WO2021176618A1 - Ultrasound image generation device, ultrasound image generation device operating method, ultrasound image generation device operating program, and ultrasound image generation circuit - Google Patents

Abstract

The ultrasound image generation device according to the present invention generates an ultrasound image by receiving a first ultrasound signal and a second ultrasound signal having frequency characteristics that are different from those of the first ultrasound signal from ultrasound echoes, and comprises: a first frequency analysis unit generating a first frequency spectrum data for a first ultrasound signal; a second frequency analysis unit generating a second frequency spectrum data for a second ultrasound signal; a combining unit for combining the first frequency spectrum data and the second frequency spectrum data to generate a combined spectrum data; and a display image data generation unit generating, on the basis of the combined spectrum data, display image data to be displayed by a display device.

Description

Ultrasound image generator, ultrasonic image generator operating method, ultrasonic image generator operating program and ultrasonic image generation circuit

The present invention relates to an ultrasonic image generator for observing tissues such as patients and animals as a subject using ultrasonic waves, an operation method of the ultrasonic image generator, an operation program of the ultrasonic image generator, and an ultrasonic image generation circuit. Regarding.

Conventionally, as a technique for expressing the texture of an observation target using ultrasonic waves, an ultrasonic echo echoed backward by the observation target is received by an ultrasonic vibrator and converted into an ultrasonic signal, and the converted ultrasonic signal is used. A technique of calculating a feature amount from a frequency spectrum and imaging the calculated feature amount is known (see, for example, Patent Document 1). Scattering of sound waves is a physical phenomenon in which sound waves can change their traveling direction by colliding with particles in a medium and exerting forces on each other (this is called interaction). Further, backscattering is a phenomenon or a component thereof that returns to the direction of the sound source in the scattering. This phenomenon is also generally referred to as reflection, but in the present application, the term backscattering will be used. The sound source at this time is an ultrasonic vibrator. In this technique, the feature amount of the frequency spectrum is extracted as an analysis value representing the texture of the observation target. After that, a feature amount image to which visual information corresponding to this feature amount, for example, color information is added is generated. Then, the feature amount image is superimposed on the ultrasonic image based on the ultrasonic signal, and the superimposed image is generated and displayed. A surgeon such as a doctor can diagnose the tissue properties of the observation target by looking at the displayed superimposed image.

In Patent Document 1, a frequency band for calculating a feature amount is set for each frequency spectrum, and the feature amount is calculated from an ultrasonic signal in the set frequency band. According to Patent Document 1, the accuracy of the feature amount is improved by setting the frequency band individually.

By the way, as an ultrasonic probe provided with the above-mentioned ultrasonic vibrator, a small-diameter ultrasonic probe is known (see, for example, Patent Document 2). This small-diameter ultrasonic probe is used for observing relatively small lumens such as the biliary pancreatic duct, ureter, and bronchi (particularly peripheral). Patent Document 2 uses a small-diameter ultrasonic probe provided with an ultrasonic transmitter / receiver for transmitting / receiving ultrasonic waves having different frequency characteristics, and receives a signal from each ultrasonic transmitter / receiver from the ultrasonic transmitter / receiver. An ultrasonic image is generated by weighting according to the depth. Patent Document 2 composites and displays a plurality of ultrasonic images having different frequency characteristics as smooth images on the same image.

Japanese Patent No. 5932184 Japanese Unexamined Patent Publication No. 8-173420

With such a small-diameter ultrasonic probe, the ultrasonic transducer to be arranged must be made smaller. When the ultrasonic vibrator becomes small, the frequency band cannot be widened, and the calculation accuracy of the feature amount may decrease. In particular, at a depth far from the ultrasonic transducer, the high-frequency component of the ultrasonic wave is attenuated, and the effective band of the originally narrow spectrum is further narrowed. Therefore, the feature amount calculation accuracy is significantly reduced. Here, the effective band is a frequency component having a level higher than the noise level in the frequency band. In Patent Document 1, since the frequency band for calculating the feature amount is changed to another effective band with respect to the frequency spectrum already obtained, the feature amount can be calculated with high accuracy in the changed effective band. However, when the ultrasonic vibrator is small, the bandwidth is originally narrow even if all the effective bands are combined, and it is difficult to change the bandwidth. Therefore, it is necessary to devise a method for further improving the accuracy of feature calculation.

Further, when the high frequency component of the ultrasonic wave is attenuated or the effective region of the frequency component is narrowed and the spectral disturbance becomes remarkable, the reception intensity of the image based on the ultrasonic signal, for example, the ultrasonic echo is measured. The resolution of the B-mode image, expressed in terms of brightness, also decreases.

The present invention has been made in view of the above, and is an ultrasonic image generator, an ultrasonic image generator capable of obtaining an image based on an ultrasonic signal and expressing the properties of a tissue with high accuracy. It is an object of the present invention to provide an operation method of an apparatus, an operation program of an ultrasonic image generator, and an ultrasonic image generation circuit.

In order to solve the above-mentioned problems and achieve the object, the ultrasonic image generator according to the present invention has frequency characteristics different from those of the first ultrasonic signal and the first ultrasonic signal from the ultrasonic echo. In an ultrasonic image generator that receives different second ultrasonic signals and generates an ultrasonic image, a first frequency analysis unit that generates first frequency spectrum data for the first ultrasonic signal and the first frequency analysis unit. A second frequency analysis unit that generates a second frequency spectrum data for the ultrasonic signal of 2, and a synthesis unit that synthesizes the first frequency spectrum data and the second frequency spectrum data to generate a composite spectrum data. It is characterized by including a display image data generation unit that generates display image data to be displayed on the display device based on the composite spectrum data.

In the above invention, the ultrasonic image generator according to the present invention generates a feature amount calculation unit that calculates a feature amount based on the composite spectrum data, and a feature amount image data to which color information is added according to the feature amount. It is characterized by further including a feature amount image data generation unit.

The ultrasonic image generator according to the present invention is characterized in that, in the above invention, the feature amount calculation unit calculates the feature amount based on a regression line calculated from the composite spectrum data.

In the above invention, the ultrasonic image generator according to the present invention uses at least one of the first ultrasonic signal and the second ultrasonic signal to generate B-mode image data. It is characterized by further providing a part.

In the ultrasonic image generator according to the present invention, in the above invention, the synthesis unit adds the first frequency spectrum data of the linear representation and the second frequency spectrum data of the linear representation to the composite spectrum. It is characterized by generating data.

In the above invention, the ultrasonic image generator according to the present invention uses at least one of the first ultrasonic signal and the second ultrasonic signal to generate B-mode image data. The image data generation unit further comprises a unit, and the image data generation unit associates the coordinates of the feature amount image data with the coordinates of the B mode image data, and provides color information according to the feature amount on the B mode image data. It is characterized by being placed in.

The ultrasonic image generator according to the present invention is characterized in that, in the above invention, the B-mode image data generation unit generates the B-mode image data using the synthetic spectrum data.

The ultrasonic image generator according to the present invention is characterized in that, in the above invention, further includes a position correction unit for correcting the acquisition position of the first frequency spectrum data and the second frequency spectrum data.

In the ultrasonic image generation device according to the present invention, in the above invention, the B mode image data generation unit mixes the first frequency spectrum data and the second frequency spectrum data according to a set mixing ratio. The B-mode image data is generated by mixing the data.

In the ultrasonic image generation device according to the present invention, in the above invention, the display image data generation unit converts the feature amount image data into the B mode image data according to a set superposition ratio of the feature amount image data. It is characterized by superimposing.

The ultrasonic image generator according to the present invention is characterized in that, in the above invention, further includes a log amplifier for logarithmically transforming the synthesized spectrum data.

The operating method of the ultrasonic image generator according to the present invention receives a first ultrasonic signal and a second ultrasonic signal having a frequency characteristic different from that of the first ultrasonic signal from the ultrasonic echo. A method of operating an ultrasonic image generator that generates an ultrasonic image, in which a first frequency analysis unit generates first frequency spectrum data for the first ultrasonic signal, and a second frequency analysis unit generates first frequency spectrum data. The second frequency spectrum data is generated for the second ultrasonic signal, and the synthesizer synthesizes the first frequency spectrum data and the second frequency spectrum data to generate the composite spectrum data, and the image The data generation unit is characterized in that the display image data to be displayed on the display device is generated based on the composite spectrum data.

The operation program of the ultrasonic image generator according to the present invention receives a first ultrasonic signal and a second ultrasonic signal having a frequency characteristic different from that of the first ultrasonic signal from the ultrasonic echo. An operation program executed by an ultrasonic image generator that generates an ultrasonic image, which generates first frequency spectrum data for the first ultrasonic signal and a second frequency for the second ultrasonic signal. Spectral data is generated, the first frequency spectrum data and the second frequency spectrum data are combined to generate synthetic spectrum data, and based on the synthetic spectrum data, display image data to be displayed on a display device is generated. It is characterized by generating.

The ultrasonic image generation circuit according to the present invention receives a first ultrasonic signal and a second ultrasonic signal having a frequency characteristic different from that of the first ultrasonic signal from the ultrasonic echo, and receives the first ultrasonic signal. A first frequency spectrum data is generated for the ultrasonic signal of the above, a second frequency spectrum data is generated for the second ultrasonic signal, and the first frequency spectrum data and the second frequency spectrum data are combined. It is characterized in that a process of generating synthetic spectrum data by synthesizing and generating display image data to be displayed on a display device based on the synthetic spectrum data is executed.

According to the present invention, it is possible to obtain an image based on an ultrasonic signal that expresses the properties of a tissue with high accuracy.

FIG. 1 is a block diagram showing a configuration of an ultrasonic diagnostic system including an ultrasonic observation device according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of an ultrasonic vibrator in an ultrasonic probe. FIG. 3 is a diagram schematically showing the scanning region of the ultrasonic vibrator and the sound line data. FIG. 4 is a diagram schematically showing a data arrangement in RF data on one sound line of an ultrasonic signal. FIG. 5 is a diagram illustrating spectrum data used in the ultrasonic observation device according to the first embodiment of the present invention. FIG. 6A is a diagram (No. 1) for explaining the calculation of the frequency feature amount using the frequency spectrum. FIG. 6B is a diagram (No. 2) for explaining the calculation of the frequency feature amount using the frequency spectrum. FIG. 6C is a diagram (No. 3) for explaining the calculation of the frequency feature amount using the frequency spectrum. FIG. 7 is a flowchart showing an outline of the processing performed by the ultrasonic observation apparatus according to the first embodiment of the present invention. FIG. 8 is a flowchart showing an outline of the processing executed by the frequency analysis unit of the ultrasonic observation apparatus according to the first embodiment of the present invention. FIG. 9 is a diagram showing a display example of an image based on an ultrasonic signal. FIG. 10 is a diagram (No. 1) for explaining the setting of the position correction data stored in the ultrasonic probe. FIG. 11 is a diagram (No. 2) for explaining the setting of the position correction data stored in the ultrasonic probe. FIG. 12 is a diagram (No. 3) for explaining the setting of the position correction data stored in the ultrasonic probe. FIG. 13 is a diagram illustrating a configuration of a main part of the ultrasonic probe according to the second embodiment of the present invention. FIG. 14 is a diagram illustrating a configuration of a main part of an ultrasonic probe according to a modified example of the second embodiment of the present invention. FIG. 15 is a block diagram showing a configuration of an ultrasonic diagnostic system including an ultrasonic observation device according to a third embodiment of the present invention. FIG. 16 is a flowchart showing an outline of processing performed by the ultrasonic observation apparatus according to the third embodiment of the present invention. FIG. 17 is a block diagram showing a configuration of an ultrasonic diagnostic system including an ultrasonic observation device according to a fourth embodiment of the present invention. FIG. 18 is a flowchart showing an outline of the processing performed by the ultrasonic observation apparatus according to the fourth embodiment of the present invention.

Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as “embodiments”) will be described with reference to the accompanying drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of an ultrasonic diagnostic system 1 provided with an ultrasonic observation device 3 according to a first embodiment of the present invention. The ultrasonic diagnostic system 1 shown in the figure is an ultrasonic probe 2 that transmits ultrasonic waves to a subject and receives ultrasonic waves back-scattered by the subject, and an ultrasonic probe 2 acquired by the connected ultrasonic probe 2. An ultrasonic observation device 3 that generates an ultrasonic image based on an ultrasonic signal, a display device 4 that displays an ultrasonic image generated by the ultrasonic observation device 3, and a control panel 5 that inputs various information related to the generation of image data. And. In the present embodiment, an intraluminal ultrasonic probe is used as the ultrasonic probe 2. In the block diagram, the solid line arrow indicates the transmission of electrical signals related to the frequency spectrum and feature quantities, the dotted line arrow indicates the transmission of electrical signals and data related to the B-mode image, and the single-point chain line arrow indicates control and others. The transmission of electrical signals and data is indicated, and the double-lined arrows indicate the transmission of electrical signals and data related to the image finally displayed on the display device 4. The circuit configuration of the ultrasonic transmission system has been omitted for convenience of explanation.

The ultrasonic probe 2 is an example of a small-diameter ultrasonic probe, and has a flexible insertion portion 21 inserted into a subject and an operation portion 22 connected to the proximal end side of the insertion portion 21. .. At the tip of the insertion portion 21, the electrical pulse signal received from the ultrasonic observation device 3 is converted into an ultrasonic pulse (acoustic pulse) and irradiated to the subject, and the subject is backscattered by the subject. It has an ultrasonic transducer (first ultrasonic transducer 211 and second ultrasonic transducer 212) that converts an ultrasonic echo into an electrical echo signal expressed by a voltage change (see FIG. 2).

FIG. 2 is a diagram illustrating a configuration of an ultrasonic vibrator in an ultrasonic probe. The insertion portion 21 has two ultrasonic vibrators (first ultrasonic vibrator 211 and second ultrasonic vibrator 212) and a backing material 213 provided between the ultrasonic vibrators at one end thereof. It has a flexible flexible shaft 214 which is connected to the backing material 213 and the other end extends toward the operation portion 22 side.

The first ultrasonic vibrator 211 and the second ultrasonic vibrator 212 are ultrasonic vibrators that transmit ultrasonic beams having different frequency characteristics from each other. _{Each ultrasonic transducer transmits ultrasonic beams E 1} and E ₂ on the scanning surface, respectively, and receives the ultrasonic waves returned by backscattering. The first ultrasonic transducer 211 and the second ultrasonic transducer 212 are each scanned scanning plane P _S, receives the come ultrasound back through the scanning plane P _S. The scanning plane P _S shown in FIG. 2 is represented by a rectangle corresponding to the display screen of the display device 4.
_{In the first embodiment, the frequency of the ultrasonic beam E 1} transmitted by the first ultrasonic vibrator 211 is higher than the frequency of the _{ultrasonic beam E 2} transmitted by the second ultrasonic vibrator 212. That is, in the first embodiment, the first ultrasonic vibrator 211 is a high frequency type ultrasonic vibrator, and the second ultrasonic vibrator 212 is a low frequency type ultrasonic vibrator. The ultrasonic vibrator is configured by using a piezoelectric element.

The backing material 213 is a member that attenuates unnecessary ultrasonic vibration generated by the operation of the piezoelectric element. Specifically, the backing material 213 attenuates unnecessary ultrasonic vibrations generated by the operation of the piezoelectric elements of the first ultrasonic vibrator 211 and the second ultrasonic vibrator 212. The backing material 213 can suppress the propagation of unnecessary ultrasonic vibration from one ultrasonic vibrator to the other ultrasonic vibrator. The backing material 13 is formed by using a material having a large damping rate.

The flexible shaft 214 is constructed using a flexible material. The flexible shaft 214 rotates about an axis extending in the longitudinal direction under the control of, for example, the ultrasonic observation device 3. When the flexible shaft 214 rotates, the first ultrasonic vibrator 211 and the second ultrasonic vibrator 212 also rotate. The rotation of the first ultrasonic vibrator 211 and the second ultrasonic vibrator 212 changes the positions of the first ultrasonic vibrator 211 and the second ultrasonic vibrator 212 in the circumferential direction of the tip of the insertion portion 21. NS. A high-frequency signal line connected to the first ultrasonic vibrator 211 and a low-frequency signal line connected to the second ultrasonic vibrator 212 are inserted into the flexible shaft 214. The first ultrasonic vibrator 211 and the second ultrasonic vibrator 212 transmit a signal to the ultrasonic observation device 3 via each signal line.

Returning to FIG. 1, the operation unit 22 is gripped by an operator such as a doctor. The operation unit 22 has a storage unit 221 inside. The storage unit 221 stores the position correction data for correcting the positional relationship of each ultrasonic vibrator with respect to the positional relationship of the first ultrasonic vibrator 211 and the second ultrasonic vibrator 212.

The ultrasonic observation device 3 includes a connection unit 300, a first A / D converter 301, a second A / D converter 302, a first frequency analysis unit 303, a second frequency analysis unit 304, a buffer 305, 306, 314, and a synthesis unit 307. 1st log amplifier 308, feature amount calculation unit 309, 1st coordinate conversion unit 310, mixing unit 311, 2nd log amplifier 312, envelope detection unit 313, 2nd coordinate conversion unit 315, superimposition unit 316, display image signal generation A unit 317 and a storage unit 318 are provided. The ultrasonic observation device 3 corresponds to an ultrasonic image generator.

The connection portion 300 has a high-frequency connection pin 300a for connecting to the high-frequency signal line and a low-frequency connection pin 300b for connecting to the low-frequency signal line, and is fixed to the housing of the ultrasonic observation device 3. .. The operation unit 22 is removable from the connection unit 300. That is, the operation unit 22 is removable from the ultrasonic observation device 3. The connection unit 300 electrically connects the ultrasonic probe 2 and the ultrasonic observation device 3 via the high-frequency signal line and the low-frequency signal line.

The first A / D converter 301 receives an echo signal, which is an electric radio frequency (RF: Radio Frequency) signal, from the ultrasonic probe 2 via a high frequency signal line, and converts it into an echo signal by A / D. It is processed to generate and output digital data (hereinafter referred to as RF data).

The second A / D converter 302 receives an electrical echo signal from the ultrasonic probe 2 via a low-frequency signal line, performs A / D conversion processing on the echo signal, and generates and outputs RF data. ..

Specifically, the first A / D converter 301 and the second A / D converter 302 first amplify the received echo signal. The first A / D converter 301 and the second A / D converter 302 perform processing such as filtering on the amplified echo signal, and then sample at an appropriate sampling frequency (for example, 50 MHz) and discretize (so-called A / D). Conversion processing). In this way, the first A / D converter 301 and the second A / D converter 302 generate discretized RF data from the amplified echo signal. The first A / D converter 301 outputs RF data to the first frequency analysis unit 303 and the mixing unit 311. The second A / D converter 302 outputs RF data to the second frequency analysis unit 304 and the mixing unit 311.

The ultrasonic observation device 3 is electrically connected to the ultrasonic probe 2 and transmits a transmission signal (pulse signal) composed of a high voltage pulse based on a predetermined waveform and transmission timing to the ultrasonic vibrator. Two circuits (not shown) are provided. One of the transmission circuits is connected to the first ultrasonic transducer 211. The frequency band of the pulse signal to be transmitted substantially covers the linear response frequency band of the first ultrasonic vibrator 211 when the first ultrasonic vibrator 211 converts the pulse signal into an ultrasonic pulse. Make it wideband. Further, another one of the transmission circuits is connected to the second ultrasonic vibrator 212. The frequency band of the pulse signal to be transmitted substantially covers the linear response frequency band of the second ultrasonic vibrator 212 when the second ultrasonic vibrator 212 converts the pulse signal into an ultrasonic pulse. Make it wideband. Further, the various processing frequency bands of the echo signal in the first A / D converter 301 and the second A / D converter 302 are the linear shape of the ultrasonic transducer when the ultrasonic transducer acoustically converts the ultrasonic echo into an echo signal. Make the wide band almost cover the response frequency band. As a result, it is possible to perform an accurate approximation when executing the frequency spectrum approximation processing described later.

The first frequency analysis unit 303 performs frequency analysis by performing a fast Fourier transform (FFT) on the RF data generated by the first A / D converter 301 to perform frequency spectrum data (hereinafter, first spectrum data). ) Is calculated. Specifically, the first frequency analysis unit 303 divides the RF data (line data) of each sound line generated by the first A / D converter 301 into a plurality of pieces at relatively short predetermined time intervals, and divides each part. By applying FFT processing to RF data (hereinafter referred to as "RF data string"), the frequency spectrum in each part of the sound line is calculated. The "frequency spectrum" here means the frequency distribution of the intensity and voltage amplitude of the echo signal obtained from the "certain reception depth z (that is, a certain round-trip distance L)" obtained by subjecting the RF data string to FFT processing. Means.

In the first embodiment, the case where the frequency distribution of the voltage amplitude of the echo signal is adopted as the frequency spectrum will be described. The case where the first frequency analysis unit 303 generates the data of the first spectrum based on the frequency component V (f) of the voltage amplitude will be described as an example. f is a frequency. The first frequency analysis unit 303 divides the frequency component V (f) of the amplitude of the RF data (in effect, the voltage amplitude of the echo signal) by the reference voltage V _c , takes the common logarithm (log), and expresses it in decibel units. After performing the logarithmic conversion process, the first spectrum data S (f) of the subject given by the following equation (1) is generated by multiplying by an appropriate positive constant α.
S (f) = α · log {V (f) / V _c } ・ ・ ・ (1)
In the first embodiment, α = 20.

Hereinafter, a method for obtaining the frequency component V (f) of the voltage amplitude by frequency analysis by the first frequency analysis unit 303 will be specifically described. In general, when the subject is a human tissue, the frequency spectrum of the echo signal tends to differ depending on the properties of the human tissue scanned by the ultrasonic waves. This is because the frequency spectrum has a correlation with the size, number density, acoustic impedance, etc. of the scatterer that scatters ultrasonic waves. The "characteristics of human tissue" here refers to the characteristics of tissues such as malignant tumors (cancers), benign tumors, endocrine tumors, mucinous tumors, normal tissues, cysts, and vessels.

FIG. 3 is a diagram schematically showing a scanning region (hereinafter, may be simply referred to as a scanning region) of the ultrasonic vibrator and sound line data. The scanning area S shown in FIG. 3 has a circular shape. In FIG. 3, the ultrasonic transducer expresses the path (sound line) through which the ultrasonic waves reciprocate as a straight line, and the sound line data as points arranged on each sound line. In FIG. 3, for convenience of later explanation, each sound line is numbered 1, 2, 3, ... In order from the start of scanning (right in FIG. 3), and the first sound line is SR ₁ , 2. The third sound line is defined _{as SR 2} , the third sound line _{is defined as SR 3} , ..., And the kth sound line _{is defined as SR k.} Further, in FIG. 3, the reception depth of the sound line data is described as z. When the ultrasonic pulse emitted from the surface of the ultrasonic vibrator scatters backward in the object at the reception depth z and returns to the ultrasonic vibrator as an ultrasonic echo, the reciprocating distance L and the reception depth z There is a relationship of z = L / 2 between them.

FIG. 4 is a diagram schematically showing a data arrangement in RF data on _{one sound line SR k of an ultrasonic signal.} The white or black rectangle on the sound line SR _k means the data at one sample point. Further, in _{the RF data on the sound line SR k} , the data located on the right side is _{the RF data from the deeper part when measured from the ultrasonic transducer along the sound line SR k} (see the arrow in FIG. 4). ). As described above, the RF data on the sound line SR _k is the RF data sampled from the echo signal by the A / D conversion process in the A / D converter and discretized. In Figure 4, there is shown a case of setting the initial value Z ^(k) ₀ in the direction of the eighth data position reception depth z of the RF data on sound ray SR _k of number k, the position of the initial value It can be set arbitrarily. The calculation result by the first frequency analysis unit 303 is stored in the storage unit 318. The maximum value Z ^(k) _max of the data position is a data position representing the deepest RF data string in the analysis range on the sound line SR _k. This maximum value k _max is the number of the leftmost sound line in the analysis range in FIG.

_{The RF data string F j} (j = 1, 2, ..., K) shown in FIG. 4 is a portion of the RF data to be subjected to FFT processing. Generally, in order to perform FFT processing, the RF data string needs to have a power of 2 data number. In this sense, F _K other RF data string _{F j (j = 1,2, ···} , K-1) is a normal RF data string by the number of data is 16 (= 2 ^4). On the other hand, the RF data string F _K is an abnormal RF data string because the number of data is 12. When performing FFT processing on an abnormal RF data string, processing is performed to generate a normal RF data string by inserting zero data for the shortage. This point will be described in detail when the frequency analysis process is described (see FIG. 8). After that, the first frequency analysis unit 303 executes the FFT process as described above, calculates the frequency component V (f) of the voltage amplitude, and obtains the first spectrum data S (f) based on the above equation (1). ) Is calculated. After that, the first frequency analysis unit 303 ^{changes the data position Z (k)} with the step width D to calculate the first spectrum data S (f) at each position. Note that FIG. 4 illustrates the case where D = 15. The first frequency analysis unit 303 further repeats this action on all the sound lines shown in FIG. 3, calculates the first spectrum data S (f) in all directions, and outputs the first spectrum data S (f) to the buffer 305. (Hereinafter, the "direction" will be described as an ultrasonic transmission / reception direction over all scanning directions in FIG. 3).

In FIG. 1, the second frequency analysis unit 304 described above performs frequency analysis by applying FFT to the RF data generated by the second A / D converter 302 in the same manner as the first frequency analysis unit 303, thereby performing frequency spectrum data. (Hereinafter referred to as second spectrum data) is calculated.

The buffer 305 temporarily stores the first spectrum data input from the first frequency analysis unit 303 and outputs it to the synthesis unit 307.
The buffer 306 temporarily stores the second spectrum data input from the second frequency analysis unit 304 and outputs it to the synthesis unit 307.

The synthesis unit 307 synthesizes the first spectrum data and the second spectrum data. The synthesis unit 307 includes a position correction unit 307a for correcting the positions of the first spectrum data and the second spectrum data on the subject. The position correction unit 307a corrects the positional deviation caused by the rotation angle of the flexible shaft 214 between the first ultrasonic vibrator 211 and the second ultrasonic vibrator 212 based on the position correction data acquired from the ultrasonic probe 2. do. The synthesizing unit 307 synthesizes the first spectrum data and the second spectrum data whose position has been corrected by the position correction unit 307a. Specifically, the synthesis unit 307 adds the linear representations of the first and second spectrum data after the position correction.

The first log amplifier 308 performs logarithmic conversion on the input voltage amplitude and outputs the converted voltage amplitude. In logarithmic conversion, data representing the amplitude or intensity of an echo signal is _{divided by a specific voltage V c} called a reference voltage, and the common logarithm is taken for conversion. The converted data is represented by a decibel value (see equation (1)). In this sound line data, values proportional to the digit of the amplitude or intensity of the echo signal indicating the intensity of backward scattering of the ultrasonic pulse expressed in decimal numbers are arranged along the transmission / reception direction (depth direction) of the ultrasonic pulse. It is data.

FIG. 5 is a diagram illustrating spectrum data used in the ultrasonic observation device according to the first embodiment of the present invention. Assuming that the linear representation of the first spectrum data input to the synthesis unit 307 via the buffers 305 and 306 is V _HO (f) and the linear representation of the second spectrum data is V _LO (f), the combination unit 307 outputs the data. The linear representation of the composite spectral data to be obtained is represented by V _HO (f) + V _LO (f). After that, the synthetic spectrum data that has passed through the first log amplifier 308 is represented by 20 log {(V _HO (f) + V _LO (f)) / V _c } as a db representation. Here, the linear representation of the spectral data represents the frequency distribution of the amplitude of the received signal, and the dB representation represents the signal level of the frequency distribution of the linear representation.

The feature amount calculation unit 309 approximates the composite spectrum data output from the first log amplifier 308 with a straight line, and calculates the feature amount of the spectrum data using the straight line. The feature amount calculation unit 309 outputs the feature amount to the first coordinate conversion unit 310.

Specifically, the feature amount calculation unit 309 performs a simple regression analysis of the composite spectrum data in a predetermined frequency band and approximates the composite spectrum data with a linear equation (regression line) to characterize the approximated linear equation. Calculate the amount. The simple regression analysis is a regression analysis when there is only one type of independent variable. The independent variable of the simple regression analysis in this embodiment corresponds to the frequency f.

6A to 6C are diagrams for explaining the calculation of the frequency feature amount using the frequency spectrum. For example, the feature amount calculation unit 309 performs a simple regression analysis in the frequency band U to obtain a regression line L _{S of the composite spectrum data S S} (see FIG. 6A). Next, the feature amount calculating unit 309, the gradient a ₁ of the regression line L _S, the center frequency (i.e., "mid band") of the intercept b _1, and the frequency band U f _M = the _{(f L + f H) /} 2 The mid-band fit, which is a value on the regression line, is calculated as a feature amount of _{c 1} = a ₁ f _M + b _1. By expressing the composite spectrum data S _S with the parameters of the linear equation (slope a ₁ , intercept b ₁ , midband fit c ₁ ) that characterize the regression line L _S , the composite spectrum data S _S is approximated to the linear equation. Become.

Returning to Figure 1, of the three feature quantity calculated from the data of the frequency spectrum, the gradient a _1, the intercept b _1, the size of the scatterer which scatters ultrasound scattering intensity of the scattering bodies, the number of scatterers It is considered to have a correlation with the density (concentration) and the like. The midband fit c ₁ provides the voltage amplitude and intensity of the echo signal at the center of the valid frequency band. Therefore, it is considered that the mid-band fit c ₁ has a certain degree of correlation with the brightness of the B-mode image in addition to the size of the scatterer, the scattering intensity of the scatterer, and the number density of the scatterer. The feature amount calculation unit 309 may approximate the frequency spectrum data with a polynomial of degree 2 or higher by regression analysis.

Here, when the feature amount is calculated using the conventional spectrum data, for example, the second spectrum data S ₂ shown in FIG. 6B, there is a discrepancy between the ideal regression line and the actually obtained regression line due to the influence of noise. Occurs. Specifically, as shown in FIG. 6C, all voltage amplitudes having an _{amplitude b 0} or less, which is determined to be a noise level, may be set to an _{amplitude b 0} (see the black circle (●)). At this time, when the value of the spectrum data is below the noise level (black circle), the amplitude b ₀ , so that the ideal regression line L _{20 of} the second spectrum data S ₂ shown in FIG. 6B is not obtained, and the slope and intercept are different. It becomes the regression line L _21.

The first coordinate conversion unit 310 generates feature amount image data to which visual information is added according to the feature amount calculated by the feature amount calculation unit 309. Specifically, the first coordinate conversion unit 310 allocates visual information related to the feature amount calculated by the feature amount calculation unit 309 corresponding to each pixel position (coordinate) of the image in the B mode image data. Generate image data. Examples of the visual information include variables in the color space constituting a predetermined color system such as hue, saturation, brightness, luminance value, R (red), G (green), and B (blue). Next, the first coordinate conversion unit 310 shows, for example, a depth length proportional to the amount of data of _{one RF data string F j (j = 1, 2, ..., K) shown in FIG. 4 and a depth length shown in FIG.} Visual information related to the feature amount calculated from the _{RF data string F j} is assigned to the pixel region defined by the directional distance between the sound lines.

In the first embodiment, an example will be described in which the first frequency analysis unit 303, the second frequency analysis unit 304, the feature amount calculation unit 309, and the first coordinate conversion unit 310 process the entire scanning region S as the analysis range. The analysis range is limited to the region of interest (Region of Interest: ROI) divided by a specific depth width and azimuth width (that is, the width in the scanning direction) in the scanning area S shown in FIG. Each process may be performed. By limiting the area of interest to the required area, the amount of calculation can be reduced and the speed for displaying can be improved.

The mixing unit 311 mixes RF data input from the first A / D converter 301 and the second A / D converter 302, respectively, based on the mixing ratio data input from the control panel 5. The mixing unit 311 outputs the mixed RF data to the second log amplifier 312.

The second log amplifier 312 performs logarithmic conversion on the input voltage amplitude in the same manner as the first log amplifier 308, and outputs the converted voltage amplitude.

The envelope detection unit 313 applies a bandpass filter and an envelope detection to the data after passing through the second log amplifier 312, and generates digital sound line data representing the amplitude or intensity of the echo signal.

The second coordinate conversion unit 315 performs coordinate conversion for rearranging the sound line data so that the generated sound line data can express the scanning range spatially correctly, and then performs interpolation processing between the sound line data to produce sound. B-mode image data is generated by filling the gaps between the line data. The B-mode image is a grayscale image in which the values of R (red), G (green), and B (blue), which are variables when the RGB color system is adopted as the color space, are matched. The second coordinate conversion unit 315 outputs the generated B-mode image data to the superimposition unit 316. The second coordinate conversion unit 315 may perform STC (Sensitivity Time Control) correction that amplifies RF data having a larger reception depth with a higher amplification factor. Further, the second coordinate conversion unit 315 may perform signal processing on the sound line data using known techniques such as gain processing and contrast processing.

The superimposition unit 316 superimposes the feature amount image data generated by the first coordinate conversion unit 310 on the B mode image data generated by the second coordinate conversion unit 315, and generates display image data to be displayed on the display device 4. do. The superimposition unit 316 superimposes the feature amount image data on the B mode image data by adjusting the brightness of the B mode image and the brightness of the feature amount based on the superimposition ratio data input from the control panel 5. .. The superimposing unit 316 corresponds to a display image data generation unit.

The display image signal generation unit 317 arranges an image corresponding to the display image data (superimposed image described later) at a predetermined position on the display screen, thins out the data according to the display range of the image on the display device 4, and performs the data thinning. A display image signal to be displayed on the display device 4 is generated by performing a predetermined process such as a gradation process. The display image signal generation unit 317 outputs the generated display image signal to the display device 4 for display.

The storage unit 318 stores calculation parameters, data, etc. of each process. The storage unit 318 acquires and stores position correction data from the connected ultrasonic probe 2. The storage unit 318 may store the generated B-mode image data, frequency spectrum data, feature amount image data, and the like. The frequency spectrum data includes at least one of the first spectrum data, the second spectrum data, and the composite spectrum data. The storage unit 318 is configured by using, for example, an HDD (Hard Disk Drive) or an SDRAM (Synchronous Dynamic Random Access Memory).

Further, in addition to the above, the storage unit 318 includes, for example, information required for various processes, information required for logarithmic conversion processing (see equation (1), for example, _{values of α and V c} ), and a window required for frequency analysis processing. Stores information such as functions (Hamming, Hanning, Blackman, etc.).

Further, as an additional memory, the storage unit 318 is a non-temporary computer-readable recording medium in which an operation program for executing the operation method of the ultrasonic observation device 3 is pre-installed, for example, a ROM (Read Only Memory) (not shown). ) Is provided. The operation program can also be recorded on a computer-readable recording medium such as a portable hard disk, flash memory, CD-ROM, DVD-ROM, or flexible disk and widely distributed. The various programs described above can also be acquired by downloading them via a communication network. The communication network referred to here is realized by, for example, an existing public line network, LAN, WAN, etc., and may be wired or wireless.

The ultrasonic observation device 3 reads information such as an operation program stored and stored in the storage unit 318, calculation parameters of each process, data, etc. from the storage unit 318, and causes each unit to execute various calculation processes related to the operation method. As a result, the ultrasonic observation device 3 is controlled in an integrated manner.

The first frequency analysis unit 303, the second frequency analysis unit 304, the synthesis unit 307, the feature amount calculation unit 309, the first coordinate conversion unit 310, the envelope detection unit 313, the second coordinate conversion unit 315, the superimposition unit 316, and the above-mentioned first frequency analysis unit 303, second frequency analysis unit 304, synthesis unit 307, and The display image signal generation unit 317 is dedicated to executing a general-purpose processor such as a CPU (Central Processing Unit) having arithmetic and control functions, or a specific function such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array). It is realized by using the integrated circuit of. It is also possible to configure a plurality of parts including at least a part of the above by using a common general-purpose processor, a dedicated integrated circuit, or the like.

The control panel 5 is configured by using a plurality of buttons capable of inputting various information, and accepts input from the operator. The control panel 5 is provided with a first knob 51 and a second knob 52. Each of the first knob 51 and the second knob 52 is rotatable and outputs an operation signal according to the rotation position.

The first knob 51 inputs the mixing ratio of RF data in the mixing unit 311. For example, the ratio (H: L) of the RF data (H) from the first A / D converter 301 to the RF data (L) from the second A / D converter 302 is set according to the rotation position of the first knob 51. ing. H: L is set to 100: 0, 0: 100, 50:50, 70:30, ..., Depending on the ratio that can be mixed.

The second knob 52 inputs the superposition ratio of the feature amount image data in the superimposition unit 316. For example, depending on the rotation position of the second knob 52, the ratio (A: B) of the feature amount image data (A) from the first coordinate conversion unit 310 to the B mode image data (B) from the second coordinate conversion unit 315. ) Is set. For A: B, 100: 0, 0: 100, 50:50, 70:30, ... Are set according to the ratio that can be superimposed.

The control panel 5 may be further provided with a touch panel provided with a display screen. The touch panel functions as a graphical user interface (GUI) by displaying ultrasonic images and various information. The touch panel includes a resistive film method, a capacitance method, an optical method, and the like, and any type of touch panel can be applied.

FIG. 7 is a flowchart showing an outline of the processing performed by the ultrasonic observation device 3 having the above configuration. When the ultrasonic probe 2 is connected to the ultrasonic observation device 3, the ultrasonic observation device 3 acquires position correction data from the ultrasonic probe 2 (step S101). Further, in this process, it is assumed that various ratio data are input from the first knob 51 and the second knob 52.

In step S102, when the observation of the subject such as the tissue inside the human body is started, the first ultrasonic vibrator 211 and the second ultrasonic vibrator 212 scan the subject and electrically transmit the echo received from the subject. Convert to echo signal. The first A / D converter 301 receives an echo signal via the first ultrasonic vibrator 211. The second A / D converter 302 receives the echo signal via the second ultrasonic transducer 212. Each A / D converter amplifies the echo signal as needed, samples the amplified echo signal at an appropriate sampling frequency (for example, 50 MHz), and disperses it to generate RF data. The first A / D converter 301 outputs the generated RF data to the first frequency analysis unit 303. The second A / D converter 302 outputs the generated RF data to the second frequency analysis unit 304.

Steps S103 to S107 are the flow of the feature amount image data generation process.
In step S103, the first frequency analysis unit 303 and the second frequency analysis unit 304 calculate frequency spectrum data from the RF data generated in step S102, respectively. The first frequency analysis unit 303 divides the RF data (line data) of each sound line into a plurality of pieces at relatively short predetermined time intervals, and performs frequency analysis by FFT calculation on the RF data of each divided part. Calculate the frequency spectrum data for the RF data string.

FIG. 8 is a flowchart showing an outline of the processing executed by the first frequency analysis unit 303 and the second frequency analysis unit 304 in step S103. Hereinafter, the frequency analysis process will be described in detail with reference to the flowchart shown in FIG. It should be noted that this process is a flow based on the process described in FIG. In the following description, the frequency analysis process performed by the first frequency analysis unit 303 will be described, but the same applies to the second frequency analysis unit 304.

In step S201, the first frequency analysis unit 303 sets the counter k for identifying the sound line to be analyzed as k ₀ . This initial value k ₀ is the number of the rightmost sound line in the analysis range in FIG.

In step S202, the first frequency analysis unit 303 sets the initial value Z ^(k) ₀ of ^{the data position (corresponding to the reception depth) Z (k)} representing a series of RF data strings acquired for the FFT calculation.

After that, the first frequency analysis unit 303 acquires the RF data string (step S203), and causes the window function stored by the storage unit 318 to act on the acquired RF data string (step S204). By acting a window function on the RF data string, it is possible to prevent the RF data string from becoming discontinuous at the boundary and prevent the occurrence of artifacts.

Subsequently, the first frequency analysis unit 303 ^{determines whether or not the RF data string at the data position Z (k)} is a normal RF data string (step S205). Hereinafter, the number of data in the normal RF data string is 2 ⁿ (n is a positive integer). In this embodiment, the data position Z ^(k) is set to be at the center of the RF data string to which ^{Z (k)} belongs as much as possible. Specifically, since the number of data in the RF data string is 2 ^{n , Z (k)} is set at the ^{2 n} / 2 (= 2 ^n-1 ) th position near the center of the RF data string. In this case, the RF data string is normal, (a = N) 2 ^n-1 -1 to the shallower side than the data position Z ^(k) there are pieces of data, than the data position Z ^(k) It means that there are ^{2 n-1} (= M) data on the deep side.

As a result of the determination in step S205, when ^{the RF data string at the data position Z (k)} is normal (step S205: Yes), the first frequency analysis unit 303 shifts to step S207 described later.

As a result of the determination in step S205, when ^{the RF data string at the data position Z (k)} is not normal (step S205: No), the first frequency analysis unit 303 inserts zero data for the shortage to obtain normal RF data. Generate a string (step S206). After step S206, the first frequency analysis unit 303 shifts to step S207, which will be described later.

In step S207, the first frequency analysis unit 303 calculates V (f) corresponding to the frequency distribution of the voltage amplitude of the echo signal by performing an FFT calculation on the RF data string. After that, the first frequency analysis unit 303 performs logarithmic conversion processing on V (f) to obtain frequency spectrum data S (f) (step S207).

In step S208, the first frequency analysis unit 303 ^{changes the data position Z (k)} with the step width D.

After that, the first frequency analysis unit 303 ^{determines whether or not the data position Z (k)} is larger than the maximum value Z ^(k) _max in the sound line SR _k (step S209). When the data position Z ^(k) is larger than the maximum value Z ^(k) _max (step S209: Yes), the first frequency analysis unit 303 increments the counter k by 1 (step S210). This means that the processing is transferred to the next sound line. On the other hand, when the data position Z ^(k) is equal to ^{or less than the maximum value Z (k)} _max (step S209: No), the first frequency analysis unit 303 returns to step S203.

After step S210, the first frequency analysis unit 303 _{determines whether or not the counter k is larger than the maximum value k max} (step S211). When the counter k is _{larger than k max} (step S211: Yes), the first frequency analysis unit 303 ends a series of frequency analysis processes. On the other hand, when the counter k is k _max or less (step S211: No), the first frequency analysis unit 303 returns to step S202.

Again, in FIG. 4, the first frequency analysis unit 303 performs a plurality of FFT calculations for each of _{the (k max} −k _{0 + 1) sound lines in the analysis target region for each depth.} The result of the FFT calculation is stored in the storage unit 318 together with the reception depth and the reception direction.

Regarding these four values, k ₀ , k _max , Z ^(k) ₀ , and Z ^(k) _max , default values including the entire scanning range of FIG. 3 are stored in advance in the storage unit 318. The first frequency analysis unit 303 appropriately reads these values and performs the processing of FIG. When the default value is read, the first frequency analysis unit 303 performs frequency analysis processing on the entire scanning range. However, these four values, k ₀ , k _max , Z ^(k) ₀ , and Z ^(k) _max , can be changed by inputting an instruction of the region of interest by the operator via the control panel 5. If it has been changed, the first frequency analysis unit 303 performs the frequency analysis process only in the region of interest in which the instruction is input.

It will be explained again with reference to FIG. 7. In step S104, the synthesis unit 307 synthesizes the first spectrum data and the second spectrum data. Specifically, the synthesis unit 307 is corrected by the position correction unit 307a to match the positions of the first spectrum data and the second spectrum data on the subject, and the position-corrected first spectrum data and the second spectrum data are present. Synthesize spectral data.

In step S105, the first log amplifier 308 performs logarithmic conversion with respect to the input voltage amplitude. The first log amplifier 308 outputs the converted voltage amplitude to the feature amount calculation unit 309.

In step S106, the feature amount calculation unit 309 approximates the composite spectrum data output from the first log amplifier 308 with a straight line, and calculates the feature amount of the spectrum data using the straight line. Feature amount calculation unit 309, for example, the gradient a ₁ of the regression line L _S described above, the intercept b _1, and of the mid-band fit c _1, calculates the specified characteristic quantity.

In step S107, the first coordinate conversion unit 310 generates feature image data to which visual information is added according to the feature calculated by the feature calculation unit 309.

In parallel with step S103, the mixing unit 311 mixes the RF data input from the first A / D converter 301 and the second A / D converter 302, respectively, based on the mixing ratio data input from the first knob 51. (Step S108).

S108 to S111 are flows of B-mode image generation processing.
In step S109, the second log amplifier 312 performs logarithmic conversion with respect to the input voltage amplitude in the same manner as the first log amplifier 308. The second log amplifier 312 outputs the converted voltage amplitude to the envelope detection unit 313.

In step S110, the envelope detection unit 313 performs envelope detection or the like on the data after passing through the second log amplifier 312, and generates digital sound line data representing the amplitude or intensity of the echo signal.

In step S111, the second coordinate conversion unit 315 performs coordinate conversion to rearrange the sound line data so that the generated sound line data can express the scanning range spatially correctly, and generates B mode image data.

Here, the feature amount image data generation processing in steps S103 to S107 and the B-mode image generation processing in steps S108 to S111 may be performed at the same time, or one of them may be performed first.

In step S112, the superimposition unit 316 superimposes the feature amount image data on the B mode image data based on the superimposition ratio data input from the second knob 52, and generates display image data to be displayed on the display device 4. do. Further, the superimposition unit 316 outputs the B mode image data to the display image signal generation unit 317.

In step S113, the display image signal generation unit 317 thins out the display image data generated by the superimposition unit 316 and the B-mode image data according to the display range of the image in the display device 4, and performs gradation processing. A display image signal is generated by performing a predetermined process such as, and is output to the display device 4 for display.

FIG. 9 shows a display example of an image corresponding to the display image data generated based on the ultrasonic signal. The display screen W of the display device 4, a B-mode image W ₁ to the feature amount image is not superimposed, the feature quantity image and superposed image W ₂ superimposed is displayed on the B-mode image.

Subsequently, an example of setting the position correction data in the ultrasonic probe 2 will be described with reference to FIGS. 10 to 12. 10 to 12 are views for explaining the setting of the position correction data stored in the ultrasonic probe 2. The position correction data is acquired, for example, at the time of shipment of the ultrasonic probe 2 in the factory.

The position correction data is generated by acquiring an ultrasonic image (B mode image) of the Tegs 100 shown in FIG. The echo signal causes the first ultrasonic vibrator 211 and the second ultrasonic vibrator 212 while rotating the flexible shaft 214 and simultaneously rotating and driving the first ultrasonic vibrator 211 and the second ultrasonic vibrator 212. Scan to obtain each echo signal. The first ultrasonic transducer 211 and the second ultrasonic transducer 212, to obtain the B-mode image including the image of the gut 100 at the scanning plane P _S.

When setting the position correction data, the ultrasonic probe 2 is connected to the ultrasonic observation device 6 for a factory (see FIG. 11). The ultrasonic observation device 6 generates a B-mode image based on the acquired echo signal. The generated B-mode image is displayed on the monitor 61. The monitor 61, B-mode and the superimposed image W _BS superimposed B-mode image based on echo signals of the first ultrasonic transducer 211 and the second ultrasonic transducer 212, B-mode based on either the echo signal The image is displayed.

Further, the control panel 7 is connected to the ultrasonic observation device 6. The control panel 7 is provided with a writing instruction button 71 for instructing writing of position correction data to the storage unit 221 and rotation instruction buttons 72 and 73 for inputting rotation instructions in opposite directions.

Here, the B-mode image based on the first echo signal by the ultrasonic transducer 211 has acquired W _BH, the gut image in the B-mode image W _BH and Q _H. Further, the B mode image based on the echo signal acquired by the second ultrasonic vibrator 212 is referred to as W _BL , and the Tegs image in this B mode image W _BL is referred to as Q _L. If the first ultrasonic transducer 211 and the second ultrasonic transducer 212 is bonded to the opposite side each other with respect to the backing material 213, in the B-mode superimposed image W _BS, and guts image Q _H and gut image Q _L is positioned on the opposite side with respect to the center echo Q ₀ (see B-mode superimposed image W _BS in FIG. 11 for example).

The user, in the B-mode superimposed image W _BS, upon depression of the rotation instruction buttons 72 and 73, about the center echoes Q ₀ by rotating the B-mode image W _BH, to match the gut image Q _H and gut image Q _L (See FIG. 12). The rotation angle θ of the B mode image W _BH when the Tegs image Q _H and the Tegs image Q _L match is set as the position correction data. When the Tegs image Q _H and the Tegs image Q _L match and the write instruction button 71 is pressed by the user, the ultrasonic observation device 6 uses the rotation angle at that time as position correction data for the ultrasonic probe 2. Write to the storage unit 221 of.

In the first embodiment of the present invention described above, the feature amount is calculated using the high-frequency echo signal received from the ultrasonic transducers having different frequency characteristics and the low-frequency echo signal. The feature amount calculation unit 309 can obtain a regression line in a sufficient frequency band. This makes it possible to calculate the feature amount more accurately than in the case of obtaining the regression line using only the high-frequency echo signal or only the low-frequency echo signal. According to the first embodiment, by calculating the feature amount with high accuracy, it becomes easy to distinguish a subtle difference between tissues.

The absolute value of the obtained feature amount is different between the first spectrum data S ₁ and the second spectrum data S ₂ and the synthetic spectrum data S _S. However, when diagnosing with a device, blue is often assigned as the reference color for normal tissues, and an appropriate color is often assigned to the relative value, which is the difference between the target tissue and the reference, rather than the absolute value. .. In the first embodiment, it is easier to distinguish subtle differences between tissues as compared with the conventional case, which is advantageous for discrimination.

Further, according to the first embodiment of the present invention, since the position correction data for correcting the error in the manufacturing of the ultrasonic probe 2 is read from the ultrasonic probe 2, the first ultrasonic vibrator 211 and the second ultrasonic transducer 211 are used. It is possible to correct the deviation that occurs when the ultrasonic vibrator 212 is attached to the backing material 213.

Although the position correction unit 307a has been described as being provided in the synthesis unit 307 in the first embodiment, it may be provided separately from the composition unit 307.

Further, in the first embodiment, the example in which the position correction data is _{the rotation angle of the B mode image W BH with} respect to the B mode image W _BL has been described, but the present invention is not limited to this. The position correction data may be, for example, a deviation of the ultrasonic vibrator in the sound line direction from the central echo (distance (difference) from the flexible shaft 214).

Further, in the first embodiment, an example in which two ultrasonic vibrators having different frequency characteristics are described has been described, but the present invention is not limited to this, and three or more ultrasonic vibrators may be provided.

(Embodiment 2)
Subsequently, a second embodiment of the present invention will be described. FIG. 13 is a diagram illustrating a configuration of a main part of an ultrasonic endoscope according to a second embodiment of the present invention. The second embodiment is different from the first embodiment described above in that the insertion portion 21 of the ultrasonic endoscope is configured. Hereinafter, the configuration of the insertion portion 21A of the ultrasonic endoscope according to the second embodiment will be described.

The insertion portion 21A converts an electrical pulse signal received from the ultrasonic observation device 3 into an ultrasonic pulse (acoustic pulse) and irradiates the subject with the tip portion thereof, and at the same time, the ultrasonic pulse is scattered backward by the subject. It has an ultrasonic vibrator 215 that converts an ultrasonic echo into an electrical echo signal expressed by a voltage change, an optical lens 216, and an image pickup element (not shown). In the second embodiment, an ultrasonic endoscope is used as the ultrasonic probe. The ultrasonic endoscope further has an optical lens for imaging and an image pickup element at the tip portion of the insertion portion 21A.

The ultrasonic vibrator 215 has a plurality of first vibrators 215a and a plurality of second vibrators 215b. The first vibrator unit 215a and the second vibrator unit 215b are composed of piezoelectric elements that transmit ultrasonic beams having different frequency characteristics from each other. The first vibrator portion 215a and the second vibrator portion 215b are alternately arranged in the circumferential direction of the insertion portion 21A. In FIG. 13, the second vibrator portion 215b is hatched to distinguish it from the first vibrator portion 215a.

The ultrasonic vibrator 215 is a radial type electronic ultrasonic vibrator in which the first vibrator portion 215a and the second vibrator portion 215b are alternately driven under the control of the ultrasonic observation device 3. For example, when acquiring a high-frequency echo signal, each first oscillator unit 215a is driven, and when acquiring a low-frequency echo signal, each second oscillator unit 215b is driven. The received echo signal is output to the ultrasonic observation device 3 and processed in the same manner as in the first embodiment. Further, the image signal captured by the image sensor is output to an image processing device (not shown), and the captured image data is generated and displayed by an image processing circuit (not shown) in the image processing device.

In the second embodiment of the present invention described above, the switching of the ultrasonic vibrator is different from each other in the ultrasonic probe (ultrasonic endoscope) which does not require a mechanical drive mechanism, as in the first embodiment. The feature amount can be calculated accurately by using the high-frequency echo signal received from the ultrasonic vibrator having the frequency characteristics and the low-frequency echo signal. According to the second embodiment, by calculating the feature amount with high accuracy, it becomes easy to discriminate subtle differences between tissues.

(Modified Example of Embodiment 2)
Subsequently, a modified example of the second embodiment of the present invention will be described. FIG. 14 is a diagram illustrating a configuration of a main part of an ultrasonic probe according to a modified example of the second embodiment of the present invention.

The insertion portion 21B according to the modified example converts an electrical pulse signal received from the ultrasonic observation device 3 into an ultrasonic pulse (acoustic pulse) and irradiates the subject at the tip thereof, and at the same time, rearward the subject. It includes an ultrasonic vibrator 217 that converts scattered ultrasonic echoes into an electrical echo signal expressed by a voltage change, an optical lens 218, and an image pickup element (not shown).

The ultrasonic vibrator 217 has a plurality of first vibrators 217a and a plurality of second vibrators 217b. The first vibrator unit 217a and the second vibrator unit 217b are composed of piezoelectric elements that transmit ultrasonic beams having different frequency characteristics from each other. The first vibrator portion 217a and the second vibrator portion 217b are alternately arranged in the longitudinal direction of the insertion portion 21B to form a curved outer surface. In FIG. 14, the second vibrator portion 217b is hatched to distinguish it from the first vibrator portion 217a. Further, the ultrasonic vibrator 217 is shown as an image of a model in which the thickness of the vibrator is emphasized for explanation, unlike the actual thickness of the vibrator and the structure in the thickness direction.

The ultrasonic vibrator 217 is a convex type electronic ultrasonic vibrator in which the first vibrator portion 217a and the second vibrator portion 217b are alternately driven under the control of the ultrasonic observation device 3. For example, when acquiring a high-frequency echo signal, each first oscillator unit 217a is driven, and when acquiring a low-frequency echo signal, each second oscillator unit 217b is driven. The received echo signal is output to the ultrasonic observation device 3 and processed in the same manner as in the first embodiment.

Also in the modification described above, the feature amount is determined by using the high frequency echo signal received from the ultrasonic transducers having different frequency characteristics and the low frequency echo signal as in the first and second embodiments. Since it is calculated, the feature amount can be calculated accurately. According to this modified example, by calculating the feature amount with high accuracy, it becomes easy to discriminate subtle differences between tissues.

(Embodiment 3)
Subsequently, the third embodiment of the present invention will be described. FIG. 15 is a block diagram showing a configuration of an ultrasonic diagnostic system 1A including the ultrasonic observation device 3A according to the third embodiment of the present invention. The same configurations as those described in the first embodiment are designated by the same reference numerals and have the same functions as those described in the first embodiment.

The ultrasonic diagnostic system 1A according to the third embodiment includes an ultrasonic observation device 3A instead of the ultrasonic observation device 3 for the configuration of the ultrasonic diagnostic system 1 according to the first embodiment described above, and is a control panel. A control panel 5A is provided instead of 5. As a configuration different from the ultrasonic diagnostic apparatus 3 of the first embodiment, the switching selection knob 53, the third frequency analysis unit 319, the first log amplifier 320, the first envelope detection unit 321 and the buffer 322, and the first coordinate conversion unit 323 , A changeover switch 324, a second envelope detection unit 325, and a display image data generation unit 326.

The third frequency analysis unit 319 performs an inverse FFT on the composite spectrum data from the synthesis unit 307. The data generated by the processing of the third frequency analysis unit 319 corresponds to the composite data of the RF data whose composite spectrum data is output from the first A / D converter 301 and the second A / D converter 302.

The first log amplifier 320 performs logarithmic conversion on the input voltage amplitude in the same manner as the first log amplifier 308, and outputs the converted voltage amplitude.

The first envelope detection unit 321 applies a bandpass filter and an envelope detector to the data after passing through the first log amplifier 320, and generates digital sound line data representing the amplitude or intensity of the echo signal.

The first coordinate conversion unit 323 performs coordinate conversion for rearranging the sound line data so that the generated sound line data can express the scanning range spatially correctly, and then performs interpolation processing between the sound line data to produce sound. The gap between the line data is filled, and new B-mode image data (new B-mode image data) after synthesizing two RF data having different frequency characteristics is generated. The first coordinate conversion unit 323 may perform STC (Sensitivity Time Control) correction that amplifies RF data having a larger reception depth with a higher amplification factor. Further, the first coordinate conversion unit 323 may perform signal processing on the sound line data using known techniques such as gain processing and contrast processing.

The changeover switch 324 selects the RF data to be input from the RF data of the first A / D converter 301 and the RF data of the second A / D converter 302 based on the changeover signal input from the control panel 5A. The changeover switch 324 outputs the selected RF data to the second log amplifier 312.

The second envelope detection unit 325 applies a bandpass filter and an envelope detector to the data after passing through the second log amplifier 312, and generates digital sound line data representing the amplitude or intensity of the echo signal.
In the third embodiment, the B-mode image data generated by the second coordinate conversion unit 315 is used as the old B-mode image data.

The display image data generation unit 326 displays the new B-mode image data generated by the first coordinate conversion unit 323 and the old B-mode image data generated by the second coordinate conversion unit 315 on the display device 4. Generate image data. The display image data generation unit 326 generates display image data in which the new B mode image data and the old B mode image data are arranged side by side.

The control panel 5A is provided with a switching selection knob 53. The switching selection knob 53 is rotatable and outputs a switching signal according to the rotation position. The control panel 5A has either RF data of the first A / D converter 301, RF data of the second A / D converter 302, or no RF data selection (no parallel display) according to the rotation position of the switching selection knob 53. The changeover signal of is output to the changeover switch 324.

FIG. 16 is a flowchart showing an outline of the processing performed by the ultrasonic observation device 3A having the above configuration. The ultrasonic observation device 3A connected to the ultrasonic probe executes the same processing as in steps S101 to S104 described above (steps S301 to S304).

In step S305, the third frequency analysis unit 319 applies an inverse FFT to the composite spectrum data to generate RF data. The third frequency analysis unit 319 outputs the generated RF data to the first log amplifier 320.

In step S306, the first log amplifier 320 performs logarithmic conversion on the input voltage amplitude. The first log amplifier 320 outputs the converted voltage amplitude to the first envelope detection unit 321.

In step S307, the first envelope detection unit 321 performs a bandpass filter and an envelope detection on the data after passing through the first log amplifier 320, and generates digital sound line data indicating the amplitude or intensity of the echo signal. do.

In step S308, the first coordinate conversion unit 323 generates new B-mode image data by performing coordinate conversion for rearranging the sound line data so that the generated sound line data can express the scanning range spatially correctly.

In parallel with step S303, the second log amplifier 312 performs logarithmic conversion on the voltage amplitude input from the changeover switch 324 (step S309). The second log amplifier 312 outputs the converted voltage amplitude to the second envelope detection unit 325.

In step S310, the second envelope detection unit 325 performs envelope detection or the like on the data after passing through the second log amplifier 312, and generates digital sound line data representing the amplitude or intensity of the echo signal.

In step S311, the second coordinate conversion unit 315 performs coordinate conversion to rearrange the sound line data so that the generated sound line data can express the scanning range spatially correctly, and generates the old B mode image data.

Here, the new B-mode image data generation processing in steps S303 to S308 and the old B-mode image generation processing in steps S309 to S311 may be performed at the same time, or one of them may be performed first. If there is no RF data selected by the switching selection knob 53, the old B-mode image generation processing in steps S309 to S311 is not performed.

In step S312, the display image data generation unit 326 generates display image data in which the new B mode image data and the old B mode image data are arranged side by side.

In step S313, the display image signal generation unit 317 thins out the display image data generated by the superimposition unit 316 and the B-mode image data according to the display range of the image in the display device 4, and performs gradation processing. A display image signal is generated by performing a predetermined process such as, and is output to the display device 4 for display.

In the third embodiment of the present invention described above, the B-mode image data to be displayed is generated by using the high-frequency echo signal received from the ultrasonic transducers having different frequency characteristics and the low-frequency echo signal. .. Since the display image data generation unit 326 generates a new B-mode image in a sufficient frequency band, it is possible to obtain B-mode image data with high resolution. According to the third embodiment, it becomes easy to discriminate subtle differences between tissues in the B mode image.

(Embodiment 4)
Subsequently, a fourth embodiment of the present invention will be described. FIG. 17 is a block diagram showing a configuration of an ultrasonic diagnostic system 1B including the ultrasonic observation device 3B according to the fourth embodiment of the present invention. The same configurations as those described in the first embodiment are designated by the same reference numerals and have the same functions as those described in the first embodiment.

The ultrasonic diagnostic system 1B according to the fourth embodiment includes an ultrasonic observation device 3B instead of the ultrasonic observation device 3 for the configuration of the ultrasonic diagnostic system 1 according to the first embodiment described above, and is a control panel. A control panel 5B is provided instead of 5. As a configuration different from the ultrasonic diagnostic apparatus 3 of the first embodiment, the ultrasonic observation apparatus 3B includes a fourth frequency analysis unit 327 and a superposition ratio setting knob 54.

The fourth frequency analysis unit 327 performs an inverse FFT on the composite spectrum data from the synthesis unit 307. The data generated by the processing of the fourth frequency analysis unit 327 corresponds to the composite data of the RF data output from the first A / D converter 301 and the second A / D converter 302. The fourth frequency analysis unit 327 outputs the generated RF data to the second log amplifier 312.

The control panel 5B is provided with a superposition ratio setting knob 54. The superposition ratio setting knob 54 is rotatable and outputs a setting signal according to the rotation position.

The superimposition ratio setting knob 54 inputs the superimposition ratio of the feature amount image data in the superimposition unit 316. For example, the ratio of the feature amount image data (A) from the first coordinate conversion unit 310 to the B mode image data (B) from the second coordinate conversion unit 315 (A:) depending on the rotation position of the superposition ratio setting knob 54. B) is set. For A: B, ratios such as 100: 0, 0: 100, 50:50, and 70:30 are set according to the ratio that can be superimposed.

FIG. 18 is a flowchart showing an outline of the processing performed by the ultrasonic observation device 3B having the above configuration. The ultrasonic observation device 3B executes the same processing as in steps S101 to S107 described above (steps S401 to S407).

In the fourth embodiment, unlike the first embodiment, after the frequency spectrum is synthesized in step S404, the process of the fourth frequency analysis unit 327 is performed in parallel with the logarithmic conversion process of step S405. The fourth frequency analysis unit 327 applies an inverse FFT to the synthesized spectrum data to generate RF data (step S408). The fourth frequency analysis unit 327 outputs the generated RF data to the second log amplifier 312.

In step S409, the second log amplifier 312 performs logarithmic conversion on the voltage amplitude input from the fourth frequency analysis unit 327 (step S309). The second log amplifier 312 outputs the converted voltage amplitude to the second envelope detection unit 325.

The ultrasonic observation device 3B executes the same processing as in steps S110 to S113 described above (steps S410 to S413). In step S412, the superimposition unit 316 superimposes the feature amount image data on the B mode image data based on the superimposition ratio data input from the superimposition ratio setting knob 54, and displays the display image data displayed on the display device 4. Generate.

In the fourth embodiment of the present invention described above, the feature amount is calculated using the high-frequency echo signal received from the ultrasonic transducers having different frequency characteristics and the low-frequency echo signal. The feature amount calculation unit 309 can obtain a regression line in a sufficient frequency band. This makes it possible to calculate the feature amount more accurately than in the case of obtaining the regression line using only the high-frequency echo signal or only the low-frequency echo signal. According to the fourth embodiment, by calculating the feature amount with high accuracy, it becomes easy to discriminate subtle differences between tissues.

Further, in the fourth embodiment, the B mode image data to be displayed is generated by using the RF data obtained by synthesizing the high frequency echo signal received from the ultrasonic transducers having different frequency characteristics and the low frequency echo signal. do. Since the new B-mode image is generated in a sufficient frequency band in the second coordinate conversion unit 315, B-mode image data having high resolution can be obtained. According to the fourth embodiment, it becomes easy to discriminate subtle differences between tissues in the B mode image.

Although the embodiments for carrying out the present invention have been described so far, the present invention should not be limited only to the above-described embodiments. For example, in an ultrasonic observation device, circuits having each function may be connected by a bus, or some functions may be incorporated in a circuit structure of another function.

Further, in the first to fourth embodiments, as the ultrasonic probe, an intraluminal ultrasonic probe having no optical lens and an imaging element and an ultrasonic endoscope having an imaging optical system have been described. However, a small-diameter ultrasonic miniature probe without an optical system may be applied. Ultrasonic miniature probes are usually inserted into the biliary tract, bile ducts, pancreatic ducts, trachea, bronchi, urethra, and ureters and used to observe surrounding organs (pancreas, lungs, prostate, bladder, lymph nodes, etc.).

Further, as the ultrasonic probe, an extracorporeal ultrasonic probe that irradiates ultrasonic waves from the body surface of the subject may be applied. Extracorporeal ultrasound probes are typically used in direct contact with the body surface when observing abdominal organs (liver, gallbladder, bladder), breasts (particularly mammary glands), and thyroid glands.

Further, the ultrasonic vibrator may be a linear type vibrator, a radial type vibrator, or a convex vibrator. When the ultrasonic oscillator is a linear oscillator, its scanning area is rectangular (rectangular, square), and when the ultrasonic oscillator is a radial oscillator or convex oscillator, its scanning area is fan-shaped or annular. Rectangle. Further, the ultrasonic vibrator may have a piezoelectric element arranged two-dimensionally. Further, the ultrasonic endoscope may be one that mechanically scans the ultrasonic vibrator, or a plurality of elements are provided in an array as the ultrasonic vibrator, and the elements involved in transmission / reception are electronically switched. Alternatively, it may be electronically scanned by delaying the transmission and reception of each element.

Further, the ultrasonic observation device is not limited to the stationary type, and may be a portable or wearable device. In the case of a portable and wearable ultrasonic observation device, the ultrasonic observation device is required to be miniaturized. Further, when the diameter of the ultrasonic probe itself is required to be reduced, there is no space for arranging the ultrasonic vibrator, and the frequency band tends to be narrowed. By applying the present embodiment to this configuration, it is possible to calculate a highly accurate feature amount and obtain a highly accurate feature amount image regardless of the depth.

The present invention may include various embodiments within a range that does not deviate from the technical idea described in the claims.

As described above, the ultrasonic image generator, the operation method of the ultrasonic image generator, the operation program of the ultrasonic image generator, and the ultrasonic image generation circuit according to the present invention are images based on the ultrasonic signal. It is useful for obtaining an image that expresses the properties of the tissue with high accuracy.

1, 1A, 1B Ultrasonic diagnostic system 2 Ultrasonic endoscope 3, 3A, 3B Ultrasonic observation device 4 Display device 5, 5A, 5B Control panel 21, 21A, 21B Insertion part 22 Operation part 211 First ultrasonic vibration Child 212 2nd ultrasonic transducer 213 Backing material 214 Flexible shaft 215, 217 Ultrasonic transducer 216 Imaging optical system 300 Connection part 301 1st A / D converter 302 2nd A / D converter 303 1st frequency analysis part 304 2nd frequency Analysis unit 305, 306, 314, 322 Buffer 307 Synthesis unit 308, 320 1st log amplifier 309 Feature calculation unit 310, 323 1st coordinate conversion unit 311 Mixing unit 312 2nd log amplifier 313 Envelopment line detection unit 315 2nd coordinates Conversion unit 316 Superimposition unit 317 Display image signal generation unit 318 Storage unit 319 Third frequency analysis unit 321 First wrapping line detection unit 324 Changeover switch 325 Second wrapping line detection unit 326 Display image data generation unit 327 Fourth frequency analysis unit

Claims (14)

1. In an ultrasonic image generator that receives a first ultrasonic signal and a second ultrasonic signal having different frequency characteristics from the first ultrasonic signal from the ultrasonic echo and generates an ultrasonic image.
   A first frequency analysis unit that generates first frequency spectrum data for the first ultrasonic signal,
   A second frequency analysis unit that generates a second frequency spectrum data for the second ultrasonic signal, and a second frequency analysis unit.
   A compositing unit that synthesizes the first frequency spectrum data and the second frequency spectrum data to generate synthetic spectrum data, and a compositing unit.
   A display image data generation unit that generates display image data to be displayed on a display device based on the composite spectrum data, and a display image data generation unit.
   An ultrasonic image generator equipped with.
2. A feature amount calculation unit that calculates a feature amount based on the composite spectrum data,
   A feature amount image data generation unit that generates feature amount image data to which color information is added according to the feature amount, and a feature amount image data generation unit.
   The ultrasonic image generator according to claim 1.
3. The feature amount calculation unit
   The feature amount is calculated based on the regression line calculated from the synthesized spectrum data.
   The ultrasonic image generator according to claim 2.
4. A B-mode image data generation unit that generates B-mode image data using at least one of the first ultrasonic signal and the second ultrasonic signal.
   The ultrasonic image generator according to claim 1.
5. The synthesis unit generates the composite spectrum data by adding the first frequency spectrum data in the linear representation and the second frequency spectrum data in the linear representation.
   The ultrasonic image generator according to claim 1.
6. A B-mode image data generation unit that generates B-mode image data using at least one of the first ultrasonic signal and the second ultrasonic signal.
   With more
   The image data generation unit makes the coordinates of the feature amount image data correspond to the coordinates of the B mode image data, and arranges color information corresponding to the feature amount on the B mode image data.
   The ultrasonic image generator according to claim 2.
7. The B-mode image data generation unit generates the B-mode image data using the composite spectrum data.
   The ultrasonic image generator according to claim 4.
8. A position correction unit that corrects the acquisition position of the first frequency spectrum data and the second frequency spectrum data.
   The ultrasonic image generator according to claim 1.
9. The B-mode image data generation unit generates the B-mode image data by mixing the first frequency spectrum data and the second frequency spectrum data according to a set mixing ratio.
   The ultrasonic image generator according to claim 6.
10. The display image data generation unit superimposes the feature amount image data on the B mode image data according to a set superposition ratio of the feature amount image data.
    The ultrasonic image generator according to claim 6.
11. A log amplifier that logarithmically transforms the synthesized spectrum data,
    The ultrasonic image generator according to claim 1.
12. A method of operating an ultrasonic image generator that receives a first ultrasonic signal and a second ultrasonic signal having different frequency characteristics from the first ultrasonic signal from the ultrasonic echo and generates an ultrasonic image. And
    The first frequency analysis unit generates the first frequency spectrum data for the first ultrasonic signal, and the first frequency analysis unit generates the first frequency spectrum data.
    The second frequency analysis unit generates the second frequency spectrum data for the second ultrasonic signal, and the second frequency analysis unit generates the second frequency spectrum data.
    The synthesizing unit synthesizes the first frequency spectrum data and the second frequency spectrum data to generate the synthesized spectrum data.
    A method of operating an ultrasonic image generation device in which an image data generation unit generates display image data to be displayed on a display device based on the composite spectrum data.
13. From the ultrasonic echo, a first ultrasonic signal and a second ultrasonic signal having a frequency characteristic different from that of the first ultrasonic signal are received and executed by an ultrasonic image generator that generates an ultrasonic image. It ’s an operation program,
    The first frequency spectrum data is generated for the first ultrasonic signal, and the first frequency spectrum data is generated.
    A second frequency spectrum data is generated for the second ultrasonic signal, and the second frequency spectrum data is generated.
    The first frequency spectrum data and the second frequency spectrum data are combined to generate synthetic spectrum data.
    Based on the synthesized spectrum data, display image data to be displayed on the display device is generated.
    Operation program of the ultrasonic image generator.
14. From the ultrasonic echo, a first ultrasonic signal and a second ultrasonic signal having a frequency characteristic different from that of the first ultrasonic signal are received, and the ultrasonic signal is received.
    The first frequency spectrum data is generated for the first ultrasonic signal, and the first frequency spectrum data is generated.
    A second frequency spectrum data is generated for the second ultrasonic signal, and the second frequency spectrum data is generated.
    The first frequency spectrum data and the second frequency spectrum data are combined to generate synthetic spectrum data.
    Based on the synthesized spectrum data, display image data to be displayed on the display device is generated.
    An ultrasonic image generation circuit that executes processing.

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