used, and the same shall apply hereinafter. There are other spectral combinations of three or four independent single orctants). A method of estimating an instantaneous frequency from a wave signal based on the autocorrelation method and the Doppler method is described in detail in Non-Patent Document 13. When based on the auto-correlation method, the signal at the position of interest of the time phase of interest and the next time phase of the complex analytic signal (spectrum of a single quadrant or orctant) in at least two or more different time phases. After calculating the instantaneous phase difference (change) from the signal at the position of interest (coarse phase matching is often performed through a cross-correlation method, a cross-spectrum phase gradient method, etc.), The instantaneous phase difference between the same signal at the position of interest in the time phase and the signal at the previous position (for example, the next sampling position) in the direction in which the instantaneous frequency is to be determined for the same position of interest in the next time phase is determined. , The difference between the instantaneous phases (corresponding to the forward difference) is calculated, and the distance (1) between the position of interest in the next time phase and the position spatially ahead is calculated. In the case of using the signal of the previous sampling position, it is effective to divided by the direction of the sampling interval). Instead of the signal of the next time phase, the signal of the previous time phase may be used, and the signal of the rear position in the direction in which the instantaneous frequency is desired to be compared with the position of interest may be used (corresponding to the rear difference). In the case of the Doppler method, in the complex analytic signal of each time phase (the spectrum of a single quadrant or an actant), the position of the position ahead in the direction in which the instantaneous phase and the instantaneous frequency of the position of interest are to be known is determined. It is effective to similarly determine the difference from the instantaneous phase of its own signal and divide by the distance between those positions. The instantaneous phase difference between two complex signals is obtained by applying the inverse tangent function to the imaginary number of their conjugate product divided by the real number, and directly to the imaginary number of each complex signal divided by the real number. An inverse tangent function may be applied to obtain each instantaneous phase, and the difference between them may be calculated. In order to stabilize the estimated value of the instantaneous frequency, a moving average can be applied in the time direction, a moving average can be applied in the spatial domain (multidimensional moving average is effective), and simultaneously performed in the time direction and the spatial direction. Yes (multi-dimensional moving average). When multidimensional moving average is applied, applying the inverse tangent function to the imaginary number of the conjugate product between two complex signals divided by the real number is performed between the local multidimensional complex signals (one of which is conjugate). The tangent inverse function is applied to the imaginary number of the inner product of the complex signal divided by the real number, and the inverse tangent function is applied directly to the imaginary number of each complex signal divided by the real number. This is multidimensional moving average. The method of applying the moving average is also described in detail in Non-Patent Document 13, but the method of estimating the instantaneous frequency is not limited thereto. For example, when estimating the instantaneous frequency based on the autocorrelation method, for two or more time phases, the position of interest in the signal of the time phase of interest and the signal of the next time phase and / or the signal of the previous time phase are used. Along with the difference of the instantaneous frequency from the position of interest, the spatial position in the direction in which the instantaneous frequency is desired to be obtained for the position of interest in the signal of the time phase of interest and the position of interest in the signal of the next time phase and / or the previous time phase. Similarly, two or more instantaneous phase differences from the forward and / or backward positions are similarly obtained, and the least squares method is applied to the distribution of the instantaneous phase difference to estimate the slope of a linear function having an intercept. Is also good. When the Doppler method is used, two or more instantaneous phases at positions ahead and / or behind the position of interest spatially with respect to the position of interest in the signal of each time phase are similarly obtained, The distribution of the instantaneous phases may be subjected to the least-squares method, and may be estimated as the slope of a linear function having an intercept. In these processes, a process including a moving average in the time direction may be performed.
For example, the digital signal processing unit 33 shown in FIG. 2 has at least three different deflection angles of zero degree or non-zero degree including waves generated by the transmission unit 31 or the reception unit 32 in the case of a three-dimensional rectangular coordinate system. At least two steered waves having different zero or non-zero deflection angles for the steered waves or including waves generated by the transmitting unit 31 or the receiving unit 32 in the case of a two-dimensional Cartesian coordinate system. In contrast, two complex analytic signals obtained from the spectrum of a single actant or quadrant corresponding to a wave data signal generated by independently scanning the measurement object with each steered wave in at least two time phases Which are orthogonal to each other, represented by the product or conjugate product signals Change in the instantaneous phase of each new wave propagating in, or waves generated by scanning the object to be measured with each steered wave in at least two time phases, which also represent the changes in each instantaneous phase Two complex analyzes using the respective phases of the product or conjugate product signal of two complex signals having at the nucleus a change in the instantaneous phase of the wave obtained from the spectrum of a single actant or quadrant corresponding to the data signal The change in the instantaneous phase of each of the new waves propagating in mutually orthogonal directions represented by the signal or the signal of the product or conjugate product of the two complex signals, respectively, By dividing by the frequency of the center of gravity, the respective displacement components in directions orthogonal to each other are calculated, and the three-dimensional orthogonal coordinates It calculates the three-dimensional displacement vector in the case of, for calculating the two-dimensional displacement vector in the case of a two-dimensional orthogonal coordinate system. As described in paragraph 0623, the instantaneous frequency or the instantaneous frequency vector or the center-of-gravity frequency vector (fx, fy) or (fx, fy, fz) having the center of gravity of the local or global spectrum as the frequency component is the wave propagation. Indicates the direction (see FIGS. 43 and 44). That is, a product or conjugate product between a wave data signal or a complex analysis signal thereof having different steering angles, or a complex autocorrelation signal or a complex signal representing a change in instantaneous phase occurring between at least two time phases. Are related to a new wave whose propagation direction is represented by the instantaneous frequency vector or the center-of-gravity frequency vector newly possessed by the nucleus. The same applies to non-linear processing.
This digital demodulation method or the non-linear calculation of <2> or <3> is based on a wave having a carrier frequency in each of a symmetry axis of an arbitrary wave intersecting in an arbitrary direction and a direction orthogonal thereto. (Waves detected in one direction or two directions), so that the waves intersect behind them in such a way as to avoid obstacles and obstacles related to those waves, A wave having a carrier frequency in an arbitrary direction that cannot be generated directly through an obstacle or a shield can be generated behind an obstacle or a shield, etc., which is normally difficult behind an obstacle or a shield. Imaging and displacement measurement. For example, when a wave having a carrier frequency in the depth direction and the lateral direction is generated via an obstacle or a shield, the situation is equivalent to realizing a situation where the obstacle or the shield is transparently viewed from the front. Yes, and in that case, the movement of the target in any direction can also be measured. The present imaging and displacement measurement can be performed not only from the front direction of an obstacle or a shield, but also from any direction. In those cases, at least one mirror may be used to generate a reflected wave to observe behind an obstacle or a shield. For example, a wave that is steered from a front direction such as an obstacle or a shield is generated, reflected by a mirror in the steering direction, and the wave may intersect behind the obstacle or the shield, The wave source may exist in a direction other than the front direction. Although the steering angle and the carrier frequency can be used in various combinations, considering that it is necessary to obtain the effects of complex products and complex conjugates, the method of solving the simultaneous equations is not restricted with respect to the combination, and the amount of calculation is small.
In the digital demodulation method or the nonlinear calculation of <2> or <3>, the bandwidth is widened in advance based on the Nyquist theorem in order to generate twice the instantaneous frequency in each direction. It is necessary to perform beamforming beforehand, to interpolate the number of beams in space, or to broaden the band other than the signal spectrum in the frequency domain to zero (data interpolation). That is, the aliasing phenomenon may not occur (however, since a complex analytic signal is used, the spectrum is a single quadrant or an acutant). These processes are also a kind of signal separation.
Alternatively, when aliasing occurs in these digital demodulation methods or in the nonlinear calculation of <2> or <3>, the Nyquist theorem is applied to the signal before processing without widening the band. In a satisfied situation, each of those processes is also performed, and the instantaneous phase difference (change) in each direction calculated in that case is 2fxdx, 2fydy, 2fzdz, while the instantaneous frequency in each direction is changed. fx, fy, and fz may be obtained from the original signal and doubled to remove the difference (change) in their instantaneous phases. There is no need for a process for widening the bandwidth, the amount of calculation is small, the speed is high, and the memory is small. It should be noted that the sum of the instantaneous frequencies in each direction estimated for each wave or each beam may be used instead of twice the instantaneous frequency. In those cases, instead of the instantaneous frequency, the center of gravity (centroid frequency or center frequency) of the local or global spectrum of the original signal may be obtained and doubled, or the sum may be obtained in the same manner. . Alternatively, a value twice the nominal frequency or a typical value obtained in advance may be used without calculation. Further, as shown in the schematic diagrams of the spectrum distributions in FIGS. 45 and 46, in a situation where the aliasing phenomenon occurs, the frequency region of the frequency coordinate where the aliasing phenomenon occurs is changed to a positive or negative half-band frequency region. In other words, twice the frequency can be calculated directly from the center of gravity of those spectra (the Nyquist theorem is satisfied for the signal before processing, so it can always be calculated). The spectral distribution may be calculated for an echo signal in a region of interest or a certain region, or may be calculated for an echo signal in a local region including each point of interest by focusing on the point of interest. FIG. 45 shows an example in which the frequency coordinate axis is read and processed when the aliasing phenomenon occurs in the two-dimensional spectrum of the band 2A (−A to A) in the depth direction due to the demodulation during the two-dimensional horizontal modulation. Is shown. FIG. 46 shows an example in which the frequency coordinate axis is read and processed when the aliasing phenomenon occurs in the two-dimensional spectrum of the horizontal band 2B (−B to B) due to the demodulation during the two-dimensional horizontal modulation. Is shown. Although there are a plurality of combinations of independent analysis signals, FIG. 45 shows that in the two analysis signals whose instantaneous (centroid) frequencies are (fx, fy) and (fx, -fy), a folding phenomenon occurs in the depth direction. In this case, an example is shown in which the center of gravity frequency in the depth direction can be calculated as 2fx. Further, FIG. 46 shows that, for two analysis signals whose instantaneous (center of gravity) frequencies are (fx, fy) and (fx, -fy), when the folding phenomenon occurs in the horizontal direction, the center of gravity frequency in the horizontal direction is 2fy. The example which can be calculated is shown. A folding phenomenon may occur simultaneously in the depth direction and the lateral direction. On the other hand, when the instantaneous frequency is used, since the instantaneous frequency expressed in the positive or negative half band in the frequency region of the frequency coordinate where the aliasing phenomenon occurs is determined, the correction is performed using the bandwidth value determined by the sampling frequency. Just do it. For example, if the spectrum of the product or the conjugate product (demodulation) has a spectrum closer to DC in each direction in the negative frequency domain than the states shown in FIGS. Since it has a negative frequency when viewed from the side, the frequency may be a frequency obtained by adding the value of the bandwidth to the estimated instantaneous frequency. The same processing can be performed even when the center of gravity frequency is used. Since the estimated center of gravity has a negative frequency when viewed from the DC side, a frequency obtained by adding a bandwidth value thereto may be used. Incidentally, when a signal having a negative frequency is used as the complex analysis signal, the signal is estimated as a positive frequency. Therefore, in both the case of using the instantaneous frequency and the case of using the center-of-gravity frequency, it is sufficient to subtract the value of the bandwidth. This is equivalent to the correction performed by reading the above frequency domain. However, as shown in the examples shown in FIGS. 45 and 46, when there is an instantaneous frequency near the adjacent positive and negative maximum frequencies, the medium has a positive frequency or a negative frequency due to frequency modulation such as scattering and attenuation in the medium. Therefore, it is difficult to perform the correction using the value of the bandwidth. For example, this corresponds to a case where a 7.5 MHz wave is sampled at a sampling frequency of 30 MHz. In such a case, when a signal of a negative frequency is used as the complex analysis signal, it is similarly difficult to correct the instantaneous frequency using the value of the bandwidth. When the distribution of the spectrum includes the highest positive and negative frequencies, the center-of-gravity frequency cannot be estimated, and correction using the value of the bandwidth cannot be performed. The processing method in these cases will be described later. Similarly, in the three-dimensional case, the frequency region of the frequency coordinate where the aliasing phenomenon occurs may be read as a positive or negative half-band frequency region, and the double frequency may be directly calculated from the center of gravity of the spectrum. Similarly, in a situation where the aliasing phenomenon occurs, the frequency domain of the frequency coordinate where the aliasing phenomenon occurs is similarly replaced with a positive or negative half-band frequency area, and then a half-band frequency area of the zero spectrum is added. It is possible to widen the bandwidth to satisfy the Nyquist theorem and obtain an analysis signal by its inverse Fourier transform. (At this timing, it is also possible to perform the widening and interpolate the signal to calculate the change in the instantaneous frequency and phase. However, the amount of calculation can be reduced as compared with widening or interpolating in advance, but the amount of calculation is larger than those processes that do not widen the band.) Of course, if no aliasing occurs in these digital demodulation methods or in the nonlinear calculation of <2> or <3>, the instant of the double or sum obtained directly without re-reading the frequency coordinate or widening the bandwidth is used. What is necessary is just to remove the difference (change) of those instantaneous phases using a frequency or a center-of-gravity frequency. When the instantaneous frequency is used, the correction using the bandwidth value can be performed in the same manner as in the two-dimensional case. However, when the instantaneous frequency is near the maximum adjacent positive and negative frequencies, the correction is similarly performed on the medium. There is a problem that the frequency is inverted between positive and negative due to frequency modulation such as scattering and attenuation. Further, when the spectrum distribution includes the highest positive and negative frequencies, the center-of-gravity frequency cannot be estimated, and similarly, correction using the value of the bandwidth cannot be performed. The processing method in these cases will be described later. Further, a value twice the nominal frequency or a typical value obtained in advance may be used without calculation. There is no problem in the range up to re-reading the frequency coordinates.However, if the bandwidth is widened by zero-filling the spectrum or interpolation processing, not only will the computational amount increase significantly, but also the accuracy may decrease. It is also useful in these respects. In the case where the band is widened and the case where the band is not widened, regularization processing may be performed as necessary.
Further, frequency modulation is performed on the received real-time signal of each wave, its complex analysis signal, the obtained complex autocorrelation signal (or complex signal), and the product or conjugate product thereof, If the result of the product or the conjugate product does not cause aliasing, or if the aliasing phenomenon is caused positively, and the center of gravity frequency of the spectrum is used, the frequency domain of the frequency coordinate is changed as described above. In the case of reading in the positive or negative half-band frequency region, and when using the center-of-gravity frequency or instantaneous frequency, a low-frequency is used for the center-of-gravity frequency or instantaneous frequency obtained by adding or subtracting the bandwidth value as described above. It is also effective to add the modulation frequency when the frequency is increased, and to subtract the modulation frequency when the frequency is increased. FIG. 47 shows an example in which frequency modulation is performed by ± fm in the example of demodulation by the product in FIG. The signal in the demodulated state may be frequency-modulated, or the signal before demodulation may be pre-frequency-modulated and processed (in the example of FIG. 47, when the frequency is modulated by ± fm / 2). Applicable). Alternatively, a value twice the nominal frequency or a typical value obtained in advance may be used without calculation. The same applies to the case of demodulation by the conjugate product in FIG. As the difference (change) in the instantaneous phase or the phase corresponding to the difference, a value obtained in a state where the frequency is modulated or a value obtained in a state where the frequency modulation is not performed may be used. Therefore, the displacement in each direction can be obtained by dividing the difference (change) in the instantaneous phase or the phase corresponding to the difference by the instantaneous frequency or the center-of-gravity frequency after correction. When using the center-of-gravity frequency at the time of the present frequency modulation, it may be locally estimated as described above and used as an equivalent to the instantaneous frequency, or a globally estimated one may be used. Sometimes. By performing the present process of performing frequency modulation in this manner, when the instantaneous frequency or the center of gravity frequency is near the highest positive and negative frequencies adjacent to each other as shown in FIGS. If the instantaneous frequency is inverted to positive or negative due to frequency modulation such as noise or attenuation and cannot be corrected using the bandwidth value, or if the spectrum distribution includes the highest positive and negative frequencies, the center of gravity The above problem that the frequency cannot be estimated can be overcome. That is, it is possible to avoid the case where the instantaneous frequency or the center of gravity frequency is located near the adjacent positive and negative maximum frequencies and the case where the spectrum distribution includes the positive and negative maximum frequencies. As a precautionary measure, if the spectrum of the product or conjugate product (demodulation) is increased in frequency through frequency modulation and has a spectrum close to DC in each direction in the negative frequency domain, the DC side Therefore, as described above, the frequency may be a frequency obtained by adding the value of the bandwidth to the estimated instantaneous frequency. The same processing can be performed even when the center of gravity frequency is used. Since the estimated center of gravity has a negative frequency when viewed from the DC side, a frequency obtained by adding a bandwidth value thereto may be used. When a signal having a negative frequency is used as the complex analysis signal, the signal is estimated as a positive frequency. Therefore, in both the case of using the instantaneous frequency and the case of using the center-of-gravity frequency, it is sufficient to subtract the value of the bandwidth. This is equivalent to the correction performed by reading the above-mentioned frequency domain, and when the center-of-gravity frequency is used, such processing may be performed.
The frequency modulation is performed as usual, and the real-time signal is multiplied by a sine signal or a cosine signal having a frequency obtained by multiplying the modulation frequency by +1 or −1, or the signal is a complex analysis signal or a complex autocorrelation signal. When expressed as (or a complex signal), the modulation frequency is multiplied by a complex exponential function having a frequency obtained by multiplying the modulation frequency by +1 or -1. In both cases, the spectrum obtained by performing a Fourier transform is modulated. It can be implemented by shifting the frequency by +1 or -1. The important thing is to always process the complex analytic signal (spectralization of a single quadrant or orctant). In the case of multiplying a real-time signal by a sine signal or a cosine signal, in which both a signal whose frequency is increased and a signal whose frequency is reduced by frequency modulation are calculated, only one of them is used. In this case, only one of those obtained by filtering using the low-pass filter or the high-pass filter after frequency modulation will be used, but the signal has a wide band and the modulation frequency is small. In such a case, care must be taken because these signals may overlap in the frequency domain and cannot be separated by filtering. On the other hand, when the signal is a complex analytic signal or a complex autocorrelation signal (or a complex signal) and a complex exponential function is multiplied, or when the signal is a real-time signal and the frequency is shifted in the frequency domain, Need only ask for one of them. These frequency modulations can be performed by the signal processing unit or data processing unit after the reception signal is output by the sensor, can be performed by digital signal processing, and can be performed by using a multiplier, a mixer, or a filter. It can also be implemented by analog signal processing. Although the description has been made on the assumption that the demodulation is performed by digital signal processing, it is also possible to perform all of the demodulation at high speed by analog processing.
In the above description, the embodiment of the displacement vector measurement has been described on the assumption that the received signal itself satisfies the sampling theorem. However, these processes useful in the case where aliasing is caused by demodulation are performed by sampling the received signal itself. It is also useful when you do not satisfy the theorem. In this case, not only the demodulation method, but also a multidimensional displacement vector measuring method such as a multidimensional cross-spectral phase gradient method, a multidimensional autocorrelation method, a multidimensional Doppler method, and a one-dimensional processing thereof ( It can also be used when using one-way displacement measurement. It may be useful other than those measurement methods.
For example, the digital signal processing unit 33 shown in FIG. 2 generates a wave data signal or a complex analysis signal thereof, or a complex autocorrelation signal or a complex signal representing a change in an instantaneous phase occurring between at least two time phases, or a complex signal thereof. When the signal of the product or the conjugate product has an aliasing phenomenon, the displacement vector or the displacement is obtained from any one of the signals to obtain the displacement vector or the displacement using the instantaneous phase change and the instantaneous frequency or the center of gravity of the spectrum. The instantaneous frequency at which the aliasing occurs or the center of gravity of the spectrum may be corrected by adding or subtracting a bandwidth value determined by the sampling frequency of the signal.
Alternatively, the digital signal processing unit 33 generates a wave data signal or a complex analysis signal thereof, or a complex autocorrelation signal or a complex signal representing an instantaneous phase change occurring between at least two time phases, or a product or a conjugate product thereof. In the case where the signal has a folding phenomenon and the spectrum has both the highest positive frequency and the highest negative frequency in the band, the displacement vector or the instantaneous frequency or the center of gravity of the spectrum using the instantaneous frequency change or the instantaneous frequency. Applying frequency modulation to any of them to determine the displacement to reduce the frequency so that no aliasing occurs, or to increase the frequency so that the spectrum has both positive and negative frequencies In the case where the center of gravity of the spectrum is used after having the In the case of using the center-of-gravity frequency or the instantaneous frequency in the frequency domain of the bandwidth, the center-of-gravity frequency or the instantaneous frequency obtained by adding or subtracting the value of the bandwidth determined by the sampling frequency of any of the signals is used. Alternatively, when the frequency is lowered by the frequency modulation, the modulation frequency may be added, and when the frequency is increased, the correction may be performed by subtracting the modulation frequency and used. Here, the frequency modulation performed by the data processing unit may be a detection process.

The above-described demodulation method and the non-linear calculation of <2> or <3> can be improved as follows to increase the accuracy. For example, a case where the two-dimensional displacement vector (dx, dy) is observed will be described. The above method is such that the instantaneous phase difference (change) between two different time phases at a point in the two-dimensional region of interest is determined by two independent single quads generated from the two intersecting beams or waves used. Using the spectrum of the runt (single quadrant), it is considered that the complex autocorrelation signal is expressed as the phase of exp [j (fxdx + fydy)] and exp [j (fxdx−fydy)], and the product and conjugate product of them are calculated. By this, exp [j (2fxdx)] and exp [j (2fydy)] are obtained, and the instantaneous phase difference 2fxdx and 2fydy in each direction is divided by the instantaneous frequencies 2fx and 2fy in each direction to obtain an unknown displacement vector. (dx, dy) (FIG. 8b of Patent Document 7 and the same as above, and there are other combinations of spectra of two independent single quadrants). However, the two beams or waves steered to be symmetrical about the axis in the two-dimensional rectangular coordinate system for observation are not actually symmetrical, and the frequency of the two directions of the two beams or waves is not equal. The absolute values are not exactly equal. For example, when the directivity of the aperture or aperture array element used is not in the front direction of each aperture, when the speed of sound of the medium is non-uniform, when there is the effect of frequency modulation due to attenuation or scattering in the medium, or when digital Or, an error of an analog delay may be caused. The above method is accomplished under the assumption that their absolute values are equal, and in practice introduces errors. In fact, the product or conjugate product of the received real-time signal, complex analytic signal, or complex autocorrelation signal (or complex signal) is, as described above, orthogonal to the symmetry axis of any wave crossing in any direction. Generates a wave with a carrier frequency in each direction and the above assumptions introduce errors.
Figure 48 As shown in (a), 2-dimensional coordinate system to observe the displacement vector (x, y) of each of steering (deflection) angle of the generated two waves 1 and wave 2 and theta ₁ and - [theta] ₂ in , And the respective instantaneous frequencies or center-of-gravity frequencies are (f _1x , f _1y ) and (f _2x , f _2y ) (the instantaneous frequency vector or the centroid frequency vector). In addition, as shown in FIG. 48B, the frequency domain (space) of the two-dimensional coordinate system (x, y) is set to (fx, fy), and the spectrum of those waves is schematically shown. In FIG. 48, the axial direction and the lateral direction are the x direction and the y direction, respectively. Here, as is usually observed when | θ ₁ |> | θ ₂ |, the absolute value of those frequencies generated at a certain point in the two-dimensional region of interest is | f _1y |> | f _2y | and | f _1x | <| f _2x | At this time, the difference between the instantaneous phase between the two different time phase (change) are expressed as the phase of the complex autocorrelation signals _{exp [j (f 1x dx +} f 1y dy)] and _{exp [j (f 2x dx +} f 2y dy)] Therefore, by calculating their product and conjugate product _{exp [j {(f 1x +} f 2x) dx + (f 1y + f 2y) dy}] and _{exp [j {(f 1x -f} 2x) dx + (f 1y -f give _{2y) dy}], f 1x} = f 2x = f x and _{f 1y = -f 2y = f y} exp is approximately expressed under the assumption [j2f _x dx] and exp [j2f _y dy] the dividing respectively 2f _x and 2f _y phase, _{or, f 1y = -f 2y = f} y and f _1x = f _2x = f each hypothetical exp represented approximately under _x [j The phases of {(f _1x + f _2x ) dx}] and exp [j {(f _1y −f _2y ) dy}] can be divided by f _1x + f _2x and f _1y −f _2y . Through the nonlinear processing of <2> or <3>, the approximate calculation can be similarly performed. The spectrum of the product and conjugate product of the complex autocorrelation signals of the two waves 1 and 2 shown in FIGS. 48A and 48B are schematically shown in FIG. The spectra can be similarly obtained through the nonlinear processing of <2> or <3>. Therefore, exp is calculated without these assumptions _{[j {(f 1x + f} 2x) dx + (f 1y + f 2y) dy}] and _{exp [j {(f 1x -f} 2x) dx + (f 1y -f when phase alpha _a and alpha _l of _2y) dy}], and their respective frequency F _a of the 'pseudo lateral fy that the perpendicular thereto' two wave axial fx pseudo be positioned symmetrically ' By dividing by F _l ', it corresponds to a two-dimensional frequency domain (space) represented by frequency coordinates (fx', fy ') in the pseudo axial direction fx' and the pseudo lateral direction fy 'orthogonal thereto. In FIG. 50, the displacements in the quasi-axial direction x ′ of the two-dimensional orthogonal coordinate system (x ′, y ′) of the space schematically shown in FIG. I get it. That is, it means that the displacement vector is observed in the two-dimensional orthogonal coordinate system (x ′, y ′) in a new space defined so that the wave 1 and the wave 2 are symmetric.
Note that the frequencies F _a ′ and F _l ′ are respectively represented by √ (F _ax ² + F _ay ² ) = √ {(f _1x + f _2x ) using (f _1x , f _1y ) and (f _2x , f _2y ). ^{_{2 + (f 1y + f 2y}} ) 2)} and ^{_{√ (F lx 2 + F ly}} 2) = √ {(f 1x -f 2x) 2 + (f 1y -f 2y) 2) or calculated as}, the complex self _Determine the center of gravity frequency (F _ax , F _ay ) and (F _lx , F _ly ) or the instantaneous frequency (F _ax , F _ay ) and (F _lx , F _ly ) of the spectrum of the product of the correlation signal and the conjugate product. (The magnitude of the instantaneous frequency vector or the center-of-gravity frequency vector).

Since the two-dimensional rectangular coordinate system for observation is (x, y), the displacement vector (dx ', dy') obtained by the two-dimensional rectangular coordinate system (x ', y') is converted to the two-dimensional rectangular coordinate system (x , y), the angle must be corrected. The angle difference (rotation angle) θ = (θ ₁ + θ ₂ ) / 2 between the two-dimensional orthogonal coordinate system (x, y) and (x ′, y ′) is the steering (deflection) angle θ ₁ = tan of the two waves. ⁻¹ (f _1y / f _1x ) and θ ₂ = tan ⁻¹ (f _2y / f _2x ), or by using (f _1x , f _1y ) and (f _2x , f _2y ) tan ^-1 ( _Fay / _Fax ) = tan- ¹ {( _f1y + _f2y ) / ( _f1x + _f2x )}, or 90 ° + tan- ¹ ( _Fly / _Flx ) when _Flx <0. = 90 ° + tan ⁻¹ {(f _1y −f _2y ) / (f _1x −f _2x )} or, when F _lx > 0, tan ⁻¹ (F _ly / F _lx ) = tan ⁻¹ {(f _1y− f _2y ) / (f _1x −f _2x )}, or the center of gravity frequencies (F _ax , F _ay ) and (F _lx , F _ly ) of the spectrum of the product of the complex autocorrelation signal and the conjugate product. Or the instantaneous frequencies (F _ax , F _ay ) and (F _lx , F _ly ) may be calculated in the same manner.

There are two methods for angle correction, one of which is to multiply the calculated (dx ', dy') by a rotation matrix to obtain the observation result (dx, dy).
Alternatively, the instantaneous frequency vector of the product and the conjugate product represented in the two-dimensional orthogonal coordinate system (x ′, y ′) or the center-of-gravity frequency vector (F _a ′, 0) and (0, F _l ′) respectively. Similarly, multiply the rotation matrix,
The instantaneous frequency vector or the center-of-gravity frequency vector ( _Fax , _Fay ) and ( _Flx , _Fly ) in the two-dimensional orthogonal coordinate system (x, y) are obtained, or ( _f1x , f _1y ) and (f _2x , f _2y ) are used to calculate (f _1x + f _2x , f _1y + f _2y ) and (f _1x −f _2x , f _1y −f _2y ), or the product of the complex autocorrelation signal And the center frequency of the spectrum of the conjugate product (F _ax , F _ay ) and (F _lx , F _ly ) or the instantaneous frequency (F _ax , F _ay ) and (F _lx , F _ly ), and a complex exponential function exp Phases α _a and α of [j {(f _x1 + f _x2 ) dx + (f _y1 + f _y2 ) dy}] and exp [j {(f _x1 −f _x2 ) dx + (f _y1 −f _y2 ) dy}] simultaneous equations for _l
Can be derived and directly solved for (dx, dy).
From this viewpoint, as shown in FIG. 51 (a), even when the axis x ′ that symmetrically oscillates the waves 1 and 2 is significantly different from the x-axis of the two-dimensional orthogonal coordinate system (x, y) for observation. By performing the same processing, FIG. 51 (corresponding to a two-dimensional frequency domain (space) composed of frequency coordinates in a pseudo axial direction fx ′ for symmetrically positioning two waves and a pseudo horizontal direction fy ′ orthogonal thereto. Displacements in the pseudo axial direction x 'of the two-dimensional orthogonal coordinate system (x', y ') in the space shown in b) and the pseudo horizontal direction y' orthogonal to the spatial coordinate axis direction are obtained. That is, the displacement vector (dx ', dy') can be observed in the two-dimensional orthogonal coordinate system (x ', y') in a new space defined so that the waves 1 and 2 are symmetric. Therefore, as in the above case, if the equation (Rot1) is directly used or the angle correction is performed using the equations (Rot2-1), (Rot2-2), and (Rot2-3), the observation coordinates The result (dx, dy) in the system (x, y) is obtained. In such observation, for example, when there is an obstacle such as a bone in the ultrasonic observation of human soft tissue, it is processed by avoiding the obstacle (by shifting the symmetry axis away from the obstacle) and acquiring a transmission or echo signal. Useful in cases. The inventor of the present application has performed not only the lateral modulation in which the sensor apertures are arranged (lateral modulation) as necessary, but also the lateral modulation in a desired direction as necessary from the past. Although the displacement vector has been observed by a multi-dimensional autocorrelation method, a multi-dimensional Doppler method, or the like, the present demodulation method can also be implemented. In other words, according to the present demodulation processing, similarly to other displacement vector measurement methods, a displacement vector can be observed even when a wave that is not symmetric with respect to the coordinate axis of the observation coordinate system is generated.
Similarly, in any of the displacement vector measurement methods, the above-described angle correction method is used to correct the displacement vector itself, or to correct the frequency to solve the equation to generate a wave motion. In addition, it is possible to observe a displacement component (displacement vector) in the coordinate axis direction of another orthogonal coordinate system. For example, simultaneous displacements (dx, dy) derived by the multidimensional autocorrelation method, the multidimensional Doppler method, the multidimensional cross spectral phase gradient method, or the present demodulation method in the two-dimensional rectangular coordinate system (x, y). equation
Here, the suffixes “1” and “2” represent two waves, and F _x and F _y represent the frequencies of the waves in the x and y directions (instantaneous frequency vector or centroid frequency vector component), respectively. .
In (2), a displacement vector (dx ", dy") consisting of a displacement component in a coordinate axis direction of a two-dimensional orthogonal coordinate system rotated by a desired angle θ in accordance with equation (Rot1) by obtaining (dx, dy) can be observed. The instant obtained by rotating the instantaneous frequency vector or the center-of-gravity frequency vector (F _1x , F _1y ) and (F _2x , F _2y ) by the same angle θ according to the equations (Rot2-1) and (Rot2-2). frequency vector or centroid frequency vector _{(F 1x ", F 1y"} ) and _{(F 2x ", F 2y"} ) rewriting the equation (Rot2-4) by using the
By solving, the displacement vector (dx ", dy") can be directly obtained.
In the three-dimensional case as well, using the spectrum of three or four independent orctants or three-dimensional rotation matrices generated from three or four intersecting beams or waves, similarly Can be performed. In the case of three dimensions, the waves are deflected (steered) and intersected so as to be symmetrical with respect to a plane including the axis and the transverse direction orthogonal to the axis (that is, all waves are symmetrical with respect to the axial direction). However, as in the two-dimensional case, the symmetry may not be accurately obtained, or may not be intentionally obtained. Therefore, the same processing is performed using a wave that is symmetrical with respect to a plane including a pseudo axis and a pseudo lateral direction orthogonal thereto (that is, all waves are symmetric with respect to the pseudo axis direction).

Here, the above-mentioned new demodulation is performed at a certain point in the two-dimensional region of interest as is usually observed when the two steering (deflection) angles are | θ ₁ |> | θ ₂ |. Although it has been described that the absolute values of the generated frequencies are | f _1y |> | f _2y | and | f _1x | <| f _2x |, the frequency modulation due to attenuation and scattering in the medium causes | f _1y |> | F _2y | and | f _1x |> | f _2x |. It also occurs when the frequency of the wave itself is different. In these cases, the pseudo axial direction x 'and the lateral direction y' considered in the above-described new demodulation processing are not orthogonal, which causes a problem. That is, Non-Patent Document 30, Patent Document 7, and the above-described demodulation processing strictly perform the instantaneous frequency or local or global center of gravity frequency of two waves themselves (that is, the instantaneous frequency vector or the local or global center of gravity). When √ (f _1x ² + f _1y ² ), which is the magnitude of the frequency vector, is completely equal to √ (f _2x ² + f _2y ² ), the coordinate system (x ′, y ′) becomes an orthogonal coordinate system and accuracy is obtained. In fact, even if √ (f _1x ² + f _1y ² ) and √ (f _2x ² + f _2y ² ) are substantially equal, the coordinate system is not strictly a rectangular coordinate system and an error occurs (see paragraph 0640). ). That is, the correction of the expression (Rot1) cannot be used. On the other hand, it will be described later that the equation (Rot2-3) is also valid in this case. FIG. 52 schematically shows a pseudo axial direction fx ′ that is not orthogonal and a pseudo horizontal direction fy ′. These fx 'and fy' and the corresponding x 'and y' in space coordinates do not become the axes of symmetry of the wave.
Therefore, as the basic processing (pre-processing) of Non-Patent Document 30, Patent Document 7, and the above-described demodulation processing, the instantaneous frequency of two observed waves or the local or global center-of-gravity frequency √ (f _1x ² + f _1y ² ) and √ (f _2x ² + f _2y ² ) so that the instantaneous phase difference (change) in one wave along with all the frequencies in the x and y directions of the two-dimensional Cartesian coordinate system to be observed. ) Is multiplied by the same constant (that is, the complex autocorrelation function uses the corrected one). Alternatively, the instantaneous frequency or local or global centroid frequency of each wave (that is, the magnitude of the instantaneous frequency vector or local or global centroid frequency vector √ (f _1x ² + f _1y ² ) or √ (f _2x ² + f _2y ² )) may be used to normalize the instantaneous phase difference (change) along with the total frequency of each wave in the x and y directions (that is, use the complex exponential function normalized as such). . Other equivalent processing such as normalizing the difference (change) between the frequency in each direction and the instantaneous phase so that the instantaneous frequency or the local or global center of gravity frequency becomes a certain value may be used. This is regarded as one of the inventions of the present application relating to demodulation, and the above-described demodulation processing is performed in Non-Patent Document 30, Patent Document 7, and the like. In any case, the accuracy is improved.
Or, without their pretreatment actually generated 'and transverse y' axis direction x of pseudo seek each angle theta _a and theta _l of, instead of the angle correction according to paragraph 0661 , using the calculated the displacement d _a and d _l in each direction, two-dimensional orthogonal coordinate system for performing observation (x, y) may be obtained displacement vector in. Since the axial direction x 'and the lateral direction y' are not clearly perpendicular, the displacement in each direction is the displacement of each direction used when the axial direction x 'and the lateral direction y' are substantially perpendicular or perpendicular. the dx 'and dy' represent with d _a and d _l of different character.
Here, θ _a and θ _l are respectively expressed as tan ⁻¹ (F _ay / F _ax ) = tan ⁻¹ {(f _1y + f _2y ) using (f _1x , f _1y ) and (f _2x , f _2y ). ) / (F _1x + f _2x )} and 180 ° + tan ⁻¹ (F _ly / F _lx ) = 180 ° + tan ⁻¹ {(f _1y −f _2y ) / (f _1x −f _2x ) when F _lx <0 } Or tan ^-1 (F _ly / F _lx ) = tan ^-1 {(f _1y −f _2y ) / (f _1x −f _2x )} when F _lx > 0, or the complex autocorrelation Similarly, determine the center-of-gravity frequencies (F _ax , F _ay ) and (F _lx , F _ly ) or the instantaneous frequencies (F _ax , F _ay ) and (F _lx , F _ly ) of the spectrum of the signal product and the conjugate product. It is good to calculate. Or, from the formula (demodu0) and the formula (Synv0),
The equation (Rot2-3) that is established in the orthogonal coordinate system (x ′, y ′) is also established in the non-orthogonal coordinate system (x, y). Equation (Synv1) may be solved.
In the observation of a three-dimensional displacement vector, three or four waves (waves 1 to 4) are similarly used as basic processing (pre-processing) of Non-Patent Document 30, Patent Document 7, and the above-described demodulation processing. √ (f _1x ² + f _1y ² + f _1z ² ) and √ (f _2x ² + f _2y ² ) which are the instantaneous frequency or the local or global centroid frequency (the magnitude of the instantaneous frequency vector or the local or global centroid frequency vector) + F _2z ² ), √ (f _3x ² + f _3y ² + f _3z ² ) and √ (f _4x ² + f _4y ² + f _4z ² ) are equalized, and observation is performed in each of two or three waves. The instantaneous phase difference (change) is corrected by multiplying the instantaneous phase difference (change) by the same constant together with all the frequencies in the x direction, y direction, and z direction of the three-dimensional rectangular coordinate system (that is, the complex exponential function is corrected so To use). Alternatively, in each wave, the instantaneous frequency or the local or global center-of-gravity frequency of each wave (ie, the magnitude of the instantaneous frequency vector or the local or global center-of-gravity frequency vector √ (f _1x ² + f _1y ² + f _1z ² ), √ (f _2x ² + f _2y ² + f _2z ² ), √ (f _3x ² + f _3y ² + f _3z ² ) and √ (f _4x ² + f _4y ² + f _4z ² )) in the x direction and y The instantaneous phase difference (change) may be normalized along with the total frequency in the direction and the z-direction (that is, the complex exponential function may be so normalized). Other equivalent processing such as normalizing the difference (change) between the frequency in each direction and the instantaneous phase so that the instantaneous frequency or the local or global center of gravity frequency becomes a certain value may be used. Alternatively, without performing the preprocessing, the angles of the pseudo axial direction x ′, the lateral direction y ′, and the elevation direction z ′ that are actually generated are similarly calculated, and the angle correction described in paragraph 0661 is performed. May be used to calculate a displacement vector in the three-dimensional orthogonal coordinate system (x, y, z) for observation using the calculated displacement in each direction, or the equation (Synv0 for two-dimensional case) )), The instantaneous phase difference (change) in each of the axial direction x ′, the lateral direction y ′, and the elevation direction z ′, and the instantaneous frequency vector or the local or global center-of-gravity frequency vector in each of those directions. It may be obtained by using an instantaneous frequency vector or a local or global center-of-gravity frequency vector component expressed in an orthogonal coordinate system for observation (as in a two-dimensional expression (Synv1)).
In the measurement imaging according to the present embodiment, the orthogonalization of the wave, which is the preprocessing in the displacement vector measurement, can be applied to the imaging of the wave itself. As described in paragraph 0641, to generate a transversely modulated image signal having independent frequencies in orthogonal directions, the carrier frequency or instantaneous frequency of the wave itself or the local or global center of gravity frequency (ie, It is necessary to generate two, three or four waves having the same instantaneous frequency vector or local or global center-of-gravity frequency vector.
For example, the control unit 34 shown in FIG. 2 performs three-dimensional orthogonalization in which the depth direction of the measurement target, the horizontal direction orthogonal to the depth direction, and the elevation direction orthogonal to the depth direction and the horizontal direction are three axes. In a coordinate system, generate at least three steered waves having different deflection angles of electronically or mechanically generated zero or non-zero degrees, or a depth direction and a transverse direction orthogonal to the depth direction. In a two-dimensional orthogonal coordinate system having two axes in directions, at least two steered waves having different deflection angles of zero degree or non-zero degree, which are generated electronically or mechanically, are generated to traverse the measurement object. The transmitting unit 31 or the receiving unit 32 is controlled to scan in the direction and generate the wave data signal in at least two time phases.
In addition, the digital signal processing unit 33 shown in FIG. 2 independently scans the measurement target with each of the steered waves in at least two time phases, and scans the measurement target to generate a single actant or quadrant corresponding to a wave data signal generated. Using a complex analytic signal whose core is the instantaneous phase of the wave obtained from the spectrum or a complex autocorrelation signal or a complex signal whose core has a change in instantaneous phase generated between at least two time phases. When calculating a three-dimensional displacement vector in the case of a coordinate system and calculating a two-dimensional displacement vector in the case of a two-dimensional orthogonal coordinate system, a complex analysis signal or a complex autocorrelation corresponding to a spectrum of a single actant or quadrant The magnitude of the instantaneous frequency vector of the signal or complex signal or the magnitude of the centroid frequency vector of the spectrum is Or when the instantaneous frequency vector component or the center-of-gravity frequency vector component of another complex analytic signal or other complex autocorrelation signal or complex signal is multiplied by a constant so as to be the same as another complex autocorrelation signal or another complex signal. The instantaneous phase or the change in the instantaneous phase is also multiplied by a constant, or the magnitude of the instantaneous frequency vector or the magnitude of the centroid frequency vector of a plurality of complex analysis signals, a plurality of complex autocorrelation signals, or a plurality of complex signals is normalized. In doing so, the instantaneous frequency vector component or the center-of-gravity frequency vector component of the plurality of complex analysis signals, the plurality of complex autocorrelation signals, or the plurality of complex signals is normalized, and the instantaneous phase or the change of the instantaneous phase is also normalized. The superposition of the waves corresponding to the spectrum of one actant or quadrant is based on a three-dimensional rectangular coordinate system or two-dimensional rectangular coordinate system or Processing the wave data signals to have an instantaneous frequency or gravity center frequency independent in the direction of the axis of the three-dimensional orthogonal coordinate system or two-dimensional orthogonal coordinate system that is rotated and al, imaging a superposition of waves.
For the displacement vector measurement and the imaging of the wave itself, various waves can be used in addition to the plurality of generated waves. For example, the transmitting unit 31, the receiving unit 32, or the digital signal processing unit 33 shown in FIG. 2 converts at least one of the plurality of waves generated in each of at least two time phases into at least one other wave. Generating at least one new wave in the same combination, using at least three steered waves including the new wave in a three-dimensional Cartesian coordinate system, or using a new wave in a two-dimensional Cartesian coordinate system. At least two steered waves may be used.
Alternatively, the digital signal processing unit 33 comprises at least one single actant or quadrant spectrum of the waves generated in each of the at least two time phases, or at least one representing the same superposition of the waves. The same division in the frequency domain is performed on the spectrum of a single actant or quadrant to generate a new spectrum of a single single actant or quadrant, and a new single spectrum is obtained in the case of a three-dimensional rectangular coordinate system. Using at least three waves including at least one wave represented by the spectrum of the actant and at least two waves including at least one wave represented by the spectrum of a new single quadrant in the case of a two-dimensional rectangular coordinate system; Waves may be used.
Alternatively, the digital signal processing unit 33 comprises at least one single actant or quadrant spectrum of the waves generated in each of the at least two time phases, or at least one representing the same superposition of the waves. Spectrum of at least one single actant or quadrant of a plurality of single actant or quadrant spectra generated by performing the same division in the frequency domain with respect to the spectrum of a single actant or quadrant Is superimposed on at least one other wave in the same combination to generate at least one new wave and at least three steered waves including the new wave in the case of a three-dimensional Cartesian coordinate system. Used for a two-dimensional rectangular coordinate system. Dynamic may be used at least two steered wave including. The waves used are not limited to these.
Alternatively, when the digital signal processing unit 33 calculates a three-dimensional displacement vector in the case of a three-dimensional rectangular coordinate system and calculates a two-dimensional displacement vector in the case of a two-dimensional rectangular coordinate system, two processes are performed as preprocessing. One complex analytic signal or complex signal such that the magnitude of the instantaneous frequency vector in the propagation direction of the wave represented by the complex analytic signal or complex autocorrelation function or the two complex signals or the magnitude of the centroid frequency vector of the spectrum is the same. When the autocorrelation function or the instantaneous frequency vector component or the center-of-gravity frequency vector component of the complex signal is multiplied by a constant, the instantaneous phase or the change in the instantaneous phase is also multiplied by a constant at the same time. When normalizing the magnitude of the instantaneous frequency vector or the centroid frequency vector of the complex signal, two complex analysis signals or A complex autocorrelation function or a complex autocorrelation function or complex signal by normalizing a complex autocorrelation function or an instantaneous frequency vector component or a center-of-gravity frequency vector component of the complex signal and simultaneously normalizing their instantaneous phase or a change in the instantaneous phase. The propagation direction of the new wave represented by the product or conjugate product signal may be orthogonal.

  As described above, according to the demodulation method of the present invention, as described above, the propagation direction (deflection direction) of a plurality of waves does not use the coordinate axis of the rectangular coordinate system for observation as the symmetric axis or the frequency of the plurality of waves. In various cases, such as when the values are different, the displacement vector can be observed with high accuracy. In other words, the same number of independent waves as the number of unknown displacement vector components with different deflection angles and frequencies are generated as in the multidimensional autocorrelation method, multidimensional Doppler method, multidimensional cross spectrum phase gradient method, etc. Displacement vector can be observed with high accuracy. Further, particularly when a wideband wave is generated in the horizontal direction, frequency division of the spectrum may be performed similarly to those other measurement methods, and the same number of independent pseudo waves as the unknown displacement vector components may be generated, It is also effective to remove the low frequency spectrum in the horizontal direction and increase the frequency in the horizontal direction, especially when a wide band wave is generated in the horizontal direction. Can be processed similarly). In addition, through processing such as generating a plurality of waves or dividing the spectrum into frequencies, an independent wave or a pseudo wave that is larger than the number of unknown displacement components is generated, and an over-determined system for the unknown displacement vector in the observation coordinate system is generated. It can also be generated and solved (pseudo waves can be processed in the same way as if they were generated directly). In some cases, a process of generating a plurality of waves or frequency-dividing a spectrum is performed at the same time (a pseudo wave can be processed in the same manner as when a wave is directly generated). To widen the waves, it is effective to generate a plurality of waves having different frequencies and deflection angles at the same time, or to generate a plurality of waves at different times even in the simultaneous phase and to perform coherent addition (superposition). In the over-detrmined system, it is useful to use the weighted least squares method such as paragraph 0391 and paragraph 0392 and various optimization methods described in the present application. The invention is not limited to these. In their optimum, the phase matching described in paragraph 0416 is effective. In this case, the phase matching may be performed by applying a coarse measurement result obtained in the observation coordinate system to a system relating to an unknown updated displacement vector in the observation coordinate system, or from a similar coarse measurement result in the form of a coarse coordinate in a pseudo coordinate axis direction. The displacement component may be obtained and applied to a system relating to the update displacement in the pseudo coordinate axis direction. When optimization is not performed, a similar coarse measurement result is obtained by demodulation in the observation coordinate system based on an old phase matching method (Patent Document 6 and Non-Patent Document 15). Displacement vector) may be added, or a coarse displacement component in the pseudo coordinate axis direction may be obtained from the same coarse measurement result and processed in addition to the update displacement in the pseudo coordinate axis direction. It may be processed in other modified ways. In addition to a method of obtaining a multidimensional analysis signal through Fourier transform (Non-Patent Document 13 and the like), an approximate processing method of Hilbert transform using differential processing described in paragraphs 0506 to 0508 is also useful. Although the case where the complex autocorrelation signal is used has been mainly described, a complex signal derived based on the multidimensional Doppler method can be used as described above (representing the relationship between the instantaneous frequency and the instantaneous phase difference), and <2> The same processing can be performed when the nonlinear signal processing of <3> or <3> is performed.

  In the above, some examples in which the present invention is applied to ultrasonic imaging or ultrasonic measurement have been presented. The present invention can be applied to waves other than ultrasonic waves as in other processing methods. If the band of the signal component calculated and generated by the present invention overlaps with the band of another signal, the two cannot be separated in the frequency domain. In that case, the pulse inversion method or the separation of multidimensional terms is used, but the inventor of the present application has previously reported that the spectrum in the superimposed state is handled or divided and processed. (See Non-Patent Document 30). In the present invention, as another method for accurately separating waves, including a case where spectra are superimposed, in order to obtain an effect of separating the waves in a frequency space, a non-linear process is performed on the superposed waves as a nonlinear process. In a situation where a multiplication operation is performed and the band is widened and represented as a harmonic, separation may be performed in a frequency space. Conversely, a high-frequency signal may be reduced in frequency, or a wide-band signal may be narrowed, displayed, or handled. After high-frequency and widening (when the order is greater than 1) or low-frequency and narrowing (when the order is less than 1) by a power operation, processing is performed with high precision in the frequency domain. May be asked. The propagation direction of the wave can be determined from the center of gravity of the generated harmonic spectrum (local direction, that is, with spatial resolution, or macroscopic and low spatial resolution, or no), or from the analysis signal to the instantaneous frequency ( (It has a spatial resolution) and can be calculated. Using the order of the implemented power, other parameters of the wave such as the frequency and bandwidth of the original wave can be calculated back and restored in a separated state (power order using restoration of the separated signal is also used) It is easy to raise to the reciprocal of.). Even in such cases, the position and arrival direction of the signal source, the intensity of the signal source, and the size and distribution of the signal source can be measured with high accuracy. In addition, when a signal having a higher frequency than the original signal is generated, it is necessary to widen the bandwidth that can be calculated in advance before performing the calculation. For this reason, the zero-filling of the spectrum is effective without approximation (see Non-Patent Document 30), but the sampling interval may be shortened in space-time directly based on interpolation approximation.

  In recent years, it has become possible to simulate nonlinear propagation at low cost. Therefore, it is also possible to generate a nonlinear signal by applying the nonlinear calculation of the present invention or such a simulation technique to an unbeam-formed signal (such as a plane wave) or an echo signal for aperture synthesis. Further, based on these, it is also possible to analyze (inverse analysis) the actually measured nonlinear signal based on an inverse problem approach and apply it to tissue diagnosis.

  For example, in the case of an ultrasonic wave, a sound velocity, a bulk modulus, an acoustic impedance, a reflection, a Rayleigh scattering, a back scattering, a multiple scattering, or an attenuation is evaluated as a tissue property of a living body, and is applied to a diagnosis. Sometimes. For other waves, inverse analysis of related phenomena and physical property values is effective (Mie scattering in light, scattering in radiation, Compton scattering, etc.).

  In addition, in the treatment by heating or heating, it is necessary to clarify the heat receiving characteristics of the target (for example, the characteristics with respect to the sound pressure of high-intensity ultrasonic waves and the effect of a contrast agent) and the characteristics of temperature rise. In some cases, a comprehensive understanding is required or it is necessary to understand on site. In such a case, the calculation including the nonlinear calculation is effective. In treatment, it is useful to evaluate and apply the effect based on the imaging of the non-linear effect according to the present invention. Alternatively, the present invention can be used to perform echo imaging or tissue displacement measurement on a received signal physically subjected to a nonlinear effect, a separated baseband signal, and a plurality of harmonics.

  The present invention is not limited to ultrasonic waves, and includes electromagnetic waves, light, radiation, mechanical vibration, sound waves other than ultrasonic waves, and non-linear operations such as multiplication and exponentiation of coherent signals of arbitrary waves such as heat waves. The present invention relates to a measurement / imaging apparatus for increasing the frequency, increasing the bandwidth, or increasing the contrast of a signal by performing the following. According to the present invention, a harmonic signal can be enhanced, simulated, or newly generated. Further, a harmonic signal can be virtually realized.

  In addition, it is possible to simultaneously obtain a baseband signal and a detection signal in any direction of a harmonic signal with a smaller amount of calculation than in a normal detection process. As a result, for example, higher frequency and wider band, higher contrast, or suppression of side lobes can be achieved, and nonlinear imaging with a high SN ratio can be performed. Further, the displacement vector can be easily measured with a small amount of calculation by using a normal one-way displacement measurement method. From the viewpoint of generating chords, difference tones, overtones, etc., high-frequency signals and low-frequency signals can be obtained, even when the frequencies of waves, beams, carrier frequencies, steering directions, or propagation directions are different. Yes, these may be used effectively for imaging and metrology. Through theory or calculation, waves and beams generated by not only linear effects but also non-linear effects can be designed (wave and beam parameters such as the propagation direction) and controlled.

  On the other hand, in the field of image measurement, a coherent signal is subjected to various types of detection (including one that simply takes the absolute value of a waveform, etc.), and an incoherent signal (result display is an image) is used to detect motion. It is well known that observations are made. Cross-correlation processing, optical flow, or a method based on the SAD (Sum and Difference) method may be used. Further, even when the present invention is applied to an incoherent signal, a wider band (higher resolution) can be obtained. The above high-resolution detection signal obtained by the present invention can also be used. The situation where the data density has increased through the increase in bandwidth is suitable for such processing, and the accuracy of motion measurement is also improved. The above method can be applied to a coherent signal, and the widening of the bandwidth is effective for improving the accuracy. That is, the present invention can be applied to arbitrary coherent signals and incoherent signals.

  In addition, according to the present invention, heating, heating, cooling, freezing, welding, repairing any medical object performed using waves (laser, ultrasonic wave, or focused high intensity ultrasonic wave), cancer in medical treatment In heating or cryotherapy of a lesion or the like, or washing an arbitrary object (such as eyeglasses), the effects can be enhanced through non-linear phenomena, high resolution can be achieved, and the effects can be predicted (for example, strong The effect can be improved through the exponential effect at the time of heating using a sound wave or the effect of multiplication as well as the addition when the effect is enhanced using a cross beam.

  In heat treatment using high-intensity ultrasonic waves, harmonics are generated by the non-linear effect of the tissue, and since it is a high frequency wave, its heat energy has a strong absorption effect, so the heat generation in the tissue can be easily understood and predicted. It is also possible. In this respect, transmitting a high-frequency signal, transmitting a broadband signal, transmitting a harmonic, generating a superimposed beam, or generating a cross beam is effective for treatment. Yes, it is easy to understand and predict. Specifically, a sound field can be simulated, or in a system capable of obtaining a received signal, the sound pressure shape and the point spread function can be estimated based on the evaluation of the autocorrelation function, and can be directly performed. It is also effective to perform a non-linear operation on the fundamental wave signal, as long as the evaluation can be performed on the harmonic signal. The same applies to other waves.

  Further, the present invention provides a method for obtaining a nonlinear effect under physical conditions in which a nonlinear effect cannot be physically obtained (for example, when the intensity cannot be increased with respect to a measurement target, or when a high intensity cannot be obtained due to a high frequency). It is also effective. Conversely, for example, during ultrasonic echo imaging, displacement measurement, or treatment, the present invention can be carried out under a condition in which a non-linear effect is enhanced using a contrast agent such as a microbubble. Although the tissue may be targeted in a state where the tissue is permeated, it is also suitable for measurement and imaging of blood in blood vessels and heart chambers. That is, the present invention can enhance, simulate, or generate new nonlinear effects. Further, the present invention can virtually realize the nonlinear effect. As described above, it is also possible to evaluate non-linear effects. Contrast agents may be used to enhance the effects of heat treatment. The same applies to other waves.

  Further, when a high-frequency signal that cannot be realized by a single signal source is generated, higher-resolution imaging and higher-accuracy Doppler measurement can be performed. Normally, the effect of attenuation is strong against high-frequency components. For example, in a microscope that is easily affected by attenuation, it is preferable that observation can be performed at a high frequency as deep as possible. For example, when a plurality of 100 MHz ultrasonic transducers are used, ultrasonic waves that are physically as many as the number of ultrasonic transducers can be generated, and a high frequency that cannot be generated by a normal transducer can be realized. In addition, a high-frequency signal (chord) can be simply generated. According to the present invention, such a high frequency can be realized by calculation. Therefore, according to the present invention, high-frequency waves and signals that cannot be physically realized can be generated. Similarly, measurement using low-frequency imaging and low-frequency signals (for example, difference sound) can be realized. It is also possible to generate a low-frequency signal that cannot be physically realized by a single signal source. These signals can also be realized theoretically or on an arithmetic basis to control the generated waves.

  Hereinafter, in order to prove the effect of the present invention, experimental data, simulation results, and materials such as photographs will be described. These demonstrate the effectiveness of the present invention by performing ultrasonic echo imaging and measurement imaging through ultrasonic simulations and agar phantom experiments. The present invention can be applied to any signal other than the ultrasonic echo method (a familiar one such as laser, light wave, OCT, electricity, magnetic field signal, radiation such as X-ray, and heat wave) and between different signals. It is. This applies in raw coherent signals or incoherent signals after signal processing.

  Non-Patent Document 30 discloses an agar phantom for aperture surface synthesis echo data (linear array probe, 7.5 MHz) with beamforming in the front direction and horizontal modulation of 3.5 MHz in the horizontal direction. The above <1> to <3> were performed using the respective echo signals at the time of performing the above.

  FIG. 53 is a diagram showing a change in the spectrum of an echo signal according to an embodiment of the present invention. In FIG. 53, the horizontal axis indicates the horizontal frequency [MHz], and the vertical axis indicates the depth frequency [MHz]. In FIG. 53, (a1) and (a2) show the spectrum of the original echo signal and the spectrum of the square of the echo signal, respectively, without steering. (B1), (b2), and (b3) show the spectrum of the original echo signal, the spectrum of the square of the one-way steering echo signal, and the spectrum of the square of the transverse modulation echo signal during the transverse modulation. Each is shown. (C) shows the spectrum of the product of the cross steering beam echo signals. From FIG. 53, the spectrum of each signal derived by the above theory can be confirmed. For each echo signal, the second harmonic spectrum is generated as a result of squaring or multiplication, and its bandwidth is wider than the original spectrum.

  FIGS. 54A to 54C are diagrams illustrating changes in an autocorrelation function of an echo signal according to an embodiment of the present invention. Here, the horizontal axis indicates the horizontal position [mm], and the vertical axis indicates the normalized autocorrelation function. FIG. 54A shows a comparison between the autocorrelation function of the original echo signal and the autocorrelation function of the second harmonic obtained by squaring the echo signal without steering. FIG. 54B shows a comparison between the autocorrelation function of the original transversely modulated echo signal and the autocorrelation function of the second harmonic by squaring the transversely modulated echo signal during the transverse modulation. FIG. 54C shows the autocorrelation function of the transverse component and the depth component for the product of the cross beam echo signals and the square of the transverse modulated echo signal. Based on the autocorrelation function, the lateral profile of the sound pressure and the point spread function can be evaluated (in the case of a depth of 19.1 mm at the center of the region of interest). Although omitted here, if a two-dimensional autocorrelation function is obtained for this two-dimensional echo signal, the two-dimensional distribution of the sound pressure and the point spread function can be estimated. Find a function.

  FIG. 55 to FIG. 57 are diagrams illustrating a change in a B-mode echo image according to an embodiment of the present invention. The depth of these echo images is 10.0 mm to 28.1 mm, and the width is 20.7 mm. In the agar phantom, a cylindrical nail (diameter: 10 mm) having a shear modulus of about 3.29 times higher than that of the surroundings exists around a depth of 19 mm.

  55 to 57, (a1), (a2), and (a3) show the echo image based on the original echo signal, the echo image based on the baseband signal, and the echo signal in the case without steering. The echo images based on the second harmonic by the square are shown respectively. When there are two images on the left and right, the image on the left is based on envelope detection, and the image on the right is based on square detection.

  (B1), (b2), (b3), (b4), and (b5) show an echo image based on the original horizontal modulation echo signal, an echo image based on the base banded signal, and a horizontal image during the horizontal modulation. An echo image based on the second harmonic by squaring the directionally modulated echo signal, an echo image based on the transverse component of the second harmonic by squaring the transversely modulated echo signal, and an echo image based on the square of the transversely modulated echo signal. Each echo image is shown based on the depth direction component of the second harmonic.

  (C1) and (c2) respectively show an echo image based on a lateral component and an echo image based on a depth component of a second harmonic generated by a product of cross beam echo signals. In the case where a plurality of waves exist, detection of superposition of coherent signals has also been reported in the past, but here, the result of superposition of each detected signal is shown.

  It can be confirmed from FIGS. 54A to 54C and FIGS. 55 to 57 that the spatial resolution has been increased in response to the broadening of the spectrum shown in FIG. Here, the DC of the basebanded data is not cut off. If the direct current or, if necessary, the spectrum of the extremely low frequency in the depth direction or the horizontal direction is removed by filtering or the like, high or low luminance lines (vertical stripes) running in the vertical direction can be completely removed (illustration shown). Is omitted). From FIG. 54A to FIG. 54C, it can be confirmed that the side lobe has been lowered. Correspondingly, the effect of increasing the contrast can be confirmed from FIGS. 55 to 57 (note the strong scatterers and the like). Since the attenuation of the original echo signal has not been corrected, the image obtained from the processed signal has a shallower signal intensity at a deep position than the original signal image as a result of an increase in contrast due to uncorrection. Extremely low compared to that of the position.

  In the imaging using the original signal, correction of attenuation in the so-called wave propagation process is performed on the coherent signal or the incoherent signal after detection. Then, the coherent signal is subjected to nonlinear processing, or the coherent signal or the incoherent signal is corrected after the nonlinear processing. The correction processing itself may be performed mainly on the basis of signal strength before or after reception beamforming or after imaging as in the case of normal correction. Corrections may be made according to Lambert's law.

  In that case, an average attenuation coefficient may be used, but the attenuation coefficient at each position on the path of the wave or beam is calculated by the signal processing or inverse analysis in the arithmetic unit 130, and the correction is performed with high accuracy. May be implemented. That is, it may be performed adaptively or automatically. Alternatively, the operator may adjust the intensity within a predetermined range at each depth via the control unit 133 while viewing the generated image. Depending on the measurement target, a selectable pattern may be prepared.

  Gain adjustment is performed by the receiver 122, the amplifier or attenuator in the filter / gain adjustment unit 123 or 125, the amplifier, attenuator or digital processing in the reception beamformer 129, or the analog or digital processing in the arithmetic unit 130. Will be In the transmitter 121, the intensity of the transmitted beam or wave may be adjusted. Further, an amplifier or an attenuator may be used as the action device 112, and the intensity of the wave itself may be adjusted. Care must be taken because the contrast agent 1a greatly affects those decisions.

  In the square calculation (<2>) of the transverse modulation echo signal in the above experiment, the transversely detected spectrum and the second harmonic of the two signals of the second harmonic detected in different directions. Because of the overlap of the waves, the inventor of the present application split the spectrum by eye. The result was compared with the result of multiplication (<3>) of two waves of the transverse modulation echo signal in the autocorrelation function (see FIG. 54C). There was no difference.

  In addition to these experiments, displacement vector measurement, strain tensor measurement, and shear modulus reconstruction were performed using a multidimensional autocorrelation method. FIG. 58 shows the results of displacement measurement in each direction using two of the second harmonic signals detected in only one different direction in <3>.

FIG. 58 is a diagram showing images of a displacement vector, a strain tensor, and a relative shear modulus measured in an agar phantom according to an embodiment of the present invention. In part of FIG. 58, the average value and the variation (in parentheses) evaluated at the center of the nail are also shown. Strain variation in the tended to noise is increased as compared to the results obtained by performing the digital demodulation in the same lateral modulated echo data (lateral direction (y) is, 9.52 × 10 from 3.08 × 10 ^{-3 −3} ), the spatial resolution was doubled, and as a result of regularization of the shear modulus reconstruction, the precision was improved (from 3.37 to 3.23).

  Although the results are omitted here, as described in paragraph 0655, many waves and beams are generated, and nonlinear processing is performed in a superimposed state, or nonlinear processing is performed in a non-superimposed state. May be superimposed on each other. Further, as described above, non-linear processing may be performed on a raw received signal that has not been subjected to beamforming (such as a case of only transmission beamforming or a case of aperture plane synthesis). A plurality of waves or beams generated under the same wave and beamforming parameters may be processed, but waves and beams generated under different parameters may be processed.

For high resolution, super-resolution in the above-described linear model is effective, and the super-resolution may be used for a plurality of such waves and beams. That is, individual waves or beams that are not superimposed may be super-resolved and superimposed, or super-resolution may be performed in a superimposed state. In some cases, both are mixed and processed. In some cases, noise reduction is performed by superimposing (averaging) under the same parameter. Significantly higher spatial resolution can be achieved for the original signal (including harmonics). Although various super-resolutions are described, for example, as described in paragraph 0363, when inverse filtering is performed using a target point spread function or a spectrum of a signal distribution such as an echo distribution as a target, the description is made in paragraphs 0390 to 0415. As described along with the displacement measurement, weighting can be performed by applying a Wiener filter for imaging the signal itself. Among them, for example, the Wiener filter used in Expression (A12 ′) or Expression (A13 ′) is used. If the underlying weights (excluding the square norm of the first signal spectrum) are used, the inverse filter
However, each of Hp (ωx, ωy, ωz) and G (ωx, ωy, ωz) is the spectrum of the signal to be processed and the target signal.
Weighted the norm of
Here, PWpn (ωx, ωy, ωz) and PWps (ωx, ωy, ωz) are the power spectrum of noise and signal, respectively. q is an arbitrary positive value.
What is necessary is just to process using. In other super-resolution modes in the linear model described above, it is possible to similarly apply a Wiener filter to suppress noise amplification. Without using a Wiener filter, in the case of applying the norm itself (AA1), the signal spectrum Hp (ωx, ωy, ωz) ε norm of (maximum norm or L ₂ norm, L ₁ norm, etc.) (<1) times The processing of only the spectrum of the frequency having the above-mentioned spectrum may be performed (the spectrum of the other frequencies is set to zero). In these, irregularly, instead of the norm of (AA1), (AA1) itself may be used, and the phase may be matched. In that case, Gp (ωx, ωy, ωz) often has phase information of the measurement target.
In addition, these weighting processes may be performed in blind deconvolution. In addition, a case where whitening is performed by inverse filtering using a separately obtained point spread function or system transfer function, a case where the point spread function or the system transfer function is conjugated, or a case where the conjugate of the formula (AA1) is multiplied is included. These weighting processes are also useful before or after beamforming (in a state of only transmission beamforming or a received signal acquired for aperture synthesis). In particular, regularization may be performed in inverse filtering. Also, it may be performed based on maximum likelihood estimation (with or without MAP).

  The above-described non-linear processing may be performed on a signal that has been subjected to super-resolution under such a linear model. Further, higher resolution and higher contrast can be realized. As a result of the super-resolution obtained under the linear model, the original (including the case of harmonics, the same shall apply hereinafter) signals are super-resolved, and those super- The objects to be processed include those that exist and are superimposed, that are super-resolved by superposing a plurality of originals, that are processed by mixing them, and the like. In some cases, there are a plurality of original signals, each of which is super-resolution under a linear model, and is subjected to non-linear processing and superimposed. They may be mixed and processed.

  Further, as described above, a signal subjected to nonlinear processing may be subjected to super-resolution performed by a linear model. Although the resolution is increased, the contrast may be reduced. As a result of the super-resolution obtained by the non-linear processing, the original (including harmonic) signals are super-resolved, and a plurality of those super-resolution signals are present and superimposed. A processed object, a super-resolution image obtained by superimposing a plurality of originals, a processed image obtained by mixing the original images, and the like are processed. In some cases, there are a plurality of original signals, each of which is super-resolved by non-linear processing, and super-resolution performed by a linear model is applied to each of them to be superimposed. They may be mixed and processed.

It should be noted that, when the non-linear processing is performed on a plurality of signals (signals representing a beam or a wave, not limited to a fundamental wave and may be harmonics) at the same position of interest, the directivity of the aperture and the If the strength of the original signal itself before processing is different due to the effects of scattering or attenuation (including the case depending on frequency) on the target, the difference may be emphasized. When generated, it may be noticeable. This difference may be positively imaged or quantitatively confirmed in a spectral image (these frequency characteristics may be emphasized and confirmed in some cases). On the other hand, in order to reduce the difference and perform imaging, before or after the non-linear processing, a process of weighting the energy of a signal or a spectrum of a specific frequency may be performed to perform imaging. The signals may be superimposed and imaged. Note that the spectrum or energy of the signal may be evaluated in a local region including the position of interest, or may be evaluated in the entire region of interest. Of course, regardless of whether or not nonlinear processing is performed, weighting may be performed in the same manner during linear superposition processing.
In addition, the signal intensity becomes weaker in the distance direction due to the influence of attenuation and reflection / scattering in the propagation process. However, for example, the degree of attenuation of a plane wave is weaker than at the time of focusing. When nonlinear processing is performed, the effect is emphasized as the order increases. Therefore, as described above, the signal strength may be corrected before or after the nonlinear processing (the correction may be performed even when the nonlinear processing is not performed). It is processed before or after the detection.
There are various other types of super-resolution, and at least one of the methods may be used in combination, applied to the same or different signals, and coherently added for use. As described above, it may be applied to the superimposed signal. In addition, they may be added incoherently, and speckle may be reduced. As described above, incoherent addition through super-resolution may not reduce the spatial resolution.
In addition, in each of these super-resolution processes, spatially non-uniform addition may be performed depending on the signal intensity, the SN ratio, and the spatial resolution. That is, the parameters of each method may be variable depending on those at each position. As described above, when the spectrum is processed, for example, in the case of the non-linear processing, the order of the power, the number of times of multiplication, and the like are used. In addition, when adding a coherent signal or an incoherent signal, the number of additions, a weight value, and the like are used. Of course, it may be spatially uniform.
As an effect of high contrast by nonlinear processing, scatterers, reflectors, and diffraction sources in a wave source or an observation target (tissue, etc.) may be remarkably well visualized. Is increased, an effect may be obtained in which the difference in signal intensity (luminance when converted to a grayscale image) becomes significant. For example, it may be easier to capture calcification after necrosis of biological tissue. In addition, for example, coloring may be performed depending on the signal intensity, and the image may be displayed by being superimposed on a normal grayscale image, a Doppler image, a power Doppler image, a contrast image, or the like. The processing may be performed after the intensity of the signal distribution is corrected. For example, a non-linear process is performed after correcting the signal received from the region of interest (before or after detection) to spatially uniform the intensity, and the scattered intensity distribution and the scattered intensity of a plurality of scatterers, or the reflected intensity distribution, The level of the reflection intensity of a plurality of reflectors may be visualized. Processing may be performed for the purpose of counting the number of reflectors and scatterers. In addition to the focus beam and aperture plane synthesis, if a plane wave, a spherical wave, or a cylindrical wave is used, the spatial resolution is low, and even in such a case, various super-resolutions including non-linear processing are useful, In particular, when a non-linear process is performed, a scattered wave or a reflected wave may be remarkably visualized at the generation position. For example, when these cross waves are generated, a cross-shaped waveform is displayed as a scattered wave with the cross-shaped waveform highlighted at the scatterer position. Diffraction sources may be of interest.

  In addition, the exponentiation and multiplication of the point spread function when using a concave aperture HIFU applicator (simulation, frequency 5 MHz, aperture diameter 12 mm, focal depth 30 mm) were calculated. . As described above, this type of calculation is effective in considering the heating effect. By collecting experimental data, it is possible to formulate the relationship between sound pressure (point spread function), sound pressure of harmonics, heat reception, etc., design of applicator and radiation sound pressure (ultrasonic parameters), etc. Can be used to improve the efficiency of heat treatment. The same applies when other waves are used.

FIG. 59 is a diagram showing a change in sound pressure according to an embodiment of the present invention when a concave HIFU applicator is used. In FIG. 59, (a1) and (a2) show images of the sound pressure based on the original signal and the sound pressure of the squared signal when one aperture is used (the left includes DC, and the right is only harmonics). The image of FIG. (B1) and (b2) show the image of the sound pressure by the original signal and the sound pressure of the multiplied signal (DC on the left) when two apertures are used (the intersection angle is ± 5 ° with respect to the horizontal direction). , And the right image shows only harmonics). The image is obtained by envelope detection, and the image size is 3.8 × 12.8 mm. ² It is. In the second harmonic component obtained by each of the square and the multiplication, it can be confirmed that the sound pressure is concentrated on a desired region and the contrast is high. In this way, the evaluation of the intensity (Intensity, that is, power) of the fundamental wave and the sound pressure distribution shape of the generated harmonic (second or higher harmonic) can be estimated. In addition, power (Intensity) consumed by harmonics can be evaluated. The same can be evaluated for harmonics actually observed. From this, it is needless to say that heat generation due to absorption of the fundamental wave and the harmonic can be evaluated. As described above, in order to enhance heat generation, microbubbles may be used, or cavities may be actively generated by the HIFU itself, the nonlinear effect may be enhanced, and harmonics may be actively generated. As the HIFU applicator, not only a concave type but also various opening shapes can be used. In some cases, the openings are constituted by array elements, and in some cases, transmission beam forming can be performed by driving each of them independently. Applicator parameters (transmission center-of-gravity frequency and transmission bandwidth determined by the structure, element shape, size and number, array configuration and shape, etc.) and wave parameters (continuous wave or burst wave or pulse) Whether it is a wave, the length of a continuous wave, the length or shape of a burst wave or a pulse wave, a beam width or a beam shape, a bandwidth, a frequency response or a spectrum with respect to a center of gravity frequency or a space-time, or a transmission beamforming parameter ( Desired HIFU irradiation is performed under irradiation intensity, apodization, focus position, steering direction, irradiation time, irradiation time interval, and the like (optimized parameters may be used).
The inventor of the present application, based on the observation of the spatial distribution and time change of the temperature of the region to be treated or repaired or the region including them, based on the thermophysical properties (heat capacity, thermal conductivity, or thermal diffusivity) of those regions. It is possible to reconstruct the distribution, and at this time it is also possible to reconstruct both the perfusion and the heat source (thermal inverse problem in Pennes equation, diffusion equation, etc., Patent Document 10, Non-Patent Document 44, paragraph 0377, 0378, 0380, 0423, etc.). This makes it possible to make a treatment plan for HIFU. At each HIFU irradiation for treatment or before repeated continuous irradiation, the temperature may be measured from a received signal obtained by the HIFU irradiation with reduced intensity, and reconstruction may be performed. In some cases, temperature measurement and reconstruction may be performed in the same manner from a received signal having a strong intensity for itself (it is important to correct the phase aberration of the received signal caused by a temperature-dependent change in sound speed by the above-described phase aberration correction method). However, it is also useful to treat from a deep part to a shallow part). HIFU parameters (heating / focus position, HIFU pressure shape, irradiation time, etc.) for the next irradiation or the next repetitive continuous irradiation are appropriately or sequentially reconstructed under temperature observation, or Is determined.
In that case, for example, the following procedure may be followed.
(1) Reconstruct the thermophysical property distribution (sometimes reconstruct the distribution of heat source and perfusion simultaneously) and calculate the distribution of heat source Q that generates the desired temperature distribution: Temperature distribution data observed at that time And the distribution of the time rate of change of the temperature (corresponding to the time derivative of the temperature, difference approximation and time element interpolation approximation in the numerical calculation) to generate the desired temperature distribution at that time is set, and Pennes is set. The distribution of the heat source Q is found in the equation. There are various notations in the Pennes equation. Here, they are expressed as follows.
ρC (dT / dt) = ∇T ・ ∇k + k∇ ^Two T + P + Q (HIFUQ0)
Or
dT / dt = ∇T ・ ∇κ + κ∇ ^Two T + P + Q (HIFUQ0 ')
Where T is the temperature of the tissue, ρ is the density, C is the heat capacity, k is the thermal conductivity, κ is the thermal diffusivity, P is the perfusion term, and Q is the heat source. (HIFUQ0 ′) is an expression that approximates (HIFUQ0) and reduces the number of unknown properties (an expression in which heat capacity and thermal conductivity are approximately aggregated and expressed as a thermal diffusivity), and the amount of calculation is reduced. , Accuracy decreases. The perfusion term P is expressed as wb · cb (T−Tb) in peripheral blood vessels, where wb, cb and Tb are the blood perfusion coefficient (dependent on the blood flow velocity), the specific heat of the blood, and the blood temperature, respectively. . In general, this is a formula used in peripheral blood vessels, but the present inventor has made it possible to express the perfusion effect by a thick blood vessel by reconstructing P itself, and in any case, wb Is also possible to reconfigure. When wb is estimated by observing the blood flow velocity, cb can be estimated.
Here, the perfusion is assumed to have no change, or the perfusion coefficient is updated to the latest value using the reconstructed value or the observed blood flow velocity. By the way, the perfusion term can be ignored when using the observed temperature data in the state of hemostasis (obstruction of the blood vessel by HIFU irradiation or using a clamp, etc.), and the term of the heat source is ignored when using the observed temperature distribution data with the heating stopped. It is possible to reconstruct the required thermophysical properties and calorie with a small calculation. If it is desired to obtain only heat source data, HIFU irradiation may be performed for a short time, and the product of the time change of temperature before heat transfer and the heat capacity may be calculated and obtained.
(2) For the distribution of the heat source Q0 reconstructed together with the distribution of the thermophysical properties, the supply power W is calculated using calibration data (generated by an acoustic or optical-based hydrophone or the like) of the set power of the HIFU device and the HIFU intensity. It is assumed that the absorption coefficient α of the HIFU at that time does not change (it may be kept constant) until the next irradiation, or α is determined with respect to the tissue type and state or the HIFU intensity I. Using the data prepared in advance, at each position of interest,
Q0 = αI0 (I0 is the HIFU strength for realizing Q0) (HIFUQ1)
Thus, the desired Q0 may be directly generated based on the data of α.
Or, to realize the desired Q,
Q = α′I (α ′ is an absorption coefficient for generating Q, I is HIFU intensity for realizing Q) (HIFUQ2)
Then
Q / Q0 = (α'I) / (αI0) (HIFUQ3)
When α '= α, Q / Q0 = I / I0 (HIFUQ3')
And I can be estimated for I0. Based on the above calibration data of the HIFU device, W for realizing I can be determined for the supply power W0 for realizing I0. Assuming that α ′ = α, no data on α is required. In these calculations, it is assumed that the estimation including the heat generation contribution of the harmonic generation is performed, but the present invention is not limited thereto. For example, the harmonic component I0 ″ or I ″ generated by the fundamental wave I0 or I is compared with those observed with the reference material (water or phantom) under W0 or W. It is evaluated by comparison with the wave components (the difference between them and their relative values, etc.), and α and α '' (harmonic intensity, tissue type and state, etc.) prepared for each of the fundamental wave and the harmonic May be kept constant, or α ″ = α, etc.) may be used instead of α and α ′ in (HIFUQ1) to (HIFUQ3 ′), and the fundamental wave In situations where the relationship between the intensity of each of the harmonics and the heat source they generate can be expressed, the power supply that generates the desired total heat source may be determined.
It should be noted that it is also possible to estimate the generated HIFU pressure shape (normalized wave shape) by providing a reception function that enables the reception and evaluating the multidimensional autocorrelation function of the reception signal. It is possible to estimate the sound pressure profile of the above harmonics, or to estimate the generated HIFU based on the calibration data of the power of the HIFU irradiation device and the generated HIFU intensity. That is, the relationship between the sound pressure waveforms of the fundamental wave and the harmonics, which can be estimated by the above-described nonlinear calculation, can be used. In addition, if a HIFU received signal can be received, fundamental waves and harmonics can be separated by the pulse inversion method or filtering, and the accuracy of the actually generated HIFU pressure shapes can be improved. The strength of the sound pressure intensity can also be improved using the strength of the received signal. The receiving sensor may be installed at various positions, such as a transmitted wave (for which degassed water or undegassed water is used) or an echo (reflectors or reflectors are representative of the focal position) for HIFU irradiation. In some cases, reflectors may be observed in various directions, and scatterers may be observed in the distribution medium.) In some cases, the HIFU applicator itself also serves as the receiving sensor (the same applies to the case where the radiation pressure used for radiation pressure imaging is handled). When observing or estimating up to the pressure shape (pressure distribution), the receiving sensor needs to be an array type or need to perform mechanical scanning, but if you want to measure the intensity at a specific position such as the focus position, However, it is not always necessary to use an array type, and a single aperture may be used. In accordance with the conversion efficiency of the receiving sensor to voltage with respect to the received sound pressure, and its band and frequency characteristics, an appropriate material such as an attenuating material (if it has scattering characteristics) at any place before the receiving sensor receives the wave May or may not be used (attenuating material may be removable to the receiving sensor), or after receiving, an attenuation circuit (directional coupler or attenuation area) may be used Or used after being corrected using the frequency characteristics of a sensor or an attenuator. (It is desirable to correct the attenuation in the entire propagation process and the attenuation of the intensity due to scattering. As described above, deconvolution or inverse filtering is performed in the space-time or frequency domain). That is, it is necessary to prepare correction (or calibration) data for obtaining the sound pressure and intensity from the received signal. For example, in the following embodiment, it is necessary to directly obtain the sound pressure and intensity. (There is no need for calibration data, especially if the received signal and the sound pressure of the observation target have a proportional relationship.) Many high-intensity ultrasonic hydrophones, such as HIFU, which are currently in practical use, have many needle types and low observable sound pressure (or intensity) (for example, at frequencies of several hundred kHz to several tens of MHz, several The optical fiber type has a comparatively high sound pressure (or intensity) observable in a wide band (for example, from several MPa to 500 MPa at several kHz to 150 MHz). Therefore, regarding the sound pressure (or intensity), frequency, and the like to be observed, they may be used in a complementary or overlapping manner (such as averaging). The hydrophone is not limited to these, and may be used together. In addition, while the hydrophone has directivity (diffraction limit), change the installation position of one or more hydrophones to be used, or observe the high sensitivity direction (main lobe direction) in different directions. In some cases, the observed signal is corrected (deconvolution, inverse filtering, etc.). In the present invention, while using a hydrophone, a transmitted wave or an echo signal at the time of HIFU irradiation is received using the above-described receiving device as described above, and the sound pressure ( Calibration data relating to the strength (amplitude or effective value), power, or energy of the received signal with respect to the amplitude, effective value, power, sound intensity, energy, or energy per unit area, etc. is obtained in advance. By using the same calibration data, a signal received by the receiving device using a low sound pressure or a high sound pressure that is unobservable with a hydrophone, a low sound pressure or a high sound pressure, a low intensity or a high intensity, or an out-of-band sound pressure or intensity. Can be calibrated and observed or estimated. In order to obtain the calibration data, it is important to use a hydrophone that is as close as possible to the frequency characteristics of the HIFU signal to be observed. And the receiving circuit (that is, the receiving device), and for the received signal of the hydrophone, the characteristics of the hydrophone (frequency characteristics and directivity, that is, the frequency characteristics of space-time) are corrected by deconvolution or inverse filtering. It is desirable to make the same correction for the receiving device if necessary. At this time, it is useful to similarly correct the attenuation in the propagation process and the attenuation of the intensity due to scattering as described above. For example, an optical fiber type is more expensive than a needle type, a capsule type, or the like. Instead, by providing the above-described receiving device at the time of HIFU irradiation, such observation or estimation can be performed, which may be useful. According to the present invention, it is possible to measure characteristics including various HIFU applicators and driving devices outside of the specifications of a hydrophone realized or owned by a user (500 W / HIFU treatment). cm ² From 5,000W / cm ² HIFU intensity is used, whereas in the case of a typical needle type, for example, about 80 to 500 W / cm ² Sometimes only lower intensities can be measured). By applying this, it is possible to not only measure the characteristics of the HIFU applicator but also obtain calibration data of, for example, the set power of the HIFU device for determining the supply power W during the above-mentioned heat treatment and the HIFU intensity to be realized. it can. In addition, it is also possible to appropriately perform calibration in the same place at the time of actual treatment. Further, when the sound pressure or the intensity to be observed exceeds the rating of the hydrophone, in the present invention, similarly to the above-described reception sensor, an attenuation material is provided even in the reception of the wave by the hydrophone, and the observation signal is similarly processed. (E.g., the attenuator may be properly used somewhere before reception by the hydrophone, may be removable on the receiving part of the hydrophone, and may be corrected using the characteristics of the attenuator after reception. Or you can do that). Of course, the receiving device other than the hydrophone may not be required, or may be used together. In addition, when the frequency has a frequency out of the band of the hydrophone, waves of the same or different frequencies are generated and mixed (superimposed in real time to obtain the effect of raising or multiplying) to increase or decrease the frequency. What is necessary is to observe and evaluate what has been done. The same applies to the case where a wave having a frequency outside the band of the receiving device is received. Here, for easy understanding, calibration of sound pressure, intensity, energy, and the like with respect to the magnitude, power, energy, and the like of a received signal has been described with focus on intensity and frequency (band). The calibration data may be generated and used by paying attention to the wave parameters (wave shape, band shape, etc.) and transmission beamforming parameters. At least two of the wave parameters and transmit beamforming parameters may be calibrated at the same time (multiple applicators with the same or different structures may be used). Although the case of observing HIFU and radiation pressure has been described in detail here, the case of observing the characteristics of a sensor used for observation (measurement or imaging) can be similarly performed using a hydrophone or a receiving device. (Some hydrophones have a high-sensitivity membrane type, but like the HIFU, there are needle-type and capsule-type types, as well as, but are not limited to). Although the case where the wave is an ultrasonic wave is described here, the same applies to a case where the wave is an audible sound wave (using a hydrophone or a microphone), an electromagnetic wave, or a heat wave. When water is used, the amount of gas contained in the water may be observed, and the propagation characteristics of the ultrasonic waves may be measured, or the spectral analysis and propagation characteristics of the optical ultrasonic waves may be measured, and calibration data obtained in advance may be used. (This example is one of the observation examples of the composition of the medium, and may be similarly observed for other substances, molecules, and atoms).
It is also useful to use these observations in combination or, alternatively, to use the estimated HIFU pressure profile data for the heat source in the Pennes equation and determine only the HIFU intensity as a variable (HIFU pressure profile). Is a constant).
In addition to the above-described treatment plan during treatment, a treatment plan may be made using thermophysical properties measured in advance before treatment is performed. Typical values of thermophysical properties may be used. In the above reconstruction, the perfusion may be treated equivalently to the heat source, or may be combined with the heat source and processed as one variable (the amount of calculation is reduced). In the case where MAP estimation is performed when there are a plurality of physical properties including the physical properties to be obtained and their calorific values in the reconstruction of thermophysical properties, dynamic reconstruction (Patent Document 9: When soft tissue is modeled as an elastic body, for example, Equation of motion ρα _i = Pδ _ij + 2Gε _ij + S, acceleration α _i And strain tensor ε _ij The shear modulus G and density ρ, average normal stress (pressure) p, force source S, inertia term ρα _i Etc. are to be reconstructed, and when soft tissue is modeled as a viscoelastic body (the term of the product of unknown viscoelastic coefficient and strain rate tensor is added) or blood is modeled as a fluid (Navier-Stokes equation is treated) ), The strain factor tensor is observed, and the viscoelastic modulus and viscosity become reconstruction targets.) As in the case of), each reconstruction target is simultaneously regularized using different regularization parameters. In the same manner as in the above, each reconstruction target is simultaneously MAP-estimated (discrete by a numerical calculation method such as a finite difference method or a finite element method, and in the equation Ax = b shown in paragraph 0417, the inverse of the matrix A is obtained. In obtaining the unknown vector x by applying to both sides, when the unknown vector x includes a distribution of a plurality of unknown physical properties or a distribution of unknown physical quantities, each reconstructed object itself or a gradient or a gradient represented as a partial vector of x is obtained. The covariance matrix of the Prussian distribution and the components of the expected value (representing each prior established prior) are subjected to ensemble averaging for a posteriori in each distribution to be reconstructed (that is, processed by obtaining multiple sample data, ), The solution of the least squares solution or the maximum likelihood estimation can be estimated by applying the averaging process under the assumption of the local stationary process, and the covariance matrix of the constant vector b can be estimated by the ensemble average or the assumption of the local stationary process. , And can be estimated by applying the averaging process, and can be solved in the same way as the equation (MAP2) expressed by the equation expressed by the equation (LM1).) In general, if the temperature is lower than 50 ° C., the thermophysical properties and the absorption coefficient α do not change, and in the temperature range or an appropriate temperature range, they are kept constant, and the amount of calculation of the reconstructed part is reduced to obtain (1) and ( Although treatment may be performed in the procedure of 2), it is desirable to make a treatment plan by performing sequential reconstruction as described above in terms of accuracy. Needless to say, the absorption coefficient including the case of 50 ° C. or higher may be measured or reconstructed as needed. The physical properties (such as the propagation velocity) of the sound wave may be measured or reconstructed at the same time. In addition, the irradiation time may be integrated on both sides of (HIFUQ0), and the irradiation time and the supplied power may be set in order to realize the time integration (one irradiation energy) of the heat source. Even in this case, it is desirable to make a treatment plan for each irradiation.
Here, supplementing the heat generation mechanism by the HIFU, a shearing phenomenon occurs in the treatment target when the acoustic wave is refracted or reflected by the HIFU irradiation at a position where the acoustic impedance changes, which also becomes a heat source. Therefore, basically, the above-mentioned absorption coefficient α of HIFU is observed as including it, but may be separately measured as a heat source. In human tissues, especially when there is a boundary near the focal point where the impedance of soft tissue, bone, lungs (air), etc. changes greatly, heat is easily generated there and the HIFU may be affected. This is a restriction when applying. In such a case, it is effective to correct the phase aberration and control the HIFU sound pressure shape under appropriate apodization for HIFU beamforming. In order to generate a desired HIFU sound pressure shape, the optimization theory may be applied as described above to determine HIFU parameters (wave, beam forming, and applicator parameters). In addition, it is also useful to influence mechanically as the influence of a shock wave, which may cause cavitation as described above, and may also break cells or facilitate the introduction of a drug. It is well known that safety is required in imaging and a thermal index and a mechanical index are used.
As described above, various imagings are effective for confirming the therapeutic effect. For example, the shear modulus reconstructed value (inverse problem) can be applied to temperature observation, but is also useful for judging the therapeutic effect (tissue degeneration, tissue coagulation and softening). For that reconstruction, it is necessary to observe the tissue strain (tensor). As described above, observation can be performed using ultrasonic waves, MRI, OCT, and the like, but observation can be performed under displacement (vector) observation using an optical ultrasonic (photoacoustic) signal. The optical ultrasonic wave may have a wide band in the propagation direction of the wave depending on the type of the tissue, and may have high resolution and high contrast, as compared with the echo or the transmitted wave by the irradiation ultrasonic wave. As a result, distortion observation also has a high resolution and a high contrast, and may be improved in accuracy. The reverse may also be the case. The center-of-gravity frequency of the generated optical ultrasound also varies depending on the type of tissue (including the type, composition, structure, shape, size, and the like of the adjacent tissue). On the other hand, in the lateral direction, for example, when irradiating parallel light and irradiating a plane wave ultrasonic wave, depending on the tissue type, the unreceived beam forming optical ultrasonic wave is an echo or transmitted wave of the irradiated ultrasonic wave. The band may be narrower in the lateral direction than that of the skin (for example, skin in a layered structure on the body surface has a narrow band, and blood and heart in blood vessels running in parallel with parenchymal tissues such as muscles and the body surface). For blood existing in a large space such as an intracavity, it is almost the same as an ultrasonic wave), and the resolution is low. The reverse may also be the case.
As an example, FIG. 60 shows a superimposed image of an optical ultrasonic wave (irradiation light 850 nm) and an ultrasonic echo (both after beamforming) obtained from a human in vivo wrist, and FIG. 61 shows their received beamforming. The two-dimensional point spread function of the previous raw received signal (estimated as a two-dimensional autocorrelation function in each tissue. The vertical corresponds to 1.2 mm in the depth direction, and the horizontal corresponds to 10.1 mm in the horizontal direction, but 1 / 2 is shown at a reduced scale of 2). The point spread function is obtained by estimating the source of the optical ultrasonic signal (in this case, the echo source) and the applied ultrasonic sound pressure (the reciprocal of the signal length in the depth direction is the bandwidth in the depth direction). The reciprocal of the vibration cycle in the depth direction corresponds to the frequency in the depth direction, the reciprocal of the width in the horizontal direction corresponds to the bandwidth in the horizontal direction, and the reciprocal of the vibration cycle in the horizontal direction corresponds to the frequency in the horizontal direction. The shorter the length in the depth direction and the shorter the lateral direction, the higher the spatial resolution in each direction.The same applies to the other directions. Also pay attention to the sound pressure distribution shape and the waveform shape.) There is a layered structure of skin (keratin, epidermis, dermis, subcutaneous), fascia, muscle, vein, muscle, artery, and muscle. These are drawn by ultrasonic echo method, but optical ultrasonic wave has melanin. Strongly produced in veins and arteries where the epidermis and blood are present. FIG. 60 and FIG. 61 show the results. Tissues with low intensity of generated optical ultrasonic waves (subcutaneous tissue and blood in blood vessels in this example) were affected by artifacts due to multiple reflection and multiple scattering of optical ultrasonic waves. If the autocorrelation function is not normalized, the autocorrelation function can be estimated including the signal strength (the same applies to a case where the autocorrelation function is applied to other signals). In an area where the point spread function is considered to be uniform, an average of estimation results of a plurality of obtained point spread functions may be presented, but here, an averaging result is shown. The ultrasonic echo signal has substantially the same point spread function in the depth direction (different tissues) (especially, the mesh-like point spread function intersecting diagonally evaluated in veins and arteries is extremely Similar). In contrast, a characteristic point spread function is obtained in the optical ultrasound signal and depends on the tissue type. Thus, presenting the autocorrelation function is useful for tissue discrimination. The autocorrelation function is equivalent to the autopower spectrum (Wiener-Hitchin's theory) and is useful for visually understanding the signal waveform, but the power spectrum and spectrum (amplitude spectrum and phase spectrum) are autocorrelated. It is useful to present the information for each tissue in the same manner as above, because it is possible to evaluate the bandwidth and the center of gravity frequency with high accuracy, and also to evaluate the spectrum shape. Is omitted here). The optical ultrasonic signals generated by these tissues were lower than the center of gravity frequency of the ultrasonic echo signal (the ultrasonic probe having a nominal frequency of 7 MHz was driven at a transmission frequency of 10 MHz and the reception was in a 20 MHz band). The optical ultrasonic signal generated in the skin had a narrower band in the depth direction than the optical ultrasonic signal generated in other tissues (contrary to blood tissue, it does not include direct current and does not include high frequency). Interestingly, the bandwidth of the deeper arteries was wider than that of the shallow veins (the method of distinguishing between veins and arteries based on oxygen saturation using light near 700 nm, a shorter wavelength than 850 nm). Are well-known, and the above-mentioned band or its conventional method may be used alone or simultaneously.) The skin and blood vessel walls were laterally narrow. Thus, presenting a point spread function, a power spectrum, and a spectrum for each tissue is useful for discriminating a tissue, and can be applied to discrimination of a lesion. The signal processing of the autocorrelation function and the spectrum is preferably one-dimensional processing when the signal is one-dimensional, two-dimensional processing when the signal is two-dimensional, and three-dimensional processing when the signal is three-dimensional (three-dimensional Fourier transform when the signal is three-dimensional). Gives a three-dimensional spectrum, and the Wiener-Hitchin theory or directly obtains a three-dimensional autocorrelation function.) In the case of two-dimensional or three-dimensional, lower-dimensional processing may be performed. is there. The generation of optical ultrasonic waves depends on the above-mentioned tissue type, and specifically generates spatial resolution and contrast (dynamic range of spatial change of optical ultrasonic intensity). It is effective to carry out these analyzes not only in the depth direction and the lateral direction but also in various directions, and the intensity, band (or spatial resolution), center of gravity frequency and waveform (before and after envelope detection) in various directions or specific directions It is useful to evaluate an optical ultrasonic wave or an ultrasonic wave with respect to a waveform or a spectral shape, and to evaluate a difference between them, in order to distinguish a tissue or a lesion.
For the displacement vector observation, the multidimensional spectral phase gradient method and the multidimensional autocorrelation method described in the present application are useful, and in the same tissue, the displacement in the depth direction and the lateral direction (omitted) and the strain tensor component could be observed. . FIG. 62 shows only the observed strain in the depth direction. The multi-dimensional cross-spectral phase gradient method has a matched filter effect, is robust against noise, and has a fairly stable result. On the other hand, the multidimensional autocorrelation method realizes the same high-precision observation only when the operation speed is relatively high but the SN ratio of the wave signal is high. (AcousticX of CYBERDYNE of LED irradiation that can realize real-time observation was used, light pulse length 35 ns, total 400 μJ / 1 pulse, compared with laser light used for ordinary optical ultrasonic waves. The light intensity is weak, and the received optical ultrasonic signal is added and averaged 256 times in total after analog amplification (amplification degree 106 dB) to improve the SN ratio, and the frame rate is 16 Hz. The ICA processing described in the present application may be performed instead of the averaging. In some cases, soft tissue deformation and blood flow were simultaneously observed. In both cases, we were able to depict the organizational structure. Lateral observation was also possible (abbreviated). As the beam forming method, the use of a lateral modulation method or the like for realizing the receiving direction described in the present application in a plurality of directions can further increase the accuracy. Phase aberration correction may be performed. These observations may be made in contrast agents (both inside and outside the body) and in ultrasound materials (emulsions, fats, ICG, water, sugar, other drugs, etc.). Optical ultrasonic waves have lower signal strength and are less likely to cause artifacts than ultrasonic echo or transmission methods, but care must be taken when performing these observations that are sensitive to weak signals. .
The same applies to the case where reception beamforming is performed. Focusing the irradiation light makes it possible to broaden the optical ultrasonic wave and reduce the influence of the size and shape of the adjacent tissue or the target, but basically depends on the above tissue type. Diagnosis of lesions using evaluations and differences of photo-ultrasonic waves and ultrasonic waves related to the intensity, band (or spatial resolution), center-of-gravity frequency, waveform (waveform before and after envelope detection, the same applies hereinafter), and spectral shape in various directions. May be done. Based on the description in paragraph 0419, the frequency dispersion of the optical ultrasonic signal (spectral shape of amplitude and phase, the center of gravity frequency, the bandwidth, etc.) and the frequency dispersion of light irradiation (using a broadband light source, Use of variable wavelength light source or multiple light sources. Absorption spectrum and generation of photo-ultrasonic waves for human tissue composition components (proteins, fats, water, carbohydrates, bone, matrix, etc.) which are abundant in the literature and measured values In consideration of the data, the direction (steering) of light irradiation can be changed, and the reception steering can be performed in multiple directions, including the case where the intensity and frequency of optical ultrasonic waves generated by adjusting the intensity and frequency of irradiation light are observed. The same applies to the case in which In some cases, the results are superimposed coherently and evaluated. Performing super-resolution as described in the present application in optical ultrasound and evaluating the generated optical ultrasound source with high spatial resolution, or performing shaping filtering to present an image with spatially uniform spatial resolution There is also. When the light irradiation and the ultrasonic irradiation are performed simultaneously, the separation of the optical ultrasonic signal and the ultrasonic echo signal (which may be a transmission signal) may be performed through ICA processing. Using at least one signal and at least one optical and at least one ultrasound signal observed alone). The irradiation position or irradiation area of the coherent light is limited to selectively generate an optical ultrasonic wave at a desired position or area, or conversely, a wide area may be targeted at once (only parallel light may be used). However, divergent light can also be used). It is also important to increase the number of light sources as needed in order to improve the SN ratio of the optical ultrasonic signal. Further, the intensity of the irradiation light and the intensity of the optical ultrasonic signal may be corrected in consideration of the attenuation with respect to the distance of the light from the light source and the attenuation in the propagation process of the generated optical ultrasonic wave. This optical ultrasonic wave is also used for temperature observation (temperature dependence of strain and shear elastic modulus) in HIFU, radiation, cooling therapy, heavy ion beam therapy, optical therapy, medication therapy, etc. Sometimes used for judgment. The temperature dependence of the optical ultrasonic wave generation is also an important diagnostic index (temperature observation), and the intensity, waveform, center of gravity frequency, band (or spatial resolution), spectral shape, and spectral shape of the optical ultrasonic signal in various directions described above. Similarly, irradiation light in various directions, frequency dispersion of optical ultrasonic signals, and the like may be used quantitatively for diagnosis. The same applies to echoes and transmitted waves of irradiated ultrasonic waves that are often observed at the same time. Observations on contrast media such as ICG (sometimes using multiple types at the same time: for example, using ICG for lymph and nerve imaging and microbubbles for angiography) are also performed. Observation and diagnosis (including tissue discrimination) may be performed. Since the depth of optical ultrasound that can be observed is limited, it may be performed during craniotomy or laparotomy or when using a laparoscope when targeting deep organs other than body surface tissue . At the same time, an appropriately miniaturized treatment device (applicator) is used at the same time. At least one of these functions is provided in the apparatus, and parameters for realizing a desired numerical value (for example, optical ultrasonic intensity or ultrasonic intensity, etc.) and a point of interest or a region of interest (for example, irradiation light, The wave parameters such as the intensity, frequency, band, and irradiation time of irradiation ultrasonic waves can be manually set, or the device may automatically determine the parameters and operate automatically. An interface for that purpose may be provided in hardware (for example, a movable knob or dial with a scale on a console, a keyboard or a mouse for inputting a numerical value, a liquid crystal touch panel, or the like). In addition, a function to provide typical data of necessary tissue characteristics (such as attenuation characteristics of light and ultrasonic waves) as a database, to observe and store and update tissue characteristics, and to display these and numerical values used May be provided.

  In the above, regarding the measurement imaging apparatus according to the embodiment of the present invention, mainly the electromagnetic wave, the vibration including sound, the heat wave, or the non-linear operation apparatus of the corresponding signal have been described. To enhance the non-linear effect, simulate the non-linear effect, or virtually realize the non-linear effect (ie, physically, chemically, or biologically, except when the non-linear effect occurs). Is also possible). In this case, the present invention can be implemented based on signals received at different times when the waves are used at the same time using the devices related to the used waves. That is, the present invention can handle a case where a plurality of waves are generated simultaneously and a case where a wave is generated alone.

  In addition, in the case of electromagnetic waves, vibrations, or heat, if the frequency is different, the dominant behavior differs depending on each measurement object (medium), and the names should be different (for example, regarding electromagnetic waves, For vibrations such as microwaves, terahertz waves, X-rays, etc., for example, when targeting human soft tissue, shear waves do not propagate as waves due to the effect of attenuation in the megahertz band, and ultrasonic waves are dominant. However, at low frequencies such as 100 Hz, an incompressible feature is strongly dominated by shear waves.) However, the present invention enhances nonlinear effects between those having different behaviors, Can be simulated or virtually realized.

  In this case, the present invention can be implemented based on signals received at different times when the waves are used at the same time using the devices related to the used waves. Of course, there is a limit that phenomena such as propagation speed, attenuation, scattering, reflection, refraction, and diffraction of each wave have dispersion characteristics and must be appropriately used in consideration of the SN ratio of a received signal. However, the application range of the present invention is very wide, including being able to generate high-frequency signals and low-frequency signals that cannot be physically generated or captured.

  It also states that nonlinear calculations and non-linear effects in the object to be measured are imaged, or that it is applied to other measurements, and that harmonics may be actively propagated to the object to be measured. Fundamental waves may be actively used together in them. Also, an over-determined system can be configured. The fundamental wave is processed in the same way as the harmonic.

  Furthermore, an arbitrary detection process is performed on at least one of the plurality of signals obtained through the non-linear operation, or a plurality of signals that may include a fundamental wave are subjected to the arbitrary detection process and then superimposed, or In some cases, a signal obtained by superimposing a plurality of signals that may include a fundamental wave as it is is subjected to arbitrary detection processing, and imaging or other measurement such as displacement may be performed. Regarding superposition, the former incoherent addition (incoherent compounding) is effective in reducing speckle, and the spatial resolution does not decrease when a high-frequency signal is generated and used. Low spatial resolution, which often occurs in normal speckle reduction, does not pose a problem. When a low-frequency signal is generated and used, the spatial resolution may be reduced but useful. On the other hand, the latter coherent addition (coherent compounding) can increase the bandwidth of a signal, that is, increase the spatial resolution. In particular, when a high frequency signal is generated and used, the frequency can be increased, and when a low frequency signal is generated and used, the frequency can be reduced. As a result, it is possible to increase the spatial resolution of the imaging and to increase the accuracy of the displacement and other measurements. As described above, a case where a plurality of beams and waves are generated, and a signal obtained through frequency division of a spectrum are also included in these processing targets including non-linear processing.

  The displacement measurement can be applied, for example, as described above. The application range is immeasurable, such as radar, sonar, and environmental measurement. In addition to displacement, for example, temperature may be measured. In some cases, temperature sensing is directly performed using a temperature sensor.In other cases, the temperature dependence of wave propagation characteristics is detected. Temperature distribution may be measured based on signal processing for distortion measurement. The chemical shift of the nuclear magnetic resonance frequency may be detected based on signal processing. A heat wave is observed, and its nonlinearity can be imaged or applied to high-efficiency heat treatment.

  In the case where the nonlinear effect in the measurement object is actively observed, and in the case where the nonlinear processing according to the present invention is actively performed, the two can be switched and used, or both can be used at the same time. In some cases, non-linear effects in the measurement object are clarified through various calculations. That is, by making full use of the nonlinearity of the signal source, the contrast agent, and the analog or digital nonlinear operation to be used, the nonlinearity effect in the measurement target can be measured with high accuracy and imaged.

  The above-described imaging and measurement are based on performing appropriate beamforming, and an appropriate detection method, a tissue displacement measurement method, and the like are also important. In the past, the inventors of the present application have proposed a transverse modulation method using a cross beam as a beamforming method in addition to quadrature detection and envelope detection as well as a square detection as a method for detecting a multidimensional reception signal (Non-patent Document 13 and 30), spectral frequency division (see [30]), adjustment of wave or beam shape by spectral filtering, methods using many cross beams, and over-determined. A system method and the like, and a multidimensional autocorrelation method, a multidimensional Doppler method, a multidimensional cross spectrum phase gradient method, a phase matching method, and the like (see Non-Patent Documents 13 and 30) have been developed as displacement vector measuring methods. In addition, (viscosity) shear modulus distribution and thermophysical property distribution can be reconstructed and imaged based on displacement and strain measurement. In addition to the original waves and signals, superimposition of multiple waves and signals, or waves and beams (which may include spurious ones) generated by nonlinear effects, spurious waves in spectral frequency division And a beam can be generated, and the shape of a wave and a beam can be adjusted in spectral filtering.

  A signal obtained by superimposing a plurality of signals that may include a fundamental wave, or a signal obtained by spectrally dividing or filtering at least one of a plurality of signals that may include a fundamental wave in a frequency domain ( Non-Patent Document 30), or an original signal that has not been subjected to these processes, or a combination thereof, constitutes an over-determined system, and forms an image by the above process. Or other measurements, such as displacement.

  As described above, the present invention provides a non-linear structure for a high intensity during wave propagation for a coherent signal obtained by detecting a transmitted wave, a reflected wave, a refracted wave, a scattered wave, or a diffracted wave of an arbitrary wave by a sensor. Non-linear effects (generation of harmonics, chords, difference tones, etc.) such as multiplication and exponentiation when reactions and waves are superimposed are obtained by performing, for example, analog computation or digital computation using a computer. As compared with the imaging using the above-mentioned signal, imaging with high frequency, wide band, high contrast and high spatial resolution is realized. It is also possible to perform imaging with a lower frequency instead of a higher frequency. Further, under the same effect, the displacement, velocity, acceleration, distortion, or distortion rate can be measured with higher spatial resolution and higher accuracy than Doppler measurement using the original signal.

  The superposition of the waves means what is physically realized during the beamforming, between the beams subjected to the beamforming, the waves not subjected to the beamforming, and the like. When the wave intensity is weak, the principle of superposition established by the linear rule is mainly observed. Waves, chords, and difference tones) are observed, and the present invention focuses on this latter phenomenon. The present invention is also characterized in that all of these wave components and superimposed waves can be used without depending on their intensities. Of course, it also applies to waves containing harmonic components that are artificially radiated or generated during propagation. Examples of harmonics generated during propagation include, for example, ultrasonic harmonic signals.

  On the other hand, according to the present invention, for example, a beam generated by beamforming (a physical thing including apodization, delay processing, or addition processing, or a calculation result) or a wave not subjected to beamforming is used. With respect to the wave itself (including a plane wave and a group of received signals for synthesizing an aperture surface), a transmitted wave, a reflected wave, a refracted wave, a scattered wave, or a diffracted wave, the same direction or different from the nonlinear effect due to high intensity. Non-linear effects such as multiplication and exponentiation caused by a case where a plurality of waves propagating in a direction (the same wave of the same physical quantity, which differs only in direction, a wave having the same physical quantity but different parameters, and a wave of a different kind of physical quantity) are overlapped. To measure or simulate with high accuracy, for example, after detecting a signal with a transducer, Are those applying operation thereof to the signal using the adder, it is possible to obtain broadband and harmonic or chords, the difference tone. It is also possible to emphasize non-linear effects physically or chemically or biologically, and to produce non-linear effects when non-linear effects cannot be observed or occur. It is possible. Further, a plurality of detection signals can be obtained simultaneously. In addition, the present invention includes an application of a baseband signal generated by a physical action (removal of a harmonic obtained from a received signal by a pulse inversion method, a filtering method, or the like, And applying the signal estimated by calculation).

  In the past, the inventor of the present application disclosed a transverse modulation method using a cross wave (such as a plane wave) or a cross beam based on a linear rule (having a carrier frequency in the depth direction and the transverse direction). According to the present invention, a power-of-power effect can be obtained in this lateral modulation, and a multiplication effect between cross waves can be obtained. In general, the power effect and the product effect can be obtained by increasing the intensity of the wave. However, according to the present invention, these nonlinear effects can be obtained without depending on the intensity.

  Further, according to the present invention, a baseband signal can be obtained by a new detection process that can be easily performed with a small amount of calculation instead of the normal quadrature detection and the envelope detection, and the effect is obtained in echo imaging and Doppler measurement. Is obtained. However, the detected signal contains a direct current, unlike a baseband signal, which is usually used. Therefore, the detected signal is used as it is, or is used after removing the direct current by analog processing or digital processing. In addition, the application of the baseband signal obtained by the physical action is also included in the present invention. Note that a signal in the baseband band generated by the calculation is also referred to as a baseband signal.

  For example, in the fields of medical ultrasonic waves and sonar, nonlinear phenomena in the propagation process of ultrasonic waves in a living body (when the sound pressure is high, the bulk elastic modulus acts high, the sound speed is high, the waveform is distorted, and the propagation process Has been applied clinically, called harmonic echo imaging, but does not disclose the application of physically generated baseband signals. No application of a baseband signal physically generated by other non-linear phenomena is disclosed. It should be noted that a baseband signal, a baseband signal, and an incoherent signal subjected to envelope detection or square detection are also included in the processing target of the present invention.

  In particular, regarding Doppler measurement, the inventor of the present application uses a multi-dimensional reception signal, which differs from ordinary Doppler measurement in which displacement in the direction of propagation of a wave is measured. , Strain tensor, or strain rate tensor can be measured with high accuracy. According to the present invention, unlike a normal detection, a signal (base banded signal) detected in an arbitrary direction can be simultaneously obtained from a multidimensional received signal, and a displacement measurement method in a normal one direction can be used. It is also possible to easily measure them in a short time with a small amount of calculation. Also in this case, echo imaging using simultaneously obtained harmonics and the above-described baseband signal is possible. In addition, side lobe suppression and high contrast can be achieved. As described above, the temperature is measured.

  Basically, multiplication between sine and cosine signals of different single frequencies will produce chords and difference tones, and power calculation will make the frequency of the signal double as high as the power (only double-width And a signal with a plurality of frequency components (distorted waves) is not only increased in frequency but also increased in bandwidth. In addition, the effect of suppressing the so-called side lobe is obtained, and the contrast is increased. Although these effects are often observed as effects during propagation of particularly strong waves, in the present invention, analog or digital arithmetic processing is performed on an arbitrary signal regardless of the intensity to enhance the nonlinear effect. Or simulate or create a new one. It can also be realized virtually. Not only in the case of having the spatial resolution, but also in the case of a continuous wave, a harmonic or a detection signal can be obtained physically or artificially. Once the physically generated baseband signal can be understood under the present invention, its application will be engineeringly useful. For example, a displacement or a displacement vector component can be measured (an ordinary one-dimensional displacement measurement method can be used). In addition, it is possible to measure the displacement and the displacement vector component using the observed harmonics (the various multidimensional displacement vector measurement methods described above can be used), or to constitute an over-determined system. It can also be applied to imaging (higher SN ratio, higher resolution, speckle reduction, etc.) and displacement component measurement (higher accuracy), as in the case of using the non-linear processing of the present invention. In these cases, it is also effective to positively apply a contrast agent to enhance the nonlinear effect.

  In addition, the present invention provides heating, heating, cooling, freezing, welding, repairing, heating of any object performed using waves (laser, ultrasonic wave, or focused high-intensity ultrasonic wave, etc.), and heating of cancer lesions and the like in medical treatment. , Cryotherapy, or washing of any object (such as eyeglasses), such as enhancing their effects through non-linear phenomena, achieving high resolution, and predicting the effects (for example, Power effect at the time of heating used, and not only high spatial resolution by addition when adding an effect using a cross beam, but also high frequency and high spatial resolution as the effect of multiplication, etc.). It becomes possible. Also in these, a continuous wave may be used, and the same effect is obtained.

  The present invention is also applicable to obtaining a non-linear effect under physical conditions in which a non-linear effect cannot be physically obtained (for example, when the intensity cannot be increased with respect to a measurement target or when a high intensity cannot be obtained due to a high frequency). Although effective, conversely, for example, the present invention is carried out under conditions in which a non-linear effect is enhanced by using a contrast agent such as microbubbles during ultrasonic echo imaging, displacement measurement, temperature measurement, or treatment. It is also effective. That is, the present invention can enhance the non-linear effect, but can also simulate, newly generate, or virtually realize. Further, the present invention can be implemented for the purpose of purely improving resolution, increasing accuracy, and increasing efficiency in imaging, displacement measurement, treatment, and the like.

  According to the present invention, similarly to the harmonic imaging, it is possible to increase the frequency and the bandwidth, to increase the contrast, or to suppress the side lobe, and it is possible to perform nonlinear imaging with a high SN ratio. In addition, analog detection or digital detection can be performed simultaneously without requiring much memory and calculation.

  The effectiveness of the present invention has been demonstrated by performing ultrasonic echo imaging and measurement imaging through simulations and agar phantom experiments. The present invention is applicable to any coherent signal other than the ultrasonic echo method (a familiar one, such as light wave, OCT, electricity, magnetic field signal, radiation such as X-ray, and heat wave), and between different types of coherent signals. Is also applicable. A signal including a signal that has been made incoherent by analog processing (for example, energy detection of a received signal using a sensor or energy detection using a non-linear element) or digital processing may be processed together with the coherent signal.

  On the other hand, in the field of image measurement, movement is often observed using an incoherent signal (result display is an image) through various detections (physical phenomena or normal signal processing) on the coherent signal. Known (various such as cross-correlation processing and optical flow). When this method is used for an incoherent signal, a wider band (higher resolution) can be obtained. The above-described high-resolution detection signal obtained by the present invention can also be used. The measurement accuracy of those movements is also improved. That is, the present invention applies to any coherent or incoherent signal.

  The above-mentioned imaging and motion measurement using the coherent signal and the incoherent signal are performed in various fields including the above example and the like, and have a very long history. Alternatively, it is effective and useful to perform wide-band high-resolution and high-contrast imaging including a low frequency, and to measure displacement or the like with high accuracy. It is effective including the engineering effect unique to multidimensional signal processing. In the above-mentioned other applications such as treatment, it is also effective and useful to evaluate and apply the effect based on imaging of the non-linear effect.

  In a measurement imaging apparatus, it is useful to perform multiplication or exponentiation to generate a harmonic component and a baseband signal (the above-described new detection signal) and generate an image signal based on them. The same effect can be obtained not only in the case of calculation but also when a higher-order nonlinear processing is performed. Depending on cost and the like, the conventional technology may be selectively adopted or used together.

  The present invention is not limited to the above embodiments, and many modifications can be made by those having ordinary knowledge in the technical field within the technical idea of the present invention. Reflection wave, transmission wave, scattered wave (forward scattered wave or backward wave) for waves such as electromagnetic wave, sound wave (compression wave), vibration wave (mechanical wave) including shear wave, surface wave, or heat wave Scattered waves), refracted waves, diffracted waves, surface waves, shock waves, those waves originating from self-emanating wave sources, waves originating from moving objects, or coming from unknown sources Appropriately set digital signal processing algorithms (in implemented digital circuits or software), such as displacement (vector) measurement and temperature measurement, or analog or digital hardware are used for observed waves such as waves Can be Patent Documents 5 to 7 and 11 relating to displacement measurement method (obtain the object displacement, particle displacement, medium displacement, etc. with high accuracy by also determining the propagation direction of the sensing wave, and observe the wave propagation. In many cases, various measurement methods disclosed in detail, such as detailed high-precision observation, etc., are disclosed mainly with respect to embodiments in the reflection method and the echo method. , And is not limited thereto. In addition, analog processing may be performed instead of digital processing for the purpose of speeding up processing.

  INDUSTRIAL APPLICABILITY The present invention can be used in a beam forming method for performing beam forming using an arbitrary wave arriving from a measurement target, and in a measurement imaging apparatus and a communication apparatus using such a beam forming method. is there.

  Radar, sonar, and other optical signals such as optical waves, sound waves, and heat waves are often generated by digital devices at present, and are often used for the purpose of applying the signals. It can be applied in conjunction with signal generation only by having the processing capability to perform the next calculation. Various devices have been made multidimensional, and the importance of the present invention will increase. The measurement target is also immeasurable, such as solid, fluid, rheology, inorganic matter, organic matter, living thing, environment, etc., and it is considered that the measurement range is expanding. In the future, the miniaturization of each device in the device will be further advanced, and the calculation stress will be more than enough, so that the computer can be incorporated at lower cost, and many real-time convenient devices have been realized. We can expect it to go. Further, it is considered that not only a simple wave measurement imaging apparatus but also an application through a measurement using a wave is developed more actively, and an application range is broadened. The digitization of various devices is expected to further advance in the future, and at that time, it is considered that demand for high-precision and high-speed beam forming capable of generating a high-precision signal according to the present invention in real time will increase. After all, in addition to the high speed of the processing, there is no need to perform the interpolation approximation previously required. However, in the present invention, further emphasis is placed on high-speed performance, and if necessary, processing involving interpolation approximation may be performed although the accuracy is reduced. It is an effective device for normal communication and sensor networks. The availability and marketability of the digital beamforming according to the invention based on digital signal processing is more than adequate. In addition, analog processing may be performed instead of digital processing for the purpose of speeding up processing.

  DESCRIPTION OF SYMBOLS 10 ... Transmission transducer (or applicator), 10a ... Transmission aperture element, 20 ... Reception transducer (or reception sensor), 20a ... Reception aperture element, 30 ... Device main body, 31 ... Transmission unit, 31a ... Transmitter, 32 ... Reception Unit, 32a: Receiver, 32b: AD converter, 32c: Memory (or storage device or storage medium), 33: Digital signal processing unit, 34: Control unit, 35: Receiving unit (or receiving device), 35a: Reception Device, 35b AD converter, 35c memory (or storage device or storage medium), 35d phasing adder, 35e other data generator, 40 input device, 50 output device, 60 external storage device DESCRIPTION OF SYMBOLS 1 ... Measurement object, 1a ... Contrast agent, 110 ... Transducer, 111 ... Nonlinear device, 112 ... Working device, 120, 1 0a, 120b: imaging apparatus body, 121: transmitter, 121a: transmission delay element, 122: receiver, 122a: reception delay element, 123: filter / gain adjustment unit, 124: nonlinear element, 125: filter / gain adjustment unit , 126: detector, 127: AD converter, 128: storage device, 129: reception beamformer, 130: operation unit, 131: image signal generation unit, 132: measurement unit, 133: control unit, 134: display device, 135 ... analog display device, 140 ... external storage device

Claims (11)

At least one sensor that transmits a measurement target, or receives a wave reflected, refracted, scattered, or diffracted by the measurement target and outputs at least one reception signal,
A signal processing unit that processes the at least one received signal;
Measurement for electronically or mechanically generating at least one steered wave, scanning the object to be measured in a lateral direction, and controlling the signal processing unit to generate a wave data signal in at least two time phases. A control unit;
A data processing unit that performs a displacement measurement method on the wave data signal generated in the at least two time phases to calculate a displacement vector;
Wherein the data processing unit converts at least three steered waves having different deflection angles of zero degrees or non-zero degrees including the waves generated by the signal processing unit in the case of a three-dimensional rectangular coordinate system. On the other hand, for at least two steered waves having different deflection angles of zero degrees or non-zero degrees including the waves generated by the signal processing unit in the case of a two-dimensional orthogonal coordinate system, The product or conjugate product of two complex analytic signals obtained from the spectrum of a single actant or quadrant corresponding to a wave data signal generated by scanning the measurement object independently with each steered wave in the time phase Change in the instantaneous phase of each of the new waves propagating in mutually orthogonal directions represented by each of the signals Or, the instantaneous phase of a wave obtained from the spectrum of a single orctant or quadrant corresponding to a wave data signal generated by scanning the measurement object independently with each steered wave in the at least two time phases. Using the respective phases of the product or conjugate product signal of the two complex signals having changes in the nucleus, each of the two complex analytic signals or the product or conjugate product signal of the two complex signals represents By dividing the respective instantaneous phase change of the new wave propagating in the orthogonal direction by the respective instantaneous frequency in the orthogonal direction or the centroid frequency of the corresponding spectrum, each displacement in the orthogonal direction is obtained. Calculating a component, calculating a three-dimensional displacement vector in the case of the three-dimensional orthogonal coordinate system, and calculating the two-dimensional orthogonal vector. Calculating a two-dimensional displacement vector when the target system, the measuring imaging device. At least one sensor that transmits a measurement target, or receives a wave reflected, refracted, scattered, or diffracted by the measurement target and outputs at least one reception signal,
A signal processing unit that processes the at least one received signal;
In a three-dimensional orthogonal coordinate system having three axes of a depth direction of the measurement object, a horizontal direction orthogonal to the depth direction, and an elevation direction orthogonal to the depth direction and the horizontal direction, electronically or mechanically. Generates at least three steered waves with different zero or non-zero deflection angles to be generated, or two-dimensional orthogonal with two axes in the depth direction and the transverse direction orthogonal to the depth direction. Generating, in a coordinate system, at least two steered waves having different deflection angles, electronically or mechanically, of zero degree or non-zero degree, and scanning the object to be measured laterally; A measurement control unit that controls the signal processing unit to generate a wave data signal in a phase;
A data processing unit that performs a displacement measurement method on the wave data signal generated in the at least two time phases to calculate a displacement vector;
Wherein the data processing unit comprises a single actant or quadrant corresponding to a wave data signal generated by scanning the measurement object independently with each of the steered waves in the at least two time phases. Using a complex analytic signal whose core is the instantaneous phase of the wave obtained from the spectrum or a complex autocorrelation signal or a complex signal whose core has a change in instantaneous phase generated between the at least two time phases, When calculating a three-dimensional displacement vector in the case of a rectangular coordinate system, and calculating a two-dimensional displacement vector in the case of the two-dimensional rectangular coordinate system, a complex analysis signal corresponding to the spectrum of the single actant or quadrant, or If the magnitude of the complex autocorrelation signal or the instantaneous frequency vector of the complex signal or the magnitude of the centroid frequency vector of the spectrum is The instantaneous frequency vector component or the centroid frequency vector of the other complex analytic signal or the other complex autocorrelation signal or the other complex signal so as to be the same as the analysis signal or the other complex autocorrelation signal or the other complex signal. When the components are multiplied by a constant, their instantaneous phase or a change in the instantaneous phase is also multiplied by a constant, or the magnitude or the center of gravity of the instantaneous frequency vector of a plurality of complex analysis signals or a plurality of complex autocorrelation signals or a plurality of complex signals. When normalizing the magnitude of the vector, normalizing instantaneous frequency vector components or centroid frequency vector components of the plurality of complex analysis signals or the plurality of complex autocorrelation signals or the plurality of complex signals and their instantaneous phases Or, the instantaneous phase change is also normalized, and the superposition of the waves corresponding to the spectrum of the single actant or quadrant is the third order. The wave data signal so as to have an instantaneous frequency or a center-of-gravity frequency independent of the direction of the axis of the rectangular coordinate system, the two-dimensional rectangular coordinate system, or the three-dimensional rectangular coordinate system or a two-dimensional rectangular coordinate system obtained by rotating them. A measurement imaging apparatus for processing the image to form an image of the superposition of the waves.   The signal processing unit or the data processing unit superimposes at least one of a plurality of waves generated in each of the at least two time phases on at least one other wave in the same combination to at least one Generate a new wave and use at least three steered waves including the new wave in the three-dimensional Cartesian coordinate system, or at least two steered waves including the new wave in the two-dimensional Cartesian coordinate system The measurement imaging apparatus according to claim 1, wherein a wave motion is used.   The data processing unit may include a spectrum of at least one single actant or quadrant of waves generated in each of the at least two phases, or at least one single representation of the same superposition of multiple waves. The same splitting in the frequency domain is performed on the spectrum of the actant or quadrant of a new plurality to generate a spectrum of a new single oractant or quadrant, and in the case of the three-dimensional rectangular coordinate system, the new single Using at least three waves, including at least one wave represented by the spectrum of the actant, and at least including at least one wave represented by the spectrum of the new single quadrant in the case of the two-dimensional rectangular coordinate system. The measurement image according to claim 1 or 2, wherein two waves are used. Grayed apparatus.   The data processing unit may include a spectrum of at least one single actant or quadrant of waves generated in each of the at least two phases, or at least one single representation of the same superposition of multiple waves. Are represented by at least one single actant or quadrant spectrum among a plurality of single actant or quadrant spectra generated by performing the same division in the frequency domain with respect to the spectrum of the actant or quadrant of the present invention. The generated wave is superimposed on at least one other wave in the same combination to generate at least one new wave, and in the case of the three-dimensional rectangular coordinate system, at least three steered waves including the new wave are generated. The two-dimensional Cartesian coordinate system and the new wave Using at least two steered wave containing, measuring imaging apparatus according to claim 1 or 2, wherein.   When the data processing unit calculates a three-dimensional displacement vector in the case of the three-dimensional rectangular coordinate system and calculates a two-dimensional displacement vector in the case of the two-dimensional rectangular coordinate system, the two processings are performed as preprocessing. One complex analysis signal or one such that the magnitude of the instantaneous frequency vector in the propagation direction of the wave represented by the complex analysis signal or the complex autocorrelation function or the two complex signals or the magnitude of the centroid frequency vector of the spectrum is the same. When the complex autocorrelation function or the instantaneous frequency vector component or the center-of-gravity frequency vector component of the complex signal is multiplied by a constant, the instantaneous phase or the change in the instantaneous phase is also simultaneously multiplied by a constant, or the two complex analysis signals or the complex autocorrelation When normalizing the magnitude of the instantaneous frequency vector or the centroid frequency vector of a function or a complex signal, the two complex analysis signals Normalizes the complex autocorrelation function or the instantaneous frequency vector component or the center-of-gravity frequency vector component of the complex signal and simultaneously normalizes the instantaneous phase or the change of the instantaneous phase at the same time, so that the two complex analysis signals or the complex autocorrelation function or The measurement imaging apparatus according to claim 1, wherein the propagation direction of a new wave represented by a product of a complex signal or a signal of a conjugate product is orthogonal. At least one sensor that transmits a measurement target, or receives a wave reflected, refracted, scattered, or diffracted by the measurement target and outputs at least one reception signal,
A signal processing unit that processes the at least one received signal;
Measurement for electronically or mechanically generating at least one steered wave, scanning the object to be measured in a lateral direction, and controlling the signal processing unit to generate a wave data signal in at least two time phases. A control unit;
A data processing unit that performs a displacement measurement method on the wave data signal generated in the at least two time phases to calculate a displacement vector;
Wherein the data processing unit comprises: the wave data signal or a complex analysis signal thereof, or a complex autocorrelation signal or a complex signal representing a change in an instantaneous phase occurring between the at least two time phases, or a product thereof. Or, in the case where the signal of the conjugate product has an aliasing phenomenon, in order to obtain the displacement vector or the displacement using the instantaneous phase change and the instantaneous frequency or the center of the spectrum, the aliasing obtained from any of the signals. A measurement and imaging apparatus, which performs correction for adding or subtracting a bandwidth value determined by the sampling frequency of the same signal to or from the instantaneous frequency or the center of gravity of the spectrum in which the above occurs. At least one sensor that transmits a measurement target, or receives a wave reflected, refracted, scattered, or diffracted by the measurement target and outputs at least one reception signal,
A signal processing unit that processes the at least one received signal;
Measurement for electronically or mechanically generating at least one steered wave, scanning the object to be measured in a lateral direction, and controlling the signal processing unit to generate a wave data signal in at least two time phases. A control unit;
A data processing unit that performs a displacement measurement method on the wave data signal generated in the at least two time phases to calculate a displacement vector;
Wherein the data processing unit comprises: the wave data signal or a complex analysis signal thereof, or a complex autocorrelation signal or a complex signal representing a change in an instantaneous phase occurring between the at least two time phases, or a product thereof. Or, when the signal of the conjugate product causes an aliasing phenomenon and the spectrum has both the highest positive frequency and the highest negative frequency in the band, the instantaneous phase change and the instantaneous frequency or the center of the spectrum are used. To obtain the displacement vector or displacement, frequency modulation is applied to any of them to reduce the frequency so that aliasing does not occur, or to increase the frequency so that the spectrum has positive and negative frequencies. Not to have both in the band,
When the center of gravity frequency of the spectrum is used, the frequency domain of the frequency coordinate is replaced with a positive or negative half bandwidth frequency domain, and when the center of gravity frequency or the instantaneous frequency is used, sampling of any of the signals is performed. To the center-of-gravity frequency or instantaneous frequency obtained by adding or subtracting the value of the bandwidth determined by the frequency, the modulation frequency is added when the frequency is lowered by the frequency modulation, and the modulation frequency is subtracted when the frequency is increased. A measurement imaging apparatus that is used after performing correction.   The measurement imaging apparatus according to claim 8, wherein the frequency modulation performed by the data processing unit is a detection process. At least one sensor that transmits a measurement target, or receives a wave reflected, refracted, scattered, or diffracted by the measurement target and outputs at least one reception signal,
A signal processing unit that processes the at least one received signal;
Measurement for electronically or mechanically generating at least one steered wave, scanning the object to be measured in a lateral direction, and controlling the signal processing unit to generate a wave data signal in at least two time phases. A control unit;
A data processing unit that performs a displacement measurement method on the wave data signal generated in the at least two time phases to calculate a displacement vector;
The signal processing unit obtains a local autocorrelation function that does not normalize the magnitude at each point of interest in the region of interest with respect to the received signal in each time phase, and superimposes the signal in the region of interest to generate a wave. A measurement imaging apparatus for generating a data signal, wherein the data processing unit forms an image of the wave data signal in each time phase, or calculates a displacement vector or a displacement component.   The measurement imaging apparatus according to claim 10, wherein the reception signal in each time phase for obtaining an autocorrelation signal is obtained by superimposing a plurality of reception signals in each time phase.