Ultrasound diagnostic apparatus, processing method, and program

Abstract

To suppress the occurrence of a speckle pattern in a case where a DMAS-system beamforming for multiplying and summing signals is used as a beamforming system.SOLUTION: An ultrasound diagnostic apparatus of an embodiment multiplies reception signals between different elements, out of a plurality of reception signals output from a plurality of elements, and executes an ultrasonic beamforming system for summing signals obtained as a result of the multiplication. The ultrasound diagnostic apparatus of the embodiment comprises a weight calculation unit and an application unit. The weight calculation unit calculates a weight coefficient based on the correlation between the multiplied reception signals. The application unit applies the weight coefficient to the signals obtained as a result of the multiplication.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] Embodiments disclosed herein and in the drawings relate to ultrasound diagnostic apparatus and programs. [Background technology]

[0002] Delay and Sum (DAS) is a commonly used beamforming technique performed by ultrasound diagnostic equipment. In recent years, various methods different from the DAS method have been proposed. For example, methods such as Minimum Variance Beamforming, Coherence Factor Imaging, and Delay Multiply and Sum Beamforming (DMAS) are known. Of these, DMAS involves multiplication and addition of signals output from different elements (piezoelectric oscillators, piezoelectric elements).

[0003] As mentioned above, DMAS involves multiplication of signals output from different elements. Therefore, compared to ultrasound image data obtained using DAS, the ultrasound image data obtained using DMAS reacts more sensitively to time differences (time difference, phase difference) between signals in the output signal, resulting in, for example, larger amplitude fluctuations in the speckle pattern (speckle noise). In other words, the speckle pattern appears more emphasized in ultrasound image data obtained using DMAS compared to ultrasound image data obtained using DAS. Thus, because DMAS involves signal multiplication, the amplitude fluctuations of the speckle echo become larger, resulting in a decrease in contrast resolution. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2001-8933 [Patent Document 2] Japanese Patent Publication No. 2018-187014 [Patent Document 3] Special Publication No. 2009-536855 [Patent Document 4] Japanese Patent Publication No. 2015-213673 [Non-patent literature]

[0005] [Non-Patent Document 1] The Delay Multiply and Sum Beamforming Algorithm in Ultrasound B-Mode Medical Imaging, IEEE Transaction 2015. [Non-Patent Document 2] Enhanced Ultrasound Harmonic Imaging Using the Filtered-Delay Multiply and Sum Beamformer, IEEE Conference Paper 2017. [Overview of the project] [Problems that the invention aims to solve]

[0006] One of the problems that the embodiments disclosed herein and in the drawings aim to solve is to suppress the generation of speckle patterns when a beamforming method that involves signal multiplication and addition is used. However, the problems that the embodiments disclosed herein and in the drawings aim to solve are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0007] The ultrasonic diagnostic apparatus of the embodiment performs an ultrasonic beamforming method in which multiple received signals output from multiple elements are multiplied between different elements, and the resulting signals are added together. The ultrasonic diagnostic apparatus of the embodiment comprises a weight calculation unit and an application unit. The weight calculation unit calculates weight coefficients based on the correlation between the multiplied received signals. The application unit applies the weight coefficients to the signals obtained as a result of the multiplication. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a block diagram showing an example configuration of an ultrasound diagnostic apparatus according to the first embodiment. [Figure 2] Figure 2 shows an example of the configuration of a beamformer that performs DMAS-type beamforming in a receiving circuit according to the first embodiment. [Figure 3] Figure 3 is a flowchart showing an example of the processing flow performed by the DMAS-type beamformer according to the first embodiment. [Figure 4] Figure 4 shows an example of an ultrasound image based on ultrasound image data obtained using conventional DMAS. [Figure 5] Figure 5 shows an example of an ultrasound image based on ultrasound image data generated by the ultrasound diagnostic device according to the first embodiment. [Figure 6] Figure 6 shows an example of the configuration of a beamformer that performs DMAS-type beamforming in a receiving circuit according to a modified example of the first embodiment. [Figure 7] Figure 7 shows an example of a part of the configuration of a beamformer according to the second embodiment. [Figure 8] Figure 8 shows an example of an ultrasound image based on ultrasound image data generated by the ultrasound diagnostic device according to the second embodiment. [Figure 9] Figure 9 shows an example of a part of the configuration of a beamformer according to the third embodiment. [Figure 10]Figure 10 shows an example of a part of the configuration of a beamformer according to the fourth embodiment. [Modes for carrying out the invention]

[0009] The following describes an ultrasonic diagnostic apparatus and program relating to embodiments and modifications, with reference to the drawings.

[0010] (First Embodiment) Figure 1 is a block diagram showing an example configuration of an ultrasound diagnostic apparatus 1 according to the first embodiment. As illustrated in Figure 1, the ultrasound diagnostic apparatus 1 according to the first embodiment includes a main body 100, an ultrasound probe 101, an input device 102, and a display 103. In the first embodiment, the ultrasound diagnostic apparatus 1 performs a DMAS method, which is an ultrasound beamforming method that multiplies the received signals between different elements from among a plurality of received signals output from a plurality of elements of the ultrasound probe 101, and adds the signals obtained as a result of the multiplication.

[0011] The ultrasonic probe 101 has, for example, multiple elements (piezoelectric transducers, piezoelectric elements). These multiple elements generate ultrasound based on a drive signal supplied from the transmitting circuit 111 of the transmitting / receiving circuit 110 of the device body 100. Specifically, the multiple elements generate ultrasound with a waveform corresponding to the transmitting drive voltage when a voltage (transmitting drive voltage) is applied by the transmitting circuit 111. The waveform of the transmitting drive voltage indicated by the drive signal is the waveform of the voltage applied to the multiple elements. In other words, the ultrasonic probe 101 transmits ultrasound corresponding to the magnitude of the applied transmitting drive voltage. The ultrasonic probe 101 also receives reflected waves from the subject P, converts them into an electrical signal called a received signal (reflected wave signal), and outputs the received signal to the device body 100. The ultrasonic probe 101 also has, for example, a matching layer provided on the elements and a backing material to prevent the propagation of ultrasound backward from the elements. The ultrasonic probe 101 is detachably connected to the device body 100.

[0012] When ultrasound is transmitted from the ultrasound probe 101 to the subject P, the transmitted ultrasound is reflected one after another by discontinuities in acoustic impedance within the subject P's internal tissues, and the reflected waves are received by multiple elements of the ultrasound probe 101. The amplitude of the received reflected waves depends on the difference in acoustic impedance at the discontinuities where the ultrasound is reflected. Furthermore, when the transmitted ultrasound pulse is reflected by a moving blood flow or the surface of the heart wall, the reflected wave undergoes a frequency shift due to the Doppler effect, depending on the velocity component of the moving object relative to the ultrasound transmission direction. The ultrasound probe 101 then outputs the received signal to the receiving circuit 112 of the transmitting / receiving circuit 110, which will be described later.

[0013] The ultrasonic probe 101 is detachably attached to the main unit 100 of the device. When scanning a two-dimensional area within the subject P (two-dimensional scanning), the operator connects a 1D array probe, for example, in which multiple elements are arranged in a row, to the main unit 100 as the ultrasonic probe 101. Examples of 1D array probes include linear ultrasonic probes, convex ultrasonic probes, and sector ultrasonic probes. When scanning a three-dimensional area within the subject P (three-dimensional scanning), the operator connects a mechanical 4D probe or a 2D array probe to the main unit 100 as the ultrasonic probe 101. A mechanical 4D probe can perform two-dimensional scanning using multiple elements arranged in a row, similar to a 1D array probe, and can also perform three-dimensional scanning by oscillating the multiple elements at a predetermined angle (oscillation angle). A 2D array probe can perform three-dimensional scanning using multiple elements arranged in a matrix, and can also perform two-dimensional scanning by focusing and transmitting ultrasound.

[0014] The input device 102 is implemented by input means such as a mouse, keyboard, buttons, panel switches, touch command screen, foot switch, trackball, or joystick. The input device 102 receives various setting requests from the operator of the ultrasound diagnostic device 1 and transmits the received setting requests to the main unit 100 of the device.

[0015] The display 103 may, for example, display a GUI (Graphical User Interface) for the operator of the ultrasound diagnostic device 1 to input various setting requests using the input device 102, or display ultrasound images based on ultrasound image data generated by the device body 100. The display 103 is implemented using an LCD monitor, a CRT (Cathode Ray Tube) monitor, or the like.

[0016] The main unit 100 generates ultrasound image data based on the received signal transmitted from the ultrasound probe 101. Note that the ultrasound image data is just an example of image data. The main unit 100 can generate two-dimensional ultrasound image data based on the received signal corresponding to the two-dimensional region of the subject P transmitted from the ultrasound probe 101. Furthermore, the main unit 100 can generate three-dimensional ultrasound image data based on the received signal corresponding to the three-dimensional region of the subject P transmitted from the ultrasound probe 101. As shown in Figure 1, the main unit 100 includes a transmit / receive circuit 110, a buffer memory 120, a signal processing circuit 130, an image generation circuit 140, an image memory 150, a storage circuit 160, and a control circuit 170.

[0017] The transmitting / receiving circuit 110, under the control of the control circuit 170, causes the ultrasonic probe 101 to transmit ultrasonic waves and the ultrasonic probe 101 to receive reflected ultrasonic waves. In other words, the transmitting / receiving circuit 110 performs scanning via the ultrasonic probe 101. Scanning is also referred to as scanning, ultrasonic scanning, or ultrasonic scanning. The transmitting / receiving circuit 110 is an example of a transmitting / receiving unit. The transmitting / receiving circuit 110 has a transmitting circuit 111 and a receiving circuit 112. The transmitting circuit 111 is an example of a transmitting unit, and the receiving circuit 112 is an example of a receiving unit.

[0018] The transmitting circuit 111, under the control of the control circuit 170, causes the ultrasonic probe 101 to transmit ultrasound. The transmitting circuit 111 includes a rate pulser generation circuit, a transmission delay circuit, and a transmitting pulser. The transmitting circuit 111 supplies a drive signal to the ultrasonic probe 101. When scanning a two-dimensional region within the subject P, the transmitting circuit 111 causes the ultrasonic probe 101 to transmit an ultrasonic beam for scanning the two-dimensional region. When scanning a three-dimensional region within the subject P, the transmitting circuit 111 causes the ultrasonic probe 101 to transmit an ultrasonic beam for scanning the three-dimensional region.

[0019] The rate pulser generation circuit, under the control of the control circuit 170, repeatedly generates rate pulses at a predetermined rate frequency (PRF: Pulse Repetition Frequency) to form a transmitted ultrasonic wave (transmitted beam). The rate pulses pass through the transmit delay circuit, applying voltages to the transmit pulser with different transmit delay times. For example, the transmit delay circuit provides each rate pulse generated by the rate pulser generation circuit with a transmit delay time for each element necessary to focus the ultrasonic waves generated from the ultrasonic probe 101 into a beam and determine the transmit directivity. The transmit pulser supplies a drive signal (drive pulse) to the ultrasonic probe 101 at a timing based on the rate pulse. That is, the transmit pulser applies a voltage (transmit drive voltage) of the waveform indicated by the drive signal to the ultrasonic probe 101 at a timing based on the rate pulse. The transmit delay circuit arbitrarily adjusts the transmission direction of the ultrasonic waves from the element surface by changing the transmit delay time applied to each rate pulse.

[0020] The drive pulse is transmitted from the transmitting pulser through the cable to the element in the ultrasonic probe 101, where it is converted from an electrical signal to a mechanical vibration. That is, when a voltage is applied to the element, it vibrates mechanically. The ultrasound generated by this mechanical vibration is transmitted into the living body (inside the subject P). Here, the ultrasound, which has a different transmission delay time for each element, is focused and propagates in a predetermined direction.

[0021] Furthermore, the transmitting circuit 111, under the control of the control circuit 170, has the function of instantaneously changing the transmitting frequency, transmitting drive voltage, etc., in order to execute a predetermined scanning sequence. In particular, the change in the transmitting drive voltage is achieved by a linear amplifier type oscillator circuit that can instantly switch the value of the transmitting drive voltage, or by a mechanism that electrically switches multiple power supply units.

[0022] The reflected ultrasonic waves transmitted by the ultrasonic probe 101 reach an element inside the ultrasonic probe 101, where they are converted from mechanical vibrations into electrical signals (received signals), and these received signals are input to the receiving circuit 112. The receiving circuit 112 includes a preamplifier, an A / D (Analog to Digital) converter, a quadrature detection circuit, and a DMAS type beamformer (described later), and performs various processes on the received signal transmitted from the ultrasonic probe 101 to generate reflected wave data (received data). The receiving circuit 112 then stores the generated reflected wave data in the buffer memory 120.

[0023] The preamplifier amplifies the received signal for each channel and performs gain adjustment (gain correction). The A / D converter converts the gain-corrected received signal into a digital signal by A / D conversion. The quadrature detection circuit converts the received signal, which has been converted into a digital signal, into a baseband in-phase signal (I signal, I) and a quadrature-phase signal (Q signal, Q). The quadrature detection circuit then transmits the I signal and Q signal (IQ signal) to a DMAS beamformer. The beamformer then performs DMAS beamforming on the IQ signal and stores the data obtained by DMAS beamforming as reflected wave data in the buffer memory 120. The DMAS beamformer will be described later.

[0024] The receiving circuit 112 generates two-dimensional reflected wave data from the two-dimensional received signal transmitted from the ultrasonic probe 101. The receiving circuit 112 also generates three-dimensional reflected wave data from the three-dimensional received signal transmitted from the ultrasonic probe 101.

[0025] The buffer memory 120 is a memory that temporarily stores reflected wave data generated by the transmitting and receiving circuit 110. For example, the buffer memory 120 is configured to store a predetermined number of frames of reflected wave data. When the buffer memory 120 has stored a predetermined number of frames of reflected wave data, and a new frame of reflected wave data is generated by the receiving circuit 112, the buffer memory 120, under the control of the receiving circuit 112, discards the oldest frame of reflected wave data generated and stores the newly generated frame of reflected wave data. For example, the buffer memory 120 can be implemented using semiconductor memory elements such as RAM (Random Access Memory) or flash memory.

[0026] The signal processing circuit 130 reads reflected wave data from the buffer memory 120, performs various signal processing on the read reflected wave data, and outputs the processed reflected wave data as B-mode data or Doppler data to the image generation circuit 140. The signal processing circuit 130 can be implemented, for example, by a processor. The signal processing circuit 130 is an example of a signal processing unit.

[0027] For example, whenever a new frame of reflected wave data is stored in the buffer memory 120, the signal processing circuit 130 reads out the newly stored frame of reflected wave data. The signal processing circuit 130 then applies various signal processing to the read frame of reflected wave data to generate a new frame of B-mode data or Doppler data. Each time the signal processing circuit 130 generates a frame of B-mode data or Doppler data, it outputs the newly generated frame of B-mode data or Doppler data to the image generation circuit 140. The following describes some examples of the various signal processing operations performed by the signal processing circuit 130.

[0028] For example, the signal processing circuit 130 performs quadrature detection on the reflected wave data read from the buffer memory 120, and then applies logarithmic amplification and envelope detection processing to generate B-mode data in which the signal intensity (amplitude intensity) for each sample point is expressed as brightness. For example, the signal processing circuit 130 outputs the generated B-mode data to the image generation circuit 140.

[0029] Furthermore, the signal processing circuit 130 performs frequency analysis on the reflected wave data read from the buffer memory 120 to extract motion information of moving objects (blood flow, tissue, contrast agent echo components, etc.) based on the Doppler effect from the reflected wave data, and generates Doppler data showing the extracted motion information. For example, the signal processing circuit 130 extracts average velocity, average variance, and average power values ​​as motion information of a moving object across multiple points, and generates Doppler data showing the extracted motion information of the moving object. The signal processing circuit 130 outputs the generated Doppler data to the image generation circuit 140.

[0030] Using the functions of the signal processing circuit 130 described above, the ultrasound diagnostic device 1 can perform color Doppler ultrasound, also known as color flow mapping (CFM). In color flow mapping, ultrasound is transmitted and received multiple times on multiple scan lines. In color flow mapping, an MTI (Moving Target Indicator) filter is applied to the data sequence at the same location to suppress signals originating from stationary or slow-moving tissue (clutter signals) and extract signals originating from blood flow (blood flow signals). In color flow mapping, blood flow information such as blood flow velocity, blood flow dispersion, and blood flow power is estimated from this blood flow signal. The signal processing circuit 130 outputs color image data showing the blood flow information estimated by color flow mapping to the image generation circuit 140. Note that the color image data is an example of Doppler data.

[0031] The signal processing circuit 130 is capable of processing both two-dimensional and three-dimensional reflected wave data.

[0032] The image generation circuit 140 generates ultrasound image data from B-mode data or Doppler data output from the signal processing circuit 130. The image generation circuit 140 is implemented by a processor.

[0033] For example, the image generation circuit 140 generates two-dimensional B-mode image data from the two-dimensional B-mode data generated by the signal processing circuit 130, representing the intensity of reflected waves in terms of brightness. The image generation circuit 140 also generates two-dimensional Doppler image data from the two-dimensional Doppler data generated by the signal processing circuit 130, which visualizes motion information or blood flow information. The two-dimensional Doppler image data that visualizes motion information may be velocity image data, dispersion image data, power image data, or a combination of these.

[0034] Here, the image generation circuit 140 generally converts the scan line signal sequence of the ultrasonic scan into a scan line signal sequence of a video format, such as that used in televisions (scan conversion), and generates ultrasonic image data for display. For example, the image generation circuit 140 generates ultrasonic image data for display by performing a coordinate transformation on the data output from the signal processing circuit 130 according to the scanning pattern of the ultrasonic probe 101. In addition to scan conversion, the image generation circuit 140 also performs various image processing tasks, such as image processing that regenerates an average brightness image using multiple image frames after scan conversion (smoothing process), and image processing that uses a differential filter within the image (edge ​​enhancement process). Furthermore, the image generation circuit 140 synthesizes various parameter text information, scales, body marks, etc., with the ultrasonic image data.

[0035] Furthermore, the image generation circuit 140 generates 3D B-mode image data by performing a coordinate transformation on the 3D B-mode data generated by the signal processing circuit 130. The image generation circuit 140 also generates 3D Doppler image data by performing a coordinate transformation on the 3D Doppler data generated by the signal processing circuit 130. In other words, the image generation circuit 140 generates "3D ultrasound image data (volume data)" from the "3D B-mode image data and 3D Doppler image data". Then, the image generation circuit 140 performs various rendering processes on the volume data to generate various 2D image data for display on the display 103.

[0036] The rendering process performed by the image generation circuit 140 includes, for example, generating MPR image data from volume data using the Multi-Planer Reconstruction (MPR) method. Another rendering process performed by the image generation circuit 140 is volume rendering (VR), which generates 2D image data that reflects 3D information. The image generation circuit 140 is an example of an image generation unit.

[0037] B-mode data and Doppler data are ultrasound image data before scan conversion processing, while the data generated by the image generation circuit 140 is ultrasound image data for display after scan conversion processing. B-mode data and Doppler data are also referred to as raw data.

[0038] The image memory 150 is a memory that stores various image data generated by the image generation circuit 140. The image memory 150 also stores data generated by the signal processing circuit 130. The B-mode data and Doppler data stored in the image memory 150 can be retrieved by the operator after a diagnosis, for example, and become ultrasound image data for display via the image generation circuit 140. For example, the image memory 150 can be implemented using semiconductor memory elements such as RAM (Random Access Memory) or flash memory, a hard disk, or an optical disk.

[0039] The memory circuit 160 stores control programs for scanning (transmission and reception of ultrasound), image processing, and display processing, as well as various data such as diagnostic information (e.g., patient ID, physician's findings, etc.), diagnostic protocols, and various body marks. The memory circuit 160 is also used, if necessary, to store data stored in the image memory 150. For example, the memory circuit 160 can be implemented using semiconductor memory elements such as flash memory, a hard disk, or an optical disk.

[0040] The control circuit 170 controls the entire process of the ultrasound diagnostic device 1. Specifically, the control circuit 170 controls the processing of the transmission circuit 111, the reception circuit 112, the signal processing circuit 130, and the image generation circuit 140 based on various setting requests input from the operator via the input device 102, and various control programs and data read from the memory circuit 160. The control circuit 170 also controls the display 103 to display an ultrasound image based on ultrasound image data for display stored in the image memory 150. For example, the control circuit 170 controls the display 103 to display a B-mode image based on B-mode image data or a color image based on color image data. The control circuit 170 also controls the display 103 to display a color image superimposed on a B-mode image. The control circuit 170 is an example of a display control unit or a control unit. The control circuit 170 is implemented, for example, by a processor. An ultrasound image is an example of an image.

[0041] Furthermore, the control circuit 170 controls the ultrasonic scanning by controlling the ultrasonic probe 101 via the transmitting and receiving circuit 110.

[0042] In this description, the term "processor" refers to circuits such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), Application Specific Integrated Circuit (ASIC), or programmable logic device (e.g., Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), or Field Programmable Gate Array (FPGA)). The processor performs its functions by reading a program stored in the memory circuit 160 and executing the read program. Alternatively, instead of storing the program in the memory circuit 160, the processor may be configured to directly incorporate the program into its circuitry. In this case, the processor performs its functions by reading and executing the program incorporated into the circuitry. In this embodiment, each processor is not limited to being configured as a single circuit; multiple independent circuits may be combined to form a single processor, and its functions may be performed by combining them. Furthermore, the multiple circuits in Figure 1 (for example, the signal processing circuit 130, the image generation circuit 140, and the control circuit 170) may be integrated into a single processor to realize their functions. In other words, the signal processing circuit 130, the image generation circuit 140, and the control circuit 170 may be integrated into a single processing circuit realized by the processor.

[0043] The overall configuration of the ultrasound diagnostic apparatus 1 according to the embodiment has been described above. Next, an example of the configuration of the beamformer that performs DMAS beamforming in the receiving circuit 112 will be described. Figure 2 is a diagram showing an example of the configuration of the beamformer that performs DMAS beamforming in the receiving circuit 112 according to the first embodiment. In the example in Figure 2, for the sake of explanation, the number of elements of the ultrasound probe 101 is 3, and one channel corresponds to one element. However, the number of elements of the ultrasound probe 101 may be N (N is a natural number) other than 3. Also, one channel may correspond to two or more elements. Furthermore, an element number n (n=1,2,3) is assigned to each element to identify the three elements. For example, the first element is assigned element number 1. The second element is assigned element number 2, and the third element is assigned element number 3.

[0044] As shown in Figure 2, the beamformer of the receiving circuit 112 comprises three delay circuits 113a to 113c, three multipliers 114a to 114c, three weight coefficient calculation circuits 115a to 115c, three multipliers 116a to 116c, and an adder 117. The beamformer may also be implemented by a processor.

[0045] If the three delay circuits 113a to 113c are not distinguished, they will be referred to as "delay circuit 113". Similarly, if the three multipliers 114a to 114c are not distinguished, they will be referred to as "multiplier 114", if the three weight coefficient calculation circuits 115a to 115c are not distinguished, they will be referred to as "weight coefficient calculation circuit 115", and if the three multipliers 116a to 116c are not distinguished, they will be referred to as "multiplier 116".

[0046] For example, one channel is provided with one delay circuit 113, one multiplier 114, one weight coefficient calculation circuit 115, and one multiplier 116.

[0047] x n(t) is an IQ signal based on the received signal output from element number n, and is the IQ signal at time t. As shown in Figure 2, the IQ signal x1(t) is input to the delay circuit 113a. The delay circuit 113a outputs the IQ signal x1(t) with a time delay τ1. That is, the delay circuit 113a outputs the IQ signal x1(t) delayed by time τ1 as the IQ signal s1(t) to the multiplier 114a, multiplier 114c, weight coefficient calculation circuit 115a, and weight coefficient calculation circuit 115c. n (t) may be an RF signal consisting only of the real part, rather than an IQ signal.

[0048] Similarly, the delay circuit 113b delays the input IQ signal x2(t) by time τ2, and outputs the IQ signal x2(t) that has been delayed by time τ2 as the IQ signal s2(t) to the multiplier 114a, the multiplier 114b, the weight coefficient calculation circuit 115a, and the weight coefficient calculation circuit 115b.

[0049] Furthermore, the delay circuit 113c delays the input IQ signal x3(t) by time τ3, and outputs the IQ signal x3(t) that has been delayed by time τ3 as the IQ signal s3(t) to the multiplier 114b, multiplier 114c, weight coefficient calculation circuit 115b, and weight coefficient calculation circuit 115c.

[0050] Time τ1 is a delay time corresponding to the positional relationship between element number 1 and the focal point. Time τ1 is also simply a delay time corresponding to the focal point. Similarly, time τ2 is a delay time corresponding to the positional relationship between element number 2 and the focal point, and time τ3 is a delay time corresponding to the positional relationship between element number 3 and the focal point. Furthermore, time τ2 and time τ3 are also simply delay times corresponding to the focal point.

[0051] As described above, the delay circuit 113 outputs multiple delayed signals by applying a delay time corresponding to the focal point position to multiple received signals output from multiple elements of the ultrasonic probe 101. The delay circuit 113 is an example of a delay unit.

[0052] The multiplier 114a multiplies the IQ signal s1(t) by the IQ signal s2(t). Then, the multiplier 114a outputs the signal s1(t)s2(t) obtained as a result of the multiplication to the multiplier 116a.

[0053] Similarly, the multiplier 114b multiplies the IQ signal s2(t) by the IQ signal s3(t), and outputs the signal s2(t)s3(t) obtained as a result of the multiplication to the multiplier 116b. Also, the multiplier 114c multiplies the IQ signal s3(t) by the IQ signal s1(t), and outputs the signal s3(t)s1(t) obtained as a result of the multiplication to the multiplier 116c.

[0054] The weight coefficient calculation circuit 115a calculates a weight coefficient (weight) applied to the signal s1(t)s2(t). Hereinafter, a specific example of a method for calculating the weight coefficient for the signal s1(t)s2(t) will be described. For example, the weight coefficient calculation circuit 115a takes the complex conjugate of the input signal s1(t) and derives the signal s1 * (t). Note that the signal s n * (t) is the complex conjugate of the complex number represented by the signal s n (t).

[0055] Then, the weight coefficient calculation circuit 115a multiplies the signal s1 * (t) by the input signal s2(t), and extracts the phase ∠(s1 * (t)s2(t)) of the signal s1 * (t)s2(t) obtained as a result of the multiplication. Note that the phase ∠(s1 * (t)s2(t)) is also the phase difference (time difference) between the signal s1(t) and the signal s2(t). Also, the phase ∠(s1 * (t)s2(t)) is also the correlation, correlation coefficient, phase information, and instantaneous phase value between the signal s1(t) and the signal s2(t).

[0056] Next, the weight coefficient calculation circuit 115a calculates a weight coefficient according to the phase ∠(s1 * (t)s2(t)). For example, the weight coefficient calculation circuit 115a calculates according to the phase ∠(s1 *We calculate weighting coefficients such that they decrease as (t)s²(t)) increases. To explain with a specific example, the weighting coefficient calculation circuit 115a calculates the weighting coefficient w(θ(t)) using the following equation (1).

[0057]

number

[0058] In equation (1), θ(t) is the phase ∠(s1 * (t)s²(t)) is the weight coefficient w(θ(t)) = weight coefficient w(∠(s1 * (t)s²(t))). Also, in equation (1), θ is the phase ∠(s1 * (t)s²(t)). Also, in equation (1), α is a coefficient used to adjust the magnitude of the weight coefficient w(θ(t)).

[0059] Then, the weight coefficient calculation circuit 115a calculates the weight coefficient w(∠(s1 * Output (t)s2(t))) to the multiplier 116a.

[0060] Similarly, the weight coefficient calculation circuit 115b calculates the weight coefficient w(θ(t)) using signals s2(t) and s3(t) in the same manner as the weight coefficient calculation circuit 115a calculated the weight coefficient w(∠(s2 * The (t)s3(t))) is calculated. Then, the weight coefficient calculation circuit 115a calculates the weight coefficient w(∠(s2 * Output (t)s3(t))) to multiplier 116b.

[0061] Furthermore, the weight coefficient calculation circuit 115c calculates the weight coefficient w(θ(t)) using signals s3(t) and s1(t) in the same manner as the weight coefficient calculation circuit 115a, using signals s3(t) and s1(t), and applies the weight coefficient w(∠(s3 *The (t)s1(t))) is calculated. Then, the weight coefficient calculation circuit 115a calculates the weight coefficient w(∠(s3 * Output (t)s1(t))) to the multiplier 116c.

[0062] Thus, the weight coefficient calculation circuit 115 calculates weight coefficients based on the correlation between the multiplied received signals. Furthermore, the weight coefficient calculation circuit 115 calculates weight coefficients based on the phase information between the multiplied delayed signals. The weight coefficient calculation circuit 115 is an example of a weight calculation unit.

[0063] Then, the multiplier 116a multiplies the signals s1(t) and s2(t) by a weighting coefficient w(∠(s1 * (t)s2(t))) is multiplied, and the resulting signal s1 ´ (t) is output to adder 117. Here, the weight coefficient w(∠(s1 * As mentioned above, (t)s2(t))) is a value that decreases as the phase difference (time difference) between signal s1(t) and signal s2(t) increases. Therefore, the multiplier 116a is such that the contribution rate to the ultrasound image data decreases as the phase difference (time difference) between signal s1(t) and signal s2(t) increases. ´ (t) can be output to the adder 117. Therefore, according to the ultrasound diagnostic apparatus 1 of this embodiment, when DMAS beamforming, which performs signal multiplication and addition, is used as the beamforming method, the generation of speckle patterns can be suppressed.

[0064] Similarly, the multiplier 116b multiplies the signals s2(t) and s3(t) by a weighting coefficient w(∠(s2 * (t)s3(t))) is multiplied, and the resulting signal s2 ´ (t) is output to adder 117. Also, multiplier 116c multiplies the signals s3(t) and s1(t) by a weight coefficient w(∠(s3 * (t)s1(t))) is multiplied, and the resulting signal s3 is obtained from the multiplication. ´ Output (t) to adder 117.

[0065] In this way, the multiplier 116 applies the weight coefficients to the signal obtained as a result of the multiplication. The multiplier 116 is an example of an application unit.

[0066] The adder 117 calculates the sum of all input signals as signal y(t). That is, the adder 117 calculates the sum of signal s1 ´ (t) and signal s2 ´ (t) and signal s3 ´ The sum of (t) and (t) is calculated as the signal y(t). Then, the adder 117 stores the signal y(t) as reflected wave data in the buffer memory 120.

[0067] As described above, the multiplier 114 multiplies the delay signal between different elements, and the adder 117 adds the signal obtained as a result of the multiplication. The multiplier 114 and adder 117 are examples of multiplication and addition units.

[0068] Figure 3 is a flowchart showing an example of the processing flow performed by the DMAS-type beamformer according to the first embodiment.

[0069] (Step S101) As shown in Figure 3, in step S101, the delay circuit 113 delays the received signal, the IQ signal, and outputs a delayed signal, which is the delayed IQ signal.

[0070] (Step S102) Next, in step S102, the multiplier 114 multiplies one of the two delay signals output from different elements by the other delay signal, and outputs the resulting signal to the multiplier 116.

[0071] (Step S103) Next, in step S103, the weight coefficient calculation circuit 115 calculates the weight coefficient w(θ(t)) and outputs the weight coefficient w(θ(t)) to the multiplier 116.

[0072] (Step S104) Next, in step S104, the multiplier 116 multiplies the signal output by the multiplier 114 by the weight coefficient w(θ(t)) output by the weight coefficient calculation circuit 115, thereby weighting the signal output by the multiplier 114, and outputs the weighted signal to the adder 117.

[0073] (Step S105) Next, in step S105, the adder 117 calculates the sum of the signals output by all the multipliers 116 as signal y(t), stores the calculated signal y(t) as reflected wave data in the buffer memory 120, and terminates the process shown in Figure 3.

[0074] Figure 4 shows an example of an ultrasound image based on ultrasound image data obtained using a conventional DMAS. Figure 5 shows an example of an ultrasound image based on ultrasound image data generated by the ultrasound diagnostic device 1 according to the first embodiment. In the ultrasound image shown in Figure 4, a relatively strong speckle pattern is visible, as indicated by the two arrows. On the other hand, in the ultrasound image shown in Figure 5, as indicated by the two arrows, the difference in density (intensity) of the speckle pattern is smaller compared to the ultrasound image shown in Figure 4. Therefore, according to this embodiment, the occurrence of a speckle pattern can be suppressed.

[0075] The ultrasound diagnostic apparatus 1 according to the first embodiment has been described above. According to the ultrasound diagnostic apparatus 1 according to the first embodiment, as described above, when DMAS beamforming, which performs signal multiplication and addition, is used as the beamforming method, the generation of speckle patterns can be suppressed.

[0076] (Modified version of the first embodiment) In the first embodiment described above, various processes may be performed on the signal output from the multiplier 114. Therefore, such modifications will be described as modifications of the first embodiment. Note that in the description of the modifications of the first embodiment, the differences from the first embodiment will be mainly described, and descriptions of configurations similar to the first embodiment may be omitted.

[0077] Figure 6 shows an example of the configuration of a beamformer that performs DMAS-type beamforming in a receiving circuit 112 according to a modified version of the first embodiment. The beamformer according to the modified version of the first embodiment differs from the beamformer according to the first embodiment shown in Figure 2 in that it includes three signal processing circuits 118a to 118c.

[0078] When the three signal processing circuits 118a to 118c are not distinguished, they are referred to as "signal processing circuit 118". For example, one signal processing circuit 118 is provided for each channel. The signal processing circuit 118 receives the signal s output from the multiplier 114. i (t)s j (t)(i,j=1,2,3,i≠j) is input. Then, the signal processing circuit 118 processes the input signal s i (t)s j Using (t), the signal s is obtained by equation (2) below. i1 Calculate (t).

[0079] s i1 (t) = sign(s i (t)s j (t))·|s i (t)s j (t) 1 / 2 (2)

[0080] Note that in equation (2), sign(s i (t)s j (t)) is, for example, as described in Non-Patent Document 1 (The Delay Multiply and Sum Beamforming Algorithm in Ultrasound B-Mode Medical Imaging, IEEE Transaction 2015), the signal s i (t)s j This function outputs the polarity (positive or negative) of (t).

[0081] For example, the signal processing circuit 118a uses the signals s1(t)s2(t) output from the multiplier 114a to process the signal s 11 (t) is calculated. Then, the signal processing circuit 118a processes the signal s 11 (t) is output to the multiplier 116a. Similarly, the signal processing circuit 118b uses the signals s2(t) and s3(t) output from the multiplier 114b to process the signal s 21 (t) is calculated, and the signal processing circuit 118c uses the signals s3(t)s1(t) output from the multiplier 114c to process the signal s 31 (t) is calculated. Then, the signal processing circuit 118b processes the signal s 21 (t) is output to the multiplier 116b, and the signal processing circuit 118c processes the signal s 31 Output (t) to multiplier 116c.

[0082] Then, the multiplier 116a processes the signal s 11 (t) has a weight coefficient w(∠(s1 * (t)s²(t))) is multiplied, and the resulting signal s is obtained from the multiplication. 11 ´ Output (t) to adder 117.

[0083] Similarly, the multiplier 116b processes the signal s 21 (t) has a weight coefficient w(∠(s2 * (t)s3(t))) is multiplied, and the signal s obtained as a result of the multiplication is obtained. 21 ´ (t) is output to adder 117. Also, multiplier 116c receives signal s 31 (t) has a weight coefficient w(∠(s3) * (t)s1(t))) is multiplied, and the signal s obtained as a result of the multiplication is s 31 ´ Output (t) to adder 117.

[0084] Adder 117 receives signal s 11 ´ (t) and signal s 21 ´ (t) and signal s 31 ´The sum of (t) and (t) is calculated as the signal y(t). Then, the adder 117 stores the signal y(t) as reflected wave data in the buffer memory 120.

[0085] The ultrasonic diagnostic apparatus 1 according to a modification of the first embodiment has been described above. The ultrasonic diagnostic apparatus 1 according to a modification of the first embodiment can achieve the same effects as the ultrasonic diagnostic apparatus 1 according to the first embodiment.

[0086] (Second embodiment) In the first embodiment, the case in which the IQ signal obtained by the quadrature detection circuit is input to the multiplier 114 was described. However, the ultrasound diagnostic device 1 may also have a sub-aperture signal input to the multiplier 114. Therefore, such an embodiment will be described as the second embodiment. In the description of the second embodiment, the differences from the first embodiment will be mainly described, and the description of configurations similar to the first embodiment may be omitted.

[0087] In the second embodiment, the ultrasonic probe 101 comprises, for example, 3k (where k is a natural number greater than or equal to 2) elements. These 3k elements are divided into three sub-apers. That is, the number of elements constituting one sub-aperture is k. Thus, the 3k elements include multiple (three) element groups. Each element group consists of k elements. Furthermore, a sub-aperture number m (m=1,2,3) is assigned to each sub-aperture to identify the three sub-apertures. For example, the first sub-aperture is assigned sub-aperture number 1. The second sub-aperture is assigned sub-aperture number 2, and the third sub-aperture is assigned sub-aperture number 3. In the second embodiment, the sub-aperture signal a m (t) is the sum of k received signals (IQ signals) at time t, output from the k elements constituting the sub-aperture with sub-aperture number m.

[0088] The following explanation will describe the case where the sub-aperture signal a1(t) is input to the multiplier 114a, with reference to Figure 7. Note that the sub-aperture signals a2(t) and a3(t) are generated using the same configuration and method as described below.

[0089] Figure 7 is a diagram showing an example of a part of the configuration of a beamformer according to the second embodiment. Figure 7 shows the configuration prior to the multiplier 114a. As shown in Figure 7, in the second embodiment, k delay circuits 113_1 to 113_k and one adder 125a are provided prior to the multiplier 114a. That is, each of the k delay circuits 113_1 to 113_k is provided corresponding to each of the k elements that constitute the sub-aperture of sub-aperture number 1. Thus, the sub-aperture beamforming unit corresponding to the sub-aperture of sub-aperture number 1 comprises k delay circuits 113_1 to 113_k and one adder 125a. This sub-aperture beamforming unit outputs a sub-aperture signal a1(t) by delay-adding the received signals output from the group of elements composed of k elements.

[0090] As shown in Figure 7, the IQ signal x g (t) is input to the delay circuit 113_g, where g is a natural number between 1 and k (inclusive). The delay circuit 113_g is input to the IQ signal x g (t) time τ g The output is delayed by only that amount of time τ. In other words, the delay circuit 113_g delays the output by time τ. g Only the delayed IQ signal x g (t) IQ signal s g Output (t) to adder 125a.

[0091] The adder 125a calculates the sum of all input signals as the sub-aperture signal a1(t). That is, the adder 125a calculates the sum of k IQ signals x g The sum of (t) is calculated as the sub-aperture signal a1(t). The adder 125a then outputs the sub-aperture signal a1(t) to the multiplier 114a (see Figure 7), the multiplier 114c (see Figure 2), the weight coefficient calculation circuit 115a (see Figure 2), and the weight coefficient calculation circuit 115c (see Figure 2).

[0092] Furthermore, in the second embodiment, the sub-aperture signal a2(t) input to multiplier 114a, multiplier 114b, weight coefficient calculation circuit 115a, and weight coefficient calculation circuit 115b is also generated by the same configuration and method as described above. Furthermore, the sub-aperture signal a3(t) input to multiplier 114b, multiplier 114c, weight coefficient calculation circuit 115b, and weight coefficient calculation circuit 115c is also generated by the same configuration and method as described above.

[0093] In the second embodiment, the sub-aperture signal a1(t) is used instead of signal s1(t), the sub-aperture signal a2(t) is used instead of signal s2(t), and the sub-aperture signal a3(t) is used instead of signal s3(t), and the same processing as in the first embodiment is performed. Therefore, in the second embodiment, the multiplier 114 multiplies the sub-aperture signals for all combinations of the element groups described above.

[0094] Figure 8 shows an example of an ultrasound image based on ultrasound image data generated by the ultrasound diagnostic device 1 according to the second embodiment. In the ultrasound image shown in Figure 8, the difference in density (intensity) of the speckle pattern is smaller compared to the ultrasound image shown in Figure 4. Therefore, according to this embodiment, the generation of speckle patterns can be suppressed.

[0095] The ultrasound diagnostic apparatus 1 according to the second embodiment has been described above. The ultrasound diagnostic apparatus 1 according to the second embodiment provides the same effects as the first embodiment. Furthermore, in the second embodiment, since the received signals from multiple elements are processed together, the calculation time in beamforming can be shortened.

[0096] (Third embodiment) In the second embodiment, each of the delay circuits 113_1 to 113_k is set to an IQ signal x1(t) to x kThe cases in which each of (t) is input have been described. However, the signals of harmonic components extracted by the pulse subtraction method (pulse inversion method) may be input to each of the delay circuits 113_1 to 113_k. That is, the ultrasound diagnostic device 1 may perform harmonic imaging by the pulse subtraction method. Hereinafter, such an embodiment will be described as the third embodiment. Note that in the description of the third embodiment, the differences from the second embodiment will be mainly described, and the description of the same configuration as the second embodiment may be omitted.

[0097] In the third embodiment, the control circuit 170 causes each element of the ultrasonic probe 101 to perform an ultrasonic scan consisting of a set of transmissions: a first ultrasonic wave and a second ultrasonic wave with the phase inverted of the first ultrasonic wave. Therefore, in the third embodiment, each element of the ultrasonic probe 101 transmits both the first ultrasonic wave and the second ultrasonic wave with the phase inverted of the first ultrasonic wave. In addition, each element outputs a first received signal upon receiving the reflected wave of the first ultrasonic wave and outputs a second received signal upon receiving the reflected wave of the second ultrasonic wave.

[0098] Below, IQ signal x g (t) is the IQ signal based on the first transmitted ultrasound, and the IQ signal x g,PS The case where (t) is an IQ signal based on a second transmitted ultrasonic wave will be explained with reference to Figure 9. Figure 9 shows an example of a part of the beamformer configuration according to the third embodiment. In the third embodiment, the subaper signal a m´ (t) are the k harmonic signals b at time t corresponding to the k elements that make up the sub-aperture with sub-aperture number m. g This is the signal obtained by adding (t). The sub-aperture signal a is referred to below. 1´ The configuration and method for generating (t) will be described, but the sub-aperture signal a will be generated using a similar configuration and method. 2´ (t) and secondary aperture signal a 3´ (t) is also generated.

[0099] FIG. 9 shows the configuration before the delay circuit 113_g. As shown in FIG. 9, in the third embodiment, an adder 119_g is provided before the delay circuit 113_g. That is, corresponding to each of the k elements constituting the sub-aperture of sub-aperture number 1, k adders 119_1 to 119_k are provided respectively.

[0100] As shown in FIG. 9, the IQ signal x g (t) and the IQ signal x g,PS (t) are input to the adder 119_g. The adder 119_g generates a harmonic signal b g (t) by adding the IQ signal x g,PS (t) to the IQ signal x g (t). The IQ signal x g (t) is an example of the first received signal. Also, the IQ signal x g,PS (t) is an example of the second received signal. Then, the adder 119_g outputs the harmonic signal b g (t) to the delay circuit 113_g. The adder 119_g is an example of a harmonic extraction unit.

[0101] The delay circuit 113_g delays the harmonic signal b g (t) by a time τ g and outputs it. That is, the delay circuit 113_g outputs the harmonic signal b g delayed by a time τ g (t) as the harmonic signal s g´ (t) to the adder 125a.

[0102] The adder 125a calculates the sum of all the input signals as the sub-aperture signal a 1´ (t). That is, the adder 125a calculates the sum of the k harmonic signals s g´ (t) as the sub-aperture signal a 1´ (t). Then, the adder 125a outputs the sub-aperture signal a 1´ (t) to the multiplier 114a (see FIG. 9), the multiplier 114c (see FIG. 2), the weight coefficient calculation circuit 115a (see FIG. 2), and the weight coefficient calculation circuit 115c (see FIG. 2).

[0103] Furthermore, in the third embodiment, the sub-aperture signal a is input to the multiplier 114a, multiplier 114b, weight coefficient calculation circuit 115a, and weight coefficient calculation circuit 115b using the same configuration and method as described above. 2´ (t) is also generated. Furthermore, the sub-aperture signal a is input to the multiplier 114b, multiplier 114c, weight coefficient calculation circuit 115b, and weight coefficient calculation circuit 115c using the same configuration and method as described above. 3´ (t) is also generated.

[0104] In the third embodiment, the sub-aperture signal a1(t) is replaced with the sub-aperture signal a 1´ (t) is used, and sub-aperture signal a is used instead of sub-aperture signal a2(t) 2´ (t) is used, and sub-aperture signal a3(t) is replaced with sub-aperture signal a 3´ (t) is used, and the same process as in the second embodiment is performed.

[0105] The ultrasound diagnostic apparatus 1 according to the third embodiment has been described above. The ultrasound diagnostic apparatus 1 according to the third embodiment provides the same effects as the first and second embodiments. In the third embodiment, the ultrasound diagnostic apparatus 1 uses an IQ signal x g (t) and IQ signal x g,PS (t) describes the case in which the harmonic signal is extracted by pulse subtraction and then delayed. However, in the third embodiment, the ultrasound diagnostic device 1 uses the IQ signal x g (t) and IQ signal x g,PS After delaying (t), the delayed IQ signal x g (t) and IQ signal x g,PS The harmonic signal may be extracted using the pulse subtraction method with (t).

[0106] (Fourth embodiment) In the first embodiment, the case in which IQ signals x1(t) to x3(t) are input to each of the delay circuits 113a to 113c was described. However, the signals of harmonic components extracted by the pulse subtraction method may also be input to each of the delay circuits 113a to 113c. That is, the ultrasound diagnostic device 1 may perform harmonic imaging by the pulse subtraction method. Therefore, such an embodiment will be described as the fourth embodiment. In the description of the fourth embodiment, the differences from the first to third embodiments described above will be mainly explained, and the description of configurations similar to those in the first to third embodiments may be omitted.

[0107] In the fourth embodiment, the ultrasonic diagnostic device 1 performs an ultrasonic beamforming method in which harmonic signals are multiplied between different elements and the resulting signals are added. In the fourth embodiment, as in the third embodiment, the control circuit 170 causes each element of the ultrasonic probe 101 to perform an ultrasonic scan, which consists of a set of transmission of a first ultrasonic wave and transmission of a second ultrasonic wave with the phase inverted of the first ultrasonic wave. Therefore, in the fourth embodiment, as in the third embodiment, each element of the ultrasonic probe 101 transmits a first ultrasonic wave and a second ultrasonic wave with the phase inverted of the first ultrasonic wave. In addition, each element outputs a first received signal by receiving the reflected wave of the first ultrasonic wave and outputs a second received signal by receiving the reflected wave of the second ultrasonic wave.

[0108] Figure 10 shows an example of a part of the configuration of a beamformer according to the fourth embodiment. The configuration and method for generating the harmonic signal c1(t) input to the delay circuit 113a will be described below, but the harmonic signals c2(t) and c3(t) are also generated using a similar configuration and method. The harmonic signal c2(t) is the signal input to the delay circuit 113b, and the harmonic signal c3(t) is the signal input to the delay circuit 113c.

[0109] Figure 10 shows the configuration prior to the delay circuit 113a. As shown in Figure 10, in the fourth embodiment, an adder 119_1 is provided prior to the delay circuit 113a. That is, one adder 119 is provided for each channel.

[0110] As shown in Figure 10, IQ signal x1(t) and IQ signal x 1,PS (t) is input to adder 119_1. Adder 119_1 adds the IQ signal x1(t) to the IQ signal x 1,PS The harmonic signal c1(t) is generated by adding (t). The adder 119_1 then outputs the harmonic signal c1(t) to the delay circuit 113a.

[0111] The delay circuit 113a outputs the harmonic signal c1(t) with a time delay τ1. That is, the delay circuit 113a outputs the harmonic signal c1(t), which has been delayed by time τ1, as the harmonic signal d1(t) to the multiplier 114a (see Figure 10), the multiplier 114c (see Figure 2), the weight coefficient calculation circuit 115a (see Figure 2), and the weight coefficient calculation circuit 115c (see Figure 2).

[0112] Furthermore, in the fourth embodiment, the harmonic signal c2(t) input to multiplier 114a, multiplier 114b, weight coefficient calculation circuit 115a, and weight coefficient calculation circuit 115b is also generated by the same configuration and method as described above. Furthermore, the harmonic signal c3(t) input to multiplier 114b, multiplier 114c, weight coefficient calculation circuit 115b, and weight coefficient calculation circuit 115c is also generated by the same configuration and method as described above. However, the harmonic signal c2(t) delayed by the delay circuit 113b is input as the harmonic signal d2(t) to multiplier 114a, multiplier 114b, weight coefficient calculation circuit 115a, and weight coefficient calculation circuit 115b. Furthermore, the harmonic signal c3(t), delayed by the delay circuit 113c, is input as the harmonic signal d3(t) to the multiplier 114b, the multiplier 114c, the weight coefficient calculation circuit 115b, and the weight coefficient calculation circuit 115c.

[0113] In the fourth embodiment, the harmonic signal d1(t) is used instead of the IQ signal s1(t), the harmonic signal d2(t) is used instead of the IQ signal s2(t), and the harmonic signal d3(t) is used instead of the IQ signal s3(t), and the same processing as in the first embodiment is performed.

[0114] The ultrasound diagnostic apparatus 1 according to the fourth embodiment has been described above. The ultrasound diagnostic apparatus 1 according to the fourth embodiment provides the same effects as the first to third embodiments. In the fourth embodiment, as with the third embodiment, the ultrasound diagnostic apparatus 1 uses an IQ signal x g (t) and IQ signal x g,PS (t) describes the case in which the harmonic signal is extracted by pulse subtraction and then delayed. However, in the fourth embodiment, the ultrasound diagnostic device 1, similar to the third embodiment, uses the IQ signal x g (t) and IQ signal x g,PS After delaying (t), the delayed IQ signal x g (t) and IQ signal x g,PS The harmonic signal may be extracted using the pulse subtraction method with (t).

[0115] The program executed by the processor is provided pre-installed in ROM (Read Only Memory) or memory circuits. This program may also be provided as a file in an installable or executable format on a computer-readable, non-transient storage medium such as a CD (Compact Disk)-ROM, FD (Flexible Disk), CD-R (Recordable), or DVD (Digital Versatile Disk). Furthermore, this program may be stored on a computer connected to a network such as the Internet and provided or distributed by downloading it via the network. For example, this program consists of modules containing the processing functions described above. In actual hardware, the CPU reads the program from a storage medium such as ROM and executes it, loading each module onto the main memory and generating it in the main memory.

[0116] According to at least one embodiment described above, when a DMAS beamforming method that performs signal multiplication and addition is used as the beamforming method, the generation of speckle patterns can be suppressed.

[0117] While several embodiments have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of symbols]

[0118] 1. Ultrasound diagnostic equipment 115a~115c Weight coefficient calculation circuit 116a~116c Multiplier

Claims

1. A plurality of multipliers provided corresponding to a plurality of elements that generate transmitted ultrasonic waves in accordance with the applied voltage and receive reflected waves from a subject, wherein the received signal based on the reflected wave received by a first element among the plurality of elements is taken as a first received signal, and the received signal based on the reflected wave received by a second element among the plurality of elements that is different from the first element is taken as a second received signal, and the first received signal and the second received signal are multiplied together, Multiple application units are provided corresponding to the multiple multiplication units, and apply weight coefficients to the multiplied signal, which is the signal after multiplication by the multiplication units, according to the correlation between the first received signal and the second received signal. The system includes a combining unit that combines the multiplied signals after the weight coefficients have been applied by the plurality of application units. Ultrasound diagnostic equipment.

2. Further comprising a plurality of calculation units provided in correspondence with the plurality of application units, which determine the correlation between the first received signal and the second received signal, The application unit applies a weight coefficient corresponding to the correlation obtained by the calculation unit to the multiplied signal, which is the signal after multiplication by the multiplication unit. The ultrasound diagnostic apparatus according to claim 1.

3. The calculation unit determines the phase difference between the first received signal and the second received signal as the correlation, The application unit applies a coefficient corresponding to the phase difference as the weight coefficient to the multiply signal. The ultrasound diagnostic apparatus according to claim 2.

4. The claim further comprises a plurality of acquisition units provided in correspondence with the plurality of elements, which acquire a delayed signal by performing delay processing on the signal output from the elements, The plurality of multiplication units use the delay signal acquired by one of the plurality of acquisition units as the first received signal, and the delay signal acquired by another acquisition unit different from the first received signal as the second received signal, and multiply the first received signal and the second received signal. An ultrasound diagnostic apparatus according to any one of claims 1 to 3.

5. The present invention further comprises a generation unit that generates ultrasonic image data based on the synthesized signal after it has been synthesized by the synthesis unit. An ultrasound diagnostic apparatus according to any one of claims 1 to 3.

6. The invention further comprises an output unit that outputs the ultrasonic image data generated by the generation unit to an output device. The ultrasound diagnostic apparatus according to claim 5.

7. A multiplication step in which a device generates a transmitted ultrasonic wave corresponding to an applied voltage, receives a first received signal based on the reflected wave from a subject at a first element among a plurality of elements that receive the reflected wave, receives a second received signal based on the reflected wave from a second element different from the first element among the plurality of elements, and multiplies the first received signal and the second received signal by a multiplier unit, An application step in which a weighting coefficient corresponding to the correlation between the first received signal and the second received signal is applied by an application unit to the multiplied signal, which is the signal after multiplication by the multiplication unit, The system includes a synthesis step in which the multiplied signals, after the weight coefficients have been applied by the application unit, are synthesized by the synthesis unit. Processing method.

8. A computer, Multiple multiplication units are provided corresponding to a plurality of elements that generate transmitted ultrasonic waves in accordance with the applied voltage and receive reflected waves from the subject, and the received signal based on the reflected wave received by the first element among the plurality of elements is taken as the first received signal, and the received signal based on the reflected wave received by the second element among the plurality of elements, which is different from the first element, is taken as the second received signal, and the first received signal and the second received signal are multiplied together. Multiple application units are provided corresponding to the multiple multiplication units, and apply weight coefficients to the multiplied signal, which is the signal after multiplication by the multiplication units, according to the correlation between the first received signal and the second received signal, and This unit functions as a combining unit that combines the multiplied signals after the weight coefficients have been applied by the multiple application units. program.

Images