JP2024155565A - Ultrasound diagnostic equipment - Google Patents

Abstract

[Problem] To reduce deterioration in accuracy. [Solution] An ultrasound diagnostic device according to an embodiment includes a determination unit and a Doppler processing unit. The determination unit determines whether or not a scan is to be performed in a plurality of image display modes, including a Doppler mode in which ultrasonic waves are transmitted and received intermittently or continuously in one direction. When a scan is to be performed in the plurality of image display modes, the Doppler processing unit applies a finite impulse response (FIR) filter as a wall filter in the Doppler mode. [Selected Figure] Figure 1

Description

The embodiments disclosed in this specification and the drawings relate to an ultrasound diagnostic device.

In addition to collecting B-mode images in which the intensity of echoes from the imaging target is expressed by brightness, ultrasound diagnostic devices also have a Doppler mode for collecting Doppler images that show blood flow and tissue movement. Examples of Doppler modes include a pulsed wave Doppler (PWD) mode that transmits and receives ultrasound intermittently in one direction, and a continuous wave Doppler (CWD) mode that transmits and receives ultrasound continuously in one direction. In these Doppler modes, if the Doppler time series data contains a signal near a DC component with a large signal strength, the dynamic range of the signal is insufficient. Therefore, a high pass filter (HPF) is often applied as a so-called wall filter before obtaining the results of frequency analysis by FFT (Fast Fourier Transform). An infinite impulse response (IIR) type filter is often applied as a wall filter, but it has the disadvantage of being difficult to predict the transient response.

For example, in an imaging method (so-called Duplex) in which B-mode and pulse Doppler modes are used together to simultaneously display B-mode and Doppler images, ultrasonic waves for Doppler mode cannot be transmitted or received during the period in which ultrasonic waves for B-mode are transmitted or received, resulting in a dead zone for Doppler mode reception. Therefore, when an IIR type filter is used as the wall filter, data in the transient response region cannot be used as data for the Doppler image, resulting in a problem of degraded accuracy of the Doppler waveform.

JP 2014-018392 A

One of the problems that the embodiments disclosed in this specification and the drawings aim to solve is the ability to reduce deterioration in accuracy. However, the problems that the embodiments disclosed in this specification and 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 below can also be positioned as other problems.

The ultrasound diagnostic device according to this embodiment includes a determination unit and a Doppler processing unit. The determination unit determines whether or not a scan is to be performed using multiple image display modes, including a Doppler mode in which ultrasound is transmitted and received intermittently or continuously in one direction. When a scan is to be performed using the multiple image display modes, the Doppler processing unit applies a finite impulse response (FIR) filter as a wall filter in the Doppler mode.

FIG. 1 is a block diagram showing an example of the configuration of an ultrasonic diagnostic apparatus. FIG. 2 is a flowchart showing an example of the operation of the ultrasonic diagnostic apparatus. FIG. 3 is a diagram showing a comparison example between an FIR filter and an IIR filter. FIG. 4 is a diagram showing an example of a Doppler waveform obtained by the ultrasound diagnostic apparatus according to this embodiment and an example of a Doppler waveform obtained by the IIR type technique.

The ultrasound diagnostic device according to this embodiment will be described below with reference to the drawings. In the following embodiment, parts with the same reference numerals perform similar operations, and duplicated descriptions will be omitted as appropriate.

Fig. 1 is a diagram showing an example of the configuration of an ultrasound diagnostic device according to this embodiment. The ultrasound diagnostic device 1 in Fig. 1 has an apparatus main body 100 including a probe control device, and an ultrasound probe 101. The apparatus main body 100 is connected to an input device 102 and an output device 103. The apparatus main body 100 is also connected to an external device 104 via a network NW. The external device 104 is, for example, a server equipped with a PACS (Picture Archiving and Communication Systems) and a workstation capable of performing post-processing.

The ultrasonic probe 101 performs an ultrasonic scan of a scan area in a living body P, which is a subject, according to control from the device main body 100, for example. The ultrasonic probe 101 has, for example, an acoustic lens, one or more matching layers, multiple transducers (piezoelectric elements), and a backing material. The acoustic lens is formed of, for example, silicone rubber, and focuses an ultrasonic beam. The one or more matching layers perform impedance matching between the multiple transducers and the living body. The backing material prevents the propagation of ultrasonic waves backward in the radiation direction from the multiple transducers. The ultrasonic probe 101 is assumed to be, for example, a linear probe or a convex probe, but may also be a radial probe capable of 360-degree scanning. The ultrasonic probe 101 is detachably connected to the device main body 100. The ultrasonic probe 101 may be provided with a button that is pressed during offset processing and an operation to freeze an ultrasonic image (freeze operation).

The multiple transducers generate ultrasonic waves based on a drive signal supplied from an ultrasonic transmission circuit 110 (described later) of the device main body 100. This causes ultrasonic waves to be transmitted from the ultrasonic probe 101 to the living body P. When ultrasonic waves are transmitted from the ultrasonic probe 101 to the living body P, the transmitted ultrasonic waves are reflected one after another at discontinuous surfaces of acoustic impedance in the body tissue of the living body P, and are received as echo signals by the multiple piezoelectric transducers. The amplitude of the received echo signal depends on the difference in acoustic impedance at the discontinuous surface where the ultrasonic waves are reflected. In addition, when the transmitted ultrasonic pulse is reflected by the surface of a moving blood flow or a heart wall, the echo signal undergoes a frequency shift due to the Doppler effect depending on the velocity component in the ultrasonic transmission direction of the moving body. The ultrasonic probe 101 receives the echo signal from the living body P and converts it into an electrical signal.

Figure 1 illustrates an example of the connection relationship between one ultrasonic probe 101 and the device main body 100. However, multiple ultrasonic probes can be connected to the device main body 100. Which of the multiple connected ultrasonic probes is to be used for ultrasonic scanning can be arbitrarily selected, for example, by using a software button on a touch panel described below.

The device body 100 is a device that generates an ultrasound image based on an echo signal received by an ultrasound probe 101. The device body 100 has an ultrasound transmission circuit 110, an ultrasound reception circuit 120, an internal storage circuit 130, an image memory 140, an input interface 150, an output interface 160, a communication interface 170, and a processing circuit 180.

The ultrasonic transmission circuit 110 is a processor that supplies a drive signal to the ultrasonic probe 101. The ultrasonic transmission circuit 110 is realized by, for example, a trigger generation circuit, a delay circuit, and a pulser circuit. The trigger generation circuit repeatedly generates a rate pulse for forming a transmission ultrasonic wave at a predetermined rate frequency. The delay circuit provides each rate pulse generated by the trigger generation circuit with a delay time for each of the multiple piezoelectric transducers required to focus the ultrasonic waves generated from the ultrasonic probe into a beam and determine the transmission directivity. The pulser circuit applies a drive signal (drive pulse) to the multiple ultrasonic transducers provided in the ultrasonic probe 101 at a timing based on the rate pulse. By changing the delay time provided to each rate pulse by the delay circuit, the transmission direction from the surface of the multiple piezoelectric transducers can be adjusted arbitrarily.

The ultrasound transmission circuit 110 can also change the output strength of the ultrasound as desired using the drive signal. In the ultrasound diagnostic device, the effect of ultrasound attenuation within the living body P can be reduced by increasing the output strength. By reducing the effect of ultrasound attenuation, the ultrasound diagnostic device can obtain an echo signal with a high signal-to-noise ratio (SNR) during reception.

Generally, when ultrasound propagates through a living body P, the strength of the ultrasound vibrations (also called acoustic power), which corresponds to the output intensity, attenuates. The attenuation of acoustic power occurs due to absorption, scattering, reflection, and the like. The degree of reduction in acoustic power also depends on the frequency of the ultrasound and the distance in the direction of ultrasound radiation. For example, the degree of attenuation increases by increasing the frequency of the ultrasound. Also, the longer the distance in the direction of ultrasound radiation, the greater the degree of attenuation.

The ultrasonic receiving circuit 120 is a processor that performs various processes on the echo signal received by the ultrasonic probe 101 to generate a received signal. The ultrasonic receiving circuit 120 generates a received signal for the echo signal of the ultrasonic wave acquired by the ultrasonic probe 101. Specifically, the ultrasonic receiving circuit 120 is realized by, for example, a preamplifier, an A/D converter, a demodulator, and a beamformer (adder). The preamplifier amplifies the echo signal received by the ultrasonic probe 101 for each channel and performs gain correction processing. The A/D converter converts the gain-corrected echo signal into a digital signal. The demodulator demodulates the digital signal. The beamformer, for example, gives the demodulated digital signal a delay time required to determine the reception directivity, and adds multiple digital signals to which the delay time has been given. The addition process of the beamformer generates a received signal in which the reflection component from the direction corresponding to the reception directivity is emphasized. The received signal may be called an IQ signal. Additionally, the ultrasonic receiving circuit 120 may store the received signal in an internal memory circuit 130 (described later) or output the signal to an external device 104 via a communication interface 170.

The internal storage circuit 130 has a processor-readable storage medium, such as a magnetic storage medium, an optical storage medium, or a semiconductor memory. The internal storage circuit 130 stores a program and various data for realizing ultrasonic transmission and reception. The program and various data may be stored in the internal storage circuit 130 in advance. The program and various data may be stored in a non-transient storage medium and distributed, and may be read from the non-transient storage medium and installed in the internal storage circuit 130. The internal storage circuit 130 also stores B-mode image data, contrast image data, and image data related to blood flow images generated by the processing circuit 180 according to an operation input via the input interface 150. The internal storage circuit 130 can also transfer the stored image data to an external device 104 or the like via the communication interface 170. The internal storage circuit 130 may store the reception signal (IQ signal) generated by the ultrasonic reception circuit 120, or may transfer the reception signal to an external device 104 or the like via the communication interface 170.

The internal memory circuit 130 may be a drive device that reads and writes various information between the internal memory circuit 130 and a portable storage medium such as a CD drive, a DVD drive, or a flash memory. The internal memory circuit 130 can also write the stored data to the portable storage medium and store the data in the external device 104 via the portable storage medium.

The image memory 140 has a processor-readable storage medium, such as a magnetic storage medium, an optical storage medium, or a semiconductor memory. The image memory 140 stores image data corresponding to a plurality of frames immediately before a freeze operation input via the input interface 150. The image data stored in the image memory 140 is displayed continuously (cine display), for example.

The above-mentioned internal memory circuit 130 and image memory 140 do not necessarily have to be realized by independent storage devices. The internal memory circuit 130 and image memory 140 may be realized by a single storage device. Furthermore, the internal memory circuit 130 and image memory 140 may each be realized by multiple storage devices.

The input interface 150 accepts various instructions from the operator via the input device 102. The input device 102 is, for example, a mouse, a keyboard, a panel switch, a slider switch, a trackball, a rotary encoder, an operation panel, and a touch command screen (TCS: Touch Command Screen). The input interface 150 is connected to the processing circuit 180 via, for example, a bus, converts the operation instructions input by the operator into electrical signals, and outputs the electrical signals to the processing circuit 180. Note that the input interface 150 is not limited to only those that connect to physical operation components such as a mouse and a keyboard. For example, a circuit that receives an electrical signal corresponding to an operation instruction input from an external input device provided separately from the ultrasound diagnostic device 1 and outputs the electrical signal to the processing circuit 180 is also included as an example of an input interface.

The output interface 160 is an interface for outputting, for example, an electrical signal from the processing circuit 180 to the output device 103. The output device 103 is any display such as a liquid crystal display, an organic EL display, an LED display, a plasma display, or a CRT display. The output device 103 may be a touch panel display that also serves as the input device 102. In addition to the display, the output device 103 may further include a speaker that outputs sound. The output interface 160 is connected to the processing circuit 180 via, for example, a bus, and outputs an electrical signal from the processing circuit 180 to the output device 103.

The communication interface 170 is connected to the external device 104, for example, via a network NW, and performs data communication with the external device 104.

The processing circuitry 180 is, for example, a processor that functions as the core of the ultrasound diagnostic device 1. The processing circuitry 180 executes a program stored in the internal storage circuitry 130 to realize a function corresponding to the program. The processing circuitry 180 has, for example, a B-mode processing function 181, a Doppler processing function 182, an image generation function 183, a judgment function 184, a display control function 186, and a system control function 187.

The B-mode processing function 181 is a function that generates B-mode data based on the reception signal received from the ultrasound receiving circuit 120. In the B-mode processing function 181, the processing circuit 180 performs, for example, envelope detection processing and logarithmic compression processing on the reception signal received from the ultrasound receiving circuit 120 to generate data (B-mode data) in which the signal strength is expressed as luminance brightness. The generated B-mode data is stored in a RAW data memory (not shown) as B-mode RAW data on a two-dimensional ultrasound scanning line (raster).

The Doppler processing function 182 is a function that performs frequency analysis on the received signal received from the ultrasound receiving circuit 120 to generate data (Doppler information) that extracts motion information based on the Doppler effect of a moving object within a region of interest (ROI) set in the scan area. The generated Doppler information is stored in a RAW data memory (not shown) as Doppler RAW data (also called Doppler data) on a two-dimensional ultrasound scan line.

Specifically, the processing circuitry 180 uses the Doppler processing function 182 to estimate, for example, the average velocity, average variance, average power value, etc., as motion information of a moving body at each of a plurality of sample points, and generates Doppler data indicating the estimated motion information. The moving body is, for example, blood flow, tissue such as a heart wall, or a contrast agent. In addition, the processing circuitry 180 uses the Doppler processing function 182 to estimate, for each of a plurality of sample points, the average velocity of blood flow, the variance value of blood flow velocity, the power value of blood flow signals, etc., as motion information of blood flow (blood flow information), and generates Doppler data indicating the estimated blood flow information.

The processing circuit 180, using the Doppler processing function 182, multiplies the received signal received from the ultrasound receiving circuit 120 by a reference frequency, which is a reference frequency for detecting Doppler shift, using quadrature detection processing, and applies a low-pass filter (LPF) to extract the Doppler shift. Then, using the Doppler processing function 182, the processing circuit 180 applies a gate to the signal of the area to be observed to extract the signal, and applies a wall filter to the extracted signal. Using the Doppler processing function 182, the processing circuit 180 applies A/D conversion processing and FFT processing to the signal after application of the wall filter to generate Doppler data.

Furthermore, the processing circuit 180 can execute a color Doppler method, also called a color flow mapping (CFM) method, by using the Doppler processing function 182. In the CFM method, ultrasonic waves are transmitted and received multiple times on multiple scanning lines. In the CFM method, for example, a moving target indicator (MTI) filter is applied to a data string at the same position to suppress signals (clutter signals) originating from stationary tissue or slow-moving tissue and extract signals originating from blood flow. In the CFM method, blood flow information such as blood flow speed, blood flow dispersion, and blood flow power is estimated using the extracted blood flow signal. The image generation function 183 described later generates the distribution of the estimated blood flow information as, for example, ultrasound image data (color Doppler image data) displayed in color in two dimensions. Note that color display is a display in which the distribution of blood flow information is displayed in correspondence with a predetermined color code, and grayscale is also included in color display.

There are various types of blood flow imaging modes depending on the desired clinical information. Generally, there is a blood flow imaging mode for velocity display, which can visualize the direction of blood flow and the average velocity of blood flow, and a blood flow imaging mode for power display, which can visualize the power of the blood flow signal.

The velocity display blood flow imaging mode is a mode that displays colors corresponding to the Doppler shift frequency according to the direction of blood flow and the average velocity of the blood flow. For example, the velocity display blood flow imaging mode shows the direction of flow as reddish colors for oncoming flows and blue colors for receding flows, and shows the difference in their velocities with different hues. The velocity display blood flow imaging mode is sometimes called the color Doppler mode or color Doppler imaging (CDI) mode.

The blood flow imaging mode for power display is, for example, a mode in which the power of the blood flow signal is represented by changes in red hue, color brightness (luminosity), or saturation. The blood flow imaging mode for power display is sometimes called a Power Doppler (PD) mode. The blood flow imaging mode for power display may be called a high-sensitivity blood flow imaging mode because it can depict blood flow with higher sensitivity than the blood flow imaging mode for velocity display.

The image generation function 183 is a function that generates B-mode image data based on data generated by the B-mode processing function 181. For example, in the image generation function 183, the processing circuitry 180 converts (scan converts) the scan line signal sequence of the ultrasound scan into a scan line signal sequence of a video format such as a television, and generates image data for display (display image data). Specifically, the processing circuitry 180 performs RAW-pixel conversion on the B-mode RAW data stored in the RAW data memory, for example, by performing coordinate conversion according to the ultrasound scanning form of the ultrasound probe 101, thereby generating two-dimensional B-mode image data (also called ultrasound image data) composed of pixels. In other words, the processing circuitry 180 generates a plurality of ultrasound images (medical images) corresponding to a plurality of consecutive frames by transmitting and receiving ultrasound through the image generation function 183.

The image generation function 183 also has a function of generating Doppler waveform data and Doppler image data based on the data generated by the Doppler processing function 182. For example, the image generation function 183 generates Doppler image data in which blood flow information is visualized by performing RAW-pixel conversion on the Doppler RAW data stored in the RAW data memory. The Doppler image data is average velocity image data, variance image data, power image data, or image data that combines these. The processing circuit 180 generates, as the Doppler image data, color Doppler image data in which blood flow information is displayed in color, and Doppler image data in which one piece of blood flow information is displayed in a grayscale wave shape. The color Doppler image data is generated when the blood flow imaging mode described above is executed.

The determination function 184 determines whether or not a scan is to be performed using multiple image display modes, including a Doppler mode in which ultrasound is transmitted and received intermittently or continuously in one direction, i.e., a Doppler mode based on the PWD method (hereinafter referred to as the PWD mode) or a Doppler mode based on the CWD method (hereinafter referred to as the CWD mode).
The setting function 185 sets parameters of the wall filter according to the shape of the Doppler waveform depicted in the Doppler mode. Specifically, the setting function 185 sets the number of filter taps, the filter coefficient, and the cutoff frequency as parameters of the wall filter so that the noise generated in the Doppler waveform is equal to or lower than a threshold. The processing of the setting function 185 may be executed as a part of the Doppler processing function 182.

The display control function 186 is a function that causes an image based on various ultrasound image data generated by the image generation function 183 to be displayed on a display serving as the output device 103. Specifically, for example, the processing circuitry 180 uses the display control function 186 to control the display on the display of an image based on B-mode image data, Doppler waveform data, Doppler image data, or image data including all of these generated by the image generation function 183.

More specifically, the processing circuitry 180 converts (scan converts) a scan line signal sequence of an ultrasonic scan into a scan line signal sequence of a video format represented by a television or the like, using the display control function 186, and generates display image data. The processing circuitry 180 may also execute various processes, such as dynamic range, brightness, contrast, and gamma curve correction, as well as RGB conversion, on the display image data. The processing circuitry 180 may also add supplementary information, such as character information of various parameters, scales, and body marks, to the display image data. The processing circuitry 180 may also generate a user interface (GUI: Graphical User Interface) for an operator to input various instructions via an input device, and display the GUI on a display.
The system control function 187 is a function that controls the overall operation of the ultrasound diagnostic apparatus 1 .

Next, an example of the operation of the ultrasound diagnostic device according to this embodiment will be described with reference to the flowchart in FIG.

In step SA1, the processing circuit 180 determines whether multiple image display modes are set by the determination function 184. In other words, it determines whether different types of image display modes, such as M mode, B mode, PWD mode or CWD mode, and color Doppler mode, are imaging methods that allow parallel display in real time, so-called Duplex or Triplex imaging. If multiple image display modes are set as the imaging mode by the determination function 184, the processing circuit 180 proceeds to step SA2. On the other hand, if an imaging mode with a single image display mode, such as only B mode or only PWD mode, is set rather than multiple image display modes, the processing circuit 180 proceeds to step SA4.

In step SA2, the processing circuitry 180 uses the determination function 184 to determine whether the multiple image display modes include PWD mode or CWD mode. If PWD mode or CWD mode is included, the process proceeds to step SA3. On the other hand, if PWD mode or CWD mode is not included, that is, if Duplex between B mode and color Doppler mode is set, there is no need to set a wall filter according to PWD mode or CWD mode, and the process ends.

In step SA3, the processing circuitry 180 uses the setting function 185 to set an FIR (Finite Impulse Response) filter as the wall filter to be used in the Doppler processing function 182. This is because, since there are multiple image display modes including the PWD mode and the CWD mode, a filter that is less affected by the transient response region is used.

In step SA4, the processing circuit 180 determines whether the image display mode is the PWD mode or the CWD mode using the determination function 184. If the image display mode is the PWD mode or the CWD mode, the process proceeds to step SA5. If the image display mode is not the PWD mode or the CWD mode, the process ends because there is no need to set a wall filter according to the PWD mode or the CWD mode.

In step SA5, the processing circuitry 180 uses the setting function 185 to set an infinite impulse response (IIR) filter as the wall filter to be used in the Doppler processing function 182. This is because, unlike multiple image display modes, there is little effect of transient response, and therefore a filter with good shoulder characteristics can be used.

Next, a comparison example between the FIR filter and the IIR filter will be described with reference to FIG.
3A illustrates a scan period of an image display mode in a triplex in which three image display modes, namely, B mode (B), PWD mode, and color Doppler mode (CDI), are displayed in parallel in real time. The scan period of the PWD mode can also be called a wall filter application period. Note that, although the PWD mode is used as an example here, the CWD mode can be processed in the same manner as the PWD mode.

Figure 3(b) shows the PWD actual data interval 34 and the estimated interval 33 when an FIR filter is used during the scanning period in PWD mode used in the ultrasound diagnostic device 1 according to this embodiment. On the other hand, Figure 3(c) shows the PWD actual data interval 34 and the estimated interval 36 when an IIR filter is used during the scanning period in PWD mode.

As shown in FIG. 3(a), a B-mode or color Doppler mode scan period 31 exists between adjacent PWD mode scan periods, so PWD mode scans cannot be performed during the B-mode or color Doppler mode scan period 31. Therefore, the B-mode or color Doppler mode scan period 31 is a reception dead zone for the PWD mode. Therefore, it is necessary to estimate and interpolate the PWD mode scan data during the reception dead zone.

In this case, the advantage of the wall filter is that it plays a role in reducing discontinuity between estimated data in the reception dead zone and the actual data actually acquired in PWD mode. On the other hand, when applying the wall filter, due to the filter characteristics of the wall filter, the first few data samples are acquired in the transient response region (timing during the transient response), so considering the deterioration of the accuracy of the Doppler waveform, it is desirable not to use data in the transient response region. In other words, the first few samples when switching from another image display mode to PWD mode are not used to generate the Doppler waveform.

Here, the transient response period 32 of the wall filter in FIG. 3(b) of this embodiment, i.e., the FIR filter, which is applied when there is a reception dead section, is shorter than the transient response period 35 in FIG. 3(c) of the IIR type.
3B according to this embodiment, the actual PWD data section 34 available for generating a Doppler waveform is longer than that of the IIR type shown in FIG. 3C. This makes it possible to perform waveform estimation while reducing the amount of data discarded in the actual PWD data section 34, and also improves the accuracy of the Doppler waveform because the actual PWD data section is longer.

Next, an example of a Doppler waveform obtained by the ultrasonic diagnostic device 1 according to this embodiment and an example of a Doppler waveform obtained by the IIR type technique will be described with reference to FIG.
4A is an example of a Doppler waveform obtained by the ultrasound diagnostic device 1 according to the present embodiment when there is a reception dead section in the PWD mode or the CWD mode. FIG. 4B is an example of a Doppler waveform obtained by the IIR type method when there is a reception dead section in the PWD mode or the CWD mode.

The Doppler waveform shown in Fig. 4(a) uses a larger number of data samples than the Doppler waveform shown in Fig. 4(b), and therefore it can be seen that the impulse-like noise is reduced more in the region 41 shown in Fig. 4(a) than in the region 42 shown in Fig. 4(b).
In addition, the set values of the parameters of the FIR filter when there is a reception dead section may be default values or may be variable according to a user instruction. Since the set values of the parameters of the FIR filter are determined by, for example, the number of taps of the filter, the filter coefficient, and the cutoff frequency, the user may change at least one of the number of taps of the filter, the filter coefficient, and the cutoff frequency while visually checking the Doppler waveform displayed on the display so as to obtain a desired Doppler waveform.

Alternatively, the parameters of the FIR filter may be set using a trained model. For example, the imaging target information is used as input data, and training data is prepared in which the parameters related to the number of taps, filter coefficients, and cutoff frequency of the FIR filter determined by the user when the user-desired Doppler waveform shape is obtained are paired with the correct answer data. The imaging target information includes, for example, patient information such as the patient's gender, age, and medical history, and information such as the imaging target part. The trained model may be generated by training the network model by supervised learning using the training data. The network model may be a model commonly used in machine learning, such as a neural network or a convolutional neural network (CNN), and details of the model will be omitted. In addition, a general machine learning method may be used for the supervised learning method, and therefore a description thereof will be omitted here.

When inferring using the trained model, the imaging subject information is input into the trained model, which outputs the setting values for the FIR filter parameters. This allows users, regardless of their skill level, to easily obtain the FIR filter parameters to obtain the optimal Doppler waveform shape from the imaging subject information.

According to the present embodiment described above, in multiple image display modes such as Duplex and Triple including PWD mode or CWD mode, an FIR filter is applied as a wall filter used in PWD mode or CWD mode. This allows the transient response period to be estimated shorter than when an IIR filter is used, and therefore allows a larger number of data samples to be used when generating a Doppler waveform. This reduces deterioration in accuracy of the Doppler waveform, and allows the generation of a good Doppler waveform with high visibility.

The wall filter setting process according to the above embodiment is performed by the processing circuit 180 of the device main body 100, but is not limited to this. For example, it can be similarly applied to an ultrasound diagnostic device that is composed of an ultrasound probe 101 equipped with a processing circuit 180 and an external display. That is, the processing circuit 180 in the ultrasound probe 101 determines whether there is a reception dead zone, and performs the above-mentioned wall filter setting process, thereby reducing deterioration in accuracy of the Doppler waveform displayed on the external display.

The term "processor" used in the above description means a circuit such as a CPU (Central Processing Unit), a GPU (Graphics 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)). When the processor is a CPU, for example, the processor realizes a function by reading and executing a program stored in a memory circuit. On the other hand, when the processor is an ASIC, for example, instead of storing the program in a memory circuit, the function is directly incorporated as a logic circuit in the circuit of the processor. Note that each processor in this embodiment is not limited to being configured as a single circuit for each processor, but may be configured as a single processor by combining multiple independent circuits to realize its function. Furthermore, multiple components in the figure may be integrated into a single processor to realize its function.

In addition, each function according to the embodiment can be realized by installing a program that executes the above-mentioned processes in a computer such as a workstation and expanding the program in memory. In this case, the program that can cause the computer to execute the above-mentioned methods can also be stored and distributed on a storage medium such as a magnetic disk (such as a hard disk), an optical disk (such as a CD-ROM or DVD), or a semiconductor memory.

Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are within the scope of the invention and its equivalents as set forth in the claims, as well as the scope and spirit of the invention.

REFERENCE SIGNS LIST 1 Ultrasound diagnostic device 31 Scan period 32, 35 Transient response period 33, 36 Estimation period 34 PWD actual data period 40 Ultrasound image 4142 Area 100 Device body 101 Ultrasound probe 102 Input device 103 Output device 104 External device 110 Ultrasound transmission circuit 120 Ultrasound reception circuit 130 Internal storage circuit 140 Image memory 150 Input interface 160 Output interface 170 Communication interface 180 Processing circuit 181 B-mode processing function 182 Doppler processing function 183 Image generation function 184 Determination function 185 Setting function 186 Display control function 187 System control function NW Network

Claims (5)

a determination unit that determines whether or not a scan is to be performed using a plurality of image display modes, including a Doppler mode in which ultrasonic waves are intermittently or continuously transmitted and received in one direction;
a Doppler processing unit that applies a finite impulse response (FIR) filter as a wall filter in the Doppler mode when scanning in the plurality of image display modes is performed;
An ultrasound diagnostic device comprising: The ultrasound diagnostic device according to claim 1, further comprising a setting unit that sets parameters of the FIR filter according to the shape of the Doppler waveform depicted in the Doppler mode. The ultrasound diagnostic device according to claim 2, wherein the setting unit sets the number of taps and the cutoff frequency of the FIR filter so that noise occurring in the Doppler waveform is equal to or less than a threshold value. The ultrasound diagnostic device of claim 1, wherein the Doppler mode is a pulsed Doppler mode or a continuous wave Doppler mode. The ultrasonic diagnostic apparatus according to claim 1 , wherein the Doppler processing unit applies an infinite impulse response (IIR) filter as a wall filter in the Doppler mode when a scan is performed in only the Doppler mode.