ULTRASONIC IMAGING APPARATUS AND SIGNAL PROCESSING METHOD

Abstract

To generate a higher-resolution image by efficient phase addition of reception signals generated by ultrasonic waves propagating complexly in a depth direction of a subject, with a suppressed circuit scale.SOLUTION: An ultrasonic imaging device delays reception signals output by multiple ultrasonic elements by a predetermined delay amount respectively corresponding to a depth of a reception focus, branches the delayed reception signals, generates phase-compensated signals obtained by shifting the phases of the post-branching reception signals by a predetermined phase shift amount, adds the phase-compensated signals to the pre-branching reception signals, and thereby generates phased signals.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an ultrasound imaging technique for capturing an image inside a subject using ultrasound. [Background technology]

[0002] Ultrasound imaging technology is a technique for non-invasively imaging the inside of a subject, including the human body, using ultrasound (sound waves that are not intended to be heard, generally high-frequency sound waves of 20 kHz or higher).

[0003] Since ultrasound imaging devices transmit and receive ultrasound using an array of ultrasound elements with a finite aperture diameter, it is difficult to improve the resolution in the azimuth direction due to the effect of ultrasound diffraction at the edges of the aperture. For this reason, new beamforming methods such as adaptive beamformers and aperture synthesis have been proposed.

[0004] Patent Document 1 discloses a technology for performing aperture synthesis using an improved virtual sound source method in an ultrasonic imaging technology that performs focused transmission. Specifically, in a region where the energy of an ultrasonic beam is converged to a focus (region A in FIG. 2 of Patent Document 1), aperture synthesis is performed by regarding the focus as a virtual sound source, and in the surrounding regions where the ultrasonic energy is diffused (regions B and C), aperture synthesis is performed by regarding a spherical wave as being radiated from the end of the probe.

[0005] Meanwhile, Patent Document 2 discloses an ultrasonic imaging device equipped with two or more delay and addition units that delay and add received signals by two or more types of delay times. The first delay and addition unit delays and adds received signals generated from a transmission beam (interference wave) transmitted from an ultrasonic element by a first delay time that phases the received signals. The second delay and addition unit delays and adds received signals by a second delay time that phases the received signals generated from a diffracted wave (spherical wave) that has a different phase from the transmitted beam. The signals after the first and second delay and addition units respectively delay and add are combined. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 10-277042 [Patent Document 2] International Publication No. 2016 / 125509 Summary of the Invention [Problem to be solved by the invention]

[0007] The technology of Patent Document 1 is a technology in which aperture synthesis is performed between transmissions, and a high-precision image cannot be obtained with only one transmission.

[0008] The technology of Patent Document 2 delays received signals by two or more different delay times and then adds them together, so that it is necessary to install two or more delay circuits for one ultrasonic element, which increases the circuit scale.

[0009] An object of the invention is to efficiently perform phasing and summing of received signals generated by ultrasonic waves that propagate in a complex manner in the depth direction of a subject while suppressing the circuit scale, thereby generating a higher resolution image. [Means for solving the problem]

[0010] The ultrasonic imaging device of the present invention has a transmission beamformer that transmits ultrasonic waves from a plurality of ultrasonic elements of a connected ultrasonic element array to a subject, the phase of which is delayed so as to be focused on a predetermined transmission focal point, and a reception beamformer that generates a phased signal by performing reception beamforming for each reception focal point set in the subject on reception signals that are received and output by the plurality of ultrasonic elements of the ultrasonic element array after the ultrasonic waves are transmitted from the subject and returned to the ultrasonic element array. The reception beamformer includes a delay circuit that delays the reception signal, an adder circuit, and a phase compensation circuit. The delay circuit delays the reception signals output by the plurality of ultrasonic elements by a predetermined delay amount according to the depth of the reception focal point. The adder circuit adds the reception signals delayed by the delay circuit to generate a phased signal. The phase compensation circuit branches the reception signal or the phased signal delayed by the delay circuit, shifts the phase of the branched reception signal or the phased signal by a predetermined phase shift amount to generate a phase-compensated signal, and adds it to the reception signal or the phased signal before branching. Effect of the Invention

[0011] According to the present invention, it is possible to provide a device that efficiently performs phasing and summing not only the transmission beam but also the reception signals generated by the spherical waves transmitted from each of a plurality of ultrasonic elements and propagating in a complex manner in the depth direction of the subject, thereby generating a higher resolution image while suppressing the circuit size. [Brief description of the drawings]

[0012] [Figure 1] 1 is a block diagram showing the configuration of an ultrasound imaging apparatus according to a first embodiment. [Diagram 2] FIG. 2A is a block diagram showing the configuration of a receive beamformer according to the first embodiment, and FIG. 2B is a block diagram of a receive beamformer according to a comparative example. [Diagram 3] 3 is an explanatory diagram showing the shape and wavefront of a transmitted beam 310 and a spherical wave. FIG. [Figure 4] FIG. 2 is a block diagram showing a configuration of a phase compensation circuit shown in FIG. [Diagram 5] 4 is a graph showing an example of a delay curve representing a delay time with respect to depth in the first embodiment. [Figure 6] 4 is a flowchart showing the operation of each unit during imaging by the ultrasonic imaging apparatus of the first embodiment. [Figure 7] FIG. 11 is a block diagram showing the configuration of a receive beamformer according to the second embodiment. [Figure 8] 13 is a graph showing an example of a delay curve representing a delay time with respect to depth in the second embodiment. [Figure 9] FIG. 11 is a block diagram showing the configuration of a receive beamformer according to a third embodiment. [Figure 10] FIG. 13 is a block diagram showing the configuration of a receive beamformer according to a fourth embodiment. [Figure 11] 13 is a graph showing an example of a delay curve representing a delay time with respect to depth in the fifth embodiment. [Figure 12] 13 is a graph showing an example of a delay curve representing a delay time with respect to depth in the fifth embodiment. [Figure 13] 13 is a graph showing an example of a delay curve representing a delay time with respect to depth in the fifth embodiment. [Figure 14] (a) Image showing an ideal point image, (b) ultrasound image of a comparative example, (c) to (e) ultrasound images captured by the ultrasound imaging device of the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An ultrasonic imaging apparatus according to an embodiment of the present invention will be described.

[0014] <<<First embodiment>>> First, an ultrasound imaging device 100 according to a first embodiment will be described with reference to Fig. 1 to Fig. 6. Fig. 1 is a diagram showing the configuration of an ultrasound diagnostic device, and Fig. 2 is a diagram showing the configuration of a receive beamformer.

[0015] 1, an ultrasonic imaging device 100 of this embodiment includes an ultrasonic imaging device main body 102, and an ultrasonic probe 116 equipped with an ultrasonic element array 101 connected to the ultrasonic imaging device main body 102. The ultrasonic element array 101 is configured by arranging a plurality of ultrasonic elements in an array shape. In the ultrasonic element array 101, a plurality of ultrasonic elements (channels) used for transmission are also called transmission channels, and a plurality of ultrasonic channels used for reception are also called reception channels.

[0016] The main parts of the ultrasonic imaging device main body 102 will be described with reference to Figures 1 and 2. The ultrasonic imaging device main body 102 includes a transmission beamformer 14, a reception beamformer 13, a phase compensation circuit control unit 17, a phase shift amount storage unit 18, a transmission / reception separation circuit 10, an AD converter 201, an imaging processing unit 15, a control unit 11, an image display unit 16, and a console 12.

[0017] In this embodiment, the receive beamformer 13 includes a delay circuit 21, a phase compensation circuit 22, and an adder circuit .

[0018] The reception signals s1 output from the multiple ultrasonic elements (reception channels 106) are converted into digital signals by the AD converter 201. The delay circuit 21 of the reception beamformer 13 delays the reception signals s1 after conversion into digital signals by a delay time determined in advance for each reception channel 106 according to the depth of the reception focal point 20. Specifically, the reception signal s1 is subjected to a delay process with a rough (low) time resolution controlled by the read timing from the memory 21a and a delay process with a high time resolution realized by an interpolation process by the interpolation circuit 21b, thereby generating multiple delayed reception signals s2. For example, the delay process is performed with a time resolution of about the wavelength of the sound wave or more at the read timing from the memory 21a, and the delay process with a high resolution of less than several times the wavelength of the sound wave is performed by the interpolation process by the interpolation circuit 21b.

[0019] The phase compensation circuit 22 branches one or more of the multiple reception signals s100 immediately after being read out from the memory 21a in the delay circuit 21, and shifts the phase of the branched one or more reception signals s100 by a predetermined amount to generate a phase-compensated reception signal s3. The phase shift amount is set in the phase compensation circuit 22 by reading out the phase shift amount for each depth of the reception focus 20 stored in advance in the phase shift amount storage unit 18 in response to a read instruction from the phase compensation circuit control unit 17. In the example of FIG. 2, the phase compensation circuit 22 branches all of the reception signals s100 delayed with a coarse time resolution read out from the memory 21a in the delay circuit 21, and shifts the phase of each to generate a phase-compensated reception signal s3.

[0020] The adder circuit 23 adds together the multiple received signals s2 each delayed by the delay circuit 21 and one or more phase-compensated received signals s3 generated by the phase compensation circuit 22, to generate a phased signal s4.

[0021] In this embodiment, by shifting the phase of the reception signal s100 immediately after being read out from the memory 21a in the delay circuit 21, reception signals s2 and s3 that are almost the same as those delayed by a plurality of different types of delay times can be generated by one delay circuit 21 and a phase compensation circuit 22. The phase compensation circuit 22 can omit the read process from the memory 21a, and therefore not only can the memory be saved, but also a physical processing line for signal processing does not need to be prepared in the circuit, so that a simpler circuit configuration can be realized than a full configuration of the delay circuit 21 prepared multiple times for the number of delay processes. Therefore, it is possible to achieve an effect almost the same as that obtained by performing phasing and summing using a plurality of types of delay times on reception signals generated by ultrasonic waves propagating in a complex manner in the depth direction of the subject 90, while suppressing the circuit scale, and generate a high-resolution image.

[0022] The ultrasonic imaging device 100 of this embodiment will be described in detail below.

[0023] The transmit beamformer 14 outputs a transmit signal to each of a plurality of ultrasonic elements (transmit channels 105) of the connected ultrasonic element array 101. The transmit channels 105 convert the transmit signals into ultrasonic waves and transmit them to the subject 90.

[0024] At this time, the transmission beamformer 14 delays the phase of the transmission signal by a predetermined amount so that the ultrasonic waves (spherical waves) 301-306 etc. transmitted from each transmission channel 105 interfere with each other and are focused at the transmission focal point 30 at a predetermined depth as shown in Fig. 3. This makes it possible to irradiate the subject 90 with a transmission beam (interference wave) 310 that is focused at the transmission focal point 30 at a desired depth. Note that, as shown in Fig. 3, the ultrasonic waves (spherical waves) 301-306 etc. transmitted from each transmission channel 105 form the above-mentioned transmission beam (interference wave) 310, and in addition, some of them propagate in each direction as the spherical waves 301-306 etc., and further, only some of them interfere with each other to form an interference wave, and propagate in a complex manner in the depth direction.

[0025] Within the subject 90 through which the transmission beam (interference wave) 310, the ultrasonic waves (spherical waves) 301 to 306, and other interference waves propagate, these waves are reflected, scattered, etc., and some of the reflected waves, scattered waves, etc. reach the ultrasonic element array 101 again. The arriving waves are received by each of the multiple receiving channels 106 of the ultrasonic element array 101 and converted into received signals.

[0026] Each AD converter 201 converts a received signal s1 output from the receiving channel 106 into a digital signal.

[0027] As shown in FIG. 2(a), the delay circuit 21 of the receive beamformer 13 receives receive signals s1 from multiple receive channels 106 via the transmit / receive separation circuit 10 and the AD converter 201, and delays each of the receive signals by a delay time specified by the control unit 11 in accordance with the depth of the receive focus 20 set within the subject 90.

[0028] Here, the delay circuit 21 includes a memory 21 a and an interpolation circuit 21 b arranged for each receiving channel 106 .

[0029] Each of the memories 21a temporarily stores the received signal s1 that has been converted into a digital signal.

[0030] The interpolation circuit 21b reads the received signal s100 from the memory 21a and performs an interpolation process. At this time, the timing of reading the received signal s100 from the memory 21a is adjusted in clock units of a digital signal, and the received signal s1 is delayed with a delay accuracy of approximately equal to or greater than the wavelength. Next, the interpolation circuit 21b performs an interpolation process on the read received signal s100 to fine-tune the delay time to less than the clock unit or to less than several times the wavelength, thereby delaying the received signal s1 by the delay time instructed by the control unit 11, and generating a delayed received signal s2.

[0031] The delay time is determined in advance according to the distance between the receiving focal point 20 and the receiving channel 106, and is stored in the delay time storage unit 19. The control unit 11 issues an instruction to read out the delay time from the delay time storage unit 19 according to the position of the receiving focal point 20, and sets it in the delay circuit 21.

[0032] The received signal s2 is obtained by delaying the received signal s1 output from each receiving channel 106 by an amount of delay corresponding to the distance between the receiving focal point 20 and the receiving channel 106, and therefore has the same phase as shown in FIG.

[0033] The phase compensation circuit 22 is arranged for each interpolation circuit 21b as shown in FIG. 2, branches the received signal s100 immediately after it is read out from the memory 21a in the delay circuit 21, shifts its phase by the phase shift amount specified by the phase compensation circuit control unit 17, and generates a phase-compensated received signal s3.

[0034] The amount of phase shift is stored in advance in the phase shift amount storage unit 18, similar to the delay time stored in the delay time storage unit 19, and is provided to the phase compensation circuit 22 in response to an instruction from the phase compensation circuit control unit.

[0035] The configuration of the interpolation circuit 21b in the delay circuit 21 and the phase compensation circuit 22 will be specifically described with reference to FIG. 4. First, the interpolation circuit 21b in the delay circuit 21 is composed of a shift register 41a and an interpolator 42a. The received signal s100 after being read from the memory is delayed with high precision to within a clock or within a few times the wavelength by minute time shifting by the shift register 41a and multiplication by the interpolator 42a with an interpolation coefficient. The control unit 11 instructs the interpolation circuit 21b on the timing of reading from the memory 21a, and also refers to the value of a LUT (lookup table) stored in the delay time storage unit 19 to provide a time shift for the shift register 41a and a delay time that is the interpolation coefficient for the interpolator 42a. This generates a received signal s2 to which a delay has been added.

[0036] The phase compensation circuit 22 has the same configuration as the interpolation circuit 21b of the delay circuit 21, and is composed of a shift register 41b and an interpolator 42b. The received signal s100 read from the memory 21a is branched, and a highly accurate phase shift of less than a clock or less than several times the wavelength is performed by the shift register 41b and the interpolator 42b of the phase compensation circuit 22. Here, the phase shift amount performed by the phase compensation circuit 22 is stored in advance in a phase shift amount storage section 18 (LUT) for each depth of the receiving focus. The phase shift amount storage section 18 sends the phase shift amount to the phase compensation circuit 22 according to a read command from the phase compensation circuit control unit 17. In addition, a control signal such as timing is sent from the phase compensation circuit control unit 17 to the phase compensation circuit 22. As a result, the phase compensation circuit 22 generates a phase-compensated received signal s3.

[0037] The adder circuit 23 can generate a phased signal s4 by adding a delayed received signal s2 of each receiving channel 106 output by the interpolator 21b of the delay circuit 21 to a received signal s3 obtained by phase-shifting the received signal s2 output by the phase compensation circuit 22.

[0038] The addition circuit 23 may be configured to add the received signal s2 and the received signal s3 for each channel, as shown in FIG. 4, and then perform addition across all channels for the signals for each channel after the addition, or may be configured to simultaneously add the received signals s2 and s3 of all channels, as shown in FIG. 2.

[0039] In this way, by adding the delayed received signal s2 and the received signal s3 obtained by phase-shifting the received signal s2, it is possible to generate a phased signal not only from the received signal generated by the transmission beam 310, but also from the received signal generated by waves propagating as spherical waves 301-306 or the like, or from the received signal generated by interference waves generated by interference of some of these waves. This will be described below.

[0040] The delay time storage unit 19 stores the delay time used by the receive beamformer 13 when delaying the receive signal s1 for each ultrasonic element (receive channel 106). This delay time differs depending on the distance between the receive focus 20 and the receive channel 106 because the receive beamformer 13 sequentially focuses on multiple receive focuses 20 on the receive scanning line set by the control unit 11, and varies depending on the depth of the receive focus 20, for example, as shown by the dashed curve 350 in Fig. 5. Here, the change in delay time for each depth is also referred to as a delay curve.

[0041] In this embodiment, in order to generate a phased signal not only from the received signal generated by the transmission beam 310 but also from waves propagating as spherical waves such as 301-306 and received signals generated from interference waves caused by interference between some of these waves, a signal (received signal s2) similar to the received signal obtained by delaying the received signal s1 by a delay time 351 different from the delay time 350 for focusing the received signal generated by the transmission beam 310 on the receiving focal point 20 is generated by phase shifting the received signal s1.

[0042] For example, as shown in Fig. 5, if the delay time (transmitting beam delay time) 350 for focusing the received signal generated by the transmitting beam 310 on the receiving focal point 20 is taken as the delay time (spherical wave delay time) 351 required for focusing the received signal of the reflected wave generated by the spherical wave 301 on the receiving focal point 20, in order to delay the received signal s1 by the spherical wave delay time 351 and then add it to obtain the phased signal s7, it is necessary to prepare another set of delay circuit 121 and adder circuit 123 as shown in Fig. 2(b). Then, it is necessary to branch the received signal s1 from the receiving channel 106, delay it by the spherical wave delay time 351 by the other set of delay circuit 121, and add it by the adder circuit 123 to obtain the received signal s6.

[0043] The inventors noticed that the received signal s6 delayed by the spherical wave delay time 351 does not have a large phase difference with the received signal s2 delayed by the transmission beam delay time 350, and the phase difference is within one wavelength (2πrad). In particular, the spherical waves themselves transmitted from each channel have a phase difference of one wavelength or more as a whole, but when the delayed signal by the transmission beam delay time in the present invention and the delayed signal by the spherical wave delay time are added, if the addition is performed with a phase difference of one wavelength or more, the resolution degradation due to the phase shift between them becomes dominant, which leads to a deterioration in resolution and an effective image quality improvement effect cannot be obtained. Therefore, the inventors have configured the phase difference with the phase of the received signal s2 delayed by the delay time 350 to be shifted by a small phase shift amount determined in advance by the phase compensation circuit 22 using the signal s100 immediately after a coarse delay time is added by reading from the memory, thereby generating a received signal s3 having a waveform and phase similar to that of the received signal s6 delayed by the delay time 351 different from the delay time 351.

[0044] The phase compensation circuit 22 can reduce the memory size and the circuit size of the delay processing compared to the case where another set of delay circuit 121 and adding circuit 123 is provided. Therefore, in the ultrasonic imaging device of this embodiment, while reducing the circuit size, it is possible to generate a phased signal s4 similar to the case where the received signal s1 is delayed by multiple delay times 350, 351.

[0045] Specifically, in the configuration of FIG. 2(a) of this embodiment, it is sufficient to configure the shift registers 41a, 41b and the interpolators 42a, 42b with a finite number of taps (number of stages of the digital filter) between 2 and 100 as shown in FIG. 4. In contrast, when a plurality of delay lines are provided for another set of delay circuits 121 as in the comparative example of FIG. 2(b), a memory buffer area of ​​1000 or more, which is the total number of samples of one scanning line, is required. Therefore, the configuration of FIG. 2(a) of this embodiment can realize a circuit that can generate a phasing signal s4 while having a much smaller implementation scale than the comparative example of FIG. 2(b).

[0046] The amount of phase shift in the phase compensation circuit 22 can be changed in accordance with the change in the delay time 351 in the depth direction, so that the receiving focal point 20 can obtain a receiving signal s3 at each depth.

[0047] In this manner, in this embodiment, the phases of not only the reception signal generated by the transmission beam 310 but also any of the spherical waves 301 to 306, etc., or reception signals generated by interference waves in which a part of them interfere with each other, can be aligned to generate reception signals s2 and s3. As a result, the reception beamformer 13 can obtain, from the same reception signal, a phased signal s4 that reflects information on the reception signal s2 generated by the transmission beam 310 and information on the reception signal s3 generated by any of the spherical waves 301, etc., for the same reception scanning line. Therefore, a phased signal with higher resolution can be obtained than a phased signal obtained only from the transmission beam 310.

[0048] The control unit 11 controls each unit to repeat transmission and reception while moving the transmission channel 105 until a phased signal of the number of reception scanning lines required for image generation is obtained. This control method is for scanning methods such as linear scanning and convex scanning. In the case of sector (phased array) type scanning, the aperture of the transmission and reception are the same, but a form is adopted in which a plurality of transmission and reception scanning lines are set on a two-dimensional plane by tilting the reception scanning line 36 in the angular direction, and an image of a sector area is taken along that direction. For example, there is a form in which about 50 to 1300 scanning lines are prepared in a sector shape of ±45° or ±60° with the center at the center of the probe aperture. Even in this case, the control unit 11 controls each unit to repeat transmission and reception while moving the angular direction of transmission instead of the transmission channel 105 until a phased signal of the number of reception scanning lines 36 required for image generation is obtained.

[0049] The imaging processor 15 generates an image from the number of phased signals required for image generation, and displays it on the connected image display unit 16. For example, the imaging processor 15 performs signal processing such as digital filter processing and interpolation processing on the delayed and added phased signals, conversion processing from RF (Radio Frequency) signals to luminance signals such as detection processing and envelope extraction processing, and image processing for sampling each of the luminance signals generated from the multiple phased signals, performing scan conversion (coordinate conversion) processing according to the scanning method, and converting the signals into signal intensity and luminance values ​​for each pixel to generate image signals, and generates an image by arranging the image signals.

[0050] Next, the operation of each unit during imaging by the ultrasonic imaging apparatus of this embodiment will be described with reference to FIG.

[0051] (Step 131) First, the control unit 11 receives transmission / reception parameters set based on the imaging condition parameters and / or the imaging parameters and / or the type of the connected ultrasound probe 116 via the console 12. The transmission / reception parameters include, for example, a transmission aperture diameter, a reception aperture system, a frequency (center frequency, frequency band), a transmission focus position, and a shape of a transmission pulse wave (wave number, amplitude).

[0052] (Step 132) The control unit 11 calculates the shape of the transmission beam 310 based on the conditions received in step 131 .

[0053] (Step 133) The control unit 11 passes transmission conditions such as the position of the transmission focal point 30, the transmission frequency, the number of transmissions, etc. to the transmission beamformer 14. The transmission beamformer 14 generates a transmission signal and outputs it to the ultrasonic elements of the transmission channel 105 of the ultrasonic element array 101. Each ultrasonic element of the transmission channel 105 converts the transmission signal into ultrasonic waves and transmits them. The reception channel 106 of the ultrasonic element array 101 receives the sound waves from the subject generated by the transmission in step 135, and outputs a reception signal s1.

[0054] (Step 134) The delay circuit 21 temporarily stores the received signal s1 in the memory 21a, the interpolation circuit 21b reads out the received signal s100 from the memory 21a at the timing of the clock unit and delays it with a coarse time resolution, and the interpolation circuit 21b performs an interpolation process on the read out received signal s100 to further delay it with a high time resolution of less than the clock unit or less than several times the wavelength, and outputs the received signal s2. In this way, under the control of the control unit 11, the delay time storage unit 19 delays the received signal s1 by the delay time instructed to the interpolation circuit 21b, and the delayed received signal s2 is generated.

[0055] (Step 135) The phase compensation circuit 22 branches the received signal s100 immediately after it is output from the memory 21a in the delay circuit 21, and further shifts the phase of the branched received signal s100 to generate a phase-shifted received signal s3. The phase shift amount is a phase shift amount stored in advance in the phase shift amount storage unit 18, and is a value set in the phase compensation circuit 22 from the phase shift amount storage unit 18 under the control of the phase compensation circuit control unit 17.

[0056] (Step 136) The adder circuit 23 adds the received signal s2 delayed by the delay circuit 21 and the received signal s3 phase-shifted by the phase compensation circuit 22 to generate a phased signal s4.

[0057] (Step 137) The imaging processor 15 performs signal processing and image processing on the phased signal s4 for each received scan line to generate an image.

[0058] In this manner, in this embodiment, it is possible to generate, by phase shifting, not only the received signal s2 generated by the transmission beam 310, but also the received signal s3 equivalent to the received signal generated from any of the spherical waves 301 to 306, etc., or an interference wave in which a part of them interferes, etc. As a result, a high-resolution image reflecting information on the received signal s2 generated by the transmission beam 310 and information on the received signal s3 generated by any of the spherical waves 301, etc. can be generated with a small amount of calculation by the receive beamformer 13 with a reduced circuit scale.

[0059] <Variation 1-1: Multiple receiving scanning lines> A modification of the ultrasonic imaging apparatus of the first embodiment will be described.

[0060] The ultrasonic imaging device of this embodiment is not limited to a configuration in which a phased signal is obtained for one reception scanning line in one transmission, but can also generate phased signals for multiple reception scanning lines in one transmission. This reduces the number of transmissions required to generate one image, making it possible to perform high-speed imaging.

[0061] <Modification 1-2: Transmit Aperture Synthesis> Another modified example of the ultrasonic imaging apparatus of the first embodiment will be described.

[0062] The ultrasonic imaging device of this embodiment can generate phased signals for multiple reception scanning lines in one transmission and perform transmit aperture synthesis as necessary. In this case, the imaging processing unit 15 is provided with a transmit aperture synthesis unit 15a as shown in FIG.

[0063] The receive beamformer 13 generates a phased signal s4 for each of a plurality of receive scanning lines for the receive signal s1 obtained in one transmission.

[0064] The transmit aperture synthesis unit 15a stores the phased signals s4 of the multiple receive scanning lines obtained in one transmission in a built-in memory. The transmit aperture synthesis unit 15a adds and synthesizes the phased signals s4 of the multiple receive scanning lines obtained in the transmission and the phased signals s4 of the receive scanning lines obtained in the previous transmission or earlier in the receive scanning lines at the same positions, to obtain a phased signal after aperture synthesis. Note that the addition may be weighted.

[0065] The imaging processor 15 generates an image using the phased signal after the aperture synthesis.

[0066] In this way, by performing aperture synthesis, the spatial resolution of the generated image can be improved.

[0067] In addition, since this embodiment is performed at the most upstream signal processing stage of the ultrasound device, that is, the receive beamformer 13, it can be used in combination with not only transmit aperture synthesis but also other ultrasound imaging methods, such as nonlinear (harmonic) imaging, Doppler imaging, color flow imaging, coherence imaging, and imaging using adaptive beamforming.

[0068] <Modification 1-3: Depth-based weighting> A further modified example of the ultrasonic imaging apparatus of the first embodiment will be described.

[0069] The adder circuit 23 of the receive beamformer 13 may be configured to add the delayed receive signal s2 and the phase-shifted receive signal s3 after weighting. In this case, the control unit 11 can be configured to set appropriate weights that provide high-resolution images by changing the weights of the weighting of the adder circuit 23 depending on the depth range. The control unit 11 can also accept weights set by an operator via the console 12, and can also change the weights depending on the imaging conditions.

[0070] <<<Second embodiment>>> An ultrasonic imaging apparatus according to the second embodiment will be described with reference to Fig. 7. Fig. 7 shows the configuration of a receive beamformer 13 of the ultrasonic imaging apparatus according to the second embodiment.

[0071] As shown in FIG. 7, the receive beamformer 13 of the second embodiment has a plurality of phase compensation circuits 22-1, 22-2, and 22-3 branched off and connected to a memory 21a in a delay circuit 21 in order to obtain a phased signal reflecting a receive signal from a plurality of spherical waves 301 to 306, etc., and some of their interference waves, etc.

[0072] The phase compensation circuits 22-1, 22-2, and 22-3 branch the received signal s100 output from the memory 21a into multiple signals, shift the phases of the signals by different amounts, and generate phase-shifted received signals s3-1, s3-2, and s3-3. The adder circuit 23 adds the received signal s2 output from the interpolator 21b to the phase-shifted received signals s3-1, s3-2, and s3-3 to generate a phased signal s4.

[0073] The phase shift amounts of the phase compensation circuits 22-1, 22-2, and 22-3 are set by the phase compensation circuit control unit 17 to phase shift amounts that produce a delay equivalent to that produced when the received signals generated in the receiving channel 106 by a plurality of spherical waves 301 to 306, etc., or three types of waves among some of their interference waves, as shown in Figure 8, are delayed by delay times 351, 352, and 353 to focus the received signals on the receiving focus 20.

[0074] This makes it possible to obtain a phased signal s4 reflecting not only the transmission beam 310 but also the plurality of spherical waves 301 to 306 and the like, and a reception signal generated by some of the interference waves thereof.

[0075] Furthermore, in this embodiment, since the circuit scale of one phase compensation circuit 22 is small, even when a plurality of phase compensation circuits 22-1, 22-2, and 22-3 are arranged, the overall circuit scale can be reduced compared to when a plurality of delay circuits 121 are arranged.

[0076] The other configurations, operations, and effects are similar to those of the first embodiment, and therefore description thereof will be omitted.

[0077] <Modification 2-1: Weighted addition> A modification of the ultrasonic imaging apparatus of the second embodiment will be described.

[0078] The adder circuit 23 of the receive beamformer 13 can be configured to weight and then add the received signal s2 from the delay circuit 21 and the received signals s3-1, s3-2, and s3-3 after phase shifting by the multiple phase compensation circuits 22-1, 22-2, and 22-3.

[0079] The control unit 11 can be configured to change the weighting of the adder circuit 23 depending on the depth range, thereby setting an appropriate weighting that allows a high-resolution image to be obtained.

[0080] The control unit 11 can receive weights set by an operator via the console 12, and can also change the weights depending on the imaging conditions.

[0081] <Modification 2-2: Phase shift processing in time series> Another modified example of the ultrasonic imaging apparatus of the second embodiment will be described.

[0082] The receive beamformer 13 can generate phase-shifted receive signals s3-1, s3-2, and s3-3 using one phase compensation circuit 22 and a memory instead of the phase compensation circuits 22-1, 22-2, and 22-3. Specifically, the phase compensation circuit 22 phase-shifts the receive signal s100 of the delay circuit 21 to generate a phase-shifted receive signal s3-1 and stores it in the memory, and then phase-shifts the receive signal s2 again to generate a phase-shifted receive signal s3-2 and stores it in the memory. The receive signal s2 without phase shift is also stored in the memory. The adder circuit 23 reads out the receive signal s2 and the phase-shifted receive signals s3-1, s3-2, and s3-3 from the memory and adds them together.

[0083] In this configuration, the circuit scale can be small because at least one phase compensation circuit 22 is required, which makes it possible to mount the receive beamformer 13 inside the ultrasound probe 116.

[0084] In addition, as with the ultrasonic imaging device of the first embodiment and the variations 1-1, 1-2, and 1-3, it is also possible for the ultrasonic imaging device of the second embodiment to generate multiple receive scanning lines for one transmission to perform high-speed imaging, to perform transmit aperture synthesis, and to perform weighted addition based on depth.

[0085] <<<Third embodiment>>> An ultrasonic imaging apparatus according to the third embodiment will be described with reference to FIG.

[0086] 9, the ultrasonic imaging apparatus of the third embodiment has a configuration in which a phase compensation circuit 222 and an adder circuit 223 are arranged in the subsequent stage of the adder circuit 23. Note that a memory for storing a phased signal is generally provided subsequent to the adder circuit 23. However, it is also possible to process the output signal continuously in a time series without providing a memory.

[0087] The phase compensation circuit 222 branches the phased signal s5 output by the adder circuit 23 of the receive beamformer, shifts the phase, and generates a phased signal s10 after the phase shift. The adder circuit 223 adds the phased signal s5 output by the adder circuit 23 and the phase-shifted phased signal s10 output by the phase compensation circuit 222 to generate a phased signal s11.

[0088] The phase compensation circuit control unit 17 sets the amount of phase shift in the phase compensation circuit 222 .

[0089] The imaging processor 15 generates an image using the phased signal s11 after the addition.

[0090] The other configurations, operations, and effects are similar to those of the first embodiment, and therefore description thereof will be omitted.

[0091] As in the third embodiment, by adding a phase signal to a signal that has been phase-aligned and added once, the implementation scale can be significantly reduced compared to the first embodiment. In the first embodiment, it is necessary to prepare a phase compensation circuit 22 for the number of channels, but in the second embodiment, it is sufficient to prepare only one phase compensation circuit 222. For example, when the number of channels is 128, the implementation scale is about 1% or less compared to the first embodiment. In addition, in the first embodiment, rounding errors occur due to the interpolation process in multiple channels, which may reduce the final image quality improvement effect, but in the third embodiment, since the phase shift is performed by only one phase compensation circuit 222, the influence of the rounding errors can be minimized. On the other hand, compared to the first embodiment, the amount of phase shift cannot be changed for each channel, which reduces the degree of freedom in design and adjustment.

[0092] In the third embodiment, it is of course possible to arrange a plurality of phase compensation circuits 222 in parallel as in FIG. 7 of the second embodiment, generate a plurality of types of phased signals with different phase shift amounts, and add them together using the adder circuit 223.

[0093] Furthermore, in the ultrasonic imaging device of the third embodiment, like the ultrasonic imaging device of the first embodiment and the variations 1-1, 1-2, and 1-3, it is also possible to generate multiple receive scanning lines for one transmission to perform high-speed imaging, to perform transmit aperture synthesis, and for the adder circuit 223 to perform weighted addition according to depth.

[0094] <<<Fourth embodiment>>> An ultrasonic imaging apparatus according to a fourth embodiment will be described with reference to FIG.

[0095] 10, a digital filter 224 arranged downstream of the adder circuit 23 adjusts the waveform of the phased signal s5 output by the adder circuit 23 to generate a phased signal s12 having a waveform similar to that of the phased signal s11 output by the ultrasonic imaging device of the third embodiment. The digital filter 224 includes at least one adder, multiplier, and delay unit, and adjusts the waveform by processing the phased signal s5 by the adder, multiplier, delay unit, etc.

[0096] The filter coefficient conversion unit 225 is connected to the digital filter 224. Either a digital FIR filter or a digital IIR filter is used as the digital filter 224. The filter coefficient conversion unit 225 receives a phase shift amount corresponding to the depth of the reception focus from the phase shift amount storage unit 18, and changes filter coefficients such as the multiplication coefficient and delay coefficient of the digital filter 224 (weight values ​​multiplied by each tap of the digital filter) according to the phase shift amount.

[0097] Specifically, as shown in Fig. 10, the filter coefficient conversion unit 225 converts the phase information (amount of phase shift) output from the phase shift amount storage unit 18 into a filter coefficient of the digital filter 224, and modifies the filter coefficient prepared in advance by the ultrasonic imaging device. The modified filter coefficient is sent to the digital filter 224 and set. The digital filter 224 processes the waveform of the phased signal s5 using the modified filter coefficient to generate a phased signal s12. This makes it possible to perform signal processing equivalent to that of the first embodiment by filter processing.

[0098] At this time, similarly to the first embodiment, the phase compensation circuit control unit 17 instructs the phase shift amount storage unit 18 to output the corresponding phase shift amount, and also instructs the filter coefficient conversion unit to perform conversion processing of an equivalent filter coefficient corresponding to the phase shift amount.

[0099] That is, the ultrasonic imaging apparatus of the fourth embodiment can generate the same phased signal S12 as in the first or third embodiment by filter control.

[0100] Other configurations, operations, and effects of the ultrasonic imaging device of the fourth embodiment are the same as those of the first embodiment, so that the description will be omitted. In addition, the ultrasonic imaging device of the fourth embodiment can achieve not only the effects of the ultrasonic imaging device of the first embodiment, but also the effects obtained by the ultrasonic imaging device having a plurality of phase compensation circuits of the second embodiment at the same time by using the digital filter 224. In addition, when an effect equivalent to that of the ultrasonic imaging device of the second embodiment having a large number of phase compensation circuits 22-1, etc. is to be achieved by the ultrasonic imaging device using the digital filter 224 of the fourth embodiment, it is sufficient to increase the number of taps (stages) of the filter coefficients of the digital filter 224. This makes it possible to generate a filter coefficient (filter coefficient sequence) having an effect equivalent to that of the plurality of phase compensation circuits 22-1, etc. in the second embodiment.

[0101] In addition, the phase shift process by the filter process of the digital filter 224 of the ultrasonic imaging device of the fourth embodiment is realized not by hardware but by software running on a CPU or GPU. Therefore, the circuit scale of the hardware can be minimized. In addition, a filter block already provided in the ultrasonic imaging device, such as a variable depth filter, can be operated as the digital filter 224 to perform the phase shift process, so that the degree of freedom of adjustment in design can be increased.

[0102] <<<Fifth embodiment>>> An ultrasonic imaging device according to the fifth embodiment will be described with reference to FIGS. 1, 7, and 11 to 13. FIG.

[0103] The configuration of the ultrasonic imaging apparatus of the fifth embodiment is similar to that of the first or second embodiment, but the number of phase-shifted reception signals generated according to the depth range of the subject 90 is made different.

[0104] For example, as shown in Figures 1 and 7, a switch 25 is provided to turn on / off the phase compensation circuit 22 and the phase compensation circuits 22-1, 22-2, and 22-3, and the control unit 11 turns off the phase compensation circuit 22 and the phase compensation circuits 22-1, 22-2, and 22-3 depending on the depth of the subject 90. As a result, for example, as shown in Figures 11 and 12, in a depth range 371 shallower than the transmission focus 30, the phase compensation circuit 22 in Figure 1 and the phase compensation circuits 22-1, 22-2, and 22-3 in Figure 7 are turned off by the switch 25 and do not operate, and in a depth range 372 shallower than the transmission focus 30, the phase compensation circuit 22 and the phase compensation circuits 22-1, 22-2, and 22-3 are turned on by the switch 25 and operated, so that a reception signal similar to one obtained by delaying a reception signal such as a spherical wave 301 by delay time 351 or delay times 351, 352, and 353, respectively, can be generated and reflected in the phasing signal s4.

[0105] This makes it possible to achieve high resolution images in a range deeper than the transmission focal point 30 while suppressing the amount of calculation in the phase compensation circuit 22.

[0106] It is also possible to change the switch 25 so that the number of phase-shifted reception signals generated in a depth range 371 shallower than the transmission focus 30 is greater than the number of phase-shifted reception signals generated in a depth range 372 deeper than the transmission focus 30. This makes it possible to generate reception signals equivalent to those generated when the portion shallower than the transmission focus 30 as shown in FIG. 13 is delayed by the delay times 350-353, and the portion deeper than the transmission focus 30 is delayed by the delay times 351-352.

[0107] For example, for each of the parts (abdomen, circulatory system, chest, legs, blood vessels, digestive system, prenatal checkup, etc.) and organs (liver, heart, kidneys, pancreas, gallbladder, ovaries, carotid artery, thyroid, etc.) of the imaging target, a depth range in which increasing the number of phase-shifted received signals generated by the phase compensation circuit 22 is effective in improving the resolution is determined in advance, and the control unit 11 turns on the phase compensation circuit 22 in that depth range using the switch 25. The selection of the part or organ is received from the operator via the console 12 connected to the control unit 11.

[0108] Furthermore, the control unit 11 may receive a depth range for which high-resolution imaging is desired from the operator via the console 12, and increase the number of phase compensation circuits 22 to be turned on within that depth range. Alternatively, the phase compensation circuits 22 may be turned on in a predetermined depth range in advance.

[0109] Furthermore, the control unit 11 has a built-in machine learning model, and various parameters related to ultrasonic imaging, such as imaging condition parameters, transmission and reception parameters, and type of probe, as well as ultrasonic images or their received signals captured as preparation before the actual imaging, can be input to the machine learning model to calculate the number of received signals after an appropriate phase shift and / or the amount of phase shift according to the depth for each depth.

[0110] The machine learning model uses the imaging conditions, the captured image or received signal, and the phase-shifted received signal used to generate the image as input data, and is pre-trained to use the obtained image, the number of phase-shifted received signals, and the amount of phase shift as correct answer data.

[0111] In addition, since the imaging accuracy and resolution vary depending on the type of organ, the machine learning model may be trained separately for different organs, such as the liver, kidneys, blood vessels, and mammary glands.

[0112] In the first to fifth embodiments described above, the receive beamformer 13 can be configured by hardware. For example, a custom IC such as an ASIC (Application Specific Integrated Circuit) or a programmable IC such as an FPGA (Field-Programmable Gate Array) may be used to design the circuit so as to realize the functions of each unit. It is also possible to realize some or all of the functions of the receive beamformer 13 by software. In this case, the receive beamformer 13 is configured by a computer or the like having a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit) and a memory, and the CPU reads and executes a program stored in the memory to realize those functions.

[0113] <<<Description of the Effects of the Embodiments>>> The effect of this embodiment will be described with reference to Figs. 14(a) to (e). Fig. 14(a) is an ideal point image representing an ideal image when imaging a phantom containing minute spherical objects. Fig. 14(b) is an ultrasonic image (comparative example) obtained by imaging the same phantom as Fig. 14(a) using an ultrasonic imaging device with a conventional delay time (one delay curve of delay time per one receiving scan line).

[0114] Fig. 14(c) shows an ultrasound image of the same phantom as Fig. 14(a) obtained by using the ultrasound imaging device of the first embodiment, and is an ultrasound image generated from a phased signal s4 obtained by adding the reception signal s2 obtained at the delay time 350 in Fig. 5 and the reception signal s3 obtained by phase shifting in the adder circuit 23. The phase shift amount of the reception signal s3 relative to the reception signal s2 is within one wavelength. It can be seen that the ultrasound image of Fig. 14(c) has suppressed side lobes and noise components due to diffracted waves around the point, and an image closer to an ideal point image is obtained, compared to the ultrasound image of Fig. 14(b) of the comparative example.

[0115] On the other hand, the ultrasound images in Fig. 14(d) and Fig. 14(e) are obtained by using the same device as the ultrasound imaging device of embodiment 1, but by setting the phase shift amount of the reception signal s3 relative to the reception signal s2 to several wavelengths or more, as in Fig. 14(c). The phase shift amount is too large, and an artifact is formed in a different location in the ultrasound image in Fig. 14(d), and a point image is split in the ultrasound image in Fig. 14(e).

[0116] As a result, the ultrasonic imaging apparatus of this embodiment can obtain a high-resolution ultrasonic image with fewer artifacts than the comparative example. It is also clear that the phase shift amount is preferably within one wavelength (2πrad). [Explanation of symbols]

[0117] s1 Received signal s100 receiving signal s2 Received signal s3 Received signal s4 phasing signal s5 phasing signal s6 Received signal s7 phasing signal s10 phasing signal s11 phasing signal s12 phasing signal 10 Transmitter / receiver separation circuit 11 Control section 12 Console 13 Receive beamformer 14 Transmit Beamformer 15 Image Processing Unit 15a Transmission aperture synthesis unit 16 Image display section 17 Phase compensation circuit control unit 18 Phase shift amount storage section 19 Delay time storage section 20 Receiving Focus 21 Delay Circuit 21a Memory 21b Interpolator 22 Phase compensation circuit 23 Addition Circuit 25 Switch 30 Transmission Focus 36 Received Scan Lines 41a, 41b Shift register 42a, 42b Interpolator 90 Subjects 100 Ultrasound imaging device 101 Ultrasonic element array 102 Ultrasound imaging device body 105 Transmission Channels 106 receiving channels 116 Ultrasonic probe 121 Delay Circuit 123 Addition Circuit 201 Converter 222 Phase compensation circuit 223 Addition Circuit 224 Filter 225 Filter coefficient conversion section 301 Spherical wave 310 Transmit Beam 350 Delay Time 351 Delay Time 371 Depth Range 372 Depth Range

Claims

1. A transmit beamformer that transmits, to a subject, ultrasonic waves whose phases are delayed so as to be focused at a predetermined transmit focal point from each of a plurality of ultrasonic elements of a connected ultrasonic element array; a reception beamformer that performs reception beamforming for each reception focal point set in the subject on reception signals that are received by the subject and returned to the ultrasonic element array from the subject that has received the transmission of the ultrasonic waves and output by the plurality of ultrasonic elements of the ultrasonic element array to generate a phased signal; the receive beamformer includes a delay circuit that delays the receive signal, an adder circuit, and a phase compensation circuit; The delay circuit is a circuit that delays the reception signals output by the plurality of ultrasonic elements by a predetermined delay amount corresponding to the depth of the reception focus, and is configured to delay the reception signals of the plurality of ultrasonic elements with a low time resolution and then delay the reception signals with a time resolution higher than the low time resolution, The phase compensation circuit branches one or more of the received signals obtained by delaying the received signals output by the plurality of ultrasonic elements with the low time resolution, and generates phase-compensated signals by shifting the phases of the one or more branched received signals by a predetermined phase shift amount, The summing circuit adds the received signals, which are delayed by the delay circuit using the low time resolution delay processing and the high time resolution delay processing, output from the plurality of ultrasonic elements, to one or more of the phase-compensated signals, the phase of which is shifted by the phase compensation circuit, to generate the phased signal. An ultrasonic imaging device characterized in that

2. A transmission beamformer that transmits, to a subject, ultrasonic waves whose phases are delayed so as to be focused on a predetermined transmission focal point from each of a plurality of ultrasonic elements of a connected ultrasonic element array; a reception beamformer that performs reception beamforming for each reception focal point set in the subject on reception signals that are received by the subject and returned to the ultrasonic element array from the subject that has received the transmission of the ultrasonic waves and output by the plurality of ultrasonic elements of the ultrasonic element array to generate a phased signal; the receive beamformer includes a delay circuit that delays the receive signal, an adder circuit, and a phase compensation circuit; The delay circuit delays the reception signals output by the plurality of ultrasonic elements by a predetermined delay amount corresponding to the depth of the reception focus, the adder circuit adds the received signals delayed by the delay circuit to generate the phased signal; the phase compensation circuit branches the received signal delayed by the delay circuit, shifts the phase of the branched received signal by a predetermined phase shift amount to generate a phase-compensated signal, and adds the phase-compensated signal to the received signal before branching that is delayed by the delay circuit; An A / D converter is disposed between the delay circuit and the ultrasonic elements to convert analog reception signals output by the ultrasonic elements into digital signals; the delay circuit includes a memory for temporarily storing the received signal, and an interpolation circuit; the interpolation circuit adjusts a timing for reading out the received signal from the memory to realize a delay process with a low time resolution, and performs an interpolation process on the received signal read out from the memory to realize a delay process with a time resolution higher than the low time resolution; The ultrasonic imaging apparatus, wherein the phase compensation circuit branches the reception signal read from the memory by the interpolation circuit, and generates the phase-compensated signal by shifting the phase by a predetermined amount.

3. 2. The ultrasonic imaging apparatus according to claim 1, wherein the summing circuit comprises a first summing circuit and a second summing circuit, the first summing circuit sums the received signals delayed by the delay circuits to generate a first phased signal; the phase compensation circuit is disposed downstream of the first adding circuit, branches the first phased signal, and generates the phase-compensated signal by shifting the phase of the branched first phased signal by a predetermined phase shift amount; The ultrasonic imaging apparatus according to claim 1, wherein the second adder circuit adds the first phased signal and the phase-compensated signal to generate a second phased signal.

4. 2. The ultrasonic imaging apparatus according to claim 1, wherein the amount of phase shift is within one wavelength.

5. A transmit beamformer that transmits, to a subject, ultrasonic waves whose phases are delayed so as to be focused at a predetermined transmit focal point from each of a plurality of ultrasonic elements of a connected ultrasonic element array; a reception beamformer that performs reception beamforming for each reception focal point set in the subject on reception signals that are received by the subject and returned to the ultrasonic element array from the subject that has received the transmission of the ultrasonic waves and output by the plurality of ultrasonic elements of the ultrasonic element array to generate a phased signal; the receive beamformer includes a delay circuit that delays the receive signal, an adder circuit, and a phase compensation circuit; The delay circuit delays the reception signals output by the plurality of ultrasonic elements by a predetermined delay amount corresponding to the depth of the reception focus, the adder circuit adds the received signals delayed by the delay circuit to generate the phased signal; The phase compensation circuit branches the received signal delayed by the delay circuit, shifts the phase of the branched received signal by a predetermined phase shift amount to generate a phase-compensated received signal, and adds it to the received signal before branching that has been delayed by the delay circuit, or the phase compensation circuit branches the phasing signal, shifts the phase of the branched phasing signal by a predetermined phase shift amount to generate a phase-compensated phasing signal, and adds it to the phasing signal before branching, Two or more phase compensation circuits are provided for one of the received signals delayed by the delay circuit or the phased signal generated by the adder circuit; The two or more phase compensation circuits each have a different phase shift amount, and the delay circuit shifts the phase of the delayed received signal by a different phase shift amount to generate two or more phase-compensated received signals, and the generated two or more phase-compensated received signals are added to the received signal before branching after being delayed by the delay circuit, or the two or more phase compensation circuits shift the phase of the phased signal by a different phase shift amount to generate two or more phase-compensated phased signals, and add them to the phased signal before branching. An ultrasonic imaging device characterized in that

6. A transmit beamformer that transmits, to a subject, ultrasonic waves whose phases are delayed so as to be focused at a predetermined transmit focal point from each of a plurality of ultrasonic elements of a connected ultrasonic element array; a reception beamformer that performs reception beamforming for each reception focal point set in the subject on reception signals that are received by the subject and returned to the ultrasonic element array from the subject that has received the transmission of the ultrasonic waves and output by the plurality of ultrasonic elements of the ultrasonic element array to generate a phased signal; the receive beamformer includes a delay circuit that delays the receive signal, an adder circuit, and a phase compensation circuit; The delay circuit delays the reception signals output by the plurality of ultrasonic elements by a predetermined delay amount corresponding to the depth of the reception focus, the adder circuit adds the received signals delayed by the delay circuit to generate the phased signal; The phase compensation circuit branches the received signal delayed by the delay circuit, shifts the phase of the branched received signal by a predetermined phase shift amount to generate a phase-compensated received signal, and adds it to the received signal before branching that has been delayed by the delay circuit, or the phase compensation circuit branches the phasing signal, shifts the phase of the branched phasing signal by a predetermined phase shift amount to generate a phase-compensated phasing signal, and adds it to the phasing signal before branching, 4. An ultrasonic imaging apparatus comprising: a first receiving portion that receives a first signal from the first receiving portion of the first receiving portion;

7. 6. The ultrasonic imaging device according to claim 5, further comprising a switch for switching the number of phase compensation circuits to be operated among the two or more phase compensation circuits in accordance with a depth of the receiving focus of the subject.

8. A transmission beamformer that transmits, to a subject, ultrasonic waves whose phases are delayed so as to be focused on a predetermined transmission focal point from each of a plurality of ultrasonic elements of a connected ultrasonic element array; a reception beamformer that performs reception beamforming for each reception focal point set in the subject on reception signals that are received by the subject and returned to the ultrasonic element array from the subject that has received the transmission of the ultrasonic waves and output by the plurality of ultrasonic elements of the ultrasonic element array to generate a phased signal; the receive beamformer includes a delay circuit that delays the receive signal, an adder circuit, and a phase compensation circuit; The delay circuit delays the reception signals output by the plurality of ultrasonic elements by a predetermined delay amount corresponding to the depth of the reception focus, the adder circuit adds the received signals delayed by the delay circuit to generate the phased signal; The phase compensation circuit branches the received signal delayed by the delay circuit, shifts the phase of the branched received signal by a predetermined phase shift amount to generate a phase-compensated received signal, and adds it to the received signal before branching that has been delayed by the delay circuit, or the phase compensation circuit branches the phasing signal, shifts the phase of the branched phasing signal by a predetermined phase shift amount to generate a phase-compensated phasing signal, and adds it to the phasing signal before branching, The ultrasonic imaging device, wherein the phase compensation circuit generates the phase-compensated receive signal or the phase-compensated phased signal only when the depth of the receive focus is within a predetermined range.

9. 2. The ultrasonic imaging apparatus according to claim 1, wherein an amount of phase shift of said phase compensation circuit changes according to a depth of said receiving focal point of said object.

10. 9. The ultrasonic imaging device according to claim 8, further comprising a phase shift amount storage unit in which a phase shift amount for each depth of the reception focus is stored in advance, and the phase compensation circuit shifts the phase of the reception signal by the phase shift amount corresponding to the depth of the reception focus stored in the phase shift amount storage unit.

11. 2. The ultrasound imaging apparatus according to claim 1, wherein the receive beamformer has a memory, The ultrasonic imaging device is characterized in that, for one transmission by the transmit beamformer, the receive beamformer generates the phased signals for multiple receive focal points on multiple receive scanning lines and stores them in memory, and for the next transmission, the receive beamformer generates phased signals for multiple receive focal points on multiple receive scanning lines, and then combines the phased signals with the phased signals already stored in memory for the receive scanning lines at the same positions, thereby performing transmit aperture synthesis.

12. A signal processing method for processing received signals that are received and output by a plurality of ultrasonic elements of an ultrasonic element array after ultrasonic waves are returned to the ultrasonic element array from a subject that has received transmitted ultrasonic waves, the method comprising: The reception signals output from the plurality of ultrasonic elements are each subjected to delay processing at a low time resolution, and then delayed at a time resolution higher than the low time resolution, thereby delaying the reception signals by a predetermined delay amount according to the depth of the reception focus; branching one or more of the received signals after the delay processing with the low time resolution, and generating a phase-compensated signal by shifting the phase of the branched one or more received signals by a predetermined phase shift amount; A phased signal is generated by adding the phase-compensated signal and a pre-branched received signal obtained by delaying the received signals output from the plurality of ultrasonic elements by the delay processing with the low time resolution and the delay processing with the high time resolution, respectively. The signal processing method is characterized by:

13. A signal processing method for processing received signals that are received and output by a plurality of ultrasonic elements of an ultrasonic element array after ultrasonic waves are returned to the ultrasonic element array from a subject that has received transmitted ultrasonic waves, the method comprising: The reception signals output from the plurality of ultrasonic elements are delayed by a predetermined delay amount corresponding to the depth of the reception focus, and the delayed reception signals are added to generate a phased signal; The phased signal is branched, and the phases of the branched phased signals are shifted by different phase shift amounts to generate two or more types of phase-compensated signals, which are then added to the phased signal before branching. The signal processing method is characterized by:

Images