Ultrasonic imaging device, signal processing device, and signal processing method

Abstract

Provided is an ultrasonic imaging device, a signal processing device, and a signal processing method that effectively phase-summation receive signals generated by ultrasonic waves that are respectively transmitted from a plurality of ultrasonic elements and complexly propagate along the depth direction of an object, and generate an image with higher resolution. The receive signals are received by a plurality of ultrasonic elements, and are obtained by ultrasonic waves that reach the ultrasonic element array from the object that transmitted the ultrasonic waves. The receive signals are respectively delayed by delay times that differ in number according to the depth range of the object, and then summed, thereby generating one or two or more phase signals according to the depth range. For the depth range for which two or more phase signals are generated, the two or more phase signals are synthesized.

Description

Technical Field

[0001] This invention relates to ultrasonic imaging technology that uses ultrasound to capture images of a subject's internal organs. Background Technology

[0002] Ultrasonic imaging technology is a technique that uses ultrasound (sound waves not intended to be heard, usually high-frequency sound waves above 20kHz) to non-invasively image the interior of a subject, such as the human body.

[0003] The transmission and reception of ultrasonic waves in ultrasonic imaging devices are achieved through an array of ultrasonic elements with a finite aperture diameter. Therefore, the diffraction of ultrasonic waves generated at the edges of the aperture makes it difficult to improve the resolution in the azimuth direction. Consequently, novel phase modulation methods such as adaptive beamformers and aperture synthesis have been proposed.

[0004] Patent Document 1 discloses the following technique: In ultrasonic imaging technology that performs convergent transmission, an improved virtual sound source method is used for aperture synthesis. Specifically, in the region where the energy of the ultrasonic beam converges to the focal point (Patent Document 1), Figure 2 In region A), the focal point is treated as a virtual sound source and open-aperture synthesis is performed. In the regions (regions B and C) around which ultrasonic energy diffuses, the spherical waves are treated as radiating from the end of the probe and open-aperture synthesis is performed.

[0005] On the other hand, Patent Document 2 discloses an ultrasonic imaging device comprising two or more delay-adding units that separately delay and add received signals using two or more delay times. The first delay-adding unit performs delay-addition using a first delay time for phase-modulating the received signal generated from a transmitted beam (interference wave), which is transmitted from an ultrasonic element. The second delay-adding unit performs delay-addition using a second delay time for phase-modulating the received signal generated from a diffracted wave (spherical wave) with a phase different from the transmitted beam. The signals after being delayed and added separately by the first and second delay-adding units are synthesized.

[0006] Prior art literature

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 10-277042

[0009] Patent Document 2: International Publication No. 2016 / 125509 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] The technology in Patent Document 1 is an aperture synthesis technique performed between transmissions, which cannot obtain a high-precision image in a single transmission.

[0012] Patent Document 2 discloses that different delay times are used for the transmitted beam (interference wave) and other diffracted waves (spherical waves), but the number of delay addition parts is fixed to two or three, and the delay time is set according to each delay addition part. Therefore, the types of delay times are also two or three.

[0013] According to the inventor's research, ultrasonic waves (spherical waves) emitted separately from multiple ultrasonic elements in an ultrasonic element array propagate within the tested body. They interfere with each other to form a transmitted beam (interference wave). Furthermore, the spherical waves remain unchanged and propagate in all directions, or only a portion interferes or crosses and propagates in a complex manner along the depth direction. Therefore, as in Patent Document 2, in two or three delay-adding sections, only a portion of the received signals generated by these waves can be phase-modulated and added. On the other hand, if the number of delay-adding sections is increased to the same level as or greater than the number of elements emitting ultrasonic waves, it becomes possible to phase-modulate and add the received signals generated by complex waves separately, but the circuit size increases.

[0014] The purpose of this invention is to effectively phase-modulate and add the received signals generated by ultrasonic waves transmitted separately from multiple ultrasonic elements and propagating in a complex manner along the depth direction of the subject, thereby generating a higher resolution image.

[0015] Methods for solving problems

[0016] The ultrasonic imaging apparatus of the present invention includes: a transmitting beamformer that causes multiple ultrasonic elements of a connected ultrasonic element array to transmit ultrasonic waves to a subject, wherein the phase of the ultrasonic waves is delayed so that they converge at a predetermined transmitting focus; a receiving beamformer that receives a received signal obtained by the multiple ultrasonic elements of the ultrasonic element array receiving ultrasonic waves returned to the ultrasonic element array from the subject after receiving the ultrasonic waves, wherein the receiving beamformer delays the received signals separately using a delay time corresponding to the depth of the subject and then adds them together to generate a phase-modulated signal; a delay time storage unit that stores a delay time for each ultrasonic element; and a synthesis unit. The number of delay times stored in the delay time storage unit varies depending on the depth range of the subject. The receiving beamformer delays the same received signal separately using two or more delay times within two or more depth ranges where the delay times stored in the delay time storage unit are stored, thereby generating two or more phase-modulated signals. The synthesis unit synthesizes two or more phase-modulated signals for the depth ranges in which two or more phase-modulated signals have been generated.

[0017] Invention Effects

[0018] According to the present invention, not only can the received signal generated by the transmitted beam be effectively phase-modulated and added, but also the received signal generated by spherical waves transmitted from multiple ultrasonic elements and propagating complexly along the depth direction of the subject can be effectively phase-modulated and added, thereby generating a higher resolution image. Attached Figure Description

[0019] Figure 1 This is a block diagram showing the structure of the ultrasonic camera device according to the first embodiment.

[0020] Figure 2 This is an explanatory diagram showing the shape of the transmitted beam 31 and the wavefront and spherical wave.

[0021] Figure 3 This is a coordinate graph showing an example of the delay curves for each depth range of the first embodiment.

[0022] Figure 4 This is a coordinate graph showing an example of the delay curves for each depth range of the first embodiment.

[0023] Figure 5 This is a coordinate graph showing an example of the delay curves for each depth range of the first embodiment.

[0024] Figure 6 This is a block diagram showing the structure of the ultrasonic camera device according to the second embodiment.

[0025] Figure 7 This is a block diagram showing the structure of the ultrasonic camera device according to the third embodiment.

[0026] Figure 8 This is a flowchart illustrating the operation of each part of the ultrasonic camera device according to the third embodiment during photography.

[0027] Figure 9 (a) is an ultrasonic image captured by the ultrasonic imaging device of the comparative example. Figure 9 (b) is an ultrasonic image captured by the ultrasonic imaging device of this embodiment. Figure 9 (c) is shown Figure 9 Coordinate graphs of the brightness profile in the depth direction of ultrasound images (a) and (b). Figure 9 (d) and (e) are shown Figure 9 Coordinate graphs of the brightness profile in the azimuth direction of the ultrasound images (a) and (b).

[0028] Explanation of reference numerals in the attached figures

[0029] 13. Receive beamformer;

[0030] 15 Synthesis Department;

[0031] 17. Delay time storage section;

[0032] 18. Delay time calculation unit;

[0033] 19. Composite weight calculation unit;

[0034] 30. Send focus;

[0035] 36. Receive scan lines;

[0036] 100 Ultrasonic camera device;

[0037] 101 Ultrasonic Element Array;

[0038] 102 Main body of ultrasonic camera device;

[0039] 103 Image display unit;

[0040] 104 Transmit beamformer;

[0041] 105 Transmitting channel (ultrasonic element);

[0042] 106 Receiving channel (ultrasonic element);

[0043] 107 Transceiver Separation Circuit (T / R);

[0044] 109 Image Processing Department;

[0045] 110 Console;

[0046] 111 Control Department;

[0047] 116 Ultrasonic probe;

[0048] 301–306 Spherical waves;

[0049] 310 Transmit beam;

[0050] 350~354 Delay time (delay curve);

[0051] 361~365 Delay time (delay curve);

[0052] Depth range of 371 and 372. Detailed Implementation

[0053] An ultrasonic imaging device according to one embodiment of the present invention will be described.

[0054] <<First Implementation>>

[0055] First, use Figures 1-5The ultrasonic camera device 100 of the first embodiment will be described. Figure 1 This is a diagram showing the structure of an ultrasound diagnostic device. Figure 2 This is a diagram illustrating an example of the wavefront of an ultrasonic wave transmitted from an array of ultrasonic elements. Figures 3-5 It is a coordinate graph showing the delay time stored at each depth in the delay time storage section.

[0056] like Figure 1 As shown, the ultrasonic imaging device 100 of this embodiment includes an ultrasonic imaging device main body 102 and an ultrasonic probe 116. The ultrasonic probe 116 has an ultrasonic element array 101 connected to the ultrasonic imaging device 102. The ultrasonic element array 101 is a structure in which multiple ultrasonic elements are arranged in an array. In the ultrasonic element array 101, the multiple ultrasonic elements (channels) used for transmitting are called transmitting channels, and the multiple ultrasonic channels used for receiving are called receiving channels.

[0057] The main body 102 of the ultrasonic camera device is configured to include a transmitting beamformer 104, a receiving beamformer 13, a delay time storage unit 17, a synthesis unit 15, a delay time calculation unit 18, a synthesis weight calculation unit 19, an image processing unit 109, a transceiver separation circuit 107, an analog-to-digital converter (ADC) 11, and a control unit 111 for controlling the whole system.

[0058] The transmit beamformer 104 outputs transmit signals to multiple transmit channels 105 of the ultrasonic element array 101, and transmits ultrasonic waves from the multiple transmit channels 105 to the subject 90 respectively. The phase of the ultrasonic waves is delayed so that they converge at a predetermined transmit focus 30 (see reference). Figure 2 ).

[0059] Therefore, as Figure 2 As shown, ultrasonic waves (spherical waves) 301-306, etc., transmitted from the transmission channel 105 propagate within the subject 90. They interfere with each other to form a transmission beam (interference wave) 310. In addition, a portion of them remain unchanged as spherical waves 301-306 and propagate in various directions, and only a portion of them interfere and propagate in a complex manner along the depth direction.

[0060] The ultrasonic waves transmitted from the subject 90, such as the received ultrasonic waves 301-306 and 310, are received by the ultrasonic element array 101 and converted into received signals through the multiple receiving channels 106 of the ultrasonic element array 101.

[0061] The receiving beamformer 13 receives received signals from multiple receiving channels 106 via the transceiver separation circuit 107 and the analog-to-digital converter. The received signals are delayed by a delay time corresponding to the depth of the subject 90 and then added together to generate a phase-modulated signal whose phase (receiving focus) is consistent with the received sound waves from multiple camera target points on the receiving scan line 36.

[0062] In the delay time storage section 17, a delay time used when the receiving beamformer 13 delays the received signal is stored for each ultrasonic element (receiving channel 106). The delay time ensures that the phase (receiving focus) is aligned with multiple imaging target points on the receiving scan line 36, therefore, for example, Figure 3 The dashed curve 350 shows how the delay time varies with depth. Here, the variation in delay time at each depth is also referred to as the delay curve.

[0063] In this embodiment, a phase-modulated signal is generated not only based on the received signal generated by the transmitted beam 310, but also based on the received signal generated from waves directly propagating from spherical waves 301-306, or interference waves in which a portion of them has interfered. Therefore, as... Figures 3-5 As illustrated, multiple delay times (delay curves) are stored in the delay time storage unit 17.

[0064] Therefore, the receiving beamformer 13 uses various delay times to delay the same received signals and then adds them together, thereby generating multiple phase-modulated signals for the same receiving scan line 36.

[0065] The combining unit 15 adds the generated phase-modulated signals at each identical depth. Therefore, for the same receiving scan line, it is possible to obtain not only a phase-modulated signal synthesized from the phase-modulated signals generated from the received signals produced by the transmitting beam 310, but also a phase-modulated signal synthesized from the phase-modulated signals generated from some or all of the received signals produced by other waves such as spherical waves 301-306. Thus, a higher resolution phase-modulated signal can be obtained compared to a phase-modulated signal obtained only for the transmitting beam 310.

[0066] At this point, in order to obtain a phase-modulated signal based on all the spherical waves 301-306 or a portion of their interference waves, the number of delay times (the number of roots of the delay curve) needs to be prepared to correspond to the number of these spherical waves 301-306 or a portion of the interference waves, requiring a number of delay times of the same magnitude as the transmitting channel. In this case, the computational load of the receiving beamformer 13 also increases.

[0067] Therefore, in this embodiment, the number of delay times (the number of roots of the delay curve) is different according to the depth range of the subject 90, thereby limiting the depth range in which the number of delay times increases and suppressing the amount of computation.

[0068] For example, it can be configured to also include a delay time calculation unit 18, which calculates the quantity and value of delay times stored in the delay time storage unit 17 by calculation according to each depth range.

[0069] The delay time calculation unit 18 calculates the number and value of delay times for each depth range, for example, based on the transmit / receive parameters and / or the type of connected ultrasonic probe 116. These transmit / receive parameters are set by the operator via the control panel (receiver unit) 110, including camera condition parameters and / or camera parameters. The camera condition parameters are input conditions explicitly displayed to the operator on the control panel 110. These include conditions selected by the operator from various camera modes (color flow imaging, Doppler imaging, nonlinear imaging, aperture synthesis, frequency / spatial synthesis, contrast / edge emphasis imaging, etc.), and values ​​that can be input by the operator through knobs or buttons that change in stages or continuously. The transmit / receive parameters are ultrasonic transceiver-related parameters converted from the aforementioned camera condition parameters through pre-prepared tables or formulas within the device. As transmission and reception parameters, such as the transmit aperture diameter, receive aperture diameter, frequency (center frequency, frequency band), transmit focus position, and the shape of the transmit pulse wave (wave number / amplitude), etc.

[0070] Specifically, the following structure can be adopted: a table is predetermined and stored in the memory of the delay time calculation unit 18. This table determines the relationship between the imaging condition parameters and / or the transmission and reception parameters and / or the type of ultrasonic probe 116 and the quantity and value of the delay time for each depth range. The delay time calculation unit 18 calculates the quantity and value of the delay time by referring to this table. Alternatively, not limited to the table, the value of the transmission parameter can be substituted into a predetermined formula to calculate the quantity and value of the delay time for each depth range.

[0071] The delay time calculation unit 18 can also be configured as follows: Figure 3 As shown, the delay time, which serves as a predetermined baseline, is multiplied by adjustment factors α1, α2, α3...αn, thereby generating n delay time values ​​(delay curves) for each depth range. α1, α2, α3...αn are functions of depth (d).

[0072] The delay time calculation unit 18 can be configured to calculate the delay time value for each depth through internal calculation of the delay line. Internal calculation of the delay line refers to the method of calculating the delay time for each depth in real time during signal processing. In this case, the delay time calculation unit 18 and the delay time storage unit 17 are located within the receiving beamformer 13. When performing internal calculation of the delay line, the delay time calculation unit 18 calculates the delay time for the received signal successively input from the ADC 11 according to extremely short time intervals such as each sample, each receiving scan line, or each acoustic wave transmission, and immediately stores it in the delay time storage unit 17, which is also located in the receiving beamformer 13. Furthermore, the delay time value in the delay time storage unit 17 is refreshed (rewritten) to the delay time value used for the next sample, receiving scan line, or acoustic wave transmission immediately after the delay addition processing in the receiving beamformer 13 is completed. According to this method, the amount of data for the delay time value stored in the delay time storage unit 17 at one time can be significantly reduced. Therefore, the delay time storage unit 17 does not need to use a large-capacity memory; for example, the delay time storage unit 17 can be replaced by the instantaneous memory inside the FPGA or ASIC.

[0073] Furthermore, the delay time calculation unit 18 can also be configured to calculate the delay time for each depth based on a predetermined acoustic wave propagation simulation. Typically, the delay curve is represented by a simple numerical model of acoustic wave propagation, but by directly executing the acoustic wave propagation simulation based on the transmit and receive parameters through the delay time calculation unit 18, a more accurate delay time can be calculated. Specifically, taking the transmitting aperture, receiving aperture, frequency, transmitting focus position, and the shape of the transmitting pulse wave as input, the propagation mode of the ultrasonic waves emitted by each transmitting channel and received by each receiving channel is calculated through propagation simulation using one-dimensional, two-dimensional, or three-dimensional differential equations, difference equations, Green's functions, etc. This accurately determines the propagation path of the acoustic waves, and the delay time of the delay curve is calculated using the propagation path. By using the accurate delay time calculated based on the acoustic wave propagation simulation for receiving beamforming, higher quality ultrasonic imaging can be achieved. Since the computational scale of the acoustic wave propagation simulation is large, when the receiving beamformer 13 utilizes logic devices such as FPGAs or ASICs, it is desirable to increase the device size to realize the acoustic wave propagation simulation. When a device used as a receiving beamformer employs a CPU or GPU architecture, sound wave propagation simulation can be appropriately achieved through software computation.

[0074] Furthermore, for example, it can be configured such that, for each pre-determined body part (abdomen, circulatory organs, chest, legs, blood vessels, digestive organs, prenatal examination, etc.) or organ (liver, heart, kidneys, pancreas, gallbladder, ovaries, carotid artery, thyroid, etc.) of the camera subject, a depth range in which increasing the number of delay times can effectively improve resolution is pre-determined, and the delay time calculation unit 18 increases the number of delay times for that depth range. The operator selects the body part or organ via the console 110 connected to the control unit 111.

[0075] Additionally, the delay time calculation unit 18 can also increase the number of delay times within the depth range of the desired high-resolution video received by the operator via the console 110. Alternatively, it can prepare a delay time pattern in advance that increases the number of delay times within a specified depth range, which the operator can use according to the depth range of the desired high-resolution video.

[0076] Furthermore, the delay time calculation unit 18 can also incorporate a machine learning model. Various parameters related to ultrasound imaging, such as camera condition parameters, transmit / receive parameters, and probe type, as well as ultrasound images captured before the actual imaging or their received signals, are input into the machine learning model. The model calculates the appropriate number of delay times and / or the value of the delay time corresponding to the depth, based on the depth. Regarding the machine learning model, it uses the following approach: taking camera conditions, the captured image or received signal, and the number of delay times used for the imaging as input data, and using a high-precision image obtained by increasing the number of delay times, the delay time at that time, and the number of delay times as forward retrieval data for pre-learning. Additionally, the imaging accuracy and resolution vary depending on the type of organ; therefore, the initial machine learning model can be learned separately for different organs such as the liver, kidneys, blood vessels, and breasts.

[0077] use Figures 3 to 5 A specific example of a delay curve will be provided. Figure 3 The delay curves are examples of preparing two delay curves 350 and 351 within a depth range 372 deeper than the transmission focus 30, and preparing only one delay curve 350 within a depth range 371 shallower than the transmission focus 30.

[0078] Figure 4 The example is that five delay curves 350 to 354 are prepared within a depth range 372 deeper than the transmission focus 30, and only one delay curve 350 is prepared within a depth range 371 shallower than the transmission focus 30.

[0079] Figure 5The delay curves are examples of preparing four delay curves 350 to 354 within a depth range 372 deeper than the transmission focus 30, and preparing six delay curves 350, 361 to 365 within a depth range 371 shallower than the transmission focus 30.

[0080] It should be noted that, Figures 3 to 5 Delay curves with different numbers of roots are set in two depth ranges 371 and 372 with the sending focus 30 as the boundary, but the depth range in this embodiment is not limited to these two ranges. Any number of arbitrary depth ranges can be set, and the desired number of delay times (the desired number of roots of delay curves) can be set according to each depth range.

[0081] The control unit 111 controls each component to move the transmission channel 105 and repeatedly transmit and receive until the required number of phase-modulated signals for the receive scan lines 36 are obtained for image generation. It should be noted that this control method applies to linear scanning, convex scanning, and other scanning methods. In the case of sector (phased array) scanning, the transmit and receive apertures are the same, but the following method is used: by tilting the receive scan lines 36 in an angular direction, multiple transmit and receive scan lines are set on a two-dimensional plane, and imaging of a sector area is performed along this direction. For example, a method is used where 50-1300 scan lines are prepared in a sector shape with the center set at ±45° or ±60° of the probe aperture. Even in this case, the control unit 111 controls each component to move the transmission angular direction instead of the transmission channel 105 and repeatedly transmit and receive until the required number of phase-modulated signals for the receive scan lines 36 are obtained for image generation.

[0082] The image processing unit 109 generates an image by arranging the image to generate the required number of phase modulation signals or by converting the phase modulation signals into signal strength / brightness values ​​for each sample / pixel, and displays the image on the connected image display unit 103.

[0083] Thus, in this embodiment, the number of delay times (the number of roots of the delay curve) varies according to the depth. As a result, not only can a phase-modulated signal be obtained from the received signal generated by the transmitted beam 310, but also from the received signal generated by some or all of other waves (spherical waves 301 to 306, etc.). Therefore, by synthesizing them according to each depth, a high-resolution phase-modulated signal can be generated while suppressing the computational load.

[0084] Furthermore, in this embodiment, a high-resolution phase-modulated signal can be effectively obtained with fewer ultrasound transmissions. Therefore, compared to high-resolution methods that use multiple transmission beams, such as transmission aperture synthesis, spatial composite, coded transceiver, and multi-beam transmission, the computational load can be significantly reduced. Moreover, unlike these methods, a high-resolution phase-modulated signal can be obtained in a single transmission. Therefore, compared to images obtained using multiple transmissions, such as transmission aperture synthesis, the temporal resolution is high, and there is no image blurring (motion, body motion artifacts) associated with the movement of a moving body. Therefore, the ultrasound imaging device of this embodiment is also suitable for imaging high-speed moving bodies (heartbeats, heart valves), high-speed vibrations of bubbles, and contrast agents requiring temporal resolution.

[0085] However, the ultrasonic imaging apparatus of this embodiment is not limited to a structure that obtains a phase-modulated signal for one receiving scan line in a single transmission; it can also generate phase-modulated signals for multiple receiving scan lines in a single transmission. This reduces the number of transmissions required to generate an image, enabling high-speed imaging. Furthermore, for imaging areas where temporal resolution is not required, transmission aperture synthesis can be performed as needed. Additionally, this embodiment represents the upstream processing of the signal processing in an ultrasonic apparatus such as the transmission beamformer 13; therefore, it can be used not only for transmission aperture synthesis but also in combination with other ultrasonic imaging methods, such as nonlinear (harmonic) imaging, Doppler imaging, color Doppler imaging, coherent imaging, and imaging using adaptive beamforming.

[0086] It should be noted that the synthesis unit 15 may also be configured to add the phase-modulated signals generated by the receiving beamformer 13 after weighting when synthesizing the signals with different numbers for each depth range. In this case, the synthesis weight calculation unit 19 may also generate appropriate weights based on the depth, such as the camera conditions and the number of delay times for each depth range set by the operator from the control console 110.

[0087] Alternatively, the receiving beamformer 13 can be configured to have multiple delay-adding circuits connected in parallel, allowing the received signals received from the multiple receiving channels 106 to be delayed and then added together using multiple delay times. Alternatively, the receiving beamformer 13 can be configured to sequentially add the same received signals using delay times arranged in a time sequence (by each sample point, by each depth-corresponding block, by each transmission, etc.) using fewer delay-adding circuits than the number of delay times, generating a phase-modulated signal, and storing the generated phase-modulated signal sequentially in a built-in memory. In the latter case, the delay-adding circuit can be as few as one, thus allowing for a smaller circuit size. Therefore, the receiving beamformer 13 can also be mounted inside the ultrasonic probe 116. Furthermore, in the latter case, time-division processing can be used to perform parallel delay-adding processing on the same received signals using multiple delay times.

[0088] Hereinafter, the structure and operation of the ultrasonic camera device of this embodiment will be specifically described in the second and third embodiments.

[0089] <<Second Implementation>>

[0090] The structure of the receiving beamformer 13 of the ultrasonic imaging device in the second embodiment will be specifically described. In the second embodiment, the receiving beamformer 13 is composed of two delay-adding circuits 13-1 and 13-2 arranged in parallel.

[0091] like Figure 6 As shown, the receiving beamformer 13 includes a first delay-adding circuit 13-1 and a second delay-adding circuit 13-2 connected in parallel. The first delay-adding circuit 13-1 and the second delay-adding circuit 13-2 include delay circuits and adding circuits, which sum the identical received signals (representing the received signals received by the multiple receiving channels 106 respectively, based on the reflected waves from the camera object and the same transmitted ultrasonic wave) after delaying them according to each receiving channel 106. The delay circuit of the first delay-adding circuit 13-1 utilizes, for example, a... Figure 3 The first delay time 350 delays the received signals before summing them, thereby generating a first phase-modulated signal. The first delay time 350 is set to phase-modulate the received signal of the reflected wave of the transmitted beam 310 after being reflected by the object 90. The second delay summing circuit 13-2 utilizes... Figure 3 The second delay time 351 delays the received signal, thereby generating a second phase-modulated signal. The second delay time is set to phase-modulate the received signal of the reflected wave of a wave other than the transmitted beam 310 (e.g., a spherical wave 301) after being reflected by the subject 90.

[0092] according to Figure 3 It is known that the first delay time 350 is set for the entire depth direction. Therefore, the first delay summing circuit 13-1 generates the first phase modulation signal for the entire depth range of the receiving scan line 36. On the other hand, the second delay time 351 is set only for the depth range deeper than the transmission focus 30. Therefore, the second delay summing circuit 13-2 generates the second phase modulation signal only for the depth range deeper than the transmission focus 30 of the receiving scan line 36.

[0093] The synthesis unit 15 receives the first phase modulation signal generated by the first delay addition circuit 13-1 through delay and the second phase modulation signal generated by the second delay addition circuit 13-2 through delay. It multiplies the signals of the same depth by the weight of each depth calculated by the synthesis weight calculation unit 19 and then adds them together.

[0094] By using the summed phase-modulated signals to generate an image, it is possible to generate an image using not only the information from the transmitted beam 310, but also the information from the spherical wave (e.g., spherical wave 301). Moreover, since the second delay time 351 is only set within a depth range deeper than the transmitted focal point 30, the computational load of the second delay summing circuit 13-2 is reduced, thereby reducing the overall computational load of the receiving beamformer 13.

[0095] It should be noted that in the second embodiment, the method used is... Figure 3 The structure with maximum two delay times of 350 and 351 means that the receiving beamformer 13 only needs two delay summing circuits 13-1 and 13-2, but in cases where... Figure 4 or Figure 5 In cases where the maximum number of delay times is five or six, a delay summing circuit with a number equal to or greater than the maximum number of delay times needs to be configured in the receiving beamformer 13.

[0096] The structure of the ultrasonic camera device other than that described above is the same as that of the first embodiment, so the description is omitted.

[0097] <<Third Implementation Method>>

[0098] As a third embodiment, another structure of the receiving beamformer 13 will be specifically described. The receiving beamformer 13 of the third embodiment has a number of delay summing circuits that are fewer than the maximum number of delay times, and generates a phase-modulated signal for the entire delay time through time-division processing.

[0099] Specifically, such as Figure 7Thus, the receiving beamformer 13 is configured to include a delay-adding circuit 13-4, a receiving signal storage unit 13-3, and a phase-modulated signal storage unit 13-5. The receiving signal storage unit 13-3 stores the received signals received from the multiple receiving channels 106 of the ultrasonic element array 101. The phase-modulated signal storage unit 13-5 stores the phase-modulated signal generated by the delay-adding circuit 13-4. The phase-modulated signal storage unit 13-5 includes n memories or storage areas, from the first memory 13-51 to the nth memory 13-5n. The phase-modulated signal calculated according to each delay curve stored in the delay time storage unit 17 is stored in a different memory or storage area. Therefore, the number n in the nth memory 13-5n is prepared to be greater than or equal to the maximum value of the delay time (delay curve) used in the generation of the phase-modulated signal.

[0100] The delay-adding circuit 13-4 uses time-division processing to generate phase-modulated signals sequentially from the received signals stored in the received signal storage unit 13-3 based on the maximum n delay curves, and stores them in the first memory 13-51 to the nth memory 13-5n.

[0101] Next, use Figure 8 The operation of each part of the ultrasonic camera device in this embodiment during recording will be explained.

[0102] (Step 131)

[0103] First, the control unit 111 receives, via the console 110, the transmit and receive parameters set based on the camera condition parameters and / or camera parameters, and / or the type of the connected ultrasonic probe 116. Transmit and receive parameters include, for example, the transmit aperture diameter, the receive aperture system, the frequency (center frequency, bandwidth), the transmit focus position, and the shape of the transmit pulse wave (wave number, amplitude), etc.

[0104] (Step 132)

[0105] Based on the conditions received in step 131, the control unit 111 calculates the shape of the transmission beam 31.

[0106] (Step 133)

[0107] The delay time calculation unit 18 uses the shape of the transmitting beam 31 calculated in step 132 to set the position of the receiving scan line 36, and sets multiple imaging target points (receiving focal points) on each receiving scan line 36. The delay time calculation unit 18 has a built-in memory that stores a table pre-stored, determining the relationship between the transmission and reception parameters, the type of ultrasonic probe 116, and the number and value of delay times (delay curves) for each receiving channel 106 in each depth range. The delay time calculation unit 18 calculates the number of delay times (delay curves) for each depth range and the delay value for each depth (phase-modulated target point) corresponding to the transmission and reception parameters and the type of ultrasonic probe 116 received in step 132.

[0108] For example, such as Figure 4 In this way, a delay curve 350 is set within a depth range 371 that is shallower than the transmission focus 30, and five delay curves 350 to 354 are set within a depth range 372 that is deeper than the transmission focus 30.

[0109] (Step 134)

[0110] The delay time calculation unit 18 stores the number and value of the delay time (delay curve) of each receiving channel 106 in each depth range in the delay time storage unit 17.

[0111] (Step 135)

[0112] The control unit 111 transmits transmission conditions such as the position of the transmission focus 30, transmission frequency, and number of transmissions to the transmission beamformer 104. The transmission beamformer 104 generates a transmission signal and outputs it to the ultrasonic elements of the transmission channel 105 of the ultrasonic element array 101. The ultrasonic elements of the transmission channel 105 convert the transmission signal into ultrasonic waves and transmit them. The receiving channel 106 of the ultrasonic element array 101 receives the sound waves from the subject generated by the transmission in step 135 and outputs a receiving signal.

[0113] (Step 136)

[0114] The control unit 111 stores the received signal, which is converted into a digital signal by the analog-to-digital converter 11, in the received signal storage unit 13-3.

[0115] (Step 137)

[0116] The delay-adding circuit 13-4 reads the first delay curve and its depth range for each receiving channel 106 from the delay time storage unit 17, and reads the received signal of each receiving channel 106 from the received signal storage unit 13-3. After delaying each received signal within the depth range of the read delay curve using the delay time shown by the delay curve of each receiving channel 106, the delayed signals are added together according to the channel for a consistent depth, thereby generating a phase-modulated signal.

[0117] (Step 138)

[0118] The generated phase modulation signal is stored in the first memory 13-51 of the phase modulation signal storage unit 13-5. At the same time, information representing the depth range of the phase modulation signal is also stored.

[0119] (Step 139)

[0120] The delay addition circuit 13-4 repeats steps 137 and 138 above for all delay curves stored in the delay time storage unit 17 until the delay addition process is completed.

[0121] (Step 140)

[0122] The synthesis unit 15 receives the phase modulation signals from the memories 13-51 to 13-5n of the phase modulation signal storage unit 13-5, reads the weight of each phase modulation signal and each depth determined by the synthesis weight calculation unit 19 through calculation, and adds the phase modulation signals after weighting them. At this time, the existing depth range is different according to the phase modulation signal. Therefore, the synthesis unit 15 adds the phase modulation signals of the same depth with reference to the depth range information attached to the phase modulation signal.

[0123] The image processing unit 109 processes the phase-modulated signals received during each ultrasonic wave transmission by performing coordinate transformation / scan transformation according to the scan line type (linear, convex, sector / phased array) and arranging them in a two-dimensional / three-dimensional coordinate space. Alternatively, it performs signal dynamic range transformation such as logarithmic compression to transform the brightness data of each pixel, or performs linear filtering such as resampling / interpolation / bandpass, and generates an image and displays it on the connected image display unit 103.

[0124] It should be noted that the above description describes the delay addition process of the delay addition circuit 13-5 being performed sequentially according to each delay curve. However, it can also be configured such that the delay curve is divided into multiple ranges within a predetermined depth range, and the delay addition process is performed according to each of the divided depth ranges.

[0125] In the third embodiment, although there is only one delay-adding circuit 13-4, a phase-modulated signal can be obtained for a single delay curve 350 within a depth range 371 shallower than the transmission focus 30, and phase modulation can be obtained for spherical waves (e.g., spherical waves 301-304) other than the transmission beam 310 using multiple (e.g., five) delay curves 350-354 within a depth range 372 deeper than the transmission focus 30.

[0126] Therefore, in the third embodiment, multiple phase modulation signals can be obtained with a small number of delay-adding circuits in a single transmission, generating a high-resolution image.

[0127] In addition, although multiple delay curves 350 to 354 are used for calculation, their depth range is limited. Therefore, compared with the case where delay curves are set throughout the entire depth range, the amount of computation and the amount of data of the phase-modulated signal after the processing delay summation can be reduced.

[0128] In this way, the circuit size of the receiving beamformer is small, and the amount of computation and the amount of data of the phase modulation signal are reduced. Therefore, the receiving beamformer can also be mounted on the ultrasonic probe 116, and the phase modulation signal can be sent from the probe to the synthesizer 15 via wireless communication.

[0129] It should be noted that in the first to third embodiments described above, the receiving beamformer 13 and the delay time calculation unit 18 can be constructed in hardware. For example, the circuit can be designed using a custom IC such as an ASIC (Application Specific Integrated Circuit) or a programmable IC such as a FPGA (Field-Programmable Gate Array) to implement the functions of each part. It should also be noted that the receiving beamformer 13 and the delay time calculation unit 18 can also implement some or all of their functions in software. In this case, the receiving beamformer 13 and the delay time calculation unit 18 can be constructed using a computer equipped with a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit) and memory. The CPU reads the program stored in memory and executes it, thereby implementing these functions.

[0130] use Figure 9 Sections (a) to (e) will explain the effects of this embodiment. Figure 9 The ultrasound image 151 in (a) is an ultrasound image obtained by photographing an ultrasound phantom using only one delay line (comparative example). Figure 9The ultrasound image 152 in (b) is an ultrasound image obtained by imaging an ultrasound phantom using two or more delay lines according to this embodiment. Compared with the ultrasound image 151 of the comparative example, it can be seen that the ultrasound image 152 of this embodiment has a greater contrast between the simulated blood vessel area and the simulated cyst area (both black areas) within the ultrasound phantom and the other tissue areas, thus improving visual confirmability. In addition, the imaging resolution of each reflector within the ultrasound phantom is also improved.

[0131] Coordinate graphs 153-155 are obtained by extracting and arranging the contours of image brightness for regions of interest (ROI) 1511-1513 in ultrasonic image 151 and regions of interest (ROI) 1521-1523 in ultrasonic image 152. Coordinate graph 153 shows the contours of image brightness in the depth direction for regions of interest 1511 and 1521, coordinate graph 154 shows the contours of image brightness in the azimuth direction for regions of interest 1512 and 1522, and coordinate graph 155 shows the contours of image brightness in the azimuth direction for regions of interest 1513 and 1523. The dashed contours 1511, 1512, and 1513 in coordinate graphs 153-155 correspond to ultrasonic image 151 using only one delay line, while the solid contours 1521, 1522, and 1523 correspond to ultrasonic image 152 using two or more delay lines in this embodiment.

[0132] When observing coordinate graphs 153 and 154, it can be confirmed that in the vascular and cyst regions, the signal brightness intensity of the solid line outlines 1521 and 1522 of this embodiment is significantly lower than that of the dashed line outlines 1511 and 1512 of the comparative example, resulting in a reduction of unwanted acoustic noise in both the depth and azimuth directions. Furthermore, when observing coordinate graph 155, it can be confirmed that the width of the point scatterer in the azimuth direction of the solid line outline 1523 of this embodiment is significantly narrower than that of the dashed line outline 1513 of the comparative example, and the resolution of the ultrasound imaging is greatly improved by this embodiment.

[0133] As mentioned above, according to Figure 9 From (a) to (e), it can be confirmed that the ultrasonic imaging device of this embodiment has the effect of improving the image quality depiction capabilities such as contrast and resolution of the obtained ultrasonic image, thereby enabling high-quality ultrasonic imaging with higher visual verifiability.

Claims

1. An ultrasonic camera device, characterized in that, The ultrasonic camera device includes: Transmitting beamformer, which causes multiple ultrasonic elements of the connected ultrasonic element array to transmit phase-delayed ultrasonic waves to the subject, so that they converge at a specified transmission focus. A receiving beamformer receives a received signal, which is a signal obtained by multiple ultrasonic elements of the ultrasonic element array receiving ultrasonic waves returned to the ultrasonic element array from the subject that received the ultrasonic waves. The receiving beamformer delays the received signals separately using a delay time corresponding to the depth of the subject and then adds them together to generate a phase-modulated signal. The delay time storage unit stores the delay time for each of the ultrasonic elements; The delay time calculation unit generates the delay time through calculation and stores it in the delay time storage unit; Synthesis section; and The control panel allows the operator to select the body part or organ of the subject to be imaged. The time delay calculation unit calculates, based on a pre-determined depth range for each part or organ of the subject across multiple parts, that effectively increases the number of time delays to improve resolution. It then calculates the depth range for increasing the number of time delays for each part or organ of the camera subject received by the operator via the console. For this depth range, the number of generated time delays is increased compared to other depth ranges. The receiving beamformer stores two or more delay times within a depth range in the delay time storage section, and uses the two or more delay times to delay the same received signal respectively, thereby generating two or more phase-modulated signals. The synthesis unit synthesizes the two or more phase-modulated signals for the depth range of which two or more phase-modulated signals have been generated.

2. The ultrasonic camera device according to claim 1, characterized in that, The ultrasonic camera device also has a receiving unit for receiving and transmitting parameters from the operator. The delay time calculation unit calculates the delay time based on the transmit and receive parameters and through calculation.

3. The ultrasonic camera device according to claim 2, characterized in that, The delay time calculation unit refers to a table that predetermines the relationship between the transmit / receive parameters and the number and value of delay times for each depth range, and calculates the number and value of delay times corresponding to the transmit / receive parameters received by the receiving unit.

4. The ultrasonic camera device according to claim 1, characterized in that, The delay time calculation unit and the delay time storage unit are disposed within the receiving beamformer. The delay time calculation unit calculates in real time, corresponding to the delay addition processing of the received signal performed by the receiving beamformer, the number of delay times that vary according to the depth range, and rewrites the delay times stored in the delay time storage unit in sequence.

5. The ultrasonic camera device according to claim 1, characterized in that, The delay time calculation unit multiplies the predetermined base delay time by predetermined adjustment coefficients α1, α2, α3...αn, thereby calculating n delay time values ​​for each depth range.

6. The ultrasonic camera device according to claim 1, characterized in that, The delay time calculation unit calculates the propagation path of the ultrasonic waves emitted and received by each ultrasonic element based on a predetermined acoustic wave propagation simulation, and uses the calculated propagation path to calculate a number of delay times that vary depending on the depth range.

7. The ultrasonic camera device according to claim 1, characterized in that, The delay time calculation unit has a machine learning model, which calculates the appropriate number of delay times and / or the value of the delay time corresponding to the depth based on the ultrasonic images or received signals previously captured by the camera.

8. The ultrasonic camera device according to claim 1, characterized in that, The receiving beamformer has a number of delay summing circuits that are the same as the maximum number of delay times stored in the delay time storage unit. The same received signal is input to each delay summing circuit, and delay summing is performed using different delay times.

9. The ultrasonic camera device according to claim 1, characterized in that, The receiving beamformer includes a delay summing circuit, a received signal storage unit, and a phase modulation signal storage unit, the number of which is less than the number of delay times stored in the delay time storage unit. Using the delay time stored in the delay time storage unit, the same received signals stored in the received signal storage unit are subjected to delay summation processing. For multiple delay times stored in the delay time storage unit, the processing stored in the phase modulation signal storage unit is performed sequentially.

10. The ultrasonic camera device according to claim 1, characterized in that, The synthesis unit adds the two or more phase-modulated signals together after weighting them according to a weight set based on depth.

11. The ultrasonic camera device according to claim 2, characterized in that, The transmit / receive parameters include at least one of the following: aperture diameter, frequency, and transmit focus position.

12. The ultrasonic camera device according to claim 1, characterized in that, The ultrasonic camera device also includes an ultrasonic probe equipped with the ultrasonic element array. The receiving beamformer is mounted on the ultrasonic probe.

13. A signal processing apparatus for receiving and processing a received signal, wherein the received signal is obtained by a plurality of ultrasonic elements receiving ultrasonic waves from a test subject that has transmitted ultrasonic waves, reaching an array of ultrasonic elements; characterized in that... The signal processing device includes: A receiving beamformer uses a delay time corresponding to the depth of the subject to delay the received signals separately and then add them together to generate a phase-modulated signal; The delay time storage unit stores the delay time for each of the ultrasonic elements; The delay time calculation unit generates the delay time through calculation and stores it in the delay time storage unit; Synthesis section; and The control panel allows the operator to select the body part or organ of the subject to be imaged. The time delay calculation unit calculates, based on a pre-determined depth range for each part or organ of the subject across multiple parts, that effectively increases the number of time delays to improve resolution. It then calculates the depth range for increasing the number of time delays for each part or organ of the camera subject received by the operator via the console. For this depth range, the number of generated time delays is increased compared to other depth ranges. The receiving beamformer stores two or more delay times within a depth range in the delay time storage section, and uses the two or more delay times to delay the same received signal respectively, thereby generating two or more phase-modulated signals. The synthesis unit synthesizes the two or more phase-modulated signals for the depth range of which two or more phase-modulated signals have been generated.

14. A signal processing method, comprising receiving and processing a received signal, wherein the received signal is obtained by multiple ultrasonic elements respectively receiving ultrasonic waves from a test subject transmitting ultrasonic waves to an array of ultrasonic elements, characterized in that, The operator selects the body part or organ to be photographed from the subject. Based on the depth range pre-determined for each part or organ of the subject under examination, where increasing the number of delay times can effectively improve resolution, the depth range from the subject's body part or organ under the operator's care, for which the number of delay times can be increased, is determined. Delay times are generated for the depth range that increases the number of delay times, as well as for other depth ranges. In this case, for the depth range that increases the number of delay times, a greater number of delay times are generated compared to the other depth ranges. By using the generated delay time, the received signals are delayed separately and then added together, thereby generating one or more phase-modulated signals according to the depth range. For depth ranges where two or more phase modulation signals have been generated, the two or more phase modulation signals are synthesized.

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