Ultrasonic diagnostic apparatus

Abstract

To improve the performance of contrast imaging.SOLUTION: An ultrasonic diagnostic apparatus according to one embodiment includes an ultrasonic probe and an aperture control part. The ultrasonic probe has elements divided in an elevation direction and transmits an ultrasonic beam a plurality of times. The aperture control part controls a transmission aperture of the ultrasonic probe so as to match the position and area of elements which form a part of ultrasonic beams transmitted the plurality of times with the position and area of elements which form remaining ultrasonic beams.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Contrast imaging is an imaging method using an ultrasound diagnostic device. Contrast imaging is an imaging method in which an ultrasound contrast agent such as microbubbles is administered, and phase-modulated or amplitude-modulated ultrasound is transmitted and received multiple times to image harmonic signals, which are nonlinear components. Contrast imaging can be broadly divided into phase modulation (PM) and amplitude modulation (AM). The PM method is a method in which the sound pressure is lowered to a level at which the contrast agent is more likely to resonate compared to B-mode tissue harmonic imaging (THI). As a result, while the spatial resolution is good, the tissue bubble contrast ratio is low and the deep sensitivity is also low. On the other hand, the AM method is a method that enhances the tissue cancellation ability, and although the spatial resolution is lower than the PM method, it has the advantage of a high tissue bubble contrast ratio and high deep sensitivity. The representative methods of the AM method are the voltage control method and the transmission aperture control method. The voltage control method has limitations in the voltage control accuracy of the pulsar, so the transmission aperture control method is generally used.

[0003] The most commonly used aperture control methods are a method of dividing the transmit aperture into the entire element or half of the element corresponding to the transmit aperture width (hereinafter referred to as the transmit aperture division method), and a method of controlling the transmit aperture by using even and odd channels separately (hereinafter referred to as the sparse transmit aperture method). The transmit aperture division method has variation in cancellation ability between the edge and center of the image, and is susceptible to the effects of bioacoustic shadows due to the small transmit aperture width. On the other hand, the sparse transmit aperture method has a problem in that it is significantly affected by crosstalk from channels that transmit ultrasound to channels that do not transmit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6118354 [Patent Document 2] Patent No. 5829680 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 performance of contrast imaging. 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 each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0006] The ultrasonic diagnostic device according to the present embodiment includes an ultrasonic probe and an aperture control unit. The ultrasonic probe is divided into elements in the elevation direction and transmits ultrasonic beams multiple times. The aperture control unit controls the transmission aperture of the ultrasonic probe so that the positions and areas of elements forming some of the ultrasonic beams transmitted multiple times are equal to the positions and areas of elements forming the remaining ultrasonic beams. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of an ultrasonic diagnostic apparatus according to the first embodiment. [Diagram 2] FIG. 2 is a conceptual diagram showing the definition of the ultrasonic beam direction according to the first embodiment. [Diagram 3] FIG. 3 is a diagram showing a first example of a transmission aperture control method according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing a second example of the transmit aperture control method according to the first embodiment. [Diagram 5] FIG. 5 is a diagram showing a third example of the transmit aperture control method according to the first embodiment. [Figure 6]FIG. 6 is a diagram showing a fourth example of the transmit aperture control method according to the first embodiment. [Figure 7] FIG. 7 is a diagram showing a fifth example of the transmit aperture control method according to the first embodiment. [Figure 8] FIG. 8 is a diagram showing a sixth example of the transmit aperture control method according to the first embodiment. [Figure 9] FIG. 9 is a flowchart showing the contrast imaging process according to the first embodiment. [Figure 10] FIG. 10 is a schematic diagram showing a contrast image acquired by the transmit aperture control method according to the first embodiment. [Figure 11] FIG. 11 is a flowchart showing a process of switching the transmission aperture control method according to the first embodiment. [Figure 12] FIG. 12 is a diagram showing a first example of a transmission aperture control method according to the second embodiment. [Figure 13] FIG. 13 is a diagram showing a second example of the transmit aperture control method according to the second embodiment. [Figure 14] FIG. 14 is a diagram showing a third example of the transmit aperture control method according to the second embodiment. [Figure 15] FIG. 15 is a diagram showing a fourth example of the transmit aperture control method according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0009] (First embodiment) Fig. 1 is a diagram showing an example of the configuration of an ultrasonic diagnostic apparatus according to this embodiment. The ultrasonic diagnostic apparatus 1 in Fig. 1 has an apparatus main body 100 including a probe control device, and an ultrasonic probe 101. The apparatus main body 100 is connected to an input device 102 and an output device 103. The apparatus main body 100 is also connected to an external device 104 via a network NW. The external device 104 is, for example, a server equipped with a PACS (Picture Archiving and Communication Systems) and a workstation capable of executing post-processing.

[0010] The ultrasonic probe 101 performs ultrasonic scanning on a scanning area in a living body P, which is a subject, according to control from the device main body 100, for example. The ultrasonic probe 101 has, for example, an acoustic lens, one or more matching layers, a plurality of transducers (piezoelectric elements), and a backing material. The acoustic lens is formed of, for example, silicone rubber, and converges an ultrasonic beam. The one or more matching layers perform impedance matching between the plurality of transducers and the living body. The backing material prevents the propagation of ultrasonic waves backward in the radiation direction from the plurality of transducers. The ultrasonic probe 101 is assumed to be, for example, a linear probe or a convex probe, but may be a radial probe capable of 360-degree scanning. The ultrasonic probe 101 is detachably connected to the device main body 100. The ultrasonic probe 101 may be provided with a button that is pressed during offset processing, an operation to freeze an ultrasonic image (freeze operation), and the like.

[0011] The multiple transducers generate ultrasonic waves based on a drive signal supplied from an ultrasonic transmission circuit 110 (described later) of the device main body 100. This causes ultrasonic waves to be transmitted from the ultrasonic probe 101 to the living body P. When ultrasonic waves are transmitted from the ultrasonic probe 101 to the living body P, the transmitted ultrasonic waves are reflected one after another at discontinuous surfaces of the acoustic impedance in the body tissue of the living body P, and are received as echo signals by the multiple piezoelectric transducers. The amplitude of the received echo signal depends on the difference in acoustic impedance at the discontinuous surface where the ultrasonic waves are reflected. In addition, when the transmitted ultrasonic pulse is reflected at the surface of a moving blood flow or a heart wall, the echo signal undergoes a frequency shift due to the Doppler effect depending on the velocity component in the ultrasonic transmission direction of the moving body. The ultrasonic probe 101 receives the echo signal from the living body P and converts it into an electric signal.

[0012] 1 illustrates an example of the connection relationship between one ultrasonic probe 101 and the device main body 100. However, it is possible to connect multiple ultrasonic probes to the device main body 100. Which of the multiple connected ultrasonic probes 101 is to be used for ultrasonic scanning can be arbitrarily selected, for example, by a software button on a touch panel described later.

[0013] The device main body 100 is a device that generates an ultrasonic image based on an echo signal received by an ultrasonic probe 101. The device main body 100 has an ultrasonic transmission circuit 110, an ultrasonic 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 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 for focusing the ultrasonic waves generated from the ultrasonic probe into a beam shape and determining 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 surfaces of the multiple piezoelectric transducers can be arbitrarily adjusted.

[0015] Furthermore, the ultrasonic transmission circuit 110 can arbitrarily change the output intensity of the ultrasonic waves by the drive signal. In the ultrasonic diagnostic device, the output intensity can be increased to reduce the influence of ultrasonic attenuation in the living body P. By reducing the influence of ultrasonic attenuation, the ultrasonic diagnostic device can acquire an echo signal with a large signal-to-noise ratio (SNR) at the time of reception.

[0016] Generally, when an ultrasonic wave propagates through a living body P, the strength of the ultrasonic vibration (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 depends on the frequency of the ultrasonic wave and the distance in the direction of ultrasonic radiation. For example, the degree of attenuation increases by increasing the frequency of the ultrasonic wave. Also, the degree of attenuation increases as the distance in the direction of ultrasonic radiation increases.

[0017] The ultrasonic receiving circuit 120 is a processor that performs various processes on the echo signal received by the ultrasonic probe 101 to generate a received signal. The ultrasonic receiving circuit 120 generates a received signal for the echo signal of the ultrasonic wave acquired by the ultrasonic probe 101. Specifically, the ultrasonic receiving circuit 120 is realized by, for example, a preamplifier, an A / D converter, a demodulator, and a beamformer (adder). The preamplifier amplifies the echo signal received by the ultrasonic probe 101 for each channel and performs a gain correction process. The A / D converter converts the gain-corrected echo signal into a digital signal. The demodulator demodulates the digital signal. For example, the beamformer gives a delay time required to determine the reception directivity to the demodulated digital signal and adds up multiple digital signals to which the delay time has been given. The addition process of the beamformer generates a received signal in which the reflection component from the direction according to the reception directivity is emphasized. The received signal may be called an IQ signal. In addition, the ultrasonic receiving circuit 120 may store the received signal in an internal storage circuit 130 (described later), or may output the received signal to the external device 104 via the communication interface 170.

[0018] The internal storage circuit 130 has a processor-readable storage medium, such as a magnetic storage medium, an optical storage medium, or a semiconductor memory. The internal storage circuit 130 stores a program and various data for implementing ultrasonic transmission and reception. The program and various data may be stored in the internal storage circuit 130 in advance. The program and various data may be stored in a non-transient storage medium and distributed, and may be read from the non-transient storage medium and installed in the internal storage circuit 130. The internal storage circuit 130 stores B-mode image data, contrast image data, and image data related to blood flow images generated by the processing circuit 180 according to an operation input via the input interface 150. The internal storage circuit 130 can also transfer the stored image data to the external device 104 or the like via the communication interface 170. The internal storage circuit 130 may store the reception signal (IQ signal) generated by the ultrasonic reception circuit 120, or may transfer the reception signal to the external device 104 or the like via the communication interface 170.

[0019] The internal storage circuit 130 may be a drive device that reads and writes various information between the internal storage circuit 130 and a portable storage medium such as a CD drive, a DVD drive, or a flash memory. The internal storage 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.

[0020] The image memory 140 includes 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.

[0021] 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. Also, the internal storage circuit 130 and the image memory 140 may each be realized by a plurality of storage devices.

[0022] The input interface 150 accepts various instructions from an 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). The input interface 150 is connected to the processing circuit 180 via, for example, a bus, converts an operation instruction input by the operator to the input device 102 into an electric signal, and outputs the electric signal to the processing circuit 180. Note that the input interface 150 is not limited to only those that are connected to physical operation components such as a mouse and a keyboard. For example, a circuit that receives an electric signal corresponding to an operation instruction input from an external input device provided separately from the ultrasound diagnostic apparatus 1 and outputs the electric signal to the processing circuit 180 is also included as an example of the input interface.

[0023] The output interface 160 is, for example, an interface for outputting an electric 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. The output device 103 may further include a speaker that outputs sound in addition to the display. The output interface 160 is connected to the processing circuit 180 via, for example, a bus, and outputs an electric signal from the processing circuit 180 to the output device 103.

[0024] The communication interface 170 is connected to the external device 104 via a network NW, for example, and performs data communication with the external device 104 .

[0025] 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 generating function 183, an aperture control function 184, a determination function 185, a display control function 186, and a system control function 187.

[0026] The B-mode processing function 181 is a function that generates B-mode data based on the reception signal received from the ultrasonic reception 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 ultrasonic reception circuit 120, and generates data (B-mode data) in which the signal intensity is expressed by the brightness of luminance. The generated B-mode data is stored in a RAW data memory (not shown) as B-mode RAW data on a two-dimensional ultrasonic scan line (raster).

[0027] 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 region of interest (ROI) set in a scan region by performing frequency analysis on a reception signal received from the ultrasonic reception circuit 120. 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 ultrasonic scan line.

[0028] Specifically, the processing circuitry 180 estimates, for example, an average velocity, an average variance value, an average power value, etc., as motion information of a moving body at each of a plurality of sample points using the Doppler processing function 182, and generates Doppler data indicating the estimated motion information. The moving body is, for example, a blood flow, tissue such as a heart wall, or a contrast agent. Furthermore, the processing circuitry 180 estimates, for each of a plurality of sample points using the Doppler processing function 182, an average velocity of the blood flow, a variance value of the blood flow velocity, a power value of the blood flow signal, etc., as motion information of the blood flow (blood flow information), and generates Doppler data indicating the estimated blood flow information.

[0029] The processing circuit 180, using the Doppler processing function 182, multiplies the received signal received from the ultrasound receiving circuit 120 by a reference frequency, which is a reference frequency for detecting Doppler shift, using quadrature detection processing, and applies a low pass filter (LPF) to extract the Doppler shift. After that, using the Doppler processing function 182, the processing circuit 180 applies a gate to the signal of the area to be observed to extract the signal, and applies a wall filter to the extracted signal. Using the Doppler processing function 182, the processing circuit 180 applies A / D conversion processing and FFT processing to the signal after application of the wall filter to generate Doppler data.

[0030] 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 a signal originating from blood flow is extracted. In the CFM method, blood flow information such as the blood flow speed, blood flow dispersion, and blood flow power is estimated using the extracted blood flow signal. An image generation function 183 described later generates the distribution of the estimated blood flow information as, for example, ultrasonic image data (color Doppler image data) displayed in color in two dimensions. Note that the color display is a display in which the distribution of blood flow information is displayed in correspondence with a predetermined color code, and grayscale is also included in the color display.

[0031] There are various types of blood flow imaging modes depending on the desired clinical information. In general, 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 blood flow signals.

[0032] 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 blood flow. For example, the velocity display blood flow imaging mode displays the flow direction as reddish colors for oncoming flows and blue colors for receding flows, and displays the difference in the velocities of each flow with different hues. The velocity display blood flow imaging mode is also called color Doppler mode or color Doppler imaging (CDI) mode.

[0033] The power display blood flow imaging mode is a mode in which the power of a blood flow signal is expressed by, for example, a change in red hue, color brightness (luminosity) or saturation. The power display blood flow imaging mode is also 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.

[0034] The image generating 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 generating function 183, the processing circuitry 180 converts (scan converts) a scan line signal sequence of an ultrasonic scan into a scan line signal sequence of a video format represented by a television or the like, 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, coordinate conversion according to the scanning form of the ultrasonic wave by the ultrasonic probe 101, thereby generating two-dimensional B-mode image data (also referred to as ultrasonic image data) composed of pixels. In other words, the processing circuitry 180 generates a plurality of ultrasonic images (medical images) corresponding to a plurality of consecutive frames by transmitting and receiving ultrasonic waves using the image generating function 183.

[0035] The image generating function 183 also has a function of generating Doppler waveform data and Doppler image data based on the data generated by the Doppler processing function 182. For example, the image generating function 183 generates Doppler image data in which blood flow information is visualized by performing RAW-pixel conversion on the Doppler RAW data stored in the RAW data memory. The Doppler image data is average velocity image data, variance image data, power image data, or image data that is a combination of these. The processing circuit 180 generates, as the Doppler image data, color Doppler image data in which blood flow information is displayed in color, and Doppler image data in which one piece of blood flow information is displayed in a grayscale wave shape. The color Doppler image data is generated when the above-mentioned blood flow imaging mode is executed.

[0036] Furthermore, the image generation function 183 generates a contrast image based on a contrast imaging signal, which will be described later.

[0037] The aperture control function 184 controls the transmission aperture of the ultrasonic probe divided in the elevation direction so that the positions and areas of the elements forming a part of the ultrasonic beams transmitted multiple times are equal to the positions and areas of the elements forming the remaining ultrasonic beams. The method of transmission aperture control by the aperture control function 184 will be described later with reference to FIG. 3 and subsequent figures.

[0038] The determination function 185 determines whether or not a bioacoustic shadow occurs in the contrast image.

[0039] The display control function 186 is a function for displaying an image based on various ultrasound image data generated by the image generation function 183 on a display serving as the output device 103. Specifically, for example, the processing circuitry 180, using the display control function 186, controls the display on the display of an image based on B-mode image data, Doppler waveform data, Doppler image data, or image data including all of these generated by the image generation function 183.

[0040] More specifically, the processing circuitry 180 converts (scan converts) a scan line signal sequence of an ultrasonic scan into a scan line signal sequence of a video format represented by a television or the like, using the display control function 186, and generates display image data. The processing circuitry 180 may also execute various processes, such as dynamic range, brightness, contrast, and gamma curve correction, as well as RGB conversion, on the display image data. The processing circuitry 180 may also add supplementary information, such as 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 an operator to input various instructions via an input device, and display the GUI on a display.

[0041] The system control function 187 is a function that controls the overall operation of the ultrasound diagnostic apparatus 1 .

[0042] Next, the definition of the ultrasonic beam direction according to this embodiment will be described with reference to the conceptual diagram of FIG. 2 is a schematic diagram of an ultrasonic beam 21 transmitted from the acoustic emission surface of the ultrasonic probe 101. In this embodiment, a 1.5-dimensional array probe or a 2-dimensional array probe in which elements are arranged in a lattice pattern is assumed. The scanning direction of the ultrasonic beam transmitted from the ultrasonic probe 101 is also called the azimuth direction, and the direction perpendicular to the irradiation direction (beam direction) of the ultrasonic beam 21 is the elevation direction, also called the slice direction.

[0043] Next, a first example of a transmission aperture control method according to the first embodiment will be described with reference to FIG. FIG. 3 is a diagram showing the element array of the ultrasonic probe 101 as viewed from the beam direction, with the elements used as the transmission aperture indicated by diagonal lines. Here, the horizontal direction is the azimuth direction, and the vertical direction is the elevation direction. The same applies to the diagrams of the transmission aperture control method below. In contrast imaging, three transmissions of ultrasonic beams are assumed as one signal group. That is, a contrast image is generated based on three echo signals corresponding to the ultrasonic beams transmitted three times. Note that the signal group is not limited to being defined by three transmissions of ultrasonic beams, and may be three or more. Note that if the number of transmissions of ultrasonic beams in one signal group increases, it takes more time to generate one contrast image, so the number of transmissions of ultrasonic beams included in the signal group may be appropriately determined according to the allowable update rate of the contrast image.

[0044] In the example of FIG. 3, three element rows are assumed to be divided in the elevation direction, and the area of ​​element row 31 located in the center is larger than the areas of element rows 32 and 33 located at the ends. Three transmissions of ultrasonic beams in the AM method are regarded as one signal group for generating a contrast image. In the following figures, the transmission aperture for transmitting the ultrasonic beam is represented by hatching. For convenience of explanation, the division between elements in the azimuth direction, that is, the formation position of one channel, is omitted from the illustration.

[0045] In the first transmission, which is the first transmission to form a signal group, an area corresponding to the area of ​​the elements in element row 31 located at the center of the element array in the elevation direction is set as a transmission aperture, and a first ultrasonic beam is transmitted by the transmission aperture.

[0046] In the second transmission, which is the second transmission for forming a signal group, an area corresponding to the area of ​​all elements is set as a transmission aperture, and a second ultrasonic beam is transmitted by the transmission aperture.

[0047] In the third transmission, which is the third transmission that forms a signal group, an area corresponding to the area of ​​the two element rows 32 and 33 at the ends of the element array in the elevation direction is set as a transmission aperture, and a third ultrasonic beam is transmitted by the transmission aperture. Here, the second ultrasonic beam is also called a part of the ultrasonic beams, and the first ultrasonic beam and the third ultrasonic beam are also called the remaining ultrasonic beams.

[0048] In this way, the aperture control function 184 causes the processing circuit 180 to control the transmit aperture for each transmission so that the size of the ultrasonic beam for the first and third transmissions is equal to the size of the ultrasonic beam of all elements for the second transmission.

[0049] The order of the positions and sizes of the transmission apertures from the first transmission to the third transmission may be any order, not limited to the example in Fig. 3. For example, the transmission of an ultrasonic beam from a transmission aperture corresponding to the area of ​​all elements, which is the second transmission shown in Fig. 3, may be the first transmission or the third transmission.

[0050] Next, a second example of the transmission aperture control method according to the first embodiment will be described with reference to FIG. The example in FIG. 4 differs from that in FIG. 3 in that the entire element row is not used as a transmission aperture, but rather the transmission aperture is divided into two in the azimuth direction in one element row.

[0051] In the first transmission, which is the first transmission, the left half region 34 of the element row 32, the right half region 35 of the element row 31, and the left half region 34 of the element row 33 are set as transmission apertures, and a first ultrasonic beam is transmitted by the transmission apertures. That is, the transmission apertures of the element rows are set alternately.

[0052] In the second transmission, which is the second transmission, an area corresponding to the area of ​​all the elements is set as a transmission aperture, and a second ultrasonic beam is transmitted by the transmission aperture.

[0053] In the third transmission, which is the third transmission, the right half region 35 in the element array 32, the left half region 34 in the element array 31, and the right half region 35 in the element array 33 are set as transmission apertures, and a third ultrasonic beam is transmitted by the transmission apertures. That is, elements that were not used in the first transmission are set as transmission apertures, and the transmission apertures of each element array are set alternately as in the first transmission.

[0054] Next, a third example of the transmission aperture control method according to the first embodiment will be described with reference to FIG. 5 shows a case where the transmit aperture is controlled by five element arrays. For example, in the case of a 1.5D array probe, five element arrays can be designed by further dividing and controlling element array 32 and element array 33 at the ends. Alternatively, in the case of a 2D array probe, the transmit aperture can be controlled so that there are five element arrays in the elevation direction.

[0055] In the first transmission, which is the first transmission, the area corresponding to the odd-numbered (1st, 3rd, and 5th) element rows from the top in the elevation direction, in other words, the area of ​​the central element row and the two end element rows, element row 41, element row 43, and element row 45, is set as the transmission aperture, and the first ultrasonic beam is transmitted by the transmission aperture.

[0056] In the second transmission, which is the second transmission, an area corresponding to the area of ​​all the elements is set as a transmission aperture, and a second ultrasonic beam is transmitted by the transmission aperture.

[0057] In the third transmission, which is the third transmission, the area corresponding to the even-numbered (second and fourth) element rows from the top in the elevation direction, in other words, the area of ​​element row 43 and the two adjacent element rows, element row 42 and element row 44, is set as the transmission aperture, and a third ultrasonic beam is transmitted by the transmission aperture.

[0058] Next, a fourth example of the transmission aperture control method according to the first embodiment will be described with reference to FIG. FIG. 6 shows an example in which the position of the transmission aperture in one transmission is different from that in FIG.

[0059] In the first transmission, which is the first transmission, an area corresponding to the area of ​​the elements in the central element row 43 is set as a transmission aperture, and a first ultrasonic beam is transmitted from the aperture.

[0060] In the second transmission, which is the second transmission, an area corresponding to the area of ​​all the elements is set as a transmission aperture, and a second ultrasonic beam is transmitted.

[0061] In the third transmission, which is the third transmission, an area corresponding to the area of ​​elements in multiple element rows other than the central element row 43, i.e., element row 41, element row 42, element row 44 and element row 45, is set as a transmission aperture, and a third ultrasonic beam is transmitted by the transmission aperture.

[0062] Next, a fifth example of the transmission aperture control method according to the first embodiment will be described with reference to FIG. FIG. 7 shows an example in which the transmit aperture in one element array is divided into two in the azimuth direction in the same manner as in FIG. 4, for the five element arrays shown in FIG. 5 and FIG.

[0063] In the first transmission, which is the first transmission, the left half region 34 of the element row 41, the right half region 35 of the element row 42, the left half region 34 of the element row 43, the right half region 35 of the element row 44, and the left half region 34 of the element row 45 are set as transmission apertures, and a first ultrasonic beam is transmitted by the transmission apertures. That is, the transmission apertures of the element rows are set alternately.

[0064] In the second transmission, which is the second transmission, an area corresponding to the area of ​​all the elements is set as a transmission aperture, and a second ultrasonic beam is transmitted by the transmission aperture.

[0065] In the third transmission, which is the third transmission, the right half region 35 in the element row 41, the left half region 34 in the element row 42, the right half region 35 in the element row 43, the left half region 34 in the element row 44, and the right half region 35 in the element row 45 are set as the transmission aperture, and a third ultrasonic beam is transmitted by the transmission aperture. That is, the elements not used in the first transmission are set as the transmission aperture, and the transmission apertures of each element row are set alternately as in the first transmission.

[0066] Next, a sixth example of the transmission aperture control method according to the first embodiment will be described with reference to FIG. FIG. 8 shows an example in which the position of the transmission aperture in one transmission is different from that in FIG.

[0067] In the first transmission, which is the first transmission, the left half region 34 of element row 41, the left half region 34 of element row 42, the right half region 35 of element row 43, the left half region 34 of element row 44, and the left half region 34 of element row 45 are set as the transmission aperture, and a first ultrasonic beam is transmitted through the transmission aperture.

[0068] In the second transmission, which is the second transmission, an area corresponding to the area of ​​all the elements is set as a transmission aperture, and a second ultrasonic beam is transmitted by the transmission aperture.

[0069] In the third transmission, which is the third transmission, the right half region 35 in the element row 41, the right half region 35 in the element row 42, the left half region 34 in the element row 43, the right half region 35 in the element row 44, and the right half region 35 in the element row 45 are set as the transmission aperture, and a third ultrasonic beam is transmitted by the transmission aperture. That is, the elements not used in the first transmission are set as the transmission aperture, and the transmission apertures of each element row are set alternately as in the first transmission.

[0070] The position and size of the transmission aperture are not limited to the examples shown in Fig. 3 to Fig. 8. For ultrasonic beams other than the second transmission, that is, for multiple ultrasonic beams other than those transmitted from all elements, the processing circuit 180 may control the transmission aperture by the aperture control function 184 so that the size of the transmission aperture is set to the element width in the azimuth direction for each ultrasonic beam, and so that ultrasonic beams are not transmitted from some of the element rows adjacent in the elevation direction. In other words, the apertures of the remaining ultrasonic beams in the signal group may be controlled so that the patterns of the ultrasonic beams are different from each other.

[0071] By controlling in this way, the aperture width in the azimuth direction is maintained, while the aperture is divided into two in the azimuth direction rather than being set for each channel as in the sparse division method, thereby reducing the effects of crosstalk.

[0072] Next, the contrast imaging process of the ultrasound diagnostic apparatus 1 according to the first embodiment will be described with reference to the flowchart of FIG.

[0073] In step SA1, the processing circuit 180 sets the position and size of the transmission aperture for the first transmission by the aperture control function 184, for example, by the transmission aperture control method shown in Figures 3 to 8. After that, the ultrasonic transmission circuit 110 transmits the first ultrasonic beam.

[0074] In step SA2, for example, the ultrasound receiving circuit 120 receives a first echo signal which is a reflected wave corresponding to the first ultrasound beam from the living body P.

[0075] In step SA3, the processing circuitry 180 sets the position and size of the transmit aperture for the second transmission using the aperture control function 184. After that, the ultrasonic transmission circuitry 110 transmits the second ultrasonic beam.

[0076] In step SA4, for example, the ultrasonic receiving circuit 120 receives a first echo signal which is a reflected wave corresponding to the second ultrasonic beam from the living body P.

[0077] In step SA5, the processing circuitry 180 sets the position and size of the transmit aperture for the third transmission using the aperture control function 184. After that, the ultrasonic transmission circuitry 110 transmits the third ultrasonic beam.

[0078] In step SA6, for example, the ultrasonic receiving circuit 120 receives a third echo signal which is a reflected wave corresponding to the third ultrasonic beam from the living body P.

[0079] In step SA7, for example, the image generating function 183 or the system control function 187 calculates the difference between some of the echo signals corresponding to the ultrasonic beam transmitted by all elements and the remaining echo signals corresponding to the ultrasonic beams, among the multiple echo signals corresponding to the signal group, and generates a difference signal (contrast imaging signal). For example, in the examples of Figures 3 to 8, the echo signal r corresponding to the second transmission, which is the ultrasonic beam transmitted by all elements, TxF (t) and the echo signal r corresponding to the first transmission TxP1 (t) and the echo signal r corresponding to the third transmission TxP2The difference between the sum of (t) and the contrast imaging signal r AM (t). That is, the contrast imaging signal r AM (t) is calculated.

[0080] r AM (t)=r TxP1 (t)+r TxP2 (t)-r TxF (t) (1) Here, the process of calculating the difference between the echo signals on the receiving side is assumed, but the transmitting side may control the process so that the difference signal is easily calculated. For example, when the transmission of an ultrasonic beam in which the transmission aperture is set in all elements is the middle of the transmission of the signal group, that is, the second transmission in the examples of Figs. 3 to 8, the processing circuit 180 may invert the polarity for each transmission of the ultrasonic beam by the aperture control function 184. As a result, the receiving side can generate a contrast imaging signal similar to the formula (1) by simply adding the echo signals. Alternatively, the phase may be inverted for each transmission of the ultrasonic beam, and the receiving side can generate a contrast imaging signal similarly by simply adding the echo signals.

[0081] In step SA8, the image generating function 183 causes the processing circuitry 180 to generate a contrast imaging signal r AM A contrast image is generated from (t).

[0082] Next, a contrast image acquired by the transmission aperture control method according to the first embodiment will be described with reference to the conceptual diagram of FIG.

[0083] Fig. 10(a) is a schematic diagram of a contrast image generated by the transmit aperture control method according to the first embodiment, Fig. 10(b) is a schematic diagram of a contrast image generated by the transmit aperture division method as a conventional example, and Fig. 10(c) is a schematic diagram of a contrast image generated by the sparse transmit aperture method as a conventional example. It is assumed that the three contrast images are generated for the imaging site of the same imaging target.

[0084] The contrast image according to the conventional example in Fig. 10(c) has a relatively poor tissue cancellation ability due to the large effect of crosstalk from the channel that transmits ultrasound to the channel that does not transmit ultrasound, and therefore, unlike an ideal contrast image in which the tissue is not visualized, the tissue is visualized.

[0085] The contrast image according to the conventional example in Fig. 10(b) has a smaller effect of crosstalk, and therefore has a higher tissue cancellation ability than the contrast image in Fig. 10(c). However, the size of the transmission aperture in the azimuth direction in the contrast image in Fig. 10(b) is smaller than that of the conventional sparse transmission aperture method, and therefore echo signals from positions deeper than the position of the tumor 50 cannot be received, and a bioacoustic shadow region 51 exists. Therefore, there is a possibility that necessary contrast information cannot be obtained beyond a certain depth.

[0086] On the other hand, in the contrast image of FIG. 10(a) by the transmission aperture control method according to the first embodiment, the transmission aperture is designed by dividing it into two in the azimuth direction, so that the influence of crosstalk from the channel that transmits ultrasound to the channel that does not transmit is small. Therefore, the tissue cancellation ability can be improved. Furthermore, in one transmission, the transmission aperture is maintained across the entire element in the azimuth direction, so that the influence of bioacoustic shadow can be reduced. Therefore, the contrast image of FIG. 10(a) has good image quality compared to the contrast images of the conventional examples of FIG. 10(b) and FIG. 10(c). The transmit aperture control method may be switched depending on whether or not a bioacoustic shadow is occurring.

[0087] The process of switching the transmission aperture control method will be described with reference to the flowchart of FIG. In step SB1, the processing circuit 180 judges whether or not a bioacoustic shadow occurs in the contrast image by the judgment function 185. Specifically, for example, a region with a pixel value equal to or less than a first threshold is extracted, and if the region is rectangular at a certain depth or more, and the difference between the pixel value of the region and a pixel value of a pixel position other than the rectangular region at the certain depth or more is equal to or more than a second threshold, it is judged that a bioacoustic shadow occurs. Alternatively, a pattern shape specific to a bioacoustic shadow may be registered by pattern recognition processing, and whether or not the pattern shape of the bioacoustic shadow exists on a contrast image may be judged by pattern matching. Alternatively, a machine learning model may train a machine learning model, typically a neural network, using a contrast image in which a bioacoustic shadow occurs as input data and, for example, a contrast image in which an annotation is manually added to the region of the bioacoustic shadow as correct answer data, to generate a learned model. By using the learned model, it may be judged whether or not a bioacoustic shadow occurs in a contrast image.

[0088] If a bioacoustic shadow is occurring, the process proceeds to step SB2, and if a bioacoustic shadow is not occurring, the process ends.

[0089] In step SB2, the processing circuit 180 changes the currently executed transmission aperture control method of the ultrasonic probe to another transmission aperture control method by the aperture control function 184. For example, if the transmission aperture control method shown in Fig. 4 is being executed, the processing may be changed to the transmission aperture control method shown in Fig. 3.

[0090] In step SB3, the processing circuit 180 generates a contrast image using a plurality of echo signals corresponding to the signal group of the ultrasonic beam transmitted by the new transmission aperture control method by the image generation function 183. After that, the process returns to step SB1 and the same process is repeated.

[0091] According to the first embodiment described above, ultrasonic beams related to three or more transmissions from an ultrasonic probe are treated as one signal group, and the transmission apertures of the ultrasonic beams of the signal group are controlled so that the position and size of the first transmission aperture corresponding to the first ultrasonic beam in the signal group are equal to the sum of the positions and sizes of the transmission apertures of the remaining ultrasonic beams in the signal group.

[0092] This maintains the transmission aperture in the azimuth direction, so that the tissue cancellation performance is less likely to vary, the tissue cancellation performance can be maintained, and the effects of crosstalk and bioacoustic shadows can be reduced, thereby improving the performance of contrast imaging.

[0093] Second embodiment In the first embodiment, transmit aperture control is assumed in which ultrasonic beams are transmitted from all or half of the elements in the azimuth direction. However, in the second embodiment, a group of elements each consisting of multiple elements in the azimuth direction is used as a transmission unit, and sparse transmit aperture control is performed, which is different from the first embodiment.

[0094] A first example of a transmission aperture control method according to the second embodiment will be described with reference to FIG. Fig. 12 is a view of the element array as seen from the beam direction, similar to Fig. 3. For convenience of explanation, Fig. 12 shows an example in which 16 elements are arranged in the azimuth direction, in order to explain each section in the azimuth direction as one element. In reality, tens or hundreds of elements are arranged in the azimuth direction in a 1.5-dimensional or 2-dimensional array ultrasonic probe, and the transmit aperture control method described below may be applied to each element.

[0095] In the first transmission of the ultrasonic beam, in each element row 31-33, a plurality of elements adjacent in the azimuth direction are set together as an element group that transmits the ultrasonic beam. That is, in the example of Fig. 12, two elements adjacent in the azimuth direction are set as an element group 1201. Furthermore, the element groups 1201 adjacent in the azimuth direction are not arranged contiguously, but are arranged with an interval of two elements between them.

[0096] Furthermore, the element groups 1201 are arranged so as not to be adjacent to each other in the elevation direction. In other words, the element groups 1201 are arranged in a checkerboard pattern in the elevation direction.

[0097] In the second transmission of the ultrasonic beam, similarly to the first embodiment, an area corresponding to the area of ​​all elements is set as a transmission aperture, and a second ultrasonic beam is transmitted by the transmission aperture.

[0098] In the third transmission of the ultrasonic beam, the elements that were not used in the first transmission of the ultrasonic beam and are symmetrical to the first transmission are set as element group 1201, and the ultrasonic beam is transmitted.

[0099] Next, a second example of the transmission aperture control method according to the second embodiment will be described with reference to FIG. In the second example of the second embodiment, three elements are set as one element group 1201. In this case, as in the first example of the second embodiment, adjacent element groups 1201 in the azimuth direction are arranged with the same interval of three elements as the element groups. Furthermore, in the elevation direction, the element groups 1201 are arranged in a checkered pattern so that they are not adjacent to each other in the direction in which the element rows are perpendicular to each other.

[0100] The interval between adjacent element groups 1201 in the azimuth direction is not limited to the number of elements constituting the element group 1201 being the same, and may be equal to or greater than two elements. For example, when five elements are set as one element group 1201, the interval between adjacent element groups 1201 may be equal to two elements. That is, the interval between adjacent element groups 1201 may be at least two elements. In this case, for example, when an ultrasonic beam is transmitted by an element group 1201 including five elements in the first transmission of an ultrasonic beam, two elements corresponding to the interval between the element groups 1201 in the first transmission may be set as the element group 1201 in the third transmission, and an ultrasonic beam may be transmitted from the element group 1201. That is, even if the number of elements constituting the element group 1201 differs between the first transmission and the third transmission of an ultrasonic beam, the first transmission and the third transmission may have a complementary relationship that can be regarded as transmission from all elements.

[0101] Next, a third example of the transmission aperture control method according to the second embodiment will be described with reference to FIG. A third example of the second embodiment shows a case where there are five element rows in the elevation direction. In the example of Fig. 14, three elements adjacent in the azimuth direction are set as one element group 1201, and the element groups 1201 are arranged in a checkered pattern in the elevation direction so that they are not adjacent to each other. In this way, even if there are three or more element rows in the elevation direction, the element groups 1201 can be set in a similar manner.

[0102] Next, a fourth example of the transmission aperture control method according to the second embodiment will be described with reference to FIG. In the fourth example of the second embodiment, as in the third example, a case is shown in which five element rows exist in the elevation direction, but here, three elements adjacent in the azimuth direction and two elements adjacent in the elevation direction are set as one element group 1201. In this way, the size of the element group may be changed in the elevation direction.

[0103] According to the second embodiment described above, a plurality of elements are grouped together in the azimuth direction, the element groups adjacent to each other in the azimuth direction are spaced apart by at least two elements, and the element groups are set in a checkered pattern so that the element groups are not adjacent to each other in the elevation direction, and ultrasonic beams are transmitted multiple times. This allows the element groups to be spaced apart by two elements, i.e., by at least two channels, thereby reducing the effect of crosstalk from a channel that transmits ultrasonic waves to a channel that does not transmit ultrasonic waves. In addition, in an ultrasonic beam by a sparse transmit aperture control method in which the virtual element pitch is generally spaced apart by at least two channels, grating lobes occur because the virtual element pitch becomes coarse. However, in the ultrasonic diagnostic device according to the second embodiment, the element positions that are sparse in the elevation direction are staggered, i.e., in a checkered pattern, so that the sound field can be complemented and grating lobes can be reduced.

[0104] The term "processor" used in the above description means a circuit such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an Application Specific Integrated Circuit (ASIC), a programmable logic device (e.g., a Simple Programmable Logic Device (SPLD), a Complex Programmable Logic Device (CPLD), and a Field Programmable Gate Array (FPGA)). When the processor is a CPU, for example, the processor realizes a function by reading and executing a program stored in a memory circuit. On the other hand, when the processor is an ASIC, for example, instead of storing the program in a memory circuit, the function is directly incorporated as a logic circuit in the circuit of the processor. Note that each processor in this embodiment is not limited to being configured as a single circuit for each processor, but may be configured as one processor by combining multiple independent circuits to realize the function. Furthermore, multiple components in the figure may be integrated into one processor to realize the function.

[0105] In addition, each function according to the embodiment can be realized by installing a program for executing the above-mentioned processes in a computer such as a workstation and expanding the program in memory. In this case, the program for causing the computer to execute the above-mentioned method can be stored in 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 and distributed.

[0106] Although some 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 in the scope of the invention and its equivalents as described in the claims, as well as the scope and spirit of the invention. [Explanation of symbols]

[0107] 1. Ultrasound diagnostic equipment 31~33, 41~45 Element row 34,35 area 50 Tumor 51 Bioacoustic Shadow Region 100 Device body 101 Ultrasound probe 102 Input Device 103 Output Device 104 External device 110 Ultrasonic transmission circuit 120 Ultrasonic receiving circuit 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 Aperture control function 185 Judgment Function 186 Display Control Function 187 System Control Functions 1201 Element Group NW Network

Claims

1. an ultrasonic probe in which elements are divided in an elevation direction and which transmits ultrasonic beams multiple times; an aperture control unit that controls a transmission aperture of the ultrasonic probe so that positions and areas of elements that form a part of the ultrasonic beams transmitted multiple times are equal to positions and areas of elements that form the remaining ultrasonic beams; An ultrasound diagnostic apparatus comprising:

2. The ultrasonic diagnostic apparatus according to claim 1 , wherein the aperture control unit controls the transmission aperture so that each ultrasonic beam has an element width in an azimuth direction of the ultrasonic probe.

3. The ultrasonic diagnostic apparatus according to claim 1 , wherein the aperture control unit controls the transmission aperture so that the remaining ultrasonic beam is not transmitted from some of the elements adjacent in the elevation direction.

4. the ultrasonic probe includes three element rows divided in the elevation direction, The part of the ultrasonic beams is an ultrasonic beam from all the elements, 2. The ultrasonic diagnostic device according to claim 1, wherein the remaining ultrasonic beams are an ultrasonic beam from one element row located at a center in the azimuth direction and ultrasonic beams from two element rows located at ends in the azimuth direction.

5. The transmission of the ultrasonic beam a plurality of times is transmission of the ultrasonic beam three times, The part of the ultrasonic beams is an ultrasonic beam transmitted for a second time, The ultrasonic diagnostic apparatus according to claim 1 , wherein the aperture control unit inverts a phase for each transmission of an ultrasonic beam.

6. The ultrasonic diagnostic apparatus according to claim 1 , further comprising an image generating unit configured to generate a contrast image based on a differential signal between an echo signal corresponding to the part of the ultrasonic beams and an echo signal corresponding to the remaining ultrasonic beams.

7. A determination unit that determines whether or not a bioacoustic shadow occurs in the contrast image, The ultrasonic diagnostic apparatus according to claim 6 , wherein the aperture control unit changes a transmission aperture control method of the ultrasonic probe when it is determined that the bioacoustic shadow occurs in the contrast image.

8. The ultrasonic diagnostic apparatus according to claim 1 , wherein the plurality of times is three or more times.

9. The ultrasonic diagnostic device according to claim 1 , wherein the remaining ultrasonic beams include a plurality of ultrasonic beams, each of which has a different pattern.

10. 2. The ultrasonic diagnostic device according to claim 1, wherein the aperture control unit groups a plurality of elements adjacent in an azimuth direction of the ultrasonic probe into an element group that transmits the ultrasonic beam, and sets a transmission aperture for the ultrasonic beam such that the element groups adjacent in the azimuth direction are spaced apart by at least two elements and form a checkered pattern in the elevation direction.

11. The ultrasonic diagnostic apparatus according to claim 10 , wherein the element group includes a plurality of elements adjacent to each other in the elevation direction.

Images