JP4772338B2 - Ultrasonic diagnostic equipment - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus having a function of receiving ultrasonic reflected waves from a plurality of directions substantially simultaneously.

  The ultrasonic diagnostic apparatus radiates an ultrasonic wave generated from an ultrasonic vibration element incorporated in an ultrasonic probe into a subject and receives a reflected wave caused by a difference in acoustic impedance of the subject tissue by the ultrasonic vibration element. Is displayed on the monitor. This diagnosis method is widely used for organ function diagnosis and morphological diagnosis because real-time two-dimensional image data can be easily obtained by a simple operation by simply bringing an ultrasonic probe into contact with the body surface.

  Ultrasound diagnostic methods for obtaining biological information from reflected waves from the tissue or blood cells of a subject have made rapid progress with the development of two major technologies, the ultrasonic pulse reflection method and the ultrasonic Doppler method, and are obtained using the above technology. The B-mode image and the color Doppler image that are obtained are indispensable in today's ultrasound diagnosis.

  In the most popular electronic scanning ultrasonic diagnostic apparatus today, a plurality of ultrasonic vibration elements are generally arranged one-dimensionally, and the driving of each of these ultrasonic vibration elements is controlled at high speed. Real-time display of image data.

  The color Doppler method scans a predetermined section in a living body with an ultrasonic pulse, and when the ultrasonic wave is irradiated to a moving reflector such as blood (blood cell), the velocity of the reflector (blood flow velocity) The Doppler frequency shift generated in response to the above is captured and imaged. This color Doppler method was initially used to image intracardiac blood flow information with a high blood flow velocity, but today it is also applied to imaging of extremely slow blood flow such as tissue blood flow in abdominal organs. Is becoming possible.

  In order to improve the diagnostic ability in the color Doppler method, excellent measurement accuracy (low flow velocity detection ability and high flow velocity detection ability), temporal resolution, and spatial resolution are required. When a moving reflector is irradiated with an ultrasonic pulse and the moving speed of the reflector is measured from the Doppler frequency shift of the reflected wave, conventionally, transmission / reception with ultrasonic waves is predetermined for this reflector. The transmission speed is measured repeatedly based on a series of reflected waves obtained at the observation time Tobs (Tobs = Tr · L).

In this case, the detection capability (low flow velocity detection capability: lower limit value of measurable flow velocity) Vmin for the low flow velocity reflector is a series of reflected waves obtained by the L times of ultrasonic transmission / reception (hereinafter referred to as transmission / reception). Is determined by the characteristics of a filter (for example, an MTI filter) used for detecting a Doppler component from the filter, that is, the cutoff frequency and shoulder characteristics of the filter. At this time, Vmin is a transmission / reception repetition frequency (rate frequency). If fr (fr = 1 / Tr), the following expression (1) is obtained.

On the other hand, the measurable upper limit of flow velocity (high flow velocity detection capability) Vmax is determined by the Nyquist frequency defined by 1/2 of the transmission / reception repetition frequency (rate frequency) fr, and is represented by the following equation (2). However, C is the sound velocity value in the subject, f0 is the center frequency of the received ultrasound, and ξ is the angle between the ultrasound transmission / reception direction and the blood flow direction. When the Doppler frequency shift exceeds the Nyquist frequency, a folding phenomenon occurs in the frequency spectrum of the Doppler signal, making it impossible to accurately measure the blood flow velocity.

  That is, in order to improve the low flow velocity detection capability Vmin, which is the first requirement item in the color Doppler method, it is necessary to set the rate frequency fr low or to increase the number of times of transmission / reception L repeatedly performed in a predetermined direction. In order to improve the high flow rate detection capability Vmax, the rate frequency fr must be set high. However, when the rate frequency fr is increased, the next ultrasonic wave is radiated before the reflected wave from the deep part is received. Therefore, the so-called residual echo is received in which the reflected wave of the adjacent rate section is mixed. Problem arises.

The real-time property, which is the second requirement item, is determined by the number of display images (frame frequency) Fn per unit time, and this frame frequency Fn is expressed by the following equation (3). However, N is the total number in the scanning direction necessary for generating one piece of color Doppler image data, and in order to improve the real-time property, the number of times of transmission / reception L or the total number N in the scanning direction must be set small. .

  Furthermore, in order to improve the spatial resolution that is the third requirement item, it is necessary to increase the total number M in the scanning direction. That is, the frame frequency Fn, the low flow velocity detection capability Vmin, the high flow velocity detection capability Vmax, and the spatial resolution are in a contradictory relationship, and it is difficult to satisfy these simultaneously. Therefore, frame frequency Fn and high flow velocity detection capability Vmax are important for blood flow measurement in the circulatory region, and frame frequency and low flow velocity detection capability Vmin are important for blood flow measurement in the abdomen and peripheral organs. It has been.

  In order to solve such problems, transmission ultrasonic waves are emitted in a predetermined direction of the subject, and reflected waves (reception ultrasonic waves) by the transmission ultrasonic waves are simultaneously transmitted from a plurality of directions adjacent to the predetermined direction. A so-called parallel simultaneous reception method that increases the amount of data received per unit time has been proposed (see, for example, Non-Patent Document 1).

  However, in the parallel simultaneous reception, the transmission / reception sensitivity is deteriorated when the central axis of the transmission beam is different from the central axis of the reception beam. Further, when the parallel simultaneous reception direction is three or more directions, the azimuth direction (ultrasonic transmission / reception direction) Uniform transmission / reception sensitivity could not be obtained.

  In order to improve such problems, a method of reducing the number (aperture) of elements of an ultrasonic transducer used for one ultrasonic transmission, and the drive signal amplitude of each vibration element are weighted with respect to the arrangement direction. Thus, a method of widening the beam width of the transmission sound field has been proposed (see, for example, Patent Document 1).

On the other hand, a method of simultaneously transmitting and receiving ultrasonic waves in a plurality of different directions has been proposed (for example, see Patent Document 2). In this method, when a plurality of arranged ultrasonic transducer elements are driven by a drive signal having a predetermined delay time to transmit a transmission ultrasonic wave in a predetermined direction, each of the plurality of transmission directions corresponds. Transmission in a plurality of directions is performed substantially simultaneously by synthesizing a drive signal having a delay time and supplying it to the ultrasonic vibration element.
Toshihiko Kawano et al., Examination of high frame rate of ultrasonic diagnostic equipment for circulatory organs, Transactions of the Japanese Society of Ultrasonic Medicine, 55,727 (1989) Japanese Patent Laid-Open No. 3-155843 (page 4-6, FIG. 1-9) US Pat. No. 5,856,955

  According to the method of Patent Document 1, the beam width of the transmission sound field is widened, which is improved from the conventional method (that is, the case where a transmission sound field comparable to that in the case where parallel simultaneous reception is not performed), but is converged. Since the transmitted sound field is used, it is difficult to expand the beam width in correspondence with the received sound field. For this reason, transmission / reception sound field distortion (hereinafter referred to as beam bending) and transmission / reception described below are performed. The problem of non-uniformity in sensitivity still remains.

  FIG. 18 shows beam bending, which is the first problem of the conventional method or the method of Patent Document 1, and FIG. 19 shows reception sensitivity non-uniformity, which is the second problem of the above method. Yes.

  FIG. 18A shows a transmission when ultrasonic transmission is performed in a predetermined direction (the central axis direction of the transmission sound field) using a convex scanning ultrasonic probe in which ultrasonic transducers are arranged on a convex surface. The parallel simultaneous reception by the sound field (solid line) and a plurality of reception sound fields (broken lines) formed overlapping with the transmission sound field is shown. In this figure, only the reception sound field Br-2 located at the center of the transmission sound field Bt and the reception sound fields Br-1 and Br-3 corresponding to the end of the transmission sound field Bt are shown in order to simplify the explanation. Is shown.

  The transmission ultrasonic waves in the conventional parallel simultaneous reception method are converged to a predetermined position (depth) of the subject as in the case of non-parallel simultaneous reception, and the ultrasonic energy is concentrated in this region. On the other hand, a so-called dynamic convergence method is applied to the reception ultrasonic wave in which the convergence point is sequentially moved in the deep direction corresponding to the reception timing, and a reception sound field that is continuously converged in the deep direction can be formed. .

  By the way, in such a case, the ultrasonic reception sensitivity is determined by the product of the transmission sound field and the reception sound field (that is, the transmission / reception sound field). Then, in the transmission / reception sound field formed by the transmission sound field Bt shown in FIG. 18A and the reception sound field (for example, reception sound field Br-1) located at the end of the transmission sound field Bt, convergence is achieved. The transmitted sound field in the region has a particularly great influence on the transmitted / received sound field. As a result, as shown in FIG. 18B, beam bending occurs in the center direction of the transmission sound field, and is generated by the transmission / reception sound field Bo-1 having such beam bending or the transmission / reception sound field Bo-3 (not shown). Image distortion occurs in the ultrasonic image data.

  Next, FIG. 19A schematically shows a transmission sound field pattern, a reception sound field pattern, and a transmission / reception sound field pattern in the azimuth direction of the parallel simultaneous reception, and transmission at the end of the transmission sound field. The sound pressure of the sound field is smaller than the central part. For this reason, when three or more simultaneous reception directions are set, the size of the transmission / reception sound field pattern (that is, transmission / reception sensitivity) is non-uniform in the azimuth direction, and the ultrasonic wave generated by this non-uniform transmission / reception sound field. On the image data, a light and dark stripe pattern is generated and the image quality is deteriorated. In addition, a significant decrease in reception sensitivity at the end of the transmission sound field not only deteriorates the image quality of the B-mode image data, but also makes it difficult to estimate the flow velocity value, dispersion value, etc. in the generation of color Doppler image data.

  Further, when the transmission sound field pattern is expanded in the azimuth direction as shown in FIG. 19B for the purpose of improving the non-uniformity of the sensitivity described above, useless transmission ultrasonic waves are generated in a region not involved in the generation of image data. Energy is radiated, not only lowering the reception sensitivity, but also increasing the frequency of occurrence of virtual images (artifacts) due to side lobes and multiple reflections.

  That is, the above-mentioned beam bending, non-uniform reception sensitivity, and further degradation in reception sensitivity degrade the image quality of the ultrasonic image data and reduce its diagnostic ability.

  On the other hand, when performing parallel simultaneous reception for organs with high movements such as the heart, in order to reduce the influence of organ movement and obtain image data with excellent spatial continuity, it is necessary to move in the adjacent ultrasonic transmission / reception direction. On the other hand, it is necessary to perform parallel simultaneous reception. When the method of Patent Document 2 described above is applied to such parallel simultaneous reception, transmission ultrasonic interference (synthesis) occurs, so that it is difficult to uniformly set the sensitivity in a plurality of reception directions in parallel simultaneous reception. .

  The present invention has been made in view of the above-mentioned problems, and its object is to eliminate beam bending of a transmission / reception sound field in parallel simultaneous reception, and to reduce deterioration and non-uniformity in transmission / reception sensitivity in each parallel reception direction. Accordingly, an object of the present invention is to provide an ultrasonic diagnostic apparatus capable of generating ultrasonic image data excellent in real-time property and image quality.

In order to solve the above problem, an ultrasonic diagnostic apparatus according to an embodiment includes a plurality of arranged vibration elements.
An ultrasonic probe including a child and the plurality of vibration elements or a part of the plurality of vibration elements;
A delay time for forming the first transmission sound field was given to the transmitting vibration element group constituted by
The first transmission delay signal overlaps the first transmission sound field in the convergence region of the transmission sound field.
Element control for generating a second transmission delay signal given a delay time for forming a second transmission sound field
Means, driving the plurality of vibration elements, driving based on the first transmission delay signal, and the second
It is performed in order with driving based on a transmission delay signal, and the first and second transmission sound fields are synthesized,
Transmitting ultrasonic waves forming a synthetic transmission sound field having a width wider than that of the first and second transmission sound fields;
Generates a reception signal based on the transmission means and the reflected wave of the ultrasonic wave obtained from a predetermined reception direction
Receiving means, and image data generating means for generating image data based on the received signal.
Have.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to reduce the beam bending of the transmission / reception sound field in parallel simultaneous reception, or the fall and nonuniformity of the transmission / reception sensitivity in each parallel reception direction. Therefore, generation of the ultrasound image data sensitivity azimuthal and excellent high image quality is possible, diagnostic performance is greatly improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  The first feature of the first embodiment of the present invention described below is that a convex scanning ultrasonic probe in which ultrasonic vibration elements (hereinafter referred to as vibration elements) are arranged one-dimensionally on a convex surface is used. When performing parallel simultaneous reception, a first transmission vibration element group composed of a plurality of adjacent vibration elements and a second transmission vibration separated from the first transmission vibration element group by a predetermined interval The element group is driven substantially simultaneously, and a transmission sound field having a wide beam width is formed by synthesizing transmission ultrasonic waves radiated from the respective transmitting vibration element groups.

  In addition, the second feature of the present embodiment is that when driving each vibration element in the first transmission vibration element group and the second transmission vibration element group, the amplitude of the drive signal is changed in the vibration element arrangement direction. Is to obtain a uniform transmitted sound field in the azimuth direction by performing weighting based on the Sinc function.

(Device configuration)
Hereinafter, the configuration of the ultrasonic diagnostic apparatus and the basic operation of each unit according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing the overall configuration of the ultrasonic diagnostic apparatus according to the present embodiment. FIGS. 2 and 6 are block diagrams showing a transmission / reception unit and a data generation unit that constitute the ultrasonic diagnostic apparatus. is there.

  An ultrasonic diagnostic apparatus 100 shown in FIG. 1 includes a plurality of (M1) vibration elements arranged one-dimensionally on a convex surface and an ultrasonic probe 3 for convex scanning that transmits and receives ultrasonic waves to and from a subject. , A first transmitting vibration element group composed of M2 vibrating elements selected from among the M1 vibrating elements, and an adjacent element selected by shifting the M0 element with respect to the first transmitting vibrating element group. A driving signal is supplied to each of the second transmitting vibrating element groups including M2 vibrating elements, and reception is performed including adjacent M4 vibrating elements selected from the M1 vibrating elements. The transmission / reception part 2 which performs the phasing addition for M direction parallel simultaneous reception with respect to the received signal obtained from the vibrating element group for operation is provided.

  In addition, the ultrasonic diagnostic apparatus 100 performs signal processing on the reception signal obtained from the transmission / reception unit 2 to generate B-mode data and color Doppler data, and the data generated by the data generation unit 4. Are stored, and an image data generation / storage unit 5 for generating two-dimensional or three-dimensional B-mode image data and color Doppler image data, and a display unit 6 for displaying the obtained image data are provided.

  Furthermore, the ultrasonic diagnostic apparatus 100 includes a reference signal generation unit 1 that supplies a continuous wave or a rectangular wave having a frequency substantially equal to the center frequency of transmission ultrasonic waves to the transmission / reception unit 2 and the data generation unit 4, and an operator An input unit 7 for inputting sample information, initial setting information of the apparatus, various command signals, and the like, and a system control unit 8 for comprehensively controlling each unit of the ultrasonic diagnostic apparatus 100 are provided.

  The ultrasound probe 3 performs ultrasound transmission / reception by bringing the front surface into contact with the surface of the subject, and M1 vibration elements are arranged in a one-dimensional manner in a convex shape on the contact surface with the subject. Yes. This vibration element is an electroacoustic transducer, which converts an electrical pulse (drive signal) into an ultrasonic pulse (transmitted ultrasonic wave) during transmission, and converts an ultrasonic reflected wave (received ultrasonic wave) into an electrical signal during reception. It has a function of converting into (received signal).

  Next, the transmission / reception unit 2 shown in FIG. 2 includes a first transmission vibration element configured by M2 vibration elements adjacent to each other selected from the M1 vibration elements by an element selection unit 22 described later. Obtained from a transmitting vibration element group composed of a transmitter 21 for supplying drive signals to the group and the second vibration element group for transmission, and M4 vibration elements adjacent to each other selected by the element selector 22 A receiving unit 23 that performs phasing and addition for parallel reception in the M direction with respect to the received signal, and a first transmitting vibrating element group, a second transmitting vibrating element group, and a receiving vibrating element group are selected and transmitted. An element selection unit 22 for connecting the unit 21 and the reception unit 23 and an element selection control unit 24 for controlling the element selection unit 22 are provided.

  The transmission unit 21 includes a rate pulse generator 211, a transmission signal generation circuit 212, a transmission amplitude control circuit 213, a transmission delay circuit 214, a transmission signal synthesis circuit 215, and a drive circuit 216.

The rate pulse generator 211 generates a rate pulse that determines the repetition period of the transmission ultrasonic wave by dividing the continuous wave supplied from the reference signal generator 1. In addition, the transmission signal generation circuit 212 generates M2 vibration elements in the first transmission vibration element group and the second transmission vibration element group in synchronization with the timing of the rate pulse supplied from the rate pulse generator 211. Corresponding transmission signals P _{1 to} P _M2 having a predetermined amplitude are generated. The amplitudes a _{1 to} a _M2 of the transmission signals P _{1 to} P _M2 are set based on the amplitude distribution information supplied from the transmission amplitude control circuit 213.

  On the other hand, the transmission amplitude control circuit 213 calculates the amplitude distribution of the transmission signal for the first transmission vibration element group and the second transmission vibration element group based on the weighting function supplied from the system control unit 8, and obtains it. The transmitted amplitude distribution information is supplied to the transmission signal generation circuit 212.

FIG. 3 shows the signal amplitudes a _{1 to} a _M2 of the transmission signals P _{1 to} P _M2 generated by the transmission signal generation circuit 212. The signal amplitudes a _{1 to} a _M2 are, for example, a transmission amplitude control circuit. It is set based on the amplitude distribution information of the Sinc function (Sinc (y) = siny / y) supplied from 213.

The transmission delay circuit 214 includes a transmission delay circuit 214a for setting a transmission delay time of a transmission signal for the vibration element of the first transmission vibration element group, and a transmission signal for the vibration element of the second transmission vibration element group. The transmission delay circuit 214b sets the transmission delay time. Each of the transmission delay circuits 214a and 214b configured by the M2 channel has a delay time for converging the transmission ultrasonic wave to a predetermined distance with respect to the transmission signals P _{1 to} P _M2 supplied from the transmission signal generation circuit 212. give.

On the other hand, the transmission signal combining circuit 215 transmits the transmission signals Pa _{1 to} Pa _M2 given the above delay time by the transmission delay circuit 214a and the transmission signals Pb _{1 to} Pb given the delay time by the transmission delay circuit 214b. the _M2 synthesized on the basis of the element selection information supplied from the element selection control unit 24 described later, to generate a transmission signal Pc ₁ to _{Pc M3} of M3 channel (M2 <M3 <M1). Details of the synthesis of the transmission signals Pa _{1 to} Pa _M2 and the transmission signals Pb _{1 to} Pb _M2 based on the element selection information will be described later.

Then, the drive circuit 216 amplifies the transmission signals Pc _{1 to} Pc _M3 generated by the synthesis in the transmission signal synthesis circuit 215, and the first transmission vibration element group and the second transmission signal selected and connected by the element selection unit 22 A drive signal for driving the vibration elements of the transmission vibration element group is generated.

  Next, the receiving unit 23 includes a preamplifier 231 and an A / D converter 232 configured with M4 channels, a channel selection circuit 233, and M channel beamformers 234-1 to 234-M. The preamplifier 231 is for amplifying the received signal of the M4 channel supplied from the element selection unit 22 to ensure sufficient S / N, and is generated in the drive circuit 216 of the transmission unit 21 at the first stage. A limiter circuit (not shown) for protecting from a high voltage drive signal is provided.

  For the M4 channel received signal amplified to a predetermined size by the preamplifier 231 and converted into a digital signal by the A / D converter 232, the channel selection circuit 233 performs parallel simultaneous reception in the M direction. Adjacent M5 channels (M5 <M4) among the M4 channels are selected at M locations, and each of the reception signal groups configured from the M5 channels is supplied to the beamformers 234-1 to 234-M.

  Each of the beam formers 234-1 to 234-M has a delay circuit and an adder circuit (not shown), and is converted into a digital signal by the A / D converter 232 and is received by the channel selection circuit 233 and received by the M5 channel. On the other hand, after adding a convergence delay time for converging an ultrasonic wave reflected from a predetermined depth, addition synthesis (phased addition) is performed. In this case, by performing so-called dynamic focusing in which the focal region is sequentially changed to a deep portion with the reception timing, a reception sound field having a substantially uniform beam width regardless of the depth is formed.

  Next, selection of the first transmission vibration element group, the second transmission vibration element group, and the reception vibration element group by the element selection unit 22 described above, and M reception signals generated by the channel selection circuit 233. The group will be described with reference to FIG.

  FIG. 4 schematically shows a method of selecting the first transmitting vibration element group, the second transmitting vibration element group, and the receiving vibration element group when performing parallel simultaneous reception in adjacent M directions. In order to simplify the explanation, the number M2 of vibration elements in the first and second transmission vibration element groups is set to 6, and the shift elements of the first transmission vibration element group and the second transmission vibration element group Although the number M0 is 2, the number of vibration elements M4 in the reception vibration element group is 8, the number of phasing addition channels M5 is 5, and the number of reception directions M in parallel simultaneous reception is 4, the present invention is not limited thereto.

  In this case, the four vibration elements in the first transmission vibration element group are commonly used as the vibration elements of the second transmission vibration element group, and therefore, simultaneously in one ultrasonic transmission. The number of elements M3 of the transmitting vibration element group used (hereinafter referred to as a third transmitting vibration element group) is 8.

  That is, when parallel simultaneous reception is performed in any four adjacent directions using the convex scanning ultrasonic probe 3 shown in FIG. 4, the element selection unit 22 is arranged in a convex shape in the ultrasonic probe 3. The vibration elements 32-X to 32- (X + 7) are selected from the vibration elements 32-1 to 32-M1 as the third transmission vibration element group and the reception vibration element group. Of these selected vibration elements, the vibration elements 32-X to 32- (X + 5) are the first transmission vibration element group, and the vibration elements 32- (X + 2) to 32- (X + 7) are the first vibration elements. 2 functions as a group of transmitting vibration elements, details of which will be described later.

  The received signals of 8 (M4 = 8) channels obtained from the above-described vibrating elements 32-X to 32-(X + 7) are received by the vibrating elements 32-X to 32- (X + 4), which are adjacent to each other in the channel selection circuit 233. It consists of 5-channel received signals obtained from 32- (X + 1) to 32- (X + 5), vibrating elements 32- (X + 2) to 32- (X + 6), and vibrating elements 32- (X + 3) to 32- (X + 7). Four received signal groups (M = 4) are collected, and each of these received signal groups is supplied to beam formers 234-1 to 234-M.

  That is, the reception signals of the vibration elements 32-X to 32- (X + 4) are supplied to the beam former 234-1, and the vibration elements 32- (X + 1) to 32- (X + 5) and vibration elements 32- (X + 2) to 32-- The reception signals of (X + 6) and the vibrating elements 32- (X + 3) to 32- (X + 7) are supplied to the beamformers 234-2 to 234-4, respectively. Each of the beam formers 234-1 to 234-M performs phasing addition processing for dynamic focusing on the reception signal of the M5 channel supplied from the channel selection circuit 233, and the vibration element 32-(X + 2) Thirty-two (X + 5) -centered reception sound fields are formed.

  By the transmission / reception method described above, four elements centered on the vibration elements 32-(X + 2) to 32-(X + 5) in the uniform synthetic transmission sound field formed by the first and second transmission vibration element groups. A reception sound field is formed, and parallel simultaneous reception in four directions is performed. In this case, the transmission direction and the reception direction of the ultrasonic waves are set in a direction perpendicular to the arrangement surface of the vibration elements, but the transmission sound field is obtained by giving a delay time for deflection by the transmission delay circuit 214 or the beam former 234. It is also possible to set the reception sound field in an arbitrary direction. However, in any case, in the parallel simultaneous reception of this embodiment, a plurality of reception sound fields are formed in the combined transmission sound field by the first and second transmitting vibration element groups.

  Next, a transmission signal synthesis method in the transmission signal synthesis circuit 215 of the transmission unit 21 will be described with reference to FIG. In this case, as in FIG. 4, the number of vibrating elements M2 in the first and second transmitting vibrating element groups is set to 6, the number of vibrating elements M3 in the third transmitting vibrating element group is set to 8, and the first transmitting element is set. The number of shift elements M0 of the trusted vibration element group and the second transmission vibration element group is 2.

FIG. 5A shows 6-channel transmission signals P _{1 to} P ₆ generated by the transmission signal generation circuit 212 in the transmission unit 21 shown in FIG. 2, and the amplitude of each transmission signal is the transmission amplitude control circuit 213. Is set based on the amplitude distribution information supplied from. In this figure, a transmission signal having an amplitude distribution in which the amplitude becomes smaller toward the end portion is shown, but in reality, an amplitude distribution based on the Sinc function in FIG. 3 is set.

FIG. 5B shows the first transmission signals Pa _{1 to} Pa ₆ or the second Pb _{1 to} Pb ₆ to which the convergence delay time is given in the transmission delay circuit 214a or the transmission delay circuit 214b. On the other hand, FIG. 5C shows combined transmission signals Pc _{1 to} Pc _{8 in} which the output signals of the transmission delay circuit 214 a and the transmission delay circuit 214 b are combined based on the element selection information supplied from the element selection control unit 24. The combined transmission signals Pc _{1 to} Pc ₈ are shown corresponding to the vibration elements 32-X to 32- (X + 7) supplied via the drive circuit 216.

That is, in this case, as shown in FIG. 4, since the first transmitting vibrating element group and the second transmitting vibrating element group are selected separately, the six channels shown in FIG. The first transmission signals Pa _{1 to} Pa ₆ and the second transmission signals Pb _{1 to} Pb ₆ are combined by shifting by two elements. Therefore, the transmission signals Pa ₃ and Pb ₁ are transmitted to the vibration element 32- (X + 2) used as the first and second transmission vibration element groups, and the transmission signal Pa is transmitted to the vibration element 32- (X + 3). ₄ and Pb ₂ , the transmission signal Pa ₅ and Pb ₃ are combined with the vibration element 32-(X + 4), and the combined transmission signal obtained by combining the transmission signals Pa ₆ and Pb ₄ is combined with the vibration element 32-(X + 5). 216 and the element selection unit 22.

  Returning to FIG. 1, the data generation unit 4 performs B-mode data to generate B-mode data by performing signal processing on the M-channel reception signals output from the beam formers 234-1 to 234-M of the reception unit 23 described above. A generation unit 41 and a color Doppler data generation unit 42 that generates color Doppler data by performing signal processing on the received signal are provided.

  The B mode data generation unit 41 of the data generation unit 4 illustrated in FIG. 6 includes an envelope detector 411 and a logarithmic converter 412. The envelope detector 411 performs envelope detection on the reception signals of the M channels output from the beam formers 234-1 to 234-M in the reception unit 23 of the transmission / reception unit 2, and the logarithmic converter 412 B-mode data for M parallel simultaneous reception directions is generated by relatively emphasizing a small signal amplitude by logarithmic conversion processing on the reception signal after envelope detection.

  On the other hand, the color Doppler data generation unit 42 of the data generation unit 4 includes a π / 2 phase shifter 421, mixers 422-1 and 422-2, and LPFs (low-pass filters) 423-1 and 423-2. Then, quadrature detection is performed on the M channel received signal supplied from the receiving unit 23 of the transmitting / receiving unit 2 to generate a complex signal (I signal and Q signal).

  The color Doppler data generation unit 42 further includes a Doppler signal storage unit 424, an MTI filter 425, and an autocorrelation calculator 426. The complex signal obtained by quadrature detection is temporarily stored in the Doppler signal storage unit 424, and then the MTI filter 425, which is a high-pass digital filter, is stored in the complex signal stored in the Doppler signal storage unit 424. The signal is read out, and the Doppler component (clutter component) caused by the reflex movement or pulsatile movement of the organ is reflected from this complex signal. Further, the autocorrelation calculator 426 calculates an autocorrelation value for the Doppler signal of the blood flow information extracted by the MTI filter 425, and further, based on the autocorrelation value, an average blood flow velocity value and a variance value And the power value is calculated to generate color Doppler data for M parallel simultaneous reception directions.

  Referring back to FIG. 1 again, the image data generation storage unit 5 sequentially stores the B mode data and color Doppler data generated in units of M rasters in the data generation unit 4 to obtain a two-dimensional or three-dimensional B mode. Image data and color Doppler image data are generated.

  The display unit 6 includes a display data generation circuit, a conversion circuit, and a monitor (not shown). The display data generation circuit performs predetermined processing on B-mode image data and color Doppler image data generated in the image data generation storage unit 5. Display data is generated by performing a scan conversion process corresponding to the display form. Next, the conversion circuit performs D / A conversion and television format conversion on the display data and displays the data on the monitor.

  On the other hand, the input unit 7 includes an input device such as a display panel, a keyboard, a trackball, a mouse, a selection button, and an input button on the operation panel, and inputs patient information, data collection conditions, display conditions, and the like. Various command signals are input. In particular, in this embodiment, the number M of parallel simultaneous reception directions, the number M2 of vibration elements in the first transmission vibration element group and the second transmission vibration element group, and the number of vibration elements in the third transmission vibration element group. M3, further, the number of vibration elements M4 in the reception vibration element group, the number of channels M5 of the reception signal group in the phasing addition, and the weighting function of the drive signal are set. However, the number of transmitting and receiving vibrating elements, the weighting function, and the like described above are automatically set based on information on the ultrasonic probe 3 to be used (for example, probe ID) and information on the number of parallel simultaneous reception directions M. Also good.

  The system control unit 8 includes a CPU and a storage circuit (not shown), and the above-described various information input or set by the operator from the input unit 7 is stored in the storage circuit. Based on these pieces of information, the CPU controls the transmission / reception unit 2, the data generation unit 4, and further the image data generation / storage unit 5 and the overall system. Further, the system control unit 8 supplies control signals to the element selection control unit 24 and the reception unit 23 in the transmission / reception unit 2, and M in the transmission sound field formed by the first and second transmission vibration element groups. Control for performing parallel simultaneous reception with respect to the direction, and control of convex scanning with respect to the subject by sequentially shifting the first and second transmitting vibration element groups and the receiving vibration element group in the transducer array direction. To do.

(Image data generation procedure)
Next, the image data generation procedure in this embodiment will be described with reference to the flowchart of FIG. For ease of explanation, the case where the number M3 of vibration elements in the third transmitting vibration element group is equal to the number M4 of vibration elements in the receiving vibration element group will be described, but the present invention is not limited to this.

  The operator of the ultrasonic diagnostic apparatus 100 first sets various conditions necessary for collecting the probe ID and image data of the ultrasonic probe 3 in the input unit 7 of FIG. 8 is stored in a storage circuit (not shown). As the above conditions, the number M of parallel simultaneous reception directions, the number M2 of vibration elements in the first transmission vibration element group and the second transmission vibration element group, the number M3 of vibration elements in the third transmission vibration element group, There are the number M4 (M4 = M3) of vibration elements in the reception vibration element group, the number M5 of channels in the reception signal group in the phasing addition, the weighting function of the drive signal, and the like (step S1 in FIG. 7).

  When the initial setting is completed, the operator fixes the tip (ultrasonic wave transmitting / receiving surface) of the ultrasonic probe 3 at a predetermined position on the surface of the subject body and starts transmitting / receiving ultrasonic waves. At this time, the system control unit 8 temporarily stores the number M2 of vibration elements in the first and second transmission vibration element groups, the number M3 of vibration elements in the third transmission vibration element group, and the reception use. Information on the number of vibration elements M3 of the vibration element group is sent to the element selection control unit 24 of the transmission / reception unit 2, information on the number of channels M5 of the reception signal group in phasing addition and information on the number of reception directions M in parallel simultaneous reception is the channel of the reception unit 23. Information relating to the weighting function of the drive signal is supplied to the selection circuit 233 and to the transmission amplitude control circuit 213 of the transmission unit 21.

  On the other hand, the transmission amplitude control circuit 213 of the transmission unit 21 calculates a transmission signal amplitude value based on, for example, a Sinc function based on the weighting function of the drive signal amplitude supplied from the system control unit 8, and uses this calculation result as a transmission signal generation circuit. (Step S2 in FIG. 7).

  Next, at the time of ultrasonic transmission / reception in the first scanning direction, the element selection control unit 24 supplies the information on the number of vibration elements M2 and M3 at the time of transmission supplied from the system control unit 8 and the number of vibration elements M3 at the time of reception. Based on the information, a control signal is supplied to a multiplexer (not shown) of the element selection unit 22, and the element selection unit 22 performs vibration element 32-1 of the first transmission vibration element group used for ultrasonic transmission / reception in the first scanning direction. Thru 32-M2 and the vibration elements 32- (M0 + 1) to 32- (M0 + M2) of the second transmitting vibration element group are selected. However, M0 (M0 element) indicates the number of shift elements of the first transmission vibration element group and the second transmission vibration element group (step S3 in FIG. 7).

  On the other hand, the rate pulse generator 211 shown in FIG. 2 generates a rate pulse that determines the repetition period Tr of the ultrasonic pulse by dividing the reference signal supplied from the reference signal generator 1 and sends it to the transmission signal generation circuit 212. Supply.

  The transmission signal generation circuit 212 generates an impulse or a predetermined waveform transmission signal synchronized with the rate pulse for the M2 channel, and further, based on the transmission signal amplitude value supplied from the transmission amplitude control circuit 213, the M2 channel. Sets the amplitude in the transmission signal. Next, the transmission delay circuits 214a and 214b give a delay time for converging the transmission ultrasonic wave to the transmission signal of the M2 channel in which the amplitude is set, and generate the first transmission signal and the second transmission signal. (Step S4 in FIG. 7).

  On the other hand, the transmission signal synthesizing circuit 215 shifts the shift amount between the first transmission vibration element group and the second transmission vibration element group calculated from the number of vibration elements M2 and M3 supplied from the element selection control unit 24. Based on the number of elements (M0), the M2 channel first transmission signal and the second transmission signal output from each of the transmission delay circuits 214a and 214b are combined to generate an M3 channel combined transmission signal, which is supplied to the drive circuit 216. Supply (step S5 in FIG. 7).

  Then, the drive circuit 216 amplifies the combined transmission signal of the M3 channel to generate a drive signal, and passes through the element selection unit 22 to the vibration elements 32-1 to 32-M3 (M3 = M0 + M2) of the ultrasonic probe 3. The transmitted ultrasonic waves are transmitted (step S6 in FIG. 7).

  A part of the transmission ultrasonic wave radiated to the subject by driving the vibration elements 32-1 to 32-M3 is reflected by the boundary surface or tissue between organs having different acoustic impedances. Further, when this ultrasonic wave is reflected by a moving reflector such as a heart wall or blood cell, the ultrasonic frequency is subjected to Doppler shift.

  The ultrasonic reflected wave (received ultrasonic wave) reflected by the tissue or blood cell of the subject is received by the receiving vibration elements 32-1 to 32-M3 that have already been selected by the element selection unit 22, and is received as an electric signal ( Received signal). Further, the received signal is supplied to the receiving unit 23 via the element selecting unit 22, amplified to a predetermined size by the preamplifier 231 of the receiving unit 23, and then converted into a digital signal by the A / D converter 232. Converted.

  The M3 channel reception signal converted into the digital signal is supplied to the channel selection circuit 233, and the channel selection circuit 233 selects an adjacent M5 channel (M5 <M4) reception signal group from these M3 channel reception signals. M are selected (see FIG. 4), and these M received signal groups are supplied to beam formers 234-1 to 234-M.

  That is, the reception signal group of the M5 channel obtained by the vibration elements 32-1 to 32-M5 is received by the beamformer 234-1 and the reception of the M5 channel obtained by the vibration elements 32-2 to 32- (M5 + 1). The signal group is supplied to the beamformer 234-2. Similarly, received signal groups obtained by the vibration elements 32-3 to 32-(M5 + 2), the vibration elements 32-4 to 32-(M5 + 3)... Are a beam former 234-3, a beam former 234-4,.・ ・ Supplied to Each of the beam formers 234-1 to 234-M performs dynamic focusing by phasing and adding the reception signals of the M5 channel.

  The M-channel received signals phased and added in the beamformers 234-1 to 234-M are supplied to the B-mode data generation unit 41 in the data generation unit 4 in FIG. 6, and after envelope detection and logarithmic conversion are performed. These are stored in the B-mode data storage area in the image data generation storage 5 of FIG.

  On the other hand, when generating color Doppler data for the first scanning direction, the transmitting vibrating elements 32-1 to 32-M3 and the receiving vibrating elements 32-1 to 32-M3 are used in the scanning direction by the same procedure as described above. On the other hand, ultrasonic transmission / reception is performed a plurality of times (L times) continuously, and a Doppler signal is detected with respect to the received signal obtained at this time.

  That is, the system control unit 8 controls the element selection control unit 24 to select the vibration elements 32-1 to 32-M3 and perform ultrasonic transmission / reception for color Doppler. Then, the obtained M-channel reception signal is supplied to the color Doppler data generation unit 42, and a complex signal is generated from quadrature detection by the mixers 422-1 and 422-2 and the LPFs 423-1 and 423-2. Next, each of the real number component (I component) and the imaginary number component (Q component) of the complex signal is temporarily stored in the Doppler signal storage unit 424. Similarly, complex signals are collected by the same procedure for received signals obtained by the second to Lth ultrasonic transmission / reception using the same vibration element group, and stored in the Doppler signal storage unit 424.

  When the storage of the M-channel complex signal obtained by L ultrasonic transmission / reception using the vibration elements 32-1 to 32-M3 is completed, the system control unit 8 stores the signal in the Doppler signal storage unit 424. L complex signal components corresponding to a predetermined position (depth) in each of the M channel complex signals are sequentially read out and supplied to the MTI filter 425. The MTI filter 425 performs a filtering process on the supplied complex signal component, for example, a reflected wave component from a fixed reflector such as a living tissue or a tissue Doppler component (clutter component) generated by a movement of a tissue such as a myocardium. The blood flow Doppler component resulting from the blood flow is extracted.

  Next, the autocorrelation calculator 426 to which the complex signal of the blood flow Doppler component is supplied from the MTI filter 425 performs autocorrelation processing using the complex signal, and further calculates the average of blood flow based on the autocorrelation processing result. Calculate speed value, variance value, power value, etc. Such calculation is also performed for other positions (depths), and the calculated average velocity value, variance value, power value, and the like of the blood flow are displayed in the color Doppler in the image data generation storage unit 5 of FIG. Save to data storage area.

  That is, in the B-mode data storage area and the color Doppler data storage area of the image data generation storage unit 5, the vibration elements 32-1 to 32-M5, the vibration elements 32-2 to 32- (M5 + 1),. By the phasing addition of the reception signal group, the M number of B-mode data and color Doppler data in the parallel simultaneous reception direction corresponding to the first scanning direction are stored (step S7 in FIG. 7).

  By the same procedure, the system control unit 8 controls the element selection control unit 24 to transmit / receive ultrasonic waves in the second scanning direction by the vibration elements 32- (M3 + 1) to 32-2M3, and the vibration elements 32- (2M3 + 1) to Repeats ultrasonic transmission / reception in the third scanning direction by 32-3M3,... Up to the Nth scanning direction, and B mode data and color Doppler data obtained by parallel simultaneous reception in the M direction in each scanning direction are used as data. The data is stored in the B mode data storage area and the color Doppler data storage area of the storage unit 6 (steps S3 to S7 in FIG. 7).

  By the above procedure, the B mode data and color Doppler data obtained from the M direction in each of the first to Nth scanning directions are sequentially stored in the image data generation storage unit 5 and are stored in a two-dimensional or three-dimensional manner. B-mode image data and color Doppler image data are generated. The display data generation circuit of the display unit 6 performs processing such as scan conversion corresponding to a predetermined display form on the B-mode image data and the color Doppler image data generated in the image data generation storage unit 5 and displays them. Data is generated, and this display data is subjected to D / A conversion and television format conversion in the conversion circuit and displayed on the monitor (step S8 in FIG. 7).

(Uniformity of transmitted sound field)
Next, the transmission sound field formed by the first transmission vibration element group and the second transmission vibration element group in the present embodiment will be described with reference to FIGS. FIG. 8 shows a case where the number of elements M2 in the first and second transmitting vibration element groups is 6 and the number of elements M3 in the third transmitting vibration element group is 8 as in the case of FIG. The first transmission sound field Bt1 formed by the vibration elements 32-X to 32- (X + 5) constituting the first transmission vibration element group is indicated by a solid line. Further, the second transmission sound field Bt2 formed by the vibration elements 32- (X + 2) to 32- (X + 7) constituting the second transmission vibration element group is indicated by a broken line, and further, the first transmission sound field. A third transmission sound field (hereinafter referred to as a synthesized sound field) Bt3 formed by synthesizing the second transmission sound field is indicated by a one-dot chain line.

  Note that the region from the vibration element array surface of Z = 0 to Z = Zo in the distance direction (Z direction in FIG. 8) of the first transmission sound field Bt1 and the second transmission sound field Bt2 is a short-distance region. A region farther than Z = Zo is a convergence region. In this convergence region, the synthesized transmission sound field Bt3 is formed such that the end of the first transmission sound field Bt1 and the end of the second transmission sound field Bt2 overlap. The boundary Z = Zo between the short distance region and the convergence region is uniquely determined by the width (opening width), focal length, ultrasonic frequency, and the like of the first and second transmitting vibration element groups. .

  On the other hand, FIG. 9 shows the first transmission sound field pattern Ct1 and the second transmission sound field pattern Ct1 in the azimuth direction at the Z = Zx (Zx> Zo) of the first transmission sound field Bt1 and the second transmission sound field Bt2 shown in FIG. The transmission sound field pattern Ct2 and the synthetic transmission sound field pattern Ct3 are shown. Usually, the transmission sound field pattern in the convergence region can be obtained by Fourier transforming the aperture function determined by the size of the transmitting vibration element group and the drive signal amplitude distribution for the transmitting vibration element group.

  The transmission signal generation circuit 212 in this embodiment is based on the information of the sinc function supplied from the transmission amplitude control circuit 213, and the amplitude distribution of the drive signal for the first transmission vibration element group and the second transmission vibration element group. Accordingly, when Z = Zx, the first transmission sound field pattern Ct1 and the second transmission sound field pattern Ct2 having a rectangular shape determined by the Fourier transform of the Sinc function are formed.

  That is, by setting the drive amplitude distribution of the first and second transmitting vibration element groups based on the Sinc function, the azimuth directions of the transmission sound fields Bt1 and Bt2 formed by these transmitting vibration element groups (FIG. 8). In the X direction), a first transmission sound field pattern Ct1 and a second transmission sound field pattern Ct2 having beam widths BW1 and BW2 of uniform intensity are obtained, and the transmission sound field Bt1 and the transmission sound field Bt2 are synthesized. In the synthesized transmission sound field Bt3 obtained in this way, a uniform transmission sound field pattern Ct3 having a beam width WB3 that is approximately twice as large and sharply attenuated at the end can be obtained.

  However, in order to generate a combined transmission sound field pattern Ct3 that is uniform in the X direction as described above, it is important to combine the first transmission sound field and the second transmission sound field so that their ends overlap. For example, the shift amount M0 between the first transmitting vibration element group and the second transmitting vibration element group is determined so as to satisfy such a condition.

  FIG. 10 shows a transmission sound field pattern, a reception sound field pattern, and a transmission / reception sound field pattern in parallel simultaneous reception according to the present embodiment. FIG. 10 (a) shows the synthesized transmission sound field pattern Ct3 and four directions. The reception sound field patterns Cr-1 to Cr-4 in the parallel simultaneous reception are formed, and FIG. 10B is formed by the synthesized transmission sound field pattern Ct3 and the reception sound field patterns Cr-1 to Cr-4. Transmission / reception sound field patterns Co-1 to Co-4 are shown. As is apparent from this figure, when a drive signal having an amplitude distribution based on the Sinc function is used, a transmission / reception sound field having a substantially uniform magnitude with respect to the azimuth direction (X direction) can be obtained.

  According to the first embodiment of the present invention described above, when parallel simultaneous reception is performed on a diagnosis target region of a subject using a convex scanning ultrasonic probe, By synthesizing the transmission sound field to be formed, a combined transmission sound field having a wide beam width and uniform transmission intensity can be obtained. Therefore, it is possible to obtain a transmission / reception sound field that is substantially uniform in the azimuth direction and in which the beam bending is greatly reduced, and can generate B-mode image data and color Doppler image data without sensitivity unevenness and image distortion. Become.

  In addition, according to the present embodiment, by driving the amplitude distribution based on the Sinc function for the vibration elements constituting the transmission vibration element group, it is excellent in uniformity and has a steep attenuation characteristic at the end. Can be obtained. Accordingly, since the transmission ultrasonic wave radiated outside the region where parallel simultaneous reception is performed becomes minute and transmission energy can be used effectively, artifacts due to side lobes and multiple reflections are reduced, and the B mode has excellent sensitivity. Image data and color Doppler image data can be generated.

  That is, according to the parallel simultaneous reception of the present embodiment, it is possible to generate ultrasonic image data excellent in real-time property and image quality, and the diagnostic ability is greatly improved.

  Next, a second embodiment of the present invention will be described. The feature of the second embodiment is that when performing parallel simultaneous reception using a sector scanning ultrasonic probe in which vibration elements are linearly arranged in a one-dimensional manner, a part or all of the plurality of vibration elements are used. A transmission ultrasonic wave is radiated in a second direction adjacent to the first transmission signal group and the first direction for radiating transmission ultrasonic waves in the first direction to the configured transmitting vibration element group. A transmission signal field having a wide beam width is generated by generating a combined transmission signal group obtained by combining the second transmission signal group for the generation and supplying the combined transmission signal group to the transmitting vibration element group. It is in.

  The second feature of the present embodiment is that the amplitude distribution of the first transmission signal group and the second transmission signal group is set based on the Sinc function, so that a uniform transmission sound field can be obtained in the azimuth direction. There is to get.

(Device configuration)
The ultrasonic diagnostic apparatus according to the second embodiment of the present invention and the ultrasonic diagnostic apparatus according to the first embodiment described above are particularly different in the configuration of the transmission / reception unit and the ultrasonic probe. The configuration and operation of the ultrasonic diagnostic apparatus according to the present embodiment will be described with reference to FIGS.

  FIG. 11 is a block diagram illustrating the overall configuration of the ultrasonic diagnostic apparatus according to the present embodiment, and FIG. 12 is a block diagram of a transmission / reception unit that configures the ultrasonic diagnostic apparatus. In the ultrasonic diagnostic apparatus of the present embodiment described below, units having the same operations and functions as those of the unit of the first embodiment described above are given the same reference numerals, and detailed descriptions thereof are omitted.

  An ultrasonic diagnostic apparatus 200 shown in FIG. 11 includes an ultrasonic probe 31 for sector scanning in which M1 vibration elements are linearly arranged in a one-dimensional array and performs ultrasonic transmission / reception with respect to a subject, and the vibration elements. A transmission / reception unit 26 that supplies a drive signal and performs phasing addition on the reception signals obtained from these vibration elements is provided, and further, functions similar to those of the ultrasonic diagnostic apparatus 100 of the first embodiment are provided. A data generation unit 4, an image data generation storage unit 5, a display unit 6, a reference signal generation unit 1, an input unit 7, and a system control unit 8.

  The transmission / reception unit 26 illustrated in FIG. 12 includes a transmission unit 27 that supplies a drive signal group including M2 channels to M2 (M2 ≦ M1) transmission vibration elements set in advance, and M3 (M3 ≦ M1). The receiving unit 28 performs phasing addition on the received signal obtained from the receiving vibration element.

  The transmission unit 27 includes a rate pulse generator 211, a transmission signal generation circuit 212, a transmission signal control circuit 213, a transmission delay circuit 214, a transmission signal synthesis circuit 215, and a drive circuit 216.

  The transmission delay circuit 214 gives a delay time necessary for transmitting an ultrasonic wave in the first direction −Δθt of the subject to the transmission signal of the M2 channel generated by the transmission signal generation circuit 212 and outputs the first transmission signal. A transmission delay circuit 214a for generating a group and a transmission delay circuit 214b for generating a second transmission signal group by giving a delay time necessary for transmitting an ultrasonic wave in the second direction Δθt of the subject.

  The transmission signal combining circuit 215 combines the first transmission signal group and the second transmission signal group to generate a combined transmission signal group. Then, the drive circuit 216 amplifies the combined transmission signal group to generate an M2 channel drive signal group, and drives the M2 transmitting vibration element groups adjacent to the ultrasonic probe 31 to generate a first object of the subject. Transmission ultrasonic waves are radiated in the direction −Δθt and the second direction Δθt.

  On the other hand, the receiving unit 28 includes a preamplifier 231 and an A / D converter 232 configured with M3 channels, and M-channel beamformers 234-1 to 234-M. Each of the beam formers 234-1 to 234-M performs phasing addition on the reception signal of the M3 channel, and simultaneously receives the reception signal from the M direction in parallel.

  Next, a transmission signal synthesis method in the transmission signal synthesis circuit 215 of the transmission unit 27 will be described with reference to the schematic diagram of FIG. In FIG. 13, the number M2 of vibration elements in the transmission vibration element group is 8, but the present invention is not limited to this.

  FIG. 13A shows an M2 channel transmission signal generated by the transmission signal generation circuit 212 of the transmission unit 27 shown in FIG. 12, and the amplitude of each transmission signal is the amplitude supplied from the transmission amplitude control circuit 213. Set based on distribution information. In this case as well, a transmission signal having an amplitude distribution in which the amplitude becomes smaller toward the end is shown, but in reality, an amplitude distribution based on the Sinc function is set.

  FIG. 13B shows a first transmission signal group in which a deflection delay time and a convergence delay time are given in the -Δθt direction in the transmission delay circuit 214a, and a deflection delay in the Δθt direction in the transmission delay circuit 214b. The second transmission signal group given time and convergence delay time is shown. On the other hand, FIG. 13C shows a combined transmission signal group generated by combining the first transmission signal group and the second transmission signal group, and this combined transmission signal group is supplied via the drive circuit 216. The vibration elements 32-1 to 32-8 of the transmission vibration element group are shown corresponding to each other.

(Image data generation procedure)
Next, the image data generation procedure in this embodiment will be described with reference to the flowchart of FIG. In the present embodiment, a combined transmission sound field formed by synthesizing a transmission sound field in the first direction and a transmission sound field in the second direction using the ultrasonic probe 31 for sector scanning. A case where generation and display of B-mode image data and color Doppler image data for a subject is applied by applying M-stage parallel simultaneous reception will be described.

  First, the operator of the ultrasonic diagnostic apparatus 100 inputs the probe ID of the ultrasonic probe 31 used in the input unit 7 of FIG. 11 and various conditions necessary for collecting the image data. The data is stored in a storage circuit (not shown) of the unit 8. The various conditions include, for example, the number M of parallel simultaneous reception directions, the number M2 of vibration elements at the time of transmission, the number M3 of vibration elements at the time of reception, and a weighting function of the drive signal. However, in the following description, the case where the number of vibration elements for reception M3 is equal to the number of vibration elements for transmission M2 will be described, but the present invention is not limited to this (step S11 in FIG. 14).

  When the initial setting is completed, the operator fixes the tip (ultrasonic wave transmitting / receiving surface) of the ultrasonic probe 31 at a predetermined position on the surface of the subject body and starts transmitting / receiving ultrasonic waves. At this time, the system control unit 8 supplies the transmission amplitude control circuit 213 of the transmission unit 27 with information regarding the weighting function of the drive signal once stored in its own storage circuit. On the other hand, the transmission amplitude control circuit 213 of the transmission unit 27 calculates a transmission signal amplitude value based on, for example, a Sinc function based on the information on the weighting function of the drive signal amplitude supplied from the system control unit 8, and the calculation result is transmitted to the transmission signal. This is supplied to the generation circuit 212.

  Next, at the time of ultrasonic transmission / reception in the first scanning direction θ1, the rate pulse generator 211 of FIG. 2 divides the reference signal supplied from the reference signal generator 1 to generate a rate pulse, and a transmission signal generation circuit (Step S12 in FIG. 14).

  The transmission signal generation circuit 212 generates an M2 channel transmission signal having an impulse or a predetermined waveform in synchronization with the rate pulse, and further transmits the M2 channel based on the transmission signal amplitude value supplied from the transmission amplitude control circuit 213. Sets the amplitude in the signal. Next, the transmission delay circuits 214a and 214b are supplied from the transmission signal generation circuit 212 with a deflection delay time for radiating transmission ultrasonic waves to θ1−Δθt and θ1 + Δθt and a convergence delay time for convergence to a predetermined distance. The first transmission signal group and the second transmission signal group are generated by giving the transmission signal of the M2 channel (step S13 in FIG. 14).

  On the other hand, the transmission signal synthesis circuit 215 generates a synthesized transmission signal group by synthesizing the first transmission signal group and the second transmission signal group of the M2 channel output from each of the transmission delay circuits 214a and 214b. (Step S14 in FIG. 14). Then, the drive circuit 216 amplifies each of the combined transmission signal groups to generate a drive signal group, and supplies the group to the vibration elements 32-1 to 32-M2 of the ultrasonic probe 31 to radiate transmission ultrasonic waves (FIG. 14 step S15).

  A part of the transmission ultrasonic wave radiated to the subject by driving the vibration elements 32-1 to 32-M2 is reflected on the boundary surface or tissue between organs having different acoustic impedances. Further, when this ultrasonic wave is reflected by a moving reflector such as a heart wall or blood cell, the ultrasonic frequency is subjected to Doppler shift.

  Ultrasonic reflected waves (received ultrasonic waves) reflected by the tissue or blood cells of the subject are received by the vibration elements 1 to M2 and converted into electric signals (received signals). Further, the received signal is supplied to the receiving unit 28, amplified to a predetermined size by the preamplifier 231 of the receiving unit 28, and then converted into a digital signal by the A / D converter 232.

  The M2 channel received signal converted into the digital signal is supplied to each of the beam formers 234-1 to 234-M, and for example, receives directivity with respect to four directions of θ1-3Δθr, θ1-Δθr, θ1 + Δθr, and θ1 + 3Δθr. The delay time for deflection for setting the value and the delay time for convergence for performing dynamic focusing are given and phased and added.

  The M-channel reception signals subjected to phasing addition in the beam formers 234-1 to 234-4M are supplied to the B-mode data generation unit 41 and the color Doppler data generation unit 42 in the data generation unit 4 of FIG. Then, B-mode data and color Doppler data for θ1-3Δθr, θ1-Δθr, θ1 + Δθr, and θ1 + 3Δθr are generated by the same method as in the first embodiment, and these obtained data are shown in FIG. The data is stored in the B-mode data storage area and the color Doppler data storage area in the image data generation storage unit 5 (step S16 in FIG. 14).

  By the same procedure, the system control unit 8 performs transmission ultrasonic wave emission for θ2−Δθt and θ2 + Δθt and parallel simultaneous reception for θ2−3Δθr, θ2−Δθr, θ2 + Δθr and θ2 + 3Δθr, and θ2−3Δθr, θ2−Δθr, θ2 + Δθr and B mode data and color Doppler data for θ2 + 3Δθr are stored in each storage area of the image data generation storage unit 5.

  By the above procedure, parallel simultaneous reception is repeated for each of the scanning directions θ3 to θN (steps S13 to S16 in FIG. 14), and the obtained B mode data and color Doppler data are sequentially stored in the image data generation storage unit 5. Thus, two-dimensional or three-dimensional B-mode image data and color Doppler image data are generated. The display data generation circuit of the display unit 6 performs processing such as scan conversion corresponding to a predetermined display form on the B-mode image data and the color Doppler image data generated in the image data generation storage 5 to display the display data. This display data is displayed on the monitor after D / A conversion and television format conversion in the conversion circuit (step S17 in FIG. 14).

The reception sound field interval 2Δθr in the parallel simultaneous reception described above is normally set to 1 / M of the scanning direction interval (for example, θ2−θ1).

(Uniformity of transmitted sound field)
Next, the transmission sound field and the transmission / reception sound field formed by the transmitting vibration element group of the present embodiment will be described with reference to FIGS. 15 and 16. FIG. 15 is similar to the case of FIG. 13, in which the number M2 of the transmitting vibration element group is 8, and when performing parallel simultaneous reception in four directions (M = 4) with respect to θ = 0, Is shown for a transmission sound field formed by transmitting in the two directions of -θt and θt. In this figure, the first transmission sound field Bt1 formed in the θ = −θt direction based on the delay time of the transmission delay circuit 214a is shown by a solid line, and θ == based on the delay time of the transmission delay circuit 214b. A second transmission sound field Bt2 formed in the θt direction is indicated by a broken line, and a combined transmission sound field Bt3 formed by combining the first transmission sound field and the second transmission sound field is indicated by a dashed line. Yes.

  In the convergence region of Z = Zx (Zx> Zo), the synthesized transmission sound field Bt3 is formed such that the end of the first transmission sound field Bt1 and the end of the second transmission sound field Bt2 overlap. At this time, the synthetic sound field pattern of the synthetic transmission sound field Bt3 is set to a suitable value for the transmission directions θt and -θt of the transmission ultrasonic wave, so that the beam width BW1 of the first transmission sound field Bt1 or the second A combined transmission sound field Bt3 having a beam width BW3 that is approximately twice the beam width BW2 of the transmission sound field Bt2 and having a uniform and sharply attenuated end can be formed.

  FIG. 16 is a diagram showing a synthetic transmission sound field pattern, a reception sound field pattern, and a transmission / reception sound field pattern in parallel simultaneous reception according to the present embodiment, and FIG. 16 (a) shows a parallel transmission sound field Bt3 set in parallel. The reception sound fields Br-1 to Br-4 for simultaneous reception are shown. FIG. 16B shows, for example, the synthesized transmission sound field pattern Ct3 in Z = Zx and the reception sound field patterns Cr-1 to Cr-4 in the parallel simultaneous reception in four directions, and FIG. The transmission / reception sound field patterns Co-1 to Co-4 formed by the synthetic transmission sound field pattern Ct3 and the reception sound field patterns Cr-1 to Cr-4 are shown.

  According to the second embodiment of the present invention described above, when the parallel simultaneous reception is performed on the diagnosis target portion of the subject using the sector scanning ultrasonic probe, the probe is formed in a plurality of adjacent directions. By synthesizing the transmission sound field, a combined transmission sound field having a wide beam width and uniform transmission intensity can be obtained. Therefore, it is possible to obtain a transmitted / received sound field that is substantially uniform in the azimuth direction and has a greatly reduced beam bending, and can generate B-mode image data and color Doppler image data without sensitivity variations and image distortion. It becomes.

  Further, according to the present embodiment, the uniformity is obtained by driving the amplitude distribution based on the Sinc function for the vibration elements constituting the transmission vibration element group in the same manner as in the first embodiment. In addition, it is possible to obtain a synthesized transmission sound field having excellent attenuation characteristics at the end. Accordingly, since the transmission ultrasonic wave radiated outside the region where parallel simultaneous reception is performed becomes minute and transmission energy can be used effectively, artifacts due to side lobes and multiple reflections are reduced, and the B mode has excellent sensitivity. Image data and color Doppler image data can be generated.

  That is, according to the parallel simultaneous reception method of the present embodiment, it is possible to generate ultrasonic image data excellent in real-time property and image quality, and the diagnostic ability is greatly improved.

  As mentioned above, although the Example of this invention has been described, this invention is not limited to said Example, It can change and implement. For example, although the amplitude distribution of the transmission signal group in the above-described embodiment is a sinc function, other amplitude distributions may be used. For example, by multiplying the Sinc function by a Hamming window function, it is possible to reduce the influence of discontinuity at the end of the amplitude distribution, so that a better transmission sound field can be formed.

  In the above-described embodiment, the case where a uniform synthesized transmission sound field is formed in the convergence region has been described. However, it is also possible to synthesize a transmission sound field in the short-range region. However, since the first transmission sound field pattern and the second transmission sound field pattern formed in this case are deteriorated in steepness at the end as shown in FIG. 17, for example, −2.4 dB with respect to the peak value. The shift amount M0 or the transmission direction Δθt is set so that the first transmission sound field pattern and the second transmission sound field pattern which are adjacent to each other at a position or angle of −3.5 dB are combined with each other.

  In the above-described embodiment, the ultrasonic probe in which the vibration elements are arranged one-dimensionally has been described. However, an ultrasonic probe arranged two-dimensionally may be used. Further, the present invention is not limited to an ultrasonic probe for convex scanning or sector scanning. In particular, when an ultrasonic probe for linear scanning is used, a uniform synthesized transmission sound field can be formed by a method similar to the method described in the first embodiment.

1 is a block diagram showing the overall configuration of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention. The block diagram which shows the structure of the transmission / reception part in the Example. The figure which shows the amplitude distribution of the transmission signal with respect to the vibration element group for transmission of the Example. The figure which shows typically the selection method of the vibration element group for transmission in the parallel simultaneous reception of the Example, and the vibration element group for reception. The figure which shows the synthetic | combination method of the transmission signal in the Example. The block diagram which shows the structure of the data generation part in the Example. 6 is a flowchart showing a procedure for generating image data in the embodiment. The figure which shows the relationship between the drive signal and transmission sound field in the Example. The figure which shows the 1st transmission sound field pattern in the Example, the 2nd transmission sound field pattern, and a synthetic | combination transmission sound field pattern. The figure which shows the synthetic | combination transmission sound field pattern in the Example, a reception sound field pattern, and a transmission / reception sound field pattern. The block diagram which shows the whole structure of the ultrasonic diagnosing device in the 2nd Example of this invention. The block diagram which shows the structure of the transmission / reception part in the Example. The figure which shows the synthetic | combination method of the transmission signal group in the Example. 6 is a flowchart showing a procedure for generating image data in the embodiment. The figure which shows the relationship between the drive signal and transmission sound field in the Example. The figure which shows the synthetic | combination transmission sound field pattern, reception sound field pattern, and transmission / reception sound field pattern in the parallel simultaneous reception of a present Example. The figure which shows the 1st transmission sound field pattern in the modification of the 1st Example of this invention, and a 2nd Example, the 2nd transmission sound field pattern, and a synthetic | combination transmission sound field pattern. The figure for demonstrating the beam bending of the transmission-and-reception sound field in the conventional parallel simultaneous reception. The figure for demonstrating the nonuniformity of the reception sensitivity in the conventional parallel simultaneous reception.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Reference signal generation part 2, 26 ... Transmission / reception part 3, 31 ... Ultrasonic probe 4 ... Data generation part 5 ... Image data generation storage part 6 ... Display part 7 ... Input part 8 ... System control part 21, 27 ... Transmission part DESCRIPTION OF SYMBOLS 22 ... Element selection part 23, 28 ... Reception part 24 ... Element selection control part 41 ... B mode data generation part 42 ... Color Doppler data generation part 100, 200 ... Ultrasonic diagnostic apparatus 211 ... Rate pulse generator 212 ... Transmission signal generation Circuit 213 ... Transmission amplitude control circuit 214 ... Transmission delay circuit 215 ... Transmission signal synthesis circuit 216 ... Drive circuit 231 ... Preamplifier 232 ... A / D converter 233 ... Channel selection circuit 234 ... Beam former 411 ... Envelope detector 412 ... Logarithm Converter 421 ... π / 2 phase shifter 422 ... Mixer 423 ... LPF
424 ... Doppler signal storage unit 425 ... MTI filter 426 ... autocorrelation calculator

Claims (5)

An ultrasonic probe having a plurality of arranged vibration elements; and
Wherein the plurality of vibrating elements or transmitting transducers group composed of part of the plurality of vibrating elements, a first transmission delay signal a delay time to form a first transmission acoustic field is given, the Sending
Generating a second transmission delay signal the delay time is given to form a second transmission sound field in which the first transmission acoustic field and the end overlap in the convergence region of the ring tone field, the first and second Synthesized transmission delay signal
Element control means for generating the combined delay signal ,
The transmitting vibration element group is driven by the combined delay signal, and the first and second transmission sound fields are combined, and combined with a wider width than the first and second transmission sound fields. A transmission means for transmitting ultrasonic waves forming a transmission sound field;
Receiving means for generating a received signal based on the reflected wave of the ultrasonic wave obtained from a predetermined receiving direction;
An ultrasonic diagnostic apparatus comprising image data generation means for generating image data based on the received signal. The element control means includes a first reception delay signal given a delay time corresponding to a first reception direction and a second reception delay signal given a delay time corresponding to a second reception direction. Generate
The ultrasonic diagnostic apparatus according to claim 1 , wherein the reception unit generates the reception signal based on a reflected wave of the ultrasonic wave obtained from the first and second reception directions. The combined transmission acoustic field at a predetermined position of the combined transmission sound hall, according to claim 1 or 2, characterized in that it has a substantially uniform intensity in a direction perpendicular to the transmission direction of the ultrasonic wave ultrasonic Ultrasonic diagnostic equipment. The element control means includes the plurality of vibrations such that each of the first transmission sound field and the second transmission sound field has a rectangular intensity distribution in a direction orthogonal to the transmission direction of the ultrasonic waves. The ultrasonic diagnostic apparatus according to any one of claims 1 to 3 , wherein the intensity of ultrasonic waves transmitted from each of the elements is controlled. The ultrasonic wave according to claim 2 , wherein the element control means controls the first and second reception directions so that the first and second reception directions are within the synthesized transmission sound field. Diagnostic device.

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