JP2024113583A - Ultrasonic diagnostic apparatus and method for processing medical data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a frame rate while reducing noise.

SOLUTION: An ultrasonic diagnostic apparatus includes a switching part, an acquisition part and a removal part. The switching part switches an ultrasonic transmission/reception switch to a reception side from a transmission side in a blank period in which an ultrasonic wave is neither transmitted nor received. The acquisition part acquires noise data including switching noise due to switching of the transmission/reception switch in the blank period. The removal part removes noise from reception data using the noise data in an ultrasonic transmission/reception period that is subsequent to a blank period.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The embodiments disclosed in this specification and the drawings relate to an ultrasound diagnostic device and a medical data processing method.

In recent years, due to the miniaturization of ultrasound diagnostic devices, devices that integrate an ultrasound transmission/reception circuit and a transmission/reception switch (TR switch) are being used. In such devices, noise synchronized with the rate may be included in the received data, causing artifacts due to the noise to appear in the ultrasound image. Noise synchronized with the rate is, for example, switching noise of a TR switch that is switched for each rate.

Switching noise mixed into the received data appears as an artifact near the probe in the ultrasound image (e.g., about 1 cm from the body surface). When diagnosing conditions near the body surface, such as rheumatism, this artifact may overlap with the affected area. Therefore, it is undesirable for noise to be mixed into the received data, as it interferes with diagnosis.

Conventionally, a method for removing the above-mentioned noise has been to obtain noise data for each raster when ultrasound is not transmitted at the first rate (first rate), obtain biometric data when ultrasound is transmitted at the subsequent second rate (second rate), and remove the noise by taking the difference between the noise data and the biometric data. However, with this method, two rates are required to create one raster data, so the frame rate is half that of when noise removal is not performed.

JP 2017-153814 A

One of the problems that the embodiments disclosed in this specification and the drawings attempt to solve is to maintain the frame rate while reducing noise. However, the problems that the embodiments disclosed in this specification and the drawings attempt to solve are not limited to the above problem. Problems that correspond 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 the embodiment includes a switching unit, an acquisition unit, and a removal unit. The switching unit switches the ultrasound transmission/reception switch from the transmission side to the reception side during a blank period in which ultrasound is not transmitted or received. The acquisition unit acquires noise data including switching noise caused by switching of the transmission/reception switch during the blank period. The removal unit removes noise from the received data using the noise data during the ultrasound transmission/reception period following the blank period.

FIG. 1 is a block diagram showing an example of the configuration of an ultrasound diagnostic apparatus according to an embodiment. FIG. 2 is a block diagram showing an example of the configuration of an ultrasonic transmission/reception circuit according to an embodiment. FIG. 3 is a flowchart for explaining the operation of a processing circuit that executes noise removal processing in the embodiment. FIG. 4 is a time chart illustrating the noise removal process in the embodiment. FIG. 5 is a block diagram showing an example of the configuration of a signal processing circuit according to the embodiment. FIG. 6 is a time chart for explaining the control of the signal processing circuit in the embodiment. FIG. 7 is a schematic diagram for explaining received data that has been subjected to noise removal processing in the embodiment. FIG. 8 is a time chart illustrating the noise removal process in an application example of the embodiment. FIG. 9 is a time chart for explaining a conventional noise removal process.

First, the flow from booting up the ultrasound diagnostic device to starting a scan will be explained. When the power is turned on, the ultrasound diagnostic device first performs initialization settings. In the initialization settings, for example, parameters such as element position information are set for the connected ultrasound probe. After the initialization settings are performed, the ultrasound diagnostic device accepts input from the user regarding the examination area and patient information, and completes preparations to start the examination.

When the ultrasound diagnostic device receives an instruction from the user to start an examination, it sets parameters for transmitting and receiving ultrasound each time it transmits and receives ultrasound for any scan line (raster), and transmits and receives ultrasound using the set parameters.

In this specification, for any raster, a period for setting parameters related to the transmission and reception of ultrasound is referred to as a blank period, and a period for transmitting and receiving ultrasound is referred to as a transmission and reception period. Furthermore, a repetition period defined by a blank period and a transmission and reception period following the blank period is referred to as a rate. Note that, since ultrasound is not transmitted or received during a blank period, the blank period may also be referred to as a period during which ultrasound is not transmitted or received. Furthermore, a rate may also be referred to as a frame.

The transmission/reception period may be divided into a transmission period and a reception period. The transmission period is a period for transmitting ultrasonic waves. The transmission period may also be rephrased as a period during which transmission of ultrasonic waves is permitted (period during which ultrasonic waves can be transmitted). The reception period is a period for receiving ultrasonic waves. The reception period may also be rephrased as a period during which reception of ultrasonic waves is permitted (period during which ultrasonic waves can be received).

Next, we will explain switching noise related to the transmit/receive switch. The transmit/receive switch is a switch that physically switches between the ultrasonic transmission circuit and the ultrasonic reception circuit connected to the ultrasonic probe. Switching noise occurs when the transmit/receive switch is switched from the receiving side to the transmitting side, or when the transmit/receive switch is switched from the transmitting side to the receiving side.

For example, if the transmit/receive switch and ultrasonic receiving circuit are configured as an integrated device, when the transmit/receive switch is switched from the transmitting side to the receiving side, switching noise may be mixed into the ultrasonic reception data received by the ultrasonic receiving circuit. If switching noise is mixed into the reception data, it will appear as an artifact in the ultrasound image when it is generated from the reception data. Hereinafter, when the term "switching noise" is used simply, it will be understood to mean "noise that occurs when the transmit/receive switch is switched from the transmitting side to the receiving side."

Next, a conventional noise removal process for the switching noise will be described with reference to FIG. 9. FIG. 9 is a time chart for explaining the conventional noise removal process. In the time chart 900 of FIG. 9, a waveform 910 indicating the position of the transmission/reception switch (TR switch), a waveform 920 indicating ON/OFF of the transmission control, and a waveform 930 indicating ON/OFF of the reception control are shown for each time of the first rate and the second rate related to two ultrasonic transmissions and receptions adjacent in time. To summarize FIG. 9 first, the time chart 900 shows that the ultrasound diagnostic device acquires noise at the first rate and removes noise contained in the reception data at the second rate following the first rate.

In the time chart 900, the first rate includes a blank period, a transmission period, and a reception period. The blank period is the period from time t10 to time t20. The transmission period is the period from time t20 to time t30. The reception period is the period from time t30 to time t40. Therefore, the first rate is the period from time t10 to time t40.

At time t10, the ultrasound diagnostic device sets the TR switch to the receiving side. The ultrasound diagnostic device also sets the transmission control and reception control to OFF. During the blank period, the transmission control and reception control are not set to ON. The reason that the transmission control and reception control are not set to ON is because there is no need to transmit or receive ultrasound during the blank period.

At time t20, the ultrasound diagnostic device switches the TR switch from the receiving side to the transmitting side. This switching puts the ultrasound diagnostic device into a transmission period, but since only noise is acquired at the first rate, the transmission control remains set to OFF. Therefore, during the transmission period at the first rate, the ultrasound diagnostic device does not transmit ultrasound.

At time t30, the ultrasound diagnostic device switches the TR switch from the transmitting side to the receiving side. This switching puts the ultrasound diagnostic device into a reception period. The ultrasound diagnostic device also sets reception control from OFF to ON. During the reception period of the first rate, the ultrasound diagnostic device acquires noise, including switching noise, generated when the TR switch is switched from the transmitting side to the receiving side, as noise data.

At time t40, the ultrasound diagnostic device sets the reception control to OFF and ends the first rate. After the first rate ends, it transitions to the second rate.

The second rate specifies the period from time t40 to time t50 as the blank period, the period from time t50 to time t60 as the transmission period, and the period from time t60 to time t70 as the reception period. Therefore, the second rate is the period from time t40 to time t70.

At time t40, the ultrasound diagnostic device sets the TR switch to the receiving side. The ultrasound diagnostic device also sets the transmission control and the reception control to OFF.

At time t50, the ultrasound diagnostic device switches the TR switch from the receiving side to the transmitting side. This switching puts the ultrasound diagnostic device into a transmission period. The ultrasound diagnostic device also sets the transmission control from OFF to ON. Therefore, during the second rate transmission period, the ultrasound diagnostic device transmits ultrasound.

At time t60, the ultrasound diagnostic device switches the TR switch from the transmitting side to the receiving side. This switching puts the ultrasound diagnostic device into a reception period. The ultrasound diagnostic device also sets the transmission control from ON to OFF and sets the reception control from OFF to ON. During the reception period at the second rate, the ultrasound diagnostic device acquires reception data associated with the transmission of ultrasound waves, on which noise including switching noise generated when the TR switch is switched from the transmitting side to the receiving side is superimposed. Furthermore, the ultrasound diagnostic device uses the noise data acquired at the first rate to remove noise from the reception data acquired at the second rate.

At time t70, the ultrasound diagnostic device sets the reception control to OFF and ends the second rate.

To summarize the above, in conventional noise removal processing, an ultrasound diagnostic device acquires noise for any raster at a first rate, and removes noise contained in the received data at a second rate subsequent to the first rate. Therefore, conventional noise removal processing can only output data at one of the two rates. In other words, conventional noise removal processing requires a rate at which ultrasonic waves are not transmitted or received (the first rate in FIG. 9 above), and therefore the frame rate is roughly half that of the case in which noise removal processing is not performed.

Below, an embodiment of an ultrasound diagnostic device will be described in detail with reference to the drawings.

(Embodiment)
Fig. 1 is a block diagram showing an example of the configuration of an ultrasound diagnostic apparatus according to an embodiment. The ultrasound diagnostic apparatus 1 in Fig. 1 includes an apparatus main body 100 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).

The ultrasonic probe 101 performs an ultrasonic scan of a scan area in a living body P, which is a subject, under the control of the device main body 100, for example. The ultrasonic probe 101 has, for example, a plurality of piezoelectric transducers, a matching layer provided between the plurality of piezoelectric transducers and a case, and a backing material that prevents the propagation of ultrasonic waves from the plurality of piezoelectric transducers in the backward direction of radiation. The ultrasonic probe 101 is, for example, a one-dimensional array linear probe in which a plurality of ultrasonic transducers are arranged along a predetermined direction. 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, an operation to freeze an ultrasonic image (freeze operation), and the like.

The multiple piezoelectric 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 the acoustic impedance in the body tissue of the living body P, and are received as reflected wave signals by the multiple piezoelectric transducers. The amplitude of the received reflected wave 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 reflected wave 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 reflected wave 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 a reflected wave signal received by an ultrasound probe 101. The device body 100 has an ultrasound transmission/reception circuit 200, an internal memory circuit 130, an image memory 140, an input interface 150, an output interface 160, a communication interface 170, and a processing circuit 180. First, the ultrasound transmission/reception circuit 200 will be described with reference to FIG. 2.

Figure 2 is a block diagram showing an example of the configuration of an ultrasonic transmission/reception circuit in an embodiment. The ultrasonic transmission/reception circuit 200 in Figure 2 includes an ultrasonic transmission circuit 110, an ultrasonic reception circuit 120, a transmission/reception switch 210 (TR switch), and a signal processing circuit 500.

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 waves 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 a reflected wave signal with a high S/N ratio when receiving.

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 reflected wave signal received by the ultrasonic probe 101 to generate a received signal. The ultrasonic receiving circuit 120 generates a received signal for the reflected wave 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, a beamformer, and the like. The preamplifier amplifies the reflected wave signal received by the ultrasonic probe 101 for each channel and performs gain correction processing. The A/D converter converts the gain-corrected reflected wave signal into a digital signal. The demodulator demodulates the digital signal. For example, the beamformer gives the demodulated digital signal a delay time required to determine the receiving directivity, and adds up multiple digital signals to which the delay time has been given. The addition process of the beamformer generates a receiving signal in which the reflected component from the direction corresponding to the receiving directivity is emphasized.

The transmission/reception switch 210 is a switch that physically switches between the ultrasonic transmission circuit 110 and the ultrasonic reception circuit 120 connected to the ultrasonic probe 101. In this specification, the state in which the ultrasonic probe 101 and the ultrasonic transmission circuit 110 are connected is referred to as the "state in which the transmission/reception switch 210 is on the transmission side," and the state in which the ultrasonic probe 101 and the ultrasonic reception circuit 120 are connected is referred to as the "state in which the transmission/reception switch 210 is on the reception side." For example, when the transmission/reception switch 210 is switched from the reception side to the transmission side, the ultrasonic probe 101 and the ultrasonic transmission circuit 110 are connected. Also, when the transmission/reception switch 210 is switched from the transmission side to the reception side, the ultrasonic probe 101 and the ultrasonic reception circuit 120 are connected. Note that instructions regarding the switching of the transmission/reception switch 210 are given by the function of the processing circuit 180, which will be described later.

The signal processing circuit 500 receives the reception signal (reception data) output from the ultrasonic receiving circuit 120, performs signal processing such as noise removal processing on the reception data, and outputs the signal-processed reception data (processed data) to the processing circuit 180. A detailed description of the signal processing circuit 500 will be given later.

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 for realizing ultrasonic transmission and reception, a program related to noise removal processing described later, and various data. The program and various data may be stored in the internal storage circuit 130 in advance, for example. 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 operations input via the input interface 150. The internal storage circuit 130 can also transfer the stored image data to an external device 104, etc. 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 internal memory circuit 130 and the image memory 140 do not necessarily have to be realized by independent storage devices. The internal memory circuit 130 and the image memory 140 may be realized by a single storage device. Furthermore, the internal memory circuit 130 and the 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 display control function 184, a switching function 185 (switching unit), an acquisition function 186 (acquisition unit), a removal function 187 (removal unit), and a system control function 188 (control unit).

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 processing circuitry 180 can also execute a contrast echo method, such as contrast harmonic imaging (CHI), by using the B-mode processing function 181. That is, the processing circuitry 180 can separate reflected wave data (harmonic components or sub-frequency components) of a living body P into which a contrast agent has been injected, and reflected wave data (fundamental wave components) whose reflection source is tissue within the living body P. This allows the processing circuitry 180 to extract harmonic components or sub-frequency components from the reflected wave data of the living body P, and generate B-mode data for generating contrast image data.

The B-mode data for generating the contrast image data is data that represents the signal strength of the reflected wave, which is reflected from the contrast agent, as brightness. The processing circuit 180 can also extract the fundamental wave component from the reflected wave data of the living body P to generate B-mode data for generating tissue image data.

When performing CHI, the processing circuitry 180 can extract harmonic components (higher harmonic components) using a method other than the above-mentioned filter processing method. Harmonic imaging uses an imaging method called the Amplitude Modulation (AM) method, Phase Modulation (PM) method, or the AMPM method, which is a combination of the AM method and the PM method.

In the AM, PM and AMPM methods, ultrasonic waves with different amplitudes and phases are transmitted multiple times along the same scan line. This causes the ultrasonic receiving circuit 120 to generate multiple pieces of reflected wave data for each scan line and output the generated reflected wave data. The processing circuit 180 uses the B-mode processing function 181 to perform addition and subtraction processing of the multiple pieces of reflected wave data for each scan line according to the modulation method, thereby extracting harmonic components. The processing circuit 180 then performs envelope detection processing and the like on the reflected wave data of the harmonic components to generate B-mode data.

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 ROI (Region Of Interest) that is set in the scan region. 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. The processing circuitry 180 according to the embodiment 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.

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. In the image generation function 183 described later, the distribution of the estimated blood flow information is generated as, for example, ultrasound image data (color Doppler image data) displayed in color in two dimensions. Hereinafter, the mode of the ultrasound diagnostic device using the color Doppler method is referred to as a blood flow image mode. Note that color display refers to displaying the distribution of blood flow information in accordance with a specified 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 power display blood flow imaging mode 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 power display blood flow imaging mode is sometimes called a Power Doppler (PD) mode. The power display blood flow imaging mode may be called a high-sensitivity blood flow imaging mode because it can depict blood flow with higher sensitivity than the velocity display blood flow imaging mode.

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 processing circuitry 180 also generates Doppler image data in which blood flow information is visualized, for example 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. As the Doppler image data, the processing circuitry 180 generates 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 display control function 184 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 184 to control the display on the display of an image based on image data including B-mode image data, Doppler image data, or both, generated by the image generation function 183.

More specifically, the processing circuitry 180 uses the display control function 184 to convert (scan convert) the scan line signal sequence of the ultrasound scan into a scan line signal sequence of a video format such as that of a television, etc., to generate display image data. The processing circuitry 180 may also perform various processes on the display image data, such as dynamic range, brightness, contrast, and gamma curve correction, as well as RGB conversion. The processing circuitry 180 may also add supplementary information, such as text 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 the operator to input various instructions using an input device, and display the GUI on a display.

The switching function 185 is a function that switches the transmission/reception switch 210. For example, in the switching function 185, the processing circuit 180 switches the transmission/reception switch 210 from the receiving side to the transmitting side, or from the transmitting side to the receiving side, based on a predetermined timing. Specifically, the processing circuit 180 switches the transmission/reception switch 210 from the transmitting side to the receiving side during a blank period in which ultrasonic waves are not transmitted or received. Also, the processing circuit 180 switches the transmission/reception switch 210 from the receiving side to the transmitting side during a transmission/reception period.

The acquisition function 186 is a function that acquires noise data and received data. For example, in the acquisition function 186, the processing circuit 180 acquires noise data and received data during a predetermined period. Specifically, the processing circuit 180 acquires noise data including switching noise caused by switching of the transmission/reception switch during a blank period. Furthermore, the processing circuit 180 acquires received data during a reception period. Note that the noise data may include power supply noise, etc.

The removal function 187 is a function that removes noise from the received data. For example, in the removal function 187, the processing circuit 180 removes noise from the received data using noise data acquired during a blank period during the transmission/reception period. Specifically, the processing circuit 180 removes noise by subtracting the noise data from the received data. Furthermore, the processing circuit 180 removes noise from the received data during the reception period. Furthermore, the processing circuit 180 removes noise from the received data during a period corresponding to the time length of the noise data. Note that the processing circuit 180 may remove noise from the received data acquired in real time. Furthermore, the noise data may be read from a memory.

Note that noise removal by the removal function 187 may be performed by controlling the signal processing circuit 500. For example, in the removal function 187, the processing circuit 180 controls the signal processing circuit 500 by outputting a control signal (corresponding to a memory selection signal and an output selection signal described later) to the signal processing circuit 500, thereby removing noise from the received data.

The system control function 188 is a function that controls the overall operation of the ultrasound diagnostic device 1. For example, in the system control function 188, the processing circuit 180 controls each part of the ultrasound diagnostic device 1 related to the transmission and reception of ultrasound. Specifically, the processing circuit 180 controls the transmission and reception of ultrasound. Note that in the system control function 188, the processing circuit 180 may also control the signal processing circuit 500.

The basic configuration of the ultrasound diagnostic device 1 according to the embodiment has been described above. Next, the operation of the ultrasound diagnostic device 1 according to the embodiment will be described using the flowchart in FIG. 3.

Figure 3 is a flowchart for explaining the operation of a processing circuit that executes noise removal processing in an embodiment. The noise removal processing in the embodiment acquires noise and removes noise contained in received data at one rate. Therefore, the explanation of the flowchart in Figure 3 will explain a series of steps for one rate.

In the flowchart of FIG. 3, the processes of steps ST110 and ST120 are performed in a blank period, and the processes of steps ST130 to ST170 are performed in a transmission/reception period. Therefore, in the explanation of each step, the descriptions such as "in a blank period" and "in a transmission/reception period" may be omitted. The noise removal process shown in FIG. 3 is started when a user gives an instruction to start an inspection.

(Step ST110)
When the noise removal process is started, the processing circuit 180 switches the transmission/reception switch 210 (TR switch) from the transmission side to the reception side during the blank period by the switching function 185 .

(Step ST120)
After switching the TR switch from the transmission side to the reception side, the processing circuit 180 acquires, by the acquisition function 186, noise data including switching noise caused by switching the TR switch.

(Step ST130)
After acquiring the noise data, the processing circuit 180 switches the TR switch from the receiving side to the transmitting side using the switching function 185 .

(Step ST140)
After switching the TR switch from the receiving side to the transmitting side, the processing circuit 180 starts transmitting ultrasonic waves.

(Step ST150)
After starting transmission of ultrasonic waves, the processing circuit 180 switches the TR switch from the transmission side to the reception side by the switching function 185 .

(Step ST160)
After the TR switch is switched from the transmission side to the reception side, the processing circuit 180 starts receiving ultrasonic waves. With the start of ultrasonic wave reception, the processing circuit 180 acquires reception data by the acquisition function 186.

(Step ST170)
After starting reception of ultrasonic waves, the processing circuitry 180 removes noise from the received data using the noise data by the removal function 187. After step ST170, the process ends.

The operation of the ultrasound diagnostic device 1 according to the embodiment has been described above. Next, the noise removal process according to the embodiment will be described using the time chart in FIG. 4.

Figure 4 is a time chart for explaining the noise removal process in the embodiment. In the time chart 400 of Figure 4, a waveform 410 showing the position of the transmit/receive switch (TR switch), a waveform 420 showing the ON/OFF of the transmission control, and a waveform 430 showing the ON/OFF of the reception control are shown for each time of the first rate. To summarize Figure 4, the time chart 400 shows that the ultrasound diagnostic device acquires noise at the first rate and removes the noise contained in the received data. Note that the blank period, transmission period, and reception period of the first rate are the same as those of the first rate of the time chart 900, so their explanations are omitted. Also, the transmission period and the reception period may partially overlap.

At time t10, the processing circuit 180 sets the TR switch to the receiving side, and sets the transmission control and reception control to OFF. At time t11, when a predetermined time has elapsed from time t10, the processing circuit 180 uses the switching function 185 to set the TR switch from the receiving side to the transmitting side. At time t12, when a predetermined time has elapsed from time t11, the processing circuit 180 uses the switching function 185 to switch the TR switch from the transmitting side to the receiving side (step ST110). Note that at time t10, the processing circuit 180 may set the TR switch to the transmitting side. In this case, it is not necessary to switch the TR switch at time t11.

During the blank period (at time t12 in FIG. 4), the TR switch is switched from the transmitting side to the receiving side, which causes the processing circuit 180 to set only the receiving control to ON while leaving the transmitting control OFF, and start acquiring noise data using the acquisition function 186 (step ST120). The noise data is acquired, for example, until time t20, when the blank period ends. Therefore, hereinafter, the period from time t12 to time t20 is referred to as the noise data acquisition period.

At time t20, the processing circuit 180 switches the TR switch from the receiving side to the transmitting side using the switching function 185 (step ST130). This switching triggers the processing circuit 180 to set the transmission control to ON and the reception control to OFF. The processing circuit 180 also starts transmitting ultrasound (step ST140).

At time t30, the processing circuit 180 switches the TR switch from the transmitting side to the receiving side by the switching function 185 (step ST150). This switching triggers the processing circuit 180 to set the transmission control to OFF and the reception control to ON. The processing circuit 180 also starts receiving ultrasonic waves and acquires the reception data by the acquisition function 186 (step ST160). In parallel with acquiring the reception data, the processing circuit 180 removes noise from the reception data by using the noise data by the removal function 187 (step ST170). The reception data is acquired, for example, until time t40 when the reception period ends.

The noise removal process in this embodiment has been described above. Next, the configuration of the signal processing circuit in this embodiment will be described using the block diagram in FIG. 5.

Figure 5 is a block diagram showing an example of the configuration of a signal processing circuit in an embodiment. The signal processing circuit 500 in Figure 5 is included in, for example, the ultrasonic transmission/reception circuit 200 in Figure 2. The signal processing circuit 500 includes a memory 510, a subtractor 520, and a multiplexer 530. The signal processing circuit 500 may be included in the ultrasonic reception circuit 120.

During the blank period, the signal processing circuit 500 inputs noise data including switching noise from the ultrasonic receiving circuit 120. During the reception period, the signal processing circuit 500 inputs reception data from the ultrasonic receiving circuit 120. During the reception period, the signal processing circuit 500 outputs to the processing circuit 180 processed data in which noise has been removed from the reception data using the noise data, or reception data that has not been processed (unprocessed data). The noise data and reception data input to the signal processing circuit 500 may be called input data (beam_in), and the processed data and unprocessed data output from the signal processing circuit 500 may be called output data (beam_out).

The memory 510 accepts input data from the ultrasonic receiving circuit 120. Specifically, during the blank period, the memory 510 inputs noise data as input data from the ultrasonic receiving circuit 120. The memory 510 also stores the noise data from the ultrasonic receiving circuit 120. Whether or not to store the noise data is controlled by a memory selection signal (mem_sel) from the processing circuit 180. For example, when the memory selection signal is "0" (disable), the memory 510 does not store noise data, and when the memory selection signal is "1" (enable), the memory 510 stores noise data. The memory 510 does not store the received data received as input data.

During the reception period, the subtractor 520 inputs the reception data from the ultrasonic receiving circuit 120 and the noise data from the memory 510. The subtractor 520 subtracts the noise data from the reception data and outputs the processed data from which the noise has been removed to the multiplexer 530.

The multiplexer 530 inputs noise data from the ultrasonic receiving circuit 120 during the blank period, and inputs received data (unprocessed data) and processed data during the receiving period. Whether or not to output any of the input data is controlled by an output selection signal (out_sel) from the processing circuit 180. For example, when the output selection signal is "0" (None), the multiplexer 530 outputs no data (or outputs zero data), when the output signal is "1" (beam_in), the multiplexer outputs unprocessed data, and when the output signal is "2" (out_sub), the multiplexer outputs processed data.

The configuration of the signal processing circuit in the embodiment has been described above. Next, the control of the signal processing circuit in the embodiment will be described using the time chart in Figure 6.

Figure 6 is a time chart for explaining the control of the signal processing circuit in the embodiment. In the time chart 600 of Figure 6, for each time of the first rate, a waveform 610 indicating the position of the transmission/reception switch (TR switch), a waveform 620 indicating ON/OFF of the transmission control, a waveform 630 indicating ON/OFF of the reception control, a waveform 640 indicating "0" or "1" of the memory selection signal (mem_sel), and a waveform 650 indicating "0", "1" or "2" of the output selection signal (out_sel) are shown. Note that the blank period, transmission period, and reception period in the first rate of the time chart 600 are the same as those in the first rate of the time chart 900, so their explanations are omitted. Also, the waveforms 610, 620, and 630 are the same as the waveforms 410, 420, and 430 of the time chart 400. The memory selection signal (mem_sel) and the output selection signal (out_sel) are explained below.

The memory selection signal (mem_sel) outputs "1" during the noise data acquisition period in the blank period (from time t12 to time t20), and outputs "0" during other periods (from time t10 to time t12, and from time t20 to time t40). Therefore, the memory 510 stores only the noise data acquired during the noise data acquisition period in accordance with the memory selection signal.

The output selection signal (out_sel) outputs "0" during periods other than the reception period (from time t10 to time t30), outputs "2" during the period from time t30 to time t31 when the period corresponding to the time length of the noise data (which is equal to the noise data acquisition period, for example) has elapsed, and outputs "1" during the period from time t31 to time t40. Thus, in accordance with the output selection signal, the multiplexer 530 outputs processed data during the period corresponding to the time length of the noise data within the reception period, outputs unprocessed data during other periods within the reception period, and outputs zero data outside the reception period.

The above describes the control of the signal processing circuit in the embodiment. Next, the received data that has been subjected to noise removal processing in the embodiment will be described using the schematic diagram in Figure 7.

Figure 7 is a schematic diagram for explaining received data that has been subjected to noise removal processing in an embodiment. Figure 7 shows (a) a waveform 710 of noise data, (b) a waveform 720 of received data including noise, and (c) a waveform 730 of received data from which noise has been removed.

Specifically, waveform 710 has a time length Δt. Time length Δt is the noise data acquisition period (the period from time t12 to time t20) in Figures 4 and 6, etc. Waveform 710 represents noise data of switching noise that occurred at time t12. Waveform 720 represents received data including switching noise that occurred at time t30. Waveform 730 represents received data from which noise has been removed using the noise data. Waveform 730 shows how the noise portion of waveform 720 (Δt = t31 - t30) has been reduced.

To summarize the above, in the noise removal process of the embodiment, the ultrasound diagnostic device acquires noise and removes noise contained in the received data at a rate defined for each raster. In particular, noise is acquired during a period when ultrasound is not transmitted or received. Therefore, the ultrasound diagnostic device in the embodiment can achieve noise removal at the same frame rate as when noise removal is not performed.

As described above, the ultrasound diagnostic device according to the embodiment switches the ultrasound transmission/reception switch from the transmission side to the reception side during a blank period in which ultrasound is not transmitted or received, acquires noise data including switching noise caused by switching the transmission/reception switch, and uses the noise data to remove noise from the received data during the ultrasound transmission/reception period following the blank period.

Therefore, the ultrasound diagnostic device according to the embodiment can maintain the frame rate while reducing noise by acquiring and removing noise within one rate. Furthermore, when the ultrasound diagnostic device according to the embodiment acquires and removes noise for each rate, for example, it can reduce the accumulation of fixed noise compared to when one noise data is reused for noise removal at multiple rates (for example, the rate required to generate one frame of ultrasound image).

(Application Example of the Embodiment)
The ultrasound diagnostic device according to the embodiment sets a blank period having a predetermined time length. On the other hand, the ultrasound diagnostic device according to the application example of the embodiment may change the blank period. Specifically, the ultrasound diagnostic device according to the application example of the embodiment sets a blank period longer than the normal blank period set by the ultrasound diagnostic device according to the embodiment.

In an application example of the first embodiment, the processing circuit 180 changes the blank period depending on at least one of the state of the inspection part and the noise data. For example, the processing circuit 180 may read out the blank period associated with the inspection part and set the read blank period. For another example, the processing circuit 180 may set the blank period depending on the time length of the noise data. If it is assumed that the majority of the noise data is switching noise, the processing circuit 180 may set the blank period according to the time length during which the switching noise is observed. In addition, the processing circuit 180 may set the blank period depending on the inspection mode.

Figure 8 is a time chart illustrating the noise removal process in an application example of the embodiment. The time chart 800 in Figure 8 shows, for each time of the first rate, a waveform 810 indicating the position of the transmit/receive switch (TR switch), a waveform 820 indicating ON/OFF of the transmit control, and a waveform 830 indicating ON/OFF of the receive control. In general, Figure 8 shows that the time chart 800 shows that the ultrasound diagnostic device acquires noise at the first rate and removes the noise contained in the received data.

In the time chart 800, the first rate includes a blank period, a transmission period, and a reception period. The blank period is the period from time t10 to time t20'. Time t20' is, for example, a time later than time t20. Therefore, the blank period in FIG. 8 is longer than a normal blank period such as in FIG. 4. The transmission period is the period from time t20' to time t30'. The reception period is the period from time t30' to time t40'. Therefore, the first rate is the period from time t10 to time t40'. Note that the transmission period and reception period in FIG. 8 are equal to the transmission period and reception period in FIG. 4.

During the blank period (at time t12 in FIG. 8), when the TR switch is switched from the transmitting side to the receiving side, the processing circuit 180 sets only the receiving control to ON while leaving the transmitting control OFF, and starts acquiring noise data using the acquisition function 186. The noise data is acquired, for example, until time t20' when the blank period ends. Therefore, in the application example of the embodiment, the period from time t12 to time t20' is called the noise data acquisition period.

The difference between time chart 400 and time chart 800 in FIG. 4 is the length of the noise data acquisition period. In time chart 400, the period from time t12 to time t20 is the noise data acquisition period. On the other hand, in time chart 800, the noise data acquisition period is longer than in time chart 400 by the time length t20'-t20. The extended time length also corresponds directly to the blank period. In other words, the blank period in time chart 800 is longer than in time chart 400 by the extended time length.

The time length of the noise data corresponds to, for example, the noise data acquisition period. When the noise data acquisition period is longer, noise data of a longer time length can be acquired. When the time length of the noise data is longer, the period for removing noise in the received data becomes longer. When focusing on switching noise, the time length of the noise data corresponds to the depth at which noise is removed in the ultrasound image. On the other hand, since the time during which switching noise can affect the ultrasound image is not long, the time length of the noise data may be determined, for example, according to the depth at which noise is to be removed in the ultrasound image (e.g., 5 cm).

As described above, the ultrasound diagnostic device according to the application example of the embodiment switches the ultrasound transmission/reception switch from the transmission side to the reception side during a blank period in which ultrasound is not transmitted or received, acquires noise data including switching noise caused by switching the transmission/reception switch, and removes noise from the received data using the noise data during the ultrasound transmission/reception period following the blank period. In addition, the ultrasound diagnostic device may change the blank period depending on either the state of the examination area or the state of the noise data.

Therefore, by extending the blank period, the ultrasound diagnostic device according to this application example can remove noise from deeper regions of the ultrasound image in areas or modes for which the frame rate is not important, compared to when the blank period is not extended. Even if the blank period is extended, the extended blank period is sufficiently small compared to the rate period. Therefore, the noise removal process of this application example can suppress a decrease in the frame rate compared to conventional noise removal processes.

According to at least one of the embodiments described above, it is possible to maintain the frame rate while reducing noise.

In addition, the term "processor" used in the above explanation refers to circuits such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an application specific integrated circuit (ASIC), 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)). If the processor is, for example, a CPU, the processor realizes the function by reading and executing a program stored in a memory circuit. On the other hand, if the processor is, for example, an ASIC, 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 the function. Furthermore, multiple components in the figure may be integrated into a single processor to realize the 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.

1 Ultrasonic diagnostic device 100 Device body 101 Ultrasonic probe 102 Input device 103 Output device 104 External device 110 Ultrasonic transmission circuit 120 Ultrasonic 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 Display control function 185 Switching function 186 Acquisition function 187 Removal function 188 System control function 200 Ultrasonic transmission/reception circuit 210 Transmission/reception switch 400, 600, 800, 900 Time chart 410, 420, 430, 610, 620, 630, 640, 650, 710, 720, 730, 810, 820, 830, 910, 920, 930 Waveform 500 Signal processing circuit 510 Memory 520 Subtractor 530 Multiplexer beam_in Input data beam_out Output data mem_sel Memory selection signal out_sel Output selection signal Δt Time length

Claims (11)

a switching unit that switches the ultrasonic transmission/reception switch from a transmission side to a reception side during a blank period in which ultrasonic waves are not transmitted or received;
an acquisition unit that acquires noise data including switching noise caused by switching of the transmission/reception switch during the blank period;
and a removal unit that removes noise from the reception data using the noise data during the ultrasound transmission/reception period following the blank period. The removal unit removes the noise by subtracting the noise data from the received data.
The ultrasonic diagnostic apparatus according to claim 1 . The removal unit removes the noise from the received data during a reception period of the transmission/reception period.
The ultrasonic diagnostic apparatus according to claim 1 . The removal unit removes the noise from the received data during a period corresponding to a time length of the noise data.
The ultrasonic diagnostic apparatus according to claim 1 . the blank period and the transmission/reception period are included in one rate defined for each raster,
The ultrasonic diagnostic apparatus according to claim 1 . The switching unit switches the transmission/reception switch from the receiving side to the transmitting side during the transmission/reception period,
The acquisition unit acquires the reception data during a reception period of the transmission/reception period.
The ultrasonic diagnostic apparatus according to claim 1 . The ultrasonic wave transmitting/receiving circuit further includes the transmitting/receiving switch.
The ultrasonic diagnostic apparatus according to claim 1 . a memory for storing the noise data during the blank period;
Further comprising:
the removal unit removes the noise from the received data by using the noise data read from the memory during the transmission/reception period.
The ultrasonic diagnostic apparatus according to claim 1 . The blank period is changed depending on the examination site.
The ultrasonic diagnostic apparatus according to claim 1 . The blank period is changed depending on the state of the noise data.
The ultrasonic diagnostic apparatus according to claim 1 . switching the ultrasonic transmission/reception switch from a transmission side to a reception side during a blank period in which ultrasonic waves are not transmitted or received;
acquiring noise data including switching noise caused by switching of the transmission/reception switch during the blank period;
removing noise from the received data using the noise data during the ultrasound transmission/reception period following the blank period.