Ultrasound diagnostic equipment and image processing equipment

Abstract

To utilize adaptive beamforming according to a spatial correlation of reflection wave signals.SOLUTION: An ultrasonic diagnostic device includes a first beamforming part, a second beamforming part, a calculation part, and a third beamforming part. The first beamforming part executes first beamforming processing for reflection wave signals output from a plurality of vibrators for receiving a reflection wave. The second beamforming part executes second beamforming processing different from the first beamforming processing for the reflection wave signals. The calculation part calculates an evaluation value of a spatial correlation of the reflection wave signals. The third beamforming part executes third beamforming processing on the basis of a first processing result, which is the processing result of the first beamforming part, a second processing result, which is the processing result of the second beamforming part, and the evaluation value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Embodiments disclosed herein and in the drawings relate to ultrasound diagnostic apparatus and image processing apparatus.

[0002] Conventionally, ultrasound diagnostic equipment performs received beamforming using the received reflected wave signal to improve image resolution. Received beamforming techniques include adaptive beamforming methods such as Minimum Variance, Coherence Factor Beamforming, and DMAS (Delay Multiply and Sum).

[0003] However, adaptive beamforming can sometimes degrade the contrast resolution-to-contrast noise ratio depending on the spatial correlation of the reflected wave signal. On the other hand, adaptive beamforming may be suitable depending on the spatial correlation of the reflected wave signal. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-39702 [Non-patent literature]

[0005] [Non-Patent Document 1] Giulia Matrone, Alessandro Stuart Savoia, Giosue Caliano, and Giovanni Magenes, “The Delay Multiply and Sum Beamforming Algorithm in Ultrasound B-Mode Medical Imaging”, IEEE Transactions On Medical Imaging, Vol. 34, No. 4, April 2015. [Overview of the Initiative] [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 the utilization of adaptive beamforming in accordance with the spatial correlation of reflected wave signals. 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 ultrasound diagnostic apparatus according to the embodiment comprises a first beamforming unit, a second beamforming unit, a calculation unit, and a third beamforming unit. The first beamforming unit performs a first beamforming process on the reflected wave signals output from a plurality of transducers that receive reflected waves. The second beamforming unit performs a second beamforming process on the reflected wave signals that is different from the first beamforming process. The calculation unit calculates an evaluation value of the spatial correlation of the reflected wave signals. The third beamforming unit performs a third beamforming process based on a first processing result, which is the processing result of the first beamforming unit, a second processing result, which is the processing result of the second beamforming unit, and the evaluation value. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a block diagram showing an example configuration of an ultrasound diagnostic device according to this embodiment. [Figure 2] Figure 2 is a diagram showing an example of the configuration of the second beamforming section. [Figure 3] Figure 3 shows an example of a reflected wave signal output from an oscillator when there is a reflector at the focal point for imaging. [Figure 4] Figure 4 shows an example of a reflected wave signal output from an oscillator when the reflector is located at a distance from the focal point where imaging takes place. [Figure 5] Figure 5 shows an example of beamforming processing performed by the ultrasound diagnostic device according to this embodiment. [Figure 6] Figure 6 shows an example of the amplitude profile of an image generated by each beamforming process. [Modes for carrying out the invention]

[0009] The following description of an ultrasound diagnostic apparatus and an image processing apparatus according to an embodiment will be given with reference to the drawings. In the following embodiment, parts with the same reference numerals perform similar operations, and redundant explanations will be omitted as appropriate.

[0010] Figure 1 is a block diagram showing an example configuration of the ultrasound diagnostic apparatus 100 according to this embodiment. As shown in Figure 1, the ultrasound diagnostic apparatus 100 includes an ultrasound probe 101, an input interface 102, a display 103, and a main unit 104. The ultrasound probe 101, the input interface 102, and the display 103 are connected to the main unit 104 in a communicative manner. The ultrasound diagnostic apparatus 100 is an example of an ultrasound diagnostic apparatus and an image processing apparatus.

[0011] The ultrasonic probe 101 has multiple transducers 101a, which generate ultrasound based on drive signals supplied from the transmitting / receiving circuit 110 of the main unit 104. The ultrasonic probe 101 also receives reflected waves from the subject P and converts them into electrical signals. The ultrasonic probe 101 is detachably connected to the main unit 104.

[0012] When ultrasonic waves are transmitted from the ultrasonic probe 101 to the subject P, the transmitted ultrasonic waves are successively reflected at the discontinuous surfaces of the acoustic impedance in the internal tissues of the subject P, and are received by a plurality of vibrators 101a included in the ultrasonic probe 101 as reflected wave signals. The amplitude of the received reflected wave signal depends on the difference in acoustic impedance at the discontinuous surface where the ultrasonic wave is reflected. When the transmitted ultrasonic pulse is reflected at the surface of a moving blood flow, a heart wall, or the like, the reflected wave signal undergoes a frequency shift depending on the velocity component of the moving object with respect to the ultrasonic transmission direction due to the Doppler effect.

[0013] Note that the form of the ultrasonic probe 101 is not particularly limited, and any form of ultrasonic probe may be used. For example, the ultrasonic probe 101 may be a 1D array probe that scans the subject P two-dimensionally. Further, the ultrasonic probe 101 may be a mechanical 4D probe or a 2D array probe that scans the subject P three-dimensionally.

[0014] The input interface 102 receives input operations of various instructions and information from the operator. Specifically, the input interface 102 converts the input operation received from the operator into an electrical signal and outputs it to the processing circuit 170 of the apparatus main body 104. For example, the input interface 102 is realized by a trackball, a switch button, a mouse, a keyboard, a touch pad that performs an input operation by touching an operation surface, a touch screen in which a display screen and a touch pad are integrated, a non-contact input circuit using an optical sensor, and an audio input circuit, etc. Note that the input interface 102 is not limited to those provided with physical operation components such as a mouse and a keyboard. For example, an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the apparatus and outputs this electrical signal to the control circuit is also included in the example of the input interface 102.

[0015] The display 103 displays various kinds of information and images. Specifically, the display 103 converts the information and image data sent from the processing circuit 170 into electrical signals for display and outputs them. For example, the display 103 is realized by a liquid crystal monitor, a CRT (Cathode Ray Tube) monitor, a touch panel, or the like. Note that the output device included in the ultrasonic diagnostic apparatus 100 is not limited to the display 103, and for example, a speaker may be provided. For example, the speaker outputs a predetermined sound such as a beep sound to notify the operator of the processing status of the apparatus main body 104.

[0016] The apparatus main body 104 is an apparatus that generates an ultrasonic image based on the reflected wave signal received by the ultrasonic probe 101. For example, the apparatus main body 104 generates a two-dimensional ultrasonic image based on the two-dimensional reflected wave data received by the ultrasonic probe 101. Further, the apparatus main body 104 generates a three-dimensional ultrasonic image based on the three-dimensional reflected wave data received by the ultrasonic probe 101.

[0017] As shown in FIG. 1, the apparatus main body 104 includes a transmission / reception circuit 110, a buffer memory 120, a signal processing circuit 130, an image generation circuit 140, a storage circuit 150, a NW (network) interface 160, and a processing circuit 170. The transmission / reception circuit 110, the buffer memory 120, the signal processing circuit 130, the image generation circuit 140, the storage circuit 150, the NW interface 160, and the processing circuit 170 are connected to each other so as to be communicable.

[0018] The transmitting and receiving circuit 110 includes a pulse generator, a transmission delay unit, a pulser, etc., and supplies a drive signal to the ultrasonic probe 101. The pulse generator repeatedly generates rate pulses at a predetermined rate frequency to form the transmitted ultrasonic waves. The transmission delay unit provides a delay time for each transducer 101a necessary to focus the ultrasonic waves generated from the ultrasonic probe 101 into a beam and determine the transmission directivity, to each rate pulse generated by the pulse generator. The pulser applies a drive signal (drive pulse) to the ultrasonic probe 101 at a timing based on the rate pulse. In other words, the transmission delay unit arbitrarily adjusts the transmission direction of the ultrasonic waves transmitted from the transducer surface by changing the delay time provided to each rate pulse.

[0019] Furthermore, the transmitting and receiving circuit 110 includes a preamplifier, an A / D (Analog to Digital) converter, a quadrature detection circuit, etc., and performs various processing on the reflected wave signal received by the ultrasonic probe 101 to generate reflected wave data.

[0020] The preamplifier amplifies the reflected wave signal for each channel and performs gain adjustment (gain correction). The A / D converter converts the gain-corrected reflected wave signal into a digital signal by A / D conversion. The quadrature detection circuit converts the A / D-converted reflected wave signal into a baseband in-phase signal (I signal, I) and a quadrature-phase signal (Q signal, Q).

[0021] The quadrature detection circuit outputs the I signal and Q signal as reflected wave data. Hereafter, the I signal and Q signal will be collectively referred to as the IQ signal. Also, since the IQ signal is A / D converted digital data, it will also be called the IQ data.

[0022] Furthermore, the transmitting and receiving circuit 110 includes a first beamforming unit 111 and a second beamforming unit 112.

[0023] The first beamforming unit 111 performs beamforming on the reflected wave signals received by a plurality of transducers 101a that receive reflected waves. For example, the first beamforming unit 111 performs phase-adding beamforming by adding a delay time to each reflected wave signal corresponding to the timing at which each transducer 101a receives the reflected wave from the point of interest, and then adding the reflected wave signals together. The point of interest is the target to which the transducer 101a transmits ultrasound.

[0024] More specifically, the first beamforming unit 111 performs phase-adding beamforming processing on the reflected wave data generated from the reflected wave signal. The first beamforming unit 111 provides the necessary delay time to determine the receiving directivity. For example, if the distance to the reflector R (see Figure 3) included in the subject P is different, the timing at which the multiple transducers 101a receive the reflected wave will be different. Therefore, the first beamforming unit 111 adds a delay time to the reflected wave data of each of the multiple transducers 101a. In this way, the first beamforming unit 111 aligns the phase of each reflected wave data.

[0025] Furthermore, the first beamforming unit 111 adds up multiple reflected wave data with a delay time. By adding up the reflected wave data, the first beamforming unit 111 emphasizes the reflected component from the direction corresponding to the receiving directivity of the reflected wave data, and forms an overall ultrasonic beam with receiving directivity and transmitting directivity.

[0026] The second beamforming unit 112 performs a second beamforming process different from the first beamforming process on the reflected wave signals received by the multiple oscillators 101a. For example, the second beamforming unit 112 performs a second beamforming process in which it adds a delay time to each reflected wave signal corresponding to the timing at which each oscillator 101a receives the reflected wave from the point of interest, and adjusts the amplitude using a reflected wave signal output by an oscillator 101a different from the oscillator 101a that output the reflected wave signal.

[0027] For example, the second beamforming unit 112 executes a second beamforming process, which is an adaptive beamforming process using the DMAS (Delay-Multiply-and-Sum) method (Non-Patent Document 1). FIG. 2 is a configuration diagram showing a configuration example of the second beamforming unit 112. As shown in FIG. 2, for the reflected wave signal x i (t) (where i is the oscillator number), the delay time τ i required to determine the reception directivity is added, and the signal is converted into s i (t).

[0028] In addition, the second beamforming unit 112 adjusts the amplitude of the signal s i (t) with respect to the reflected wave data generated from the reflected wave signals output from different oscillators 101a than the oscillator 101a that output the reflected wave signal serving as the basis of this reflected wave data. That is, the second beamforming unit 112 multiplies the amplitude of the reflected wave data of one oscillator 101a by the amplitude of the reflected wave data of another different oscillator 101a to obtain s i (t)s j (t). Further, the second beamforming unit 112 calculates the square root of the absolute value of s i (t)s j (t). Then, the second beamforming unit 112 multiplies the calculated square root of the absolute value of s i (t)s j (t) by the sign sign(s i (t)s j (t)) of s i (t)s j (t) and integrates to calculate s ij (t). This is represented by Equation (1).

[0029]

Equation

[0030] In addition, the second beamforming unit 112 adds s ij (t) across the oscillators 101a to obtain y* DMAS We calculate (t). This is expressed by equation (2). In equation (2), i and j represent the numbers of oscillators 101a, and N represents the total number of oscillators 101a.

[0031]

number

[0032] As a result, the second beamforming unit 112 emphasizes the reflected component from the direction corresponding to the receiving directivity of the reflected wave data, and a comprehensive ultrasonic beam is formed by the receiving directivity and transmitting directivity. In addition, the second beamforming unit 112 multiplies the amplitude of other reflected wave data, and because the number of additions is increased, the amplitude is further increased in areas with high amplitude and further reduced in areas with low amplitude.

[0033] The transmitting / receiving circuit 110 then stores the reflected wave data for which beamforming processing has not been performed, the reflected wave data that is the result of the first beamforming processing, and the reflected wave data that is the result of the second beamforming processing in the buffer memory 120.

[0034] The second beamforming unit 112 may perform adaptive beamforming processing using the DMAS method, as well as the Minimum Variance method, the Coherence Factor Beamforming method, or other adaptive beamforming methods. The Minimum Variance method is a method that increases spatial resolution by multiplying the input ultrasonic signal by a coefficient that matches the input ultrasonic signal. The Coherence Factor Beamforming method is a method that increases spatial resolution by weighting the reflected ultrasonic signal using a phase coherence factor obtained from the phase variance of the received ultrasonic signal.

[0035] The buffer memory 120 is implemented by semiconductor memory elements such as RAM (Random Access Memory) or flash memory. The buffer memory 120 stores the reflected wave data output from the transmit / receive circuit 110. More specifically, the buffer memory 120 stores reflected wave data for which beamforming processing has not been performed, reflected wave data as a result of the first beamforming processing, and reflected wave data as a result of the second beamforming processing.

[0036] Furthermore, the buffer memory 120 stores the reflected wave data generated by the third beamforming function 172.

[0037] The signal processing circuit 130 acquires reflected wave data generated by the third beamforming function 172 stored in the buffer memory 120. The signal processing circuit 130 also performs logarithmic amplification, envelope detection, etc. on the reflected wave data acquired from the buffer memory 120 to generate data (B-mode data) in which signal intensity is expressed as brightness. Furthermore, the signal processing circuit 130 performs frequency analysis on velocity information from the reflected wave data acquired from the buffer memory 120, extracts blood flow, tissue, and contrast agent echo components due to the Doppler effect, and generates data (Doppler data) in which moving object information such as velocity, dispersion, and power is extracted for multiple points.

[0038] Furthermore, the signal processing circuit 130 is capable of processing both two-dimensional and three-dimensional reflected wave data. That is, the signal processing circuit 130 generates two-dimensional B-mode data from two-dimensional reflected wave data and three-dimensional B-mode data from three-dimensional reflected wave data. In addition, the signal processing circuit 130 generates two-dimensional Doppler data from two-dimensional reflected wave data and three-dimensional Doppler data from three-dimensional reflected wave data.

[0039] The image generation circuit 140 generates an ultrasound image from the data generated by the signal processing circuit 130. For example, the image generation circuit 140 generates a two-dimensional B-mode image from the two-dimensional B-mode data generated by the signal processing circuit 130, in which the intensity of the reflected wave is represented by brightness.

[0040] Furthermore, for example, the image generation circuit 140 generates a two-dimensional Doppler image in which blood flow information is visualized from the two-dimensional Doppler data generated by the signal processing circuit 130. The two-dimensional Doppler image is image data that represents the average velocity of blood flow, dispersion image data that represents the dispersion value of blood flow, power image data that represents the power of blood flow, or image data that combines these. In addition, the image generation circuit 140 can generate a color Doppler image in which blood flow information such as the average velocity, dispersion value, and power of blood flow is displayed in color, or a Doppler image in which a single piece of blood flow information is displayed in grayscale.

[0041] Furthermore, for example, the image generation circuit 140 can generate an M-mode image from time-series data of B-mode data on one scan line generated by the signal processing circuit 130. The image generation circuit 140 can also generate Doppler waveforms plotting blood flow and tissue velocity information over time from the Doppler data generated by the signal processing circuit 130.

[0042] 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 an ultrasonic image for display. Specifically, the image generation circuit 140 generates an ultrasonic image for display by performing coordinate transformations according to the ultrasonic 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.

[0043] In other words, B-mode data and Doppler data are data before scan conversion processing, while the data generated by the image generation circuit 140 is image data for display after scan conversion processing. Hereinafter, the data before scan conversion processing (B-mode data and Doppler data) will also be referred to as "RAW data".

[0044] The image generation circuit 140 generates two-dimensional ultrasound images, namely two-dimensional B-mode images and two-dimensional Doppler images, from two-dimensional B-mode data and two-dimensional Doppler data, which are RAW data. The image generation circuit 140 can also generate superimposed images, for example, by superimposing a color Doppler image on a two-dimensional B-mode image.

[0045] The memory circuit 150 stores various types of data. For example, the memory circuit 150 stores control programs for ultrasound transmission and reception, image processing and display processing, diagnostic information (e.g., patient ID, doctor's findings, etc.), diagnostic protocols, and various body marks. For example, the memory circuit 150 can be implemented using semiconductor memory elements such as RAM (Random Access Memory) and flash memory, or a hard disk drive (HDD), optical disc, etc.

[0046] Furthermore, the data stored in the memory circuit 150 can be transferred to an external device via the NW interface 160. The external device could be, for example, a personal computer (PC) or tablet used by a physician performing diagnostic imaging, an image storage device for storing images, or a printer.

[0047] The NW interface 160 controls communication between the main unit 104 and external devices. Specifically, the NW interface 160 receives various types of information from external devices and outputs the received information to the processing circuit 170. For example, the NW interface 160 can be implemented using a network card, network adapter, NIC (Network Interface Controller), etc.

[0048] The processing circuit 170 controls the entire processing of the ultrasound diagnostic device 100. Specifically, the processing circuit 170 controls the processing of the transmitting / receiving circuit 110, the signal processing circuit 130, and the image generation circuit 140 based on various setting requests input from the operator via the input interface 102, and various control programs and data read from the memory circuit 150. The processing circuit 170 also controls the display of the ultrasound image.

[0049] Furthermore, the processing circuit 170 executes the evaluation value calculation function 171, the third beamforming function 172, and the weight coefficient input function 173. Here, for example, each processing function of the components of the processing circuit 170, namely the evaluation value calculation function 171, the third beamforming function 172, and the weight coefficient input function 173, is stored in the memory circuit 150 in the form of a program that can be executed by a computer. The processing circuit 170 is a processor. For example, the processing circuit 170 reads the program from the memory circuit 150 and executes it to realize the function corresponding to each program. In other words, the processing circuit 170 in the state in which each program has been read will have the functions shown in the processing circuit 170 of Figure 1. Note that in Figure 1, the processing functions performed by the evaluation value calculation function 171, the third beamforming function 172, and the weight coefficient input function 173 are realized by a single processor, but it is also possible to configure the processing circuit 170 by combining multiple independent processors, and each processor can realize the functions by executing a program. Furthermore, although Figure 1 describes a single memory circuit 150 that stores programs corresponding to each processing function, it is also possible to have multiple memory circuits distributed and have the processing circuit 170 read the corresponding programs from individual memory circuits.

[0050] In the above explanation, the term "processor" refers to circuits such as a CPU (Central Processing Unit), a GPU (Graphical Processing Unit), an Application Specific Integrated Circuit (ASIC), or a programmable logic device (e.g., a Simple Programmable Logic Device (SPLD), a Complex Programmable Logic Device (CPLD), and a Field Programmable Gate Array (FPGA)). The processor functions by reading and executing a program stored in the memory circuit 150. Alternatively, instead of storing the program in the memory circuit 150, the processor may be configured to directly incorporate the program into its circuitry. In this case, the processor functions by reading and executing the program incorporated into the circuitry.

[0051] Here, the ultrasound diagnostic device 100 utilizes adaptive beamforming based on the spatial correlation of the reflected wave signals.

[0052] First, we will explain the spatial correlation of the reflected wave signal using Figures 3 and 4. After explaining the reflected wave signal output from oscillator 101a using Figures 3 and 4, we will explain the spatial correlation of the reflected wave signal.

[0053] Figure 3 shows an example of a reflected wave signal output from the transducer 101a when a reflector R is located at the imaging focal point F. Figure 4 shows an example of a reflected wave signal output from the transducer 101a when a reflector R is located at a distance from the imaging focal point F. In Figures 3 and 4, the ultrasound diagnostic device 100 generates an image of the focal point F. The reflector R shown in Figures 3 and 4 is assumed to be sufficiently smaller than the ultrasound wavelength.

[0054] As shown in Figures 3 and 4, the distance from each transducer 101a to the focal point F is different. Therefore, the ultrasound diagnostic device 100 adds a delay time according to the round-trip propagation time of the ultrasound from transducer 101a to the focal point F. As a result, as shown in Figure 3, the ultrasound diagnostic device 100 can acquire reflected wave signals with phase alignment between them when a reflector R is present inside the focal point F. However, as shown in Figure 4, when a reflector R is located far from the focal point F, the reflected wave reflected at the focal point F is affected by the reflected wave reflected by the reflector R. Therefore, as shown in Figure 4, the ultrasound diagnostic device 100 acquires reflected wave signals with phase differences between them.

[0055] Next, the spatial correlation of reflected wave signals will be explained. When there is only one reflector R, the ultrasound diagnostic device 100 determines that the phases of each reflected wave signal output from each transducer 101a are approximately the same at the time position of the focal point F. The ultrasound diagnostic device 100 then determines that the spatial correlation of the reflected wave signals is high when the phases of each reflected wave signal are approximately the same.

[0056] On the other hand, when there are multiple reflectors R, the ultrasound diagnostic device 100 determines that the phases of the reflected wave signals corresponding to each transducer 101a vary at the time position of the focal point F. In other words, there is a phase difference between the reflected wave signals. The ultrasound diagnostic device 100 then determines that the spatial correlation of the reflected wave signals is low when the phases of each reflected wave signal vary.

[0057] Here, the second beamforming unit 112 multiplies the amplitudes of multiple reflected wave signals in DMAS-type adaptive beamforming, adding them more than in the phase-matching summation method. Therefore, when the phases of the reflected wave signals are aligned, the second beamforming unit 112 outputs a large value as the result of the second beamforming process. On the other hand, when the phases of the reflected wave signals are scattered, the second beamforming unit 112 outputs a small value as the result of the second beamforming process, which is adaptive beamforming.

[0058] Thus, in adaptive beamforming, the second beamforming unit 112 outputs values ​​that vary depending on the spatial correlation of each reflected wave signal. In other words, the second beamforming unit 112 outputs values ​​that vary depending on the spatial correlation of the reflected wave signals. Therefore, because the output of the ultrasound diagnostic device 100 for reflected waves from points of interest where multiple reflectors R are densely clustered varies, the contrast resolution and contrast-to-noise ratio with respect to such points of interest may deteriorate.

[0059] In contrast, the first beamforming unit 111 performs phase-additive beamforming processing. Phase-additive beamforming processing does not involve multiplying the amplitudes of multiple reflected wave signals or increasing the number of additions. In other words, phase-additive beamforming processing is less affected by reflected waves reflected from reflectors R located near the focal point F. Therefore, even if the spatial correlation of the reflected wave signals is low, the processing results of the first beamforming unit 111 are less variable than those of the second beamforming unit 112.

[0060] Therefore, the ultrasound diagnostic device 100 combines the processing results of the first beamforming unit 111 with the processing results of the first beamforming unit 111 according to the spatial correlation of the reflected wave signals. This suppresses the deterioration of contrast resolution and contrast-to-noise ratio in the ultrasound diagnostic device 100.

[0061] The evaluation value calculation function 171 calculates an evaluation value that indicates the spatial correlation of the reflected wave signals. In other words, the evaluation value calculation function 171 calculates an evaluation value of the spatial correlation of the reflected wave signals received by multiple oscillators 101a. The evaluation value calculation function 171 is an example of a calculation unit. The evaluation value calculation function 171 performs a process to calculate an evaluation value for reflected wave data output from the transmitting / receiving circuit 110 that has not undergone beamforming processing by the first beamforming unit 111 or the second beamforming unit 112.

[0062] More specifically, the evaluation value calculation function 171 calculates the evaluation value w(t) represented by the following formula (3) when the second beamforming unit 112 performs adaptive beamforming using the DMAS method shown in Figure 2 (Non-Patent Literature 1). Note that s(t) in formula (3) represents s(t) in formula (1). Also, N in formula (3) represents the total number of oscillators 101a.

[0063]

number

[0064] Furthermore, the evaluation value calculation function 171 calculates an evaluation value for each pixel of the ultrasound image. The evaluation value calculation function 171 then performs the process of calculating the evaluation value for the target area of ​​the beamforming process. As a result, the evaluation value calculation function 171 generates a spatial correlation map in which the evaluation value is registered for each pixel of the target area of ​​the beamforming process. Although formula (3) is used here as an example for calculating the evaluation value, the method is not limited to using the multiplied signal in this way. For example, a method that evaluates the correlation between transducer received signals, such as the Coherence Factor Beamforming method, may also be used.

[0065] Furthermore, the evaluation value calculation function 171 may calculate abnormal values ​​when calculating an evaluation value for speckle generated by reflected waves reflected by multiple reflectors R. Therefore, the evaluation value calculation function 171 may set a lower limit by assuming uncorrelated reflected waves with no correlation.

[0066] The third beamforming function 172 performs beamforming utilizing the processing results of adaptive beamforming. More specifically, the third beamforming function 172 performs third beamforming processing based on the first processing result, which is the processing result of the first beamforming unit 111, the second processing result, which is the processing result of the second beamforming unit 112, and the evaluation value calculated by the evaluation value calculation function 171. The third beamforming function 172 is an example of a third beamforming unit.

[0067] For example, the third beamforming function 172 combines the reflected wave data, which is the result of the first processing, and the reflected wave data, which is the result of the second processing, according to a synthesis ratio corresponding to the evaluation value. More specifically, the third beamforming function 172 performs the processing shown in equation (4) below. In equation (4), w(t) is the evaluation value defined in equation (3), and is an index that determines the weighting of the reflected wave data, which is the result of the first processing, and the reflected wave data, which is the result of the second processing, in equation (4). BF1(t) represents the reflected wave data, which is the result of processing by the first beamforming unit 111. BF2(t) represents the reflected wave data, which is the result of processing by the second beamforming unit 112. α represents a parameter (adjustment parameter) for adjusting the weighting of BF1(t) and BF2(t).

[0068]

number

[0069] As shown in equation (4), the third beamforming function 172 performs third beamforming by combining the first processing result, which is the processing result of the first beamforming unit 111 to which a weighting coefficient has been applied, and the second processing result, which is the processing result of the second beamforming unit 112 to which a weighting coefficient has been applied, using a synthesis ratio corresponding to the evaluation value. The ultrasound diagnostic device 100 can arbitrarily change the weight in the evaluation value by changing the adjustment parameter for the weighting coefficient. Note that α, the adjustment parameter for the weighting coefficient in equation (4), only needs to be proportional to the evaluation value W(t), and may also be in the form of division, such as W(t) / α.

[0070] The third beamforming function 172 then stores the processing result of the third beamforming process in the buffer memory 120. That is, the third beamforming function 172 stores the reflected wave data, which is a combination of the reflected wave data, which is the result of the first processing, and the reflected wave data, which is the result of the second processing, in the buffer memory 120.

[0071] The weight coefficient input function 173 accepts input specifying adjustment parameters for the weight coefficients. The weight coefficient input function 173 is an example of an input unit. For example, the weight coefficient input function 173 accepts input specifying adjustment parameters for the weight coefficients from the input interface 102. Alternatively, the weight coefficient input function 173 accepts input specifying adjustment parameters for the weight coefficients from the NW interface 160.

[0072] Next, we will describe the processes performed by the ultrasound diagnostic device 100.

[0073] Figure 5 shows an example of beamforming processing performed by the ultrasound diagnostic device 100 according to this embodiment.

[0074] The transmitting and receiving circuit 110 generates ultrasonic data from ultrasonic signals output from multiple transducers 101a of the ultrasonic probe 101 (step S1).

[0075] The first beamforming unit 111 of the transmitting / receiving circuit 110 performs a first beamforming process on the ultrasonic data (step S2). For example, the first beamforming unit 111 performs a phase-adding beamforming process.

[0076] The second beamforming unit 112 of the transmitting / receiving circuit 110 performs a second beamforming process on the ultrasonic data (step S3). For example, the second beamforming unit 112 performs a DMAS-type beamforming process.

[0077] The evaluation value calculation function 171 performs the process of calculating an evaluation value of the spatial correlation of the reflected wave signal for the ultrasonic data (step S4).

[0078] The third beamforming function 172 performs a third beamforming process based on the processing results of the first beamforming unit 111, the processing results of the second beamforming unit 112, and the evaluation value (step S5). More specifically, the third beamforming function 172 performs a third beamforming process that combines the processing results of the first beamforming unit 111 and the processing results of the second beamforming unit 112 according to a combination ratio corresponding to the evaluation value.

[0079] As a result, the ultrasound diagnostic device 100 completes the beamforming process. The ultrasound diagnostic device 100 then generates an ultrasound image from the reflected wave data, which is the result of the third beamforming process.

[0080] Thus, the ultrasound diagnostic device 100 can improve contrast resolution and suppress amplitude variation by using the processing results after the third beamforming process has been performed. Here, Figure 6 is a diagram showing an example of the amplitude profile of an image generated by each beamforming process. Figure 6 shows the amplitude of the scan lines of images taken using different beamforming processes on a phantom for performance evaluation of the ultrasound diagnostic device 100. Figure 6(1) shows the amplitude of the scan lines of an image taken using the first beamforming process, i.e., the phase-adding beamforming process. Figure 6(2) shows the amplitude of the scan lines of an image taken using the second beamforming process, i.e., the DMAS beamforming process. Figure 6(3) shows the amplitude of the scan lines of an image taken using the third beamforming process.

[0081] Here, we compare the comparison signal A1 (1), the comparison signal A2 (2), and the comparison signal A3 (3) shown in Figure 6. The width of comparison signal A2 is narrower than the width of comparison signal A1. The third beamforming function 172 then performs a third beamforming process that combines the processing results of the first beamforming process and the processing results of the second beamforming process. Therefore, the width of comparison signal A3 is narrower than that of comparison signal A1. In other words, the image generated by the third beamforming process is a sharp image. In this way, the third beamforming process can improve contrast resolution.

[0082] Furthermore, we compare the comparison region B1 in (1), the comparison region B2 in (2), and the comparison region B3 in (3) shown in Figure 6. The comparison region B1 in (1), the comparison region B2 in (2), and the comparison region B3 in (3) represent the reflected echo region from numerous scatterers in the region below the wavelength surrounding the focal point F, that is, the variation in the amplitude of the ultrasonic signal interfered with by the reflected wave reflected by the reflector R near the focal point F. The amplitude variation in comparison region B1 is approximately 38 dB, the amplitude variation in comparison region B2 is approximately 55 dB, and the amplitude variation in comparison region B3 is approximately 40 dB.

[0083] The third beamforming function 172 combines the processing results of the first beamforming process and the processing results of the second beamforming process. As a result, the amplitude variation in the comparison region B3 is greater than or equal to the amplitude variation in the comparison region B1, and less than the amplitude variation in the comparison region B1. In other words, the third beamforming process can suppress the amplitude variation due to interference signals more effectively than the second beamforming process.

[0084] As described above, the ultrasound diagnostic apparatus 100 according to this embodiment performs a first beamforming process such as a phase-correcting summation method and a second beamforming process which is adaptive beamforming such as a DMAS method. The ultrasound diagnostic apparatus 100 also calculates an evaluation value of the spatial correlation of the reflected wave signals output from the plurality of transducers 101a. Then, the ultrasound diagnostic apparatus 100 performs a third beamforming process based on the processing results of the first beamforming process, the processing results of the second beamforming process, and the evaluation value.

[0085] As a result, the ultrasound diagnostic device 100 uses the processing result of a first beamforming process, such as a phase-correcting summation method, when there is a large variation in the phase of each reflected wave signal output from multiple transducers 101a, and uses a second beamforming process, which is adaptive beamforming, when there is a small variation in the phase of each reflected wave signal. Therefore, the ultrasound diagnostic device 100 can utilize adaptive beamforming according to the spatial correlation of the reflected wave signals.

[0086] (Variation 1) In this embodiment, the third beamforming function 172 was described as performing a third beamforming process that combines the processing result of the first beamforming process and the processing result of the second beamforming process according to a combination ratio corresponding to the evaluation value. However, the third beamforming function 172 is not limited to combining processing results according to the evaluation value, but may also select processing results according to the evaluation value.

[0087] The third beamforming function 172 performs third beamforming, selecting either the first processing result, which is the processing result of the first beamforming unit 111, or the second processing result, which is the processing result of the first beamforming unit 111, based on a composite ratio corresponding to the evaluation value. For example, the third beamforming function 172 selects the processing result of the second beamforming process when the evaluation value is higher than a threshold, and selects the processing result of the first beamforming process when the evaluation value is lower than a threshold. That is, the third beamforming function 172 selects the processing result of the second beamforming process when the evaluation value of the spatial correlation of each reflected wave signal output from the multiple transducers 101a is higher than a threshold, and selects the processing result of the first beamforming process when the evaluation value of the spatial correlation of each reflected wave signal is lower than a threshold. As a result, the ultrasound diagnostic device 100 can utilize adaptive beamforming according to the spatial correlation of the reflected wave signals.

[0088] (Modification 2) In this embodiment, the first beamforming unit 111 of the transmitting / receiving circuit 110 performs the first beamforming process. However, all or part of the functions of the first beamforming unit 111 may be performed by a program. That is, the processing circuit 170 may realize all or part of the functions of the first beamforming unit 111 by executing a program. Also, the second beamforming unit 112 of the transmitting / receiving circuit 110 performs the second beamforming process. However, all or part of the functions of the second beamforming unit 112 may be performed by a program. That is, the processing circuit 170 may realize all or part of the functions of the second beamforming unit 112 by executing a program.

[0089] Furthermore, it was explained that the evaluation value calculation function 171 and the third beamforming function 172 are realized by executing a program. However, all or part of the functions of the evaluation value calculation function 171 and the third beamforming function 172 may be realized by hardware such as circuits.

[0090] (Variation 3) In this embodiment, the main body of the device 104 is described as comprising a first beamforming unit 111, a second beamforming unit 112, an evaluation value calculation function 171, and a third beamforming function 172. However, the first beamforming unit 111, the second beamforming unit 112, the evaluation value calculation function 171, and the third beamforming function 172 are not limited to the main body of the device 104, but may also be provided by the ultrasonic probe 101.

[0091] (Modification 4) In this embodiment, the ultrasound diagnostic device 100 is described as comprising a first beamforming unit 111, a second beamforming unit 112, an evaluation value calculation function 171, and a third beamforming function 172. However, the first beamforming unit 111, the second beamforming unit 112, the evaluation value calculation function 171, and the third beamforming function 172 may be provided by computer equipment such as a server or workstation. For example, the ultrasound diagnostic device 100 transmits reflected wave data generated by the transmitting / receiving circuit 110 to the computer equipment via an interface such as an NW interface 160. The computer equipment may then perform various processes on the received reflected wave data using the first beamforming unit 111, the second beamforming unit 112, the evaluation value calculation function 171, and the third beamforming function 172.

[0092] According to at least one embodiment described above, adaptive beamforming can be utilized in accordance with the spatial correlation of the reflected wave signal.

[0093] 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 implemented in a variety of other forms, and various omissions, substitutions, modifications, and combinations of embodiments are possible 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]

[0094] 100 Ultrasound diagnostic equipment 101 Ultrasound probe 101a Oscillator 102 Input Interfaces 103 displays 104 Main unit of the device 110 Transmit / Receive Circuit 111 First beamforming section 112 Second beamforming section 120 buffer memory 130 Signal Processing Circuits 140 Image generation circuit 150 Memory circuit 160 NW Interfaces 170 Processing Circuits 171 Evaluation Value Calculation Function 172 Third beamforming function 173 Weight coefficient input function F focus P Subject R reflector A1, A2, A3 Comparison Signals B1, B2, B3 Comparison Areas

Claims

1. A first beamforming unit performs a first beamforming process on reflected wave signals output from multiple oscillators that receive reflected waves, A second beamforming unit performs a second beamforming process on the reflected wave signal that is different from the first beamforming process, A calculation unit that calculates an evaluation value showing the correlation between the reflected wave signals output from each of the different oscillators, A third beamforming unit performs a third beamforming process based on the first processing result, which is the processing result of the first beamforming unit, the second processing result, which is the processing result of the second beamforming unit, and the evaluation value. Equipped with, The third beamforming unit performs the third beamforming process, which combines the first processing result and the second processing result according to a synthesis ratio corresponding to the evaluation value. Ultrasound diagnostic equipment.

2. A first beamforming unit that performs a first beamforming process on reflected wave signals output from a plurality of oscillators that receive reflected waves, A second beamforming unit performs a second beamforming process on the reflected wave signal that is different from the first beamforming process, A calculation unit that calculates an evaluation value showing the correlation between the reflected wave signals output from each of the different oscillators, The system includes a third beamforming unit that performs a third beamforming process based on a first processing result, which is the processing result of the first beamforming unit, a second processing result, which is the processing result of the second beamforming unit, and the evaluation value. The third beamforming unit performs the third beamforming process, which combines the first processing result to which a weighting coefficient is applied and the second processing result to which a weighting coefficient is applied, according to a synthesis ratio corresponding to the evaluation value. Ultrasound diagnostic equipment.

3. The system further includes an input section that accepts input specifying adjustment parameters for the weight coefficients. The ultrasound diagnostic apparatus according to claim 2.

4. A first beamforming unit that performs a first beamforming process on reflected wave signals output from a plurality of oscillators that receive reflected waves, A second beamforming unit performs a second beamforming process on the reflected wave signal that is different from the first beamforming process, A calculation unit that calculates an evaluation value showing the correlation between the reflected wave signals output from each of the different oscillators, The system includes a third beamforming unit that performs a third beamforming process based on a first processing result, which is the processing result of the first beamforming unit, a second processing result, which is the processing result of the second beamforming unit, and the evaluation value. The third beamforming unit executes the third beamforming process, selecting either the first processing result or the second processing result according to the evaluation value. Ultrasound diagnostic equipment.

5. The first beamforming unit performs a phase-correcting summation first beamforming process, which adds the reflected wave signals together by adding a delay time to each of the reflected wave signals corresponding to the timing at which each of the oscillators receives the reflected wave. An ultrasound diagnostic apparatus according to any one of claims 1 to 4.

6. The second beamforming unit performs a second beamforming process in which it adds a delay time to each of the reflected wave signals corresponding to the timing at which each of the transducers receives the reflected wave, and adjusts the amplitude using the reflected wave signal output by a transducer different from the transducer that output the reflected wave signal. An ultrasound diagnostic apparatus according to any one of claims 1 to 5.

7. The second beamforming unit performs one of the following second beamforming processes: DMAS (Delay-Multiply-and-Sum) method, Minimum Variance method, and Coherence Factor Beamforming method. The ultrasound diagnostic apparatus according to claim 6.

8. A first beamforming unit performs a first beamforming process on reflected wave signals output from multiple oscillators that receive reflected waves, A second beamforming unit performs a second beamforming process on the reflected wave signal that is different from the first beamforming process, A calculation unit that calculates an evaluation value showing the correlation between the reflected wave signals output from each of the different oscillators, A third beamforming unit performs a third beamforming process based on the first processing result, which is the processing result of the first beamforming unit, the second processing result, which is the processing result of the second beamforming unit, and the evaluation value. Equipped with, The system includes a third beamforming unit that performs a third beamforming process based on a first processing result, which is the processing result of the first beamforming unit, a second processing result, which is the processing result of the second beamforming unit, and the evaluation value. The third beamforming unit performs the third beamforming process, which combines the first processing result and the second processing result according to a synthesis ratio corresponding to the evaluation value. Image processing device.

9. A first beamforming unit that performs a first beamforming process on reflected wave signals output from a plurality of oscillators that receive reflected waves, A second beamforming unit performs a second beamforming process on the reflected wave signal that is different from the first beamforming process, A calculation unit that calculates an evaluation value showing the correlation between the reflected wave signals output from each of the different oscillators, The system includes a third beamforming unit that performs a third beamforming process based on a first processing result, which is the processing result of the first beamforming unit, a second processing result, which is the processing result of the second beamforming unit, and the evaluation value. The third beamforming unit performs the third beamforming process, which combines the first processing result to which a weighting coefficient is applied and the second processing result to which a weighting coefficient is applied, according to a synthesis ratio corresponding to the evaluation value. Image processing device.

10. A first beamforming unit that performs a first beamforming process on reflected wave signals output from a plurality of oscillators that receive reflected waves, A second beamforming unit performs a second beamforming process on the reflected wave signal that is different from the first beamforming process, A calculation unit that calculates an evaluation value showing the correlation between the reflected wave signals output from each of the different oscillators, The system includes a third beamforming unit that performs a third beamforming process based on a first processing result, which is the processing result of the first beamforming unit, a second processing result, which is the processing result of the second beamforming unit, and the evaluation value. The third beamforming unit executes the third beamforming process, selecting either the first processing result or the second processing result according to the evaluation value. Image processing device.

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