Ultrasound diagnostic device, ultrasound diagnostic method, and ultrasound diagnostic program

Abstract

To improve saturation signal discrimination accuracy.SOLUTION: An ultrasonic diagnostic apparatus includes an extraction unit, a determination unit, and a generation unit. The extraction unit extracts an odd-order harmonic component from a reflection wave signal received by each element of an ultrasonic probe. The determination unit determines whether or not the reflection wave signal is saturated using the extracted odd-order harmonic component. The generation unit multiplies the reflection wave signal of the element determined to be saturated by a weighting coefficient, subjects the reflection wave signal multiplied by the weighting coefficient to phasing addition processing, and generates reflection wave data.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The embodiments disclosed in the present specification and drawings relate to an ultrasound diagnostic apparatus, an ultrasound diagnostic method, and an ultrasound diagnostic program. [Background technology]

[0002] In a typical ultrasound diagnostic device, an analog circuit performs various processes to visualize ultrasound reflected wave signals (echo signals) from a living body. The analog circuit may significantly amplify weak reflected wave signals from deep within the body to visualize the signals (e.g., harmonic imaging, imaging of blood flow with a small scattering coefficient). In such cases, the amplified signals exceed the dynamic range of the analog circuit, resulting in signal saturation. Signal saturation modulates the phase of the received echo, and its effects can be observed, for example, as an increase in sidelobe artifacts or the appearance of nonlinear components (high-brightness points) in the image. Therefore, to improve the visibility of images, it is necessary to reduce the effects of signal saturation on visualization while adequately maintaining biological information.

[0003] To achieve this objective, for example, a method is available in which a reflected wave signal received by each element of an ultrasound probe is determined to be saturated based on a threshold, and then the contribution of the reflected wave signal determined to be saturated is reduced to produce an image. However, in this method, a signal that is not actually saturated (a non-saturated signal) may be erroneously determined to be saturated (a saturated signal) in the threshold processing, which may reduce the contribution of the non-saturated signal. This reduces the number of elements contributing to the image (effective aperture), making it impossible to fully achieve the above-mentioned objective. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-55845 A Summary of the Invention [Problem to be solved by the invention]

[0005] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to improve the accuracy of discriminating between saturated signals. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of the configurations of the embodiments described below can also be positioned as other problems. [Means for solving the problem]

[0006] An ultrasound diagnostic apparatus according to an embodiment includes an extractor, a determiner, and a generator. The extractor extracts odd-order harmonic components from reflected wave signals received by each element of an ultrasound probe. The determiner uses the extracted odd-order harmonic components to determine whether the reflected wave signals are saturated. The generator multiplies the reflected wave signals of elements determined to be saturated by weighting coefficients and performs phased sum of the reflected wave signals multiplied by the weighting coefficients to generate reflected wave data. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an example of the arrangement of an ultrasound diagnostic apparatus according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the operation of the ultrasound diagnostic apparatus according to the first embodiment. [Figure 3] FIG. 3 is a diagram showing an example of the arrangement of an ultrasound diagnostic apparatus according to the second embodiment. [Figure 4] FIG. 4 is a diagram showing an example of the operation of the ultrasound diagnostic apparatus according to the second embodiment. [Figure 5] FIG. 5 is a diagram showing the results of determining whether a baseband signal is saturated in each element of each ultrasonic diagnostic apparatus according to the second embodiment and the conventional configuration. [Figure 6] FIG. 6 is a diagram showing the amplitude of a baseband signal at a central element of each ultrasonic diagnostic apparatus according to the second embodiment and a conventional configuration. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an ultrasonic diagnostic apparatus, an ultrasonic diagnostic method, and an ultrasonic diagnostic program according to embodiments will be described with reference to the drawings. In the following embodiments, parts with the same reference numerals perform similar operations, and redundant descriptions will be omitted as appropriate.

[0009] (First embodiment) FIG. 1 is a diagram showing an example of the configuration of an ultrasound diagnostic apparatus 1 according to the first embodiment. The ultrasound diagnostic apparatus 1 has 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 PACS (Picture Archiving and Communication Systems).

[0010] The ultrasonic probe 101 performs an ultrasonic scan of a scan region in a living body P, which is a subject, under the control of the device main body 100. The ultrasonic probe 101 includes, for example, a plurality of piezoelectric transducers (also referred to as "elements"), a matching layer provided between the plurality of piezoelectric transducers and a case, and a backing material that prevents ultrasonic waves from propagating backward in the transmission direction of the ultrasonic waves from the plurality of piezoelectric transducers. The ultrasonic probe 101 is, for example, a two-dimensional array probe in which a plurality of piezoelectric transducers are arranged along a first element array direction (elevation direction) and a second element array direction (azimuth direction). The ultrasonic probe 101 is detachably connected to the device main body 100. The ultrasonic probe 101 may also include a button that is pressed for offset processing and an operation to freeze an ultrasonic image (freeze operation).

[0011] The multiple piezoelectric transducers generate ultrasonic waves based on a drive signal supplied from the ultrasonic transmission circuit 110 of the device main body 100. This causes ultrasonic waves to be transmitted from the ultrasonic probe 101 to the living body P. The transmitted ultrasonic waves are reflected one after another by discontinuous surfaces of 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 signals depends on the difference in acoustic impedance at the discontinuous surfaces. Furthermore, when the transmitted ultrasonic waves are reflected by the surface of a moving object (e.g., red blood cells, heart wall, contrast agent), the reflected wave signals undergo a frequency shift due to the Doppler effect depending on the velocity component of the moving object in the ultrasonic transmission direction. The ultrasonic probe 101 receives the reflected wave signals from the living body P and converts them into electrical signals.

[0012] In this embodiment, one ultrasound probe 101 is connected to the device main body 100. In another embodiment, multiple ultrasound probes 101 are connected to the device main body 100. Which of the multiple connected ultrasound probes 101 is to be used for ultrasound scanning can be arbitrarily selected by using a software button on the touch panel.

[0013] The device main body 100 is a device that generates an ultrasound image based on a reflected wave signal received by an ultrasound probe 101. The device main 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.

[0014] The ultrasonic transmission circuit 110 is a processor that supplies a drive signal to the ultrasonic probe 101. The ultrasonic transmission circuit 110 is composed of, for example, a trigger generation circuit, a delay circuit, and a pulser circuit. The trigger generation circuit repeatedly generates rate pulses at a predetermined rate frequency to form transmitted ultrasonic waves. The delay circuit imparts a delay time to the generated rate pulse for each piezoelectric vibrator. By changing the delay time for each piezoelectric vibrator, the transmission direction of ultrasonic waves from the multiple piezoelectric vibrators can be adjusted arbitrarily. In other words, the delay circuit determines the transmission directivity of ultrasonic waves generated from the ultrasonic probe 101. The pulser circuit applies drive signals (drive pulses) to the multiple piezoelectric vibrators provided in the ultrasonic probe 101 at a timing based on the rate pulse.

[0015] Furthermore, the ultrasound transmission circuit 110 arbitrarily changes the output intensity of the transmitted ultrasound using a drive signal. For example, the ultrasound diagnostic device 1 increases the output intensity to reduce the influence of ultrasound attenuation within the living body P. This allows the ultrasound diagnostic device 1 to acquire a reflected wave signal with a large S / N (Signal / Noise) ratio during reception.

[0016] When ultrasonic waves propagate through a living body P, the strength of the ultrasonic vibrations (also called "acoustic power"), which corresponds to the output intensity, attenuates. The attenuation of acoustic power is caused by absorption, scattering, reflection, and the like. The degree of attenuation of acoustic power depends on the frequency and propagation distance of the ultrasonic waves. For example, the higher the frequency of the ultrasonic waves, the greater the degree of attenuation. Furthermore, the longer the propagation distance of the ultrasonic waves, the greater the degree of attenuation.

[0017] The ultrasonic receiving circuit 120 is a processor that performs various processes on the reflected wave signals received by the ultrasonic probe 101 to generate reflected wave data. Specifically, the ultrasonic receiving circuit 120 is realized by, for example, an amplifier circuit, an A / D (Analog / Digital) conversion circuit, a quadrature detection (IQ) circuit, and a generation circuit (also referred to as a "beamformer"). The amplifier circuit amplifies the reflected wave signals received by the ultrasonic probe 101 for each element and performs gain correction processing. The A / D conversion circuit converts the gain-corrected reflected wave signals into digital signals. The quadrature detection circuit converts the digital signals into in-phase signals (I signals, I: In-phase) and quadrature signals (Q signals, Q: Quadrature-phase) in the baseband. The I signals and Q signals are each an example of a baseband signal. The generation circuit imparts a delay time required to determine the reception directivity to the baseband signals and performs phasing and summing of multiple baseband signals (i.e., I signals and Q signals) that have been given the delay time. The generation circuit performs phasing and summing to generate reflected wave data in which signal components from a direction corresponding to the reception directivity are emphasized. The generated reflected wave data is transferred to the processing circuit 180.

[0018] The ultrasonic receiving circuit 120 is an example of an analog circuit. An ultrasonic receiving circuit 120 may be provided for each element, or one ultrasonic receiving circuit 120 may be provided for all elements.

[0019] In this embodiment, the ultrasonic receiving circuit 120 includes at least one processor. The term "processor" refers to a circuit such as a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), or a field programmable gate array (FPGA)). When the processor is a CPU, the processor realizes each function by reading and executing a program stored in the internal storage circuit 130. On the other hand, when the processor is an ASIC, instead of storing a program in the internal storage circuit 130, each function is directly incorporated as a logic circuit within the circuit of the processor. The processor may be configured as a single circuit or may be configured by combining multiple independent circuits. The ultrasonic wave receiving circuit 120 realizes various functions (for example, an extraction function 120A, an amplification function 120B, a determination function 120C, and a generation function 120D).

[0020] The extraction function 120A extracts odd-order harmonic components from the reflected wave signal received by each element of the ultrasonic probe 101. For example, the extraction function 120A extracts odd-order harmonic components from the reflected wave signal by applying frequency filtering processing that passes odd-order harmonic bands to the reflected wave signal received by each element of the ultrasonic probe 101. The extraction function 120A can be realized by a filter circuit.

[0021] The amplification function 120B amplifies the amplitude of the extracted odd-order harmonic components by a gain value. The gain value may be a predetermined value. Alternatively, the amplification function 120B may determine a gain value according to the amplitude of the extracted odd-order harmonic components and amplify the amplitude by the determined gain value. The amplification function 120B may be realized by an amplifier circuit.

[0022] The determination function 120C uses the extracted odd-order harmonic components to determine whether the reflected wave signal is saturated. For example, the determination function 120C determines that the reflected wave signal is saturated when the amplitude of the extracted odd-order harmonic components is equal to or greater than a threshold. In particular, when the extracted odd-order harmonic components are amplified, the determination function 120C determines that the reflected wave signal is saturated when the amplitude of the amplified odd-order harmonic components is equal to or greater than a threshold. The determination function 120C can be implemented by a comparison circuit.

[0023] The generation function 120D multiplies the reflected wave signals of the elements determined to be saturated by a weighting coefficient. The generation function 120D also generates reflected wave data by phasing and adding the reflected wave signals multiplied by the weighting coefficient. The generation function 120D can be realized by a generation circuit of the ultrasonic receiving circuit 120.

[0024] The internal storage circuitry 130 includes a processor-readable storage medium (e.g., a magnetic storage medium, an optical storage medium, or a semiconductor memory). The internal storage circuitry 130 stores various data, including programs related to ultrasound transmission and reception and image generation processing. The various data may be pre-stored in the internal storage circuitry 130. Alternatively, the various data may be stored in a non-transitory storage medium and distributed, and then read from the non-transitory storage medium and installed in the internal storage circuitry 130. The internal storage circuitry 130 also stores various data (e.g., B-mode image data, contrast image data, image data related to blood flow images, and three-dimensional data) generated by the processing circuitry 180 in accordance with operations input via the input interface 150. The internal storage circuitry 130 may transfer the various data to the external device 104 via the communication interface 170.

[0025] The internal storage circuit 130 may be a drive device that reads and writes various information from and to a portable storage medium (e.g., a CD drive, a DVD drive, or a flash memory). The internal storage circuit 130 may write stored data to the portable storage medium and store the data in the external device 104 via the portable storage medium.

[0026] The image memory 140 has a storage medium (e.g., a magnetic storage medium, an optical storage medium, or a semiconductor memory) that can be read by a processor. For example, the image memory 140 stores image data corresponding to multiple frames immediately before a freeze operation input via the input interface 150. The image data stored in the image memory 140 can be continuously displayed (cine display). The image memory 140 is not limited to storing image data, and may also store three-dimensional data.

[0027] The internal storage circuit 130 and the image memory 140 do not necessarily have to be realized by independent storage devices. The internal storage circuit 130 and the image memory 140 may be realized by a single storage device. Furthermore, the internal storage circuit 130 and the image memory 140 may each be realized by multiple storage devices.

[0028] The input interface 150 accepts various instructions from an operator via the input device 102. Examples of the input device 102 include a mouse, a keyboard, a panel switch, a slider switch, a trackball, a rotary encoder, an operation panel, and a touch panel. The input interface 150 is connected to the processing circuit 180 via a bus, for example, converts 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 those connected to physical operation components such as a mouse and a keyboard. For example, examples of the input interface 150 also include circuits that receive electrical signals corresponding to operation instructions input from an external input device provided separately from the ultrasound diagnostic apparatus 1 and output the received electrical signals to the processing circuit 180. The operator may be, for example, a doctor, a nurse, a licensed practical nurse, a diagnostic radiologist, or a clinical laboratory technician.

[0029] 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 a display, the output device 103 may also be a speaker that outputs audio. The output interface 160 is connected to the processing circuit 180 via, for example, a bus, and outputs the electrical signal from the processing circuit 180 to the output device 103.

[0030] The communication interface 170 is connected to the external device 104 via, for example, a network NW, and performs data communication with the external device 104 .

[0031] The processing circuitry 180 controls the overall operation of the ultrasound diagnostic device 1. In this embodiment, the processing circuitry 180 includes at least one processor. As mentioned above, the term "processor" refers to a circuit such as a CPU, a GPU, or an application-specific integrated circuit. Specifically, the processing circuitry 180 realizes each function (e.g., a B-mode processing function 181, a Doppler processing function 182, an image generation function 183, a three-dimensional data generation function 184, a display control function 185, and a system control function 186).

[0032] The B-mode processing function 181 is a function that generates B-mode data based on the reflected wave data transferred from the ultrasound receiving circuit 120. Specifically, the processing circuit 180 performs envelope detection processing, logarithmic compression processing, and the like on the reflected wave data using the B-mode processing function 181 to generate B-mode data in which the signal intensity of the reflected wave data is expressed as a brightness value. The generated B-mode data is stored in a RAW data memory (not shown) as B-mode RAW data on a two-dimensional ultrasound scan line (raster).

[0033] Furthermore, the processing circuitry 180 can perform harmonic imaging using a B-mode processing function 181. Harmonic imaging utilizes harmonic components among the various frequency components contained in the reflected ultrasonic wave signal. Harmonic imaging is classified into tissue harmonic imaging (THI), which does not use a contrast agent, and contrast harmonic imaging (CHI), which uses a contrast agent.

[0034] THI extracts harmonic components using an imaging method called the Amplitude Modulation (AM) method, the Phase Modulation (PM) method, or an AMPM method that combines the AM and PM methods.

[0035] In the AM, PM, and AMPM methods, ultrasonic waves with modulated amplitude and phase 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 extracts harmonic components by performing addition and subtraction processing on the multiple pieces of reflected wave data for each scan line using the B-mode processing function 181 in accordance with the modulation method. 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.

[0036] In CHI, for example, harmonic components are extracted using a frequency filter. The processing circuitry 180 separates reflected wave data (fundamental wave components) whose reflection source is tissue in the living body P from reflected wave data (harmonic components) whose reflection source is the contrast agent using a B-mode processing function 181. As a result, the processing circuitry 180 can select harmonic components from the contrast agent using a frequency filter and generate B-mode data for generating contrast image data.

[0037] For example, the ultrasonic diagnostic apparatus 1 may cause the ultrasonic probe 101 to perform ultrasonic scanning in which a first transmitted ultrasonic wave and a second transmitted ultrasonic wave with the phase of the first transmitted ultrasonic wave inverted are taken as a set by a B-mode processing function 181 (an example of a control unit). Subsequently, the ultrasonic diagnostic apparatus 1 adds, by an extraction function 120A, a reflected wave signal of the first transmitted ultrasonic wave and a reflected wave signal of the second transmitted ultrasonic wave received by each element of the ultrasonic probe 101, and applies frequency filtering processing that passes through an odd harmonic band to the added reflected wave signal, thereby extracting an odd harmonic component from the added reflected wave signal. Thereby, the ultrasonic diagnostic apparatus 1 can extract an odd harmonic component from the reflected wave signal.

[0038] Further, the ultrasonic diagnostic apparatus 1 may cause the ultrasonic probe 101 to perform ultrasonic scanning in which a first transmitted ultrasonic wave, a second transmitted ultrasonic wave with the phase of the first transmitted ultrasonic wave modulated by N (N is a real number satisfying 0 < N < 180) degrees in the positive direction, and a third transmitted ultrasonic wave with the phase of the first transmitted ultrasonic wave modulated by N degrees in the negative direction are taken as a set by a B-mode processing function 181 (an example of a control unit). Subsequently, the ultrasonic diagnostic apparatus 1 adds, by an extraction function 120A, a reflected wave signal of the first transmitted ultrasonic wave, a reflected wave signal of the second transmitted ultrasonic wave, and a reflected wave signal of the third transmitted ultrasonic wave received by each element of the ultrasonic probe 101, and applies frequency filtering processing that passes through an odd harmonic band to the added reflected wave signal, thereby extracting an odd harmonic component from the added reflected wave signal. Thereby, the ultrasonic diagnostic apparatus 1 can extract an odd harmonic component from the reflected wave signal.

[0039] The B-mode data for generating contrast image data is data representing the echo reflection intensity with the contrast agent as a reflection source by luminance values. Further, the processing circuit 180 can also extract a fundamental wave component from the reflected wave data of the living body P and generate B-mode data for generating tissue image data.

[0040] The Doppler processing function 182 is a function that generates data (Doppler information) that extracts motion information based on the Doppler effect of a moving object within a ROI (Region Of Interest) set in a scan area by frequency analyzing the reflected wave data transferred from the ultrasound receiving circuit 120. The generated Doppler information is stored in a RAW data memory (not shown) as Doppler RAW data (also referred to as Doppler data) on a two-dimensional ultrasound scan line.

[0041] Specifically, the processing circuitry 180 uses the Doppler processing function 182 to estimate, for example, the average velocity, average variance, average power, etc. as motion information of a moving object at each of a plurality of sample points, and generates Doppler data indicating the estimated motion information. 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 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.

[0042] The image generation function 183 is a function that generates B-mode image data based on the B-mode data generated by the B-mode processing function 181. For example, the processing circuitry 180 converts (scan converts) a scan line signal sequence of an ultrasound scan into a scan line signal sequence of a video format typified by a television or the like, using the image generation function 183, and generates image data for display (display image data). Specifically, the processing circuitry 180 performs RAW-to-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 referred to as 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 waves using the image generation function 183.

[0043] Furthermore, the processing circuitry 180 generates Doppler image data in which blood flow information is visualized, for example, by performing RAW-to-pixel conversion on the Doppler RAW data stored in the RAW data memory. The Doppler image data is mean velocity image data, variance image data, power image data, or image data that combines these. The processing circuitry 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 waveform.

[0044] The three-dimensional data generation function 184 is a function that generates three-dimensional B-mode data (three-dimensional data) based on the reflected wave data received from the ultrasound receiving circuit 120. In the three-dimensional data generation function 184, the processing circuit 180 generates three-dimensional data by using the B-mode data generated by the B-mode processing function 181 to assign brightness values ​​to voxels arranged in three-dimensional space. This three-dimensional data may also be called volume data. Note that, since the brightness values ​​correspond to the echo reflection intensity, it may also be interpreted that the echo reflection intensity is assigned to the voxels of the volume data.

[0045] The display control function 185 is a function that displays images based on various ultrasound image data generated by the image generation function 183 on a display serving as the output device 103. For example, the processing circuitry 180 uses the display control function 185 to control the display of images based on image data including B-mode image data, Doppler image data, or both generated by the image generation function 183 on a display.

[0046] More specifically, the processing circuitry 180 uses the display control function 185 to convert (scan convert) a scan line signal sequence of, for example, an ultrasound scan into a scan line signal sequence of a video format such as that used in a television, and generates image data for display. The processing circuitry 180 may also perform various processes on the image data for display, 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 image data for display. 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.

[0047] The system control function 186 is a function that comprehensively controls the operation of the entire ultrasound diagnostic apparatus 1. For example, in the system control function 186, the processing circuitry 180 controls the ultrasound transmission circuitry 110 and the ultrasound reception circuitry 120 based on parameters related to the transmission and reception of ultrasound.

[0048] 2 is a diagram showing an example of the operation of the ultrasound diagnostic device 1 according to the first embodiment. In this example of operation, ultrasound is transmitted and received once each. That is, the process of generating reflected wave data in one transmission and reception of ultrasound is described. This example of operation corresponds to a scanning method (all raster parallel simultaneous reception) in which a single plane wave transmission or a transmission similar to a plane wave transmission is performed over a wide area to obtain all reception rasters within the ultrasound scan range in real time in a single transmission.

[0049] In step S101, the ultrasound diagnostic device 1 transmits ultrasound waves from each element. Specifically, the ultrasound diagnostic device 1 generates ultrasound waves in each element of the ultrasound probe 101 based on a drive signal supplied from the ultrasound transmission circuit 110. The ultrasound diagnostic device 1 then transmits the generated ultrasound waves to a living body. As described above, the transmitted ultrasound waves are reflected successively by discontinuous surfaces of acoustic impedance in the body tissue of the living body, thereby generating reflected waves successively. The generated reflected waves propagate within the living body and reach each element of the ultrasound probe 101.

[0050] In step S102, the ultrasound diagnostic device 1 receives reflected wave signals from each element. Specifically, the ultrasound diagnostic device 1 receives reflected wave signals by piezoelectrically converting the waves reflected from the living body in each element of the ultrasound probe 101. As a result, each element receives reflected wave signals for each depth (or time) in the living body. The received reflected wave signals are transferred from each element of the ultrasound probe 101 to the ultrasound receiving circuit 120 of the device main body 100. As mentioned above, the longer the propagation distance of ultrasound, the greater the attenuation, so the weaker the reflected wave signals from deeper in the living body. Therefore, in certain applications (e.g., harmonic imaging, visualization of blood flow with a small scattering coefficient), it is necessary to greatly amplify the reflected wave signals for visualization.

[0051] In step S103, the ultrasound diagnostic device 1 amplifies the reflected wave signal. Specifically, the ultrasound receiving circuit 120 of the ultrasound diagnostic device 1 amplifies the reflected wave signal from each element for each depth and performs gain correction processing. According to one example, the ultrasound receiving circuit 120 amplifies the reflected wave signal by 18 dB and then passes it through a variable attenuation circuit of 0 to −24 dB. This makes it possible to visualize weak reflected wave signals from deep within a living body. Note that if the ultrasound receiving circuit 120 does not need to amplify the reflected wave signal, this step may be omitted.

[0052] However, the dynamic range of the ultrasonic receiving circuit 120 has a limit (usually around 60 dB). For this reason, reflected wave signals from, for example, strong reflectors (e.g., blood vessel walls, diaphragms) are saturated primarily in the amplifier circuit of the ultrasonic receiving circuit 120. That is, even for reflected wave signals received by the same element, reflected wave signals from depths where strong reflectors exist may saturate, while reflected wave signals from depths where no strong reflectors exist may not saturate. Furthermore, in color Doppler mode, reflected wave signals are received with a high gain value to obtain weak blood flow signals with a better S / N ratio. Thus, if the reflected wave signal exceeds the dynamic range of the ultrasonic receiving circuit 120, the reflected wave signal will saturate in the ultrasonic receiving circuit 120, resulting in signal saturation.

[0053] Here, the saturated reflected wave signal (saturated signal) contains not only second-order and higher harmonic components generated by the phenomenon of waveform distortion as ultrasound propagates through a living body (also called "nonlinear effect"), but also odd-order harmonic components increased by saturation. For performance and circuit protection, amplifier circuits are designed to clip signals when signals exceeding the limits of their amplification characteristics pass through. The received signal s and the clipped received signal s are clip is expressed by the following equation.

[0054]

number

[0055]

number

[0056] In step S104, the ultrasound diagnostic device 1 extracts odd-order harmonic components from the reflected wave signal using the extraction function 120A. Specifically, the ultrasound receiving circuit 120 of the ultrasound diagnostic device 1 extracts odd-order harmonic components from the reflected wave signal by applying frequency filtering to the reflected wave signal, which passes odd-order high-frequency bands. The frequency filtering can be achieved by a filter circuit that passes specific frequency components. For example, if the frequency component to be extracted is a third-order harmonic component, a filter circuit (high-pass filter) that passes third-order and higher frequency components can be used. The ultrasound receiving circuit 120 extracts the third-order odd-order harmonic component by passing the reflected wave signal through the filter circuit. Fifth-order and higher odd-order harmonic components may be extracted using a similar method. Of course, multiple types of odd-order harmonic components may also be extracted. Furthermore, odd-order harmonic components may be extracted by arithmetic processing of received signals obtained by multiple transmissions with phase or amplitude modulation, as used in the AM and PM harmonic imaging methods. The extraction of odd-order harmonic components may be performed on the reflected wave signal before or after A / D conversion (that is, the analog signal or the digital signal).

[0057] In step S105, the ultrasound diagnostic device 1 amplifies the odd-order harmonic components using the amplification function 120B. Specifically, the ultrasound receiving circuit 120 of the ultrasound diagnostic device 1 amplifies the amplitude of the extracted odd-order harmonic components by a gain value. For example, the ultrasound receiving circuit 120 determines a gain value according to the amplitude of the extracted odd-order harmonic components and amplifies the amplitude by the determined gain value. Note that the gain value may be set to any value by the operator of the ultrasound diagnostic device 1, or may be incorporated into the circuit design of the ultrasound receiving circuit 120 as hardware. This amplification increases the amplitude difference between the amplitude of the odd-order harmonic components of a saturated reflected wave signal and the amplitude of the harmonic components of a non-saturated reflected wave signal. In threshold processing, the ultrasound diagnostic device 1 can more accurately distinguish between saturated and non-saturated signals by setting a threshold to, for example, the median value of this amplitude difference. Thus, the ultrasound diagnostic device 1 can specifically detect saturated signals. If the ultrasonic receiving circuit 120 does not need to amplify odd-order harmonic components, this step may be omitted.

[0058] In step S106, the ultrasound diagnostic device 1 uses the extracted odd-order harmonic components to determine whether the reflected wave signal is saturated using the determination function 120C. Specifically, the ultrasound receiving circuit 120 of the ultrasound diagnostic device 1 determines that the reflected wave signal is saturated when the amplitude of the extracted odd-order harmonic components is equal to or greater than a threshold. The threshold may be set to any value by the operator of the ultrasound diagnostic device 1, or may be incorporated into the circuit design of the ultrasound receiving circuit 120 as hardware. Note that when multiple types of odd-order harmonic components are extracted, the ultrasound receiving circuit 120 may determine whether the reflected wave signal is saturated based on a threshold set for each type of odd-order harmonic component.

[0059] In step S107, the ultrasound diagnostic device 1 uses the generation function 120D to multiply the reflected wave signal of the element determined to be saturated by a weighting coefficient. Specifically, the ultrasound receiving circuit 120 of the ultrasound diagnostic device 1 multiplies the reflected wave signal of the element determined to be saturated by a weighting coefficient ranging from 0 to 1, thereby reducing the contribution of the reflected wave signal. Of course, the ultrasound receiving circuit 120 may set the value of the reflected wave signal determined to be saturated to 0. This allows the ultrasound receiving circuit 120 to reduce the possibility of the added reflected wave signal being saturated when the reflected wave signals from each element are phased and added.

[0060] In step S108, the ultrasonic diagnostic apparatus 1 generates reflected wave data by performing phasing addition on the reflected wave signals multiplied by the weighting coefficients using the generation function 120D. As described above, the generated reflected wave data is transferred to the processing circuitry 180.

[0061] After the delay-and-sum process, the processing circuitry 180 generates B-mode data from the transferred reflected wave data using the B-mode processing function 181. Next, the processing circuitry 180 generates B-mode image data from the B-mode data using the image generation function 183. Thereafter, the processing circuitry 180 causes the display control function 185 to display an ultrasound image based on the B-mode image data on the output device 103 as a display. The displayed ultrasound image is observed by, for example, the operator of the ultrasound diagnostic apparatus 1 and used for medical diagnosis, etc.

[0062] The ultrasonic diagnostic device 1 according to the first embodiment has been described above. According to the first embodiment, the ultrasonic diagnostic device 1 uses odd-order harmonic components included in the reflected wave signal to specifically detect saturated signals among saturated and non-saturated signals. The ultrasonic diagnostic device 1 then multiplies the saturated signal by a weighting coefficient to selectively reduce the contribution of the saturated signal. This configuration reduces the possibility of the ultrasonic diagnostic device 1 misidentifying a non-saturated signal as a saturated signal, thereby reducing the possibility of reducing the contribution of the non-saturated signal. As a result, the ultrasonic diagnostic device 1 visualizes the reflected wave signal using a wider effective aperture while reducing the effects of signal saturation, thereby improving the visibility of the image. This configuration is particularly effective in visualizing the third-order harmonic components included in the reflected wave signal.

[0063] (Second embodiment) 3 is a diagram showing an example of the configuration of an ultrasonic diagnostic apparatus 1 according to the second embodiment. The configuration of the ultrasonic diagnostic apparatus 1 according to the second embodiment is generally the same as the configuration of the ultrasonic diagnostic apparatus 1 according to the first embodiment. The ultrasonic diagnostic apparatus 1 according to the second embodiment further includes a conversion function 120E and an interpolation phasing function 120F as functions of the ultrasonic receiving circuit 120.

[0064] The conversion function 120E converts into a baseband signal the reflected wave signal received by each element of the ultrasonic probe 101. The conversion function 120E can be realized by a quadrature detection circuit.

[0065] The interpolation phasing function 120F performs interpolation and phasing on the converted baseband signal. The interpolation phasing function 120F can be realized by a generation circuit of the ultrasonic receiving circuit 120.

[0066] 4 is a diagram showing an example of the operation of the ultrasound diagnostic device 1 according to the second embodiment. Unlike the first embodiment, the ultrasound diagnostic device 1 according to the second embodiment converts a reflected wave signal into a baseband signal. That is, the process of generating reflected wave data based on the baseband signal is described. Note that steps S201 to S203 are similar to steps S101 to S103, and therefore a description thereof will be omitted.

[0067] In step S204, the ultrasonic diagnostic apparatus 1 converts the reflected wave signal into a baseband signal using the conversion function 120E.

[0068] In step S205, the ultrasonic diagnostic apparatus 1 performs a thinning process on the baseband signal.

[0069] In step S206, the ultrasonic diagnostic apparatus 1 uses the interpolation phasing function 120F to interpolate and phase the baseband signal.

[0070] In step S207, the ultrasound diagnostic apparatus 1 extracts odd-order harmonic components from the baseband signal using the extraction function 120A. Step S207 is similar to step S104.

[0071] In step S208, the ultrasound diagnostic apparatus 1 amplifies the extracted odd-order harmonic components using the amplification function 120B. Step S208 is similar to step S105.

[0072] In step S209, the ultrasonic diagnostic apparatus 1 determines saturation of the baseband signal using odd-order harmonic components with the determination function 120C. Step S209 is similar to step S106.

[0073] In step S210, the ultrasonic diagnostic apparatus 1 multiplies the baseband signals of the elements determined to be saturated by a weighting coefficient using the generating function 120D. Step S210 is similar to step S107.

[0074] In step S211, the ultrasonic diagnostic apparatus 1 performs phasing and summing of the baseband signals using the generation function 120D to generate reflected wave data. Step S211 is similar to step S108.

[0075] The above describes an example of the operation of the ultrasound diagnostic device 1 according to the second embodiment. Below are shown the results of determining whether a baseband signal is saturated by the ultrasound diagnostic device 1 based on this example of operation, and, for comparison, the results of determining whether a baseband signal is saturated by an ultrasound diagnostic device with a conventional configuration.

[0076] 5 is a diagram showing the results of determining whether a baseband signal is saturated in each element of the ultrasonic diagnostic devices according to the second embodiment and the conventional configuration. The ultrasonic diagnostic device 1 according to the second embodiment extracted odd-order harmonic components from the baseband signal and determined whether the signal is saturated based on the amplitude of the extracted odd-order harmonic components. On the other hand, the ultrasonic diagnostic device according to the conventional configuration determined whether the signal is saturated based on the amplitude of the baseband signal. Prior to determining whether the signal is saturated, each ultrasonic diagnostic device transmitted and received ultrasound in the same experimental system.

[0077] In the experimental system described above, six wires were arranged perpendicular to the direction of ultrasound transmission (depth direction) from a central element (center element) among the elements arranged on the ultrasound probe of each ultrasound diagnostic device. The wires were arranged at approximately regular intervals in the depth direction from the center element in a water tank filled with water. However, the distance between the fourth and fifth wires in the depth direction, starting from the center element, was approximately twice as long as the distance between the other wires. In this experimental system, each ultrasound diagnostic device transmitted ultrasound with the ultrasound probe in contact with the water surface of the water tank, and then received reflected waves from each wire with each element to obtain reflected wave signals. Each ultrasound diagnostic device converted the reflected wave signals into baseband signals and then determined the saturation of the baseband signals for each element at each depth. The ultrasound transmission and reception conditions were set so that the reflected wave signals from the shallowest two wires of the six wires were unsaturated signals and the reflected wave signals from the remaining four wires were saturated signals.

[0078] FIG. 5(A) shows the saturation determination results obtained by the ultrasound diagnostic device 1 according to the second embodiment. FIG. 5(B) shows the saturation determination results obtained by the ultrasound diagnostic device according to the conventional configuration. In each figure, the horizontal axis indicates the "element number" of each element of the ultrasound probe, and the vertical axis indicates the "depth" from each element. Approximately 200 elements are arranged in the array direction of the ultrasound probe, with the central element corresponding to approximately the 100th element. Depth "0" roughly corresponds to the depth at which the surface (acoustic radiation surface) on which each element of the ultrasound probe is arranged is located. Here, the baseband signals of each element determined to be saturated are shown in black for each depth.

[0079] As can be seen from each figure, the saturation of the baseband signal is distributed in six arcs that curve in the depth direction with the central element at the center. The arc-shaped distribution means that the reflected wave generated at each wire reaches the central element first, while the further away from the central element, the slower it arrives. Each arc-shaped distribution indicates the saturation of the baseband signal due to the reflected wave from each wire. Here, saturation determination is performed on the element signal before the phasing process, but saturation determination may also be performed after the interpolation phasing process shown in step S206.

[0080] Here, two distributions enclosed by region 200, which indicates the depth range of "200 to 400", are compared between Figures 5(A) and 5(B). These two distributions indicate saturation of baseband signals due to reflected waves from the first and second wires in the depth direction, in descending order from the center element. Specifically, in Figure 5(A), the first distribution is not visible, and the second distribution is slightly visible. On the other hand, in Figure 5(B), the first distribution is slightly visible, and the second distribution is fully visible. In other words, it can be seen that the ultrasound diagnostic device 1 according to the second embodiment reduces the frequency of erroneously detecting non-saturated signals as saturated signals compared to the conventional configuration.

[0081] 6A and 6B show the amplitude of the baseband signal at the central element of each ultrasonic diagnostic device according to the second embodiment and the conventional configuration. Specifically, FIGS. 6A and 6B show the amplitude of the baseband signal at each depth at the central element of each of FIGS. 5A and 5B, respectively. In each figure, the horizontal axis indicates the "depth" from each element of the ultrasonic probe (i.e., corresponds to the vertical axis of FIGS. 5A and 5B), and the vertical axis indicates the amplitude in decibels. Note that region 200 in FIG. 5 corresponds to region 200 in FIG. 6.

[0082] As can be seen from each figure, six peaks are observed from depth "200" onward. Each waveform represents the amplitude of the baseband signal resulting from the reflected wave from each wire. Here, we focus on the amplitude difference between the amplitude value at the peak of the waveform at the shallowest position (leftmost) in the depth direction and the amplitude value at the peak of the waveform at the deepest position (rightmost). This amplitude difference is represented by "d1" in FIG. 6(A) and "d2" in FIG. 6(B). That is, the processing result by the ultrasound diagnostic apparatus 1 according to the second embodiment corresponds to "d1," and the processing result by the ultrasound diagnostic apparatus according to the conventional configuration corresponds to "d2." Specifically, d1 indicates a range of approximately "0 to -10 dB," and d2 indicates a range of approximately "0 to -5 dB." That is, it can be seen that d1 is approximately 5 dB higher than d2.

[0083] The ultrasound diagnostic device 1 according to the second embodiment can accurately distinguish between saturated and non-saturated signals by setting the threshold to, for example, "approximately -5 dB," which is the median value of the amplitude difference d1, as shown in Fig. 5(A). On the other hand, in the ultrasound diagnostic device according to the conventional configuration, since the amplitude difference d2 is narrower than d1, even if the threshold is set to the median value of the amplitude difference, it becomes difficult to accurately distinguish between saturated and non-saturated signals, as shown in Fig. 5(B).

[0084] The above describes the ultrasonic diagnostic apparatus 1 according to the second embodiment. According to the second embodiment, even when the reflected wave signal is converted into a baseband signal, the same effects as those of the first embodiment can be obtained.

[0085] According to at least one of the embodiments described above, it is possible to improve the accuracy of discriminating saturated signals.

[0086] 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 included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0087] 1. Ultrasound diagnostic equipment 100 Device body 101 Ultrasound probe 102 Input Device 103 Output Device 104 External device 110 Ultrasonic transmission circuit 120 Ultrasonic receiving circuit 120A Extraction Function 120B Amplification Function 120C judgment function 120D Generation Function 120E conversion function 120F Interpolated phasing function 130 Internal memory 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 3D data generation function 185 Display Control Function 186 System Control Functions 200 areas

Claims

1. an extractor that extracts odd-order harmonic components from the reflected wave signals received by each element of the ultrasonic probe; an amplifier that amplifies the amplitude of the extracted odd-order harmonic components by a gain value; a determination unit that determines that the reflected wave signal is saturated when the amplitude of the amplified odd-order harmonic component is equal to or greater than a threshold; a generating unit that generates reflected wave data by multiplying the reflected wave signals of the elements determined to be saturated by weighting coefficients and performing phasing addition of the reflected wave signals multiplied by the weighting coefficients; An ultrasound diagnostic device comprising:

2. The determination unit further determines that the reflected wave signal is saturated when the amplitude of the extracted odd-order harmonic component is equal to or greater than a threshold. The ultrasonic diagnostic apparatus according to claim 1 .

3. the amplifier determines the gain value in accordance with the amplitude of the extracted odd-order harmonic component, and amplifies the amplitude by the determined gain value. The ultrasonic diagnostic apparatus according to claim 1 .

4. the extraction unit extracts the odd-order harmonic components from the reflected wave signals by applying a frequency filtering process that passes odd-order harmonic bands to the reflected wave signals received by each element of the ultrasound probe. The ultrasonic diagnostic apparatus according to any one of claims 1 to 3.

5. a control unit that causes the ultrasonic probe to perform ultrasonic scanning using a set of a first transmitted ultrasonic wave and a second transmitted ultrasonic wave obtained by inverting the phase of the first transmitted ultrasonic wave; Further comprising: the extraction unit adds together the reflected wave signal of the first transmitted ultrasonic wave and the reflected wave signal of the second transmitted ultrasonic wave received by each element of the ultrasonic probe, and applies frequency filtering processing to the added reflected wave signal to pass odd-order harmonic bands, thereby extracting the odd-order harmonic components from the added reflected wave signal; The ultrasonic diagnostic apparatus according to any one of claims 1 to 3.

6. a control unit that causes the ultrasonic probe to perform ultrasonic scanning using a set of a first transmitted ultrasonic wave, a second transmitted ultrasonic wave obtained by modulating the phase of the first transmitted ultrasonic wave by N degrees in a positive direction, and a third transmitted ultrasonic wave obtained by modulating the phase of the first transmitted ultrasonic wave by N degrees in a negative direction; Further comprising: The N is a real number satisfying 0<N<180, the extraction unit adds together the reflected wave signal of the first transmitted ultrasonic wave, the reflected wave signal of the second transmitted ultrasonic wave, and the reflected wave signal of the third transmitted ultrasonic wave, which are received by each element of the ultrasonic probe, and applies frequency filtering processing that passes odd-order harmonic bands to the added reflected wave signal, thereby extracting the odd-order harmonic components from the added reflected wave signal; The ultrasonic diagnostic apparatus according to any one of claims 1 to 3.

7. extracting odd-order harmonic components from the reflected wave signals received by each element of the ultrasonic probe; amplifying the amplitude of the extracted odd-order harmonic component by a gain value; determining that the reflected wave signal is saturated when the amplitude of the amplified odd-order harmonic component is equal to or greater than a threshold value; multiplying the reflected wave signal of the element determined to be saturated by a weighting coefficient; generating reflected wave data by phasing and adding the reflected wave signals multiplied by the weighting coefficients; Ultrasound diagnostic methods.

8. On the computer, an extraction function for extracting odd-order harmonic components from the reflected wave signals received by each element of the ultrasonic probe; an amplification function for amplifying the amplitude of the extracted odd-order harmonic components by a gain value; a determination function that determines that the reflected wave signal is saturated when the amplitude of the amplified odd-order harmonic component is equal to or greater than a threshold; a generation function of generating reflected wave data by multiplying the reflected wave signals of the elements determined to be saturated by weighting coefficients and performing phasing addition of the reflected wave signals multiplied by the weighting coefficients; Ultrasound diagnostic program that realizes this.

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