Ultrasonic imaging method and device

Abstract

The invention is suitable for the field of ultrasonic functional imaging, and provides an ultrasonic imaging method and device. Ultrasonic pulse waves are sent to a target needing ultrasonic detection, pulse signals passing through the target are collected, and initial transit time and an initial speed reconstruction value vector are determined through the first pulse signal; and calculating the transition time difference of each adjacent pulse signal by using a digital phase locking method, determining the speed reconstruction value vector of the next pulse signal according to the transition time difference of the adjacent pulse signals and the previous speed reconstruction value vector, and so on. And determining a two-dimensional pixel map of the to-be-measured target according to the velocity reconstruction value vectors corresponding to the series of sound channels, wherein each pixel in the two-dimensional pixel map corresponds to the temperature value. The method has the advantages of being good in space axial resolution, high in signal-to-noise ratio, accurate in result, small in calculation amount and good in real-time performance. The method can also monitor the cavitation phenomenon of ultrasonic treatment so as to solve the problem that the position and the feature size of microbubbles generated by ultrasonic treatment cannot be determined.

Description

Technical Field

[0001] The present application relates to the field of ultrasonic functional imaging, and in particular to an ultrasonic imaging method and device. Background Art

[0002] Ultrasonic CT is a non-destructive testing technology that uses ultrasound as an information carrier to reconstruct the internal features of an object. Its basic principle is to emit multiple beams of ultrasound to pass through the object to be tested, and to use the different acoustic characteristics of different tissue structures in the body when ultrasound propagates in the human body, which will cause the sound wave propagation speed to change. By measuring the transit time required for ultrasound to penetrate the object to be tested, the distribution of the sound velocity of the object to be tested can be inferred. Based on the temperature-sound velocity characteristics of the local tissue, the temperature distribution inside the object to be tested is inverted using the local sound velocity as a parameter. Ultrasonic CT has the advantages of high time resolution, no radiation, low cost, anti-electromagnetic interference and easy integration with therapeutic ultrasound systems. This technology is an ideal choice for real-time monitoring of the temperature field in the treatment area in ultrasonic tumor thermal ablation technology.

[0003] In ultrasound CT sound velocity reconstruction, the reconstruction method based on wave theory has higher imaging resolution, but is greatly affected by small error disturbances, so it is not stable enough and has a huge amount of calculation. The mathematical model of the reconstruction method based on ray theory is simpler, with less calculation, good robustness and real-time performance. However, due to the cavitation phenomenon that occurs during ultrasound treatment, a large number of microbubbles are generated in the focal range of the transmitted ultrasound field, and the location and characteristic size of the microbubbles are probabilistic and uncertain, which increases the difficulty of decoupling the sound velocity information from the microbubble interference. Summary of the invention

[0004] In view of this, the present application provides an ultrasonic imaging method and device to solve the problems that the existing ultrasonic temperature field imaging method is not stable enough, has a large amount of calculation, and is interfered by cavitation bubbles.

[0005] In a first aspect, the present application provides an ultrasonic imaging method, which is applied to an ultrasonic detection device, and the method comprises: Step 1, transmitting focused ultrasonic pulses to the target to be measured from different angles at a certain pulse repetition frequency through the transmitting array elements of the annular ultrasonic array, and collecting the pulse signal passing through the target to be measured, wherein the pulse signal includes a sinusoidal signal of several cycles; Step 2, determine the initial transit time, discretize the imaging area into spatial grids according to the number of acoustic channels, determine the path length of the ultrasonic pulse through each grid in combination with the propagation path of the ultrasonic pulse in the medium, so as to obtain the path vector of the ultrasonic pulse; determine the initial velocity reconstruction value vector by the initial transit time and path vector corresponding to each acoustic channel, wherein the initial transit time is the transit time of the first pulse signal; the acoustic channel is the path of the ultrasonic pulse propagating in the medium during the process of the ultrasonic pulse being emitted from the array element to the receiving array element; Step 3, determining the difference in transit time between adjacent pulse signals, and determining the velocity reconstruction value vector of each pulse signal according to the transit time difference, the path vector and the initial velocity reconstruction value vector; Step 4, determining a two-dimensional velocity matrix according to the velocity reconstruction value vector, determining a two-dimensional temperature value matrix according to the two-dimensional velocity matrix, and determining a two-dimensional pixel map of the target to be measured based on the two-dimensional temperature value matrix; Step 5, reading the newly collected pulse signal in the register of each sound channel, and executing steps 3 and 4 until the transmitting array element of the annular ultrasonic array stops transmitting the ultrasonic pulse.

[0006] Optionally, the ultrasonic detection device further includes an inner and outer ring confocal therapeutic ultrasonic transducer and an annular ultrasonic array; the method further includes: The inner and outer ring confocal transducers transmit two beams of high-frequency ultrasonic waves of different frequencies to the target to be measured, so that the target to be measured is acted upon by the acoustic radiation force to emit low-frequency vibration acoustic signals outward; The low-frequency vibration sound signal is collected by the multi-channel ultrasonic array and monitored in real time. When it is determined that the amplitude of the vibration sound signal has a transition, the sound path and transition time of the vibration sound signal collected on different sound channels are calculated to determine the cavitation position. The frequency of the vibration sound signal is different from that of the pulse signal, so the annular ultrasonic array can be divided into different frequency bands to collect and analyze the vibration sound signal and the ultrasonic pulse signal at the same time.

[0007] Optionally, determining the initial transit time includes: Determine the initial value of the transit time of the first pulse signal by a double threshold method, and then correct the initial value of the transit time by a digital phase-locked method to obtain a corrected value of the first transit time; The initial value and the corrected value are combined to obtain the initial transit time.

[0008] Optionally, determining the difference in transit time between adjacent pulse signals includes: For the pulse signal 1 of the same array element and the subsequent pulse signal 2 adjacent in time sequence, the first maximum amplitude point of the sinusoidal signal contained in the pulse signal 1 is t1_first The starting point of the matching window is the time t at the last maximum amplitude of the pulse signal 1. 1_last The length w of the matching window and the first window data W1 in the matching window are determined as the end point of the matching window, and at the time t of the pulse signal 2 1_first A second window data W2 with a length of w is intercepted at the position of the first window data and the second window data, a time delay is determined by performing phase-locked calculation through the first window data and the second window data, and the time delay is determined as a difference between the transit times of the pulse signal 1 and the pulse signal 2; The above steps are respectively performed between adjacent pulse signals to obtain the difference in transit time between each adjacent pulse signal.

[0009] Optionally, determining the velocity reconstruction value vector of each pulse signal according to the difference in the transit time and the initial velocity reconstruction value vector includes: For the first pulse signal 1 and the corresponding initial velocity reconstruction value vector emitted by the same array element, as well as the adjacent pulse signal 2, the velocity reconstruction value vector difference between the pulse signals 1 and 2 is determined by the transit time difference between the pulse signal 1 and the pulse signal 2 and the path vector corresponding to the pulse signal, and the velocity reconstruction value vector 2 of the pulse signal 2 is determined by the velocity reconstruction value vector difference between the pulse signals 1 and 2 and the initial velocity reconstruction value vector; For a pulse signal 3 other than the first pulse signal and the corresponding speed reconstruction value vector 3, the speed reconstruction value vector difference between the pulse signals 2 and 3 is determined by the transit time difference between the pulse signal 2 and the pulse signal 3 and the path vector corresponding to the pulse signal, and then the speed reconstruction value vector 3 of the pulse signal 3 is determined by the speed reconstruction value vector difference between the pulse signals 2 and 3 and the speed reconstruction value vector 2; The above steps are performed on each pulse signal respectively to obtain a velocity reconstruction value vector of each pulse signal.

[0010] A second aspect of the present application provides an ultrasonic imaging device, which is applied to ultrasonic detection equipment, and the device comprises: A data acquisition unit transmits focused ultrasonic pulses to a target to be measured from different angles at a certain pulse repetition frequency through the transmitting array elements of the annular ultrasonic array, and collects pulse signals passing through the target to be measured, wherein the pulse signals include a plurality of cycles of sinusoidal signals; An initial time and speed determination unit determines an initial transit time, discretizes the imaging area into spatial grids according to the number of acoustic channels, and determines the path length of the ultrasonic pulse through each grid in combination with the propagation path of the ultrasonic pulse in the medium to obtain the path vector of the ultrasonic pulse; determines an initial velocity reconstruction value vector according to the initial transit time and path vector corresponding to each acoustic channel, wherein the initial transit time is the transit time of the first pulse signal; and the acoustic channel is the path of the ultrasonic pulse propagating in the medium during the process of the ultrasonic pulse being emitted from the array element to the receiving array element; A speed reconstruction value vector determining unit, used to determine the difference in transit time between adjacent pulse signals, and determine the speed reconstruction value vector of each pulse signal according to the difference in transit time, the path vector and the initial speed reconstruction value vector; An imaging unit, used to determine a two-dimensional velocity matrix according to the velocity reconstruction value vector, determine a two-dimensional temperature value matrix according to the two-dimensional velocity matrix, and determine a two-dimensional pixel map of the target to be measured based on the two-dimensional temperature value matrix; The circular imaging unit is used to read the newly collected pulse signal in the register of each sound channel and execute the steps in the velocity reconstruction value vector determination unit and the imaging unit until the transmitting array element of the annular ultrasonic array stops transmitting the ultrasonic pulse.

[0011] Optionally, the ultrasonic detection equipment further includes an inner and outer ring confocal therapeutic ultrasonic transducer and a multi-channel annular ultrasonic array; the device further includes: A cavitation position determination unit, used for transmitting two beams of high-frequency ultrasonic waves of different frequencies to the target to be measured through the inner and outer ring confocal transducers, so that the target to be measured emits low-frequency vibration sound signals outward under the action of acoustic radiation force; The vibration sound signal is collected by the multi-channel ultrasonic array and monitored in real time. When it is determined that the amplitude of the vibration sound signal has a transition, the sound path and transition time of the vibration sound signal on different sound channels are calculated to determine the cavitation position.

[0012] Optionally, determining the initial transit time in the initial time and speed determining unit includes: Determine the initial value of the transit time of the first pulse signal by a double threshold method, and then correct the initial value of the transit time by a digital phase-locked method to obtain a corrected value of the first transit time; The initial value and the corrected value are combined to obtain the initial time of flight TOF1.

[0013] Optionally, the determining of the difference in transit time between adjacent pulse signals in the velocity reconstruction value vector determining unit includes: For a pulse signal 1 emitted by the same array element and a subsequent pulse signal 2 that is adjacent in time sequence, the first maximum amplitude point of the sinusoidal signal contained in the pulse signal 1 is t 1_first The starting point of the matching window is the time t at the last maximum amplitude of the pulse signal. 1_last The length w of the matching window and the first window data W1 in the matching window are determined as the end point of the matching window, and at the time t of the pulse signal 2 1_first A second window data W2 with a length of w is intercepted at the position of the first window data and the second window data, a time delay is determined by performing phase-locked calculation through the first window data and the second window data, and the time delay is determined as a difference between the transit times of the pulse signal 1 and the pulse signal 2; The above steps are respectively performed between adjacent pulse signals to obtain the difference in transit time between each adjacent pulse signal.

[0014] Optionally, the determining of the velocity reconstruction value vector of each pulse signal according to the difference in the transit time, the path vector and the initial velocity reconstruction value vector in the velocity reconstruction value vector determining unit includes: For the first pulse signal 1 and the corresponding initial velocity reconstruction value vector emitted by the same array element, as well as the adjacent pulse signal 2, the velocity reconstruction value vector difference between the pulse signals 1 and 2 is determined by the transit time difference between the pulse signal 1 and the pulse signal 2 and the grid path of the imaging area, and the velocity reconstruction value vector 2 of the pulse signal 2 is determined by the velocity reconstruction value vector difference between the pulse signals 1 and 2 and the initial velocity reconstruction value vector; For a pulse signal 3 other than the first pulse signal and the corresponding velocity reconstruction value vector 3, the velocity reconstruction value vector difference between the pulse signals 2 and 3 is determined by the transit time difference between the pulse signal 2 and the pulse signal 3 and the path vector of the imaging area, and then the velocity reconstruction value vector 3 of the pulse signal 3 is determined by the velocity reconstruction value vector difference between the pulse signals 2 and 3 and the velocity reconstruction value vector 2; The above steps are performed on each pulse signal respectively to obtain a velocity reconstruction value vector of each pulse signal.

[0015] In the embodiment provided by the present application, for a target to be ultrasonically detected, an ultrasonic pulse is emitted to the target, and after the pulse signal passing through the target is collected, the initial transit time and the initial velocity reconstruction value vector are determined according to the first pulse signal; the transit time difference of each adjacent pulse signal is determined by each adjacent pulse signal, and the velocity reconstruction value vector of each pulse signal is determined by the transit time difference and the initial velocity reconstruction value vector, and finally the two-dimensional pixel map of the target to be detected is determined according to the velocity reconstruction value vector, and each pixel in the two-dimensional pixel map corresponds to a temperature value. Compared with the prior art, the present method has the characteristics of good spatial axial resolution, high signal-to-noise ratio, accurate results, small calculation amount, and good real-time performance.

[0016] Furthermore, the method can also determine the location where cavitation occurs during ultrasonic imaging through inner and outer ring confocal transducers and a multi-channel annular ultrasonic array, thereby realizing cavitation detection to solve the problem that the location and characteristic size of microbubbles generated during ultrasonic treatment cannot be determined, thereby suppressing the interference of microbubbles on imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of the method provided in the embodiment of the present application; Figure 2 A schematic diagram of a ring-shaped ultrasound array provided in an embodiment of the present application; Figure 3 Schematic diagram of the ultrasonic CT algorithm provided in the embodiment of the present application; Figure 4 A pulse signal phase-locking principle diagram provided in an embodiment of the present application; Figure 5 A schematic diagram of a focused ultrasonic imaging device provided in an embodiment of the present application; Figure 6 A program structure diagram provided for an embodiment of the present application; Figure 7 A schematic diagram of the internal structure of a computer device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0018] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0019] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0020] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0021] The present application provides an ultrasonic imaging method and device to improve the accuracy of the ultrasonic imaging method and reduce the amount of calculation.

[0022] The technical solution of the present application is described in detail with specific embodiments below. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0023] like Figure 1 As shown, it is a flow chart of an ultrasonic imaging method provided by the present application. The method is applied to ultrasonic detection equipment, and the specific steps include: Step 1: transmit focused ultrasonic pulses to the target to be measured from different angles at a certain pulse repetition frequency through the transmitting elements of the annular ultrasonic array, and collect pulse signals passing through the target to be measured, wherein the pulse signals include sinusoidal signals of several cycles.

[0024] In this embodiment, when the target to be measured is tested by emitting focused ultrasonic pulse waves, the emitting array element will emit pulse waves to the target to be measured at a certain pulse repetition frequency. The pulse waves pass through the target to be measured and are collected by the preset receiving array element. The propagation time of the ultrasonic pulse from emission to collection is its transit time, and the path of the pulse wave propagating in the medium is the acoustic channel. The ultrasonic array sequentially excites multiple groups of emitting array elements in a preset order to emit pulse waves to the target to be measured from different directions and angles, such as Figure 2 shown.

[0025] In this embodiment, the sound waves emitted by the transmitting array are focused ultrasonic waves, and the far-field sound waves are less likely to diverge, have better spatial lateral resolution, and the collected sound signals have a better signal-to-noise ratio, such as Figure 5 shown.

[0026] Step 2, determine the initial transit time, and discretize the imaging area into a spatial grid according to the number of acoustic channels, such as Figure 3 , combining the propagation path of the ultrasonic pulse in the medium to determine the path length of the ultrasonic pulse through each grid, so as to obtain the path vector of the ultrasonic pulse; determining the initial velocity reconstruction value vector through the initial transit time corresponding to each acoustic channel and the path vector.

[0027] In this embodiment, the transit time of the first pulse signal is determined as the initial transit time, which can be determined by the following method: 1. Determine the initial value of the initial transit time by the double threshold method. First, set two thresholds, such as k1 and k2. When the ultrasonic sampling sequence is greater than or equal to the thresholds k1 and k2 for the first time, record the current time t1 and t2. In the interval between t1 and t2, search for the time t when the ultrasonic sampling sequence changes from a negative value to a positive value for the first time. Subtract the time of two ultrasonic cycles from the time t and record it as the initial value of the initial transit time tof.

[0028] 2. Correct the above initial value by digital phase-locking method. Select the sinusoidal signal set by the pulse signal as the reference waveform R1(t)=A sin(ωt), and then select the measured waveform with the length of the pulse starting from the tof moment as the detection waveform, expressed as S(t)=A sin(ωt+φ)+N(t), where the sinusoidal wave component A sin(ωt+φ) represents the extracted signal in the measured signal, and N(t) represents the noise component in the measured signal. Phase shift the reference waveform R1(t) by 90° as the reference waveform R2(t). The two reference waveforms and the measured waveform S(t) are multiplied by the multiplier, and the formula is as follows: , , the above two signal results are passed through a low-pass filter, and the output is: , , and further obtain the phase values ​​of the reference signal and the signal to be detected as: , Phase Divide by the signal angular velocity The corrected value t1 of the transit time can be obtained, then TOF=tof+t1, and the above corrected TOF is the initial transit time.

[0029] After determining the initial transit time corresponding to the pulse signal of each acoustic channel, the imaging area is spatially discretized into grids according to the number of acoustic channels, and the path length of each grid through which the pulse passes is determined in combination with the propagation path of the pulse in the medium, that is, the path vector of the pulse; the initial transit time corresponding to each acoustic channel and the path vector determine the initial velocity reconstruction value vector.

[0030] For example, Figure 3 As shown in the figure, the imaging area is divided into several grids of the same size, {T1, T2...T9} is the initial transit time corresponding to the first pulse signal on each sound channel, and Figure 3 The path length L corresponding to each grid in which the pulse signal propagates along the i-th sound channel can be determined. i {l i1 , l i2 ...l i9} , by solving the time equation of ultrasonic wave propagation along each channel, such as Figure 3 As shown, the speed v1, v2...v9 of the pulse signal passing through each grid can be determined. The speed set {v1, v2...v9} is the speed reconstruction value vector corresponding to the first pulse signal, that is, the initial speed reconstruction value vector mentioned above.

[0031] In this embodiment, the advantages of the dual threshold method and the digital phase-locked method are combined. The dual threshold method can effectively solve the transit time "wave jumping" problem that is prone to occur in the upstream and downstream processes at high flow rates. The digital phase-locked method breaks through the sampling rate limitation of the digital signal acquisition system and improves the time resolution of the system. The measurement accuracy and measurement stability can be guaranteed, thereby achieving high-precision ultrasonic transit time measurement.

[0032] Step 3, determine the difference in transit time between adjacent pulse signals, and determine the velocity reconstruction value vector of each pulse signal according to the difference in transit time, the path vector and the initial velocity reconstruction value vector.

[0033] In this embodiment, Figure 4 For each pulse signal collected by the same transmitting array element and receiving array element, the transit time difference between two adjacent pulse signals to be determined can also be determined by the digital phase-locking method. Taking the first data and the second data in the figure as an example, the first maximum amplitude of the sinusoidal signal of the first data is t 1_first is the window starting point, with the last maximum value of the first data at time t 1_last is the end point of the window, the window length is recorded as w, and the window data in the matching window is recorded as W1. Then, on the second data of the corresponding channel, after the second pulse is transmitted, the delay t 1_first The window data of the window to be tested with a length of w is recorded as W2; then, using W1 as the reference signal and W2 as the signal to be tested, referring to the calculation formula of S102, the phase shift between the two is calculated and converted into a time quantity, which is the difference between the transit time of the first data and the second data.

[0034] As for the transit time of the next pulse signal, i.e. the third data, W2 is used as the reference signal of the digital phase-locked method, and the first maximum amplitude moment t of the sinusoidal signal of the second data is detected by the double threshold method. 2_first In the third data t 2_first At time t, the third window data W3 of length w is intercepted, and the phase-locked calculation is performed through the third window data W3 and the window W2 of the second data to determine the difference in transit time between the second data and the third data. In this way, the difference in transit time between adjacent pulse signals can be determined.

[0035] In the above method, the velocity reconstruction value vector and transit time of the first pulse signal have been determined. The velocity reconstruction value vector of the next pulse signal can be determined by the transit time difference between the first pulse signal and the next pulse signal (recorded as pulse signal 1 and pulse signal 2, respectively). For example, the transit time of the first pulse signal mentioned above is {T1, T2...T9}, and the difference in transit time between the two is {T1', T2'...T9'}. The path-slowness-time equation group is constructed: LΔS=ΔT, where ΔS is the slowness change to be solved, L is the grid path length matrix, and ΔT is the difference in transit time. The quasi-Newton method is used to solve the equation group, and a one-dimensional vector ΔS containing 9 elements is obtained. Then determine the slowness A of the ultrasonic pulse in the test area, that is, 1 / v j , v j is the propagation speed of the ultrasonic pulse in the j-th grid. The reciprocal of the slowness A of the previous pulse signal plus the slowness change ΔS is 1 / (A+ΔS). The reciprocal can be used to determine the speed reconstruction value vector of pulse signal 2.

[0036] Similarly, for pulse signal 3, the speed reconstruction value vector of pulse signal 3 is determined by the speed reconstruction value vector of pulse signal 2 and the difference in transit time between pulse signal 2 and pulse signal 3. Each pulse signal is cumulatively calculated to finally obtain the speed reconstruction value vector of each pulse signal.

[0037] In another embodiment, the determined transit time differences may be screened according to a preset condition to determine a valid transit time difference. The preset condition may be a preset value interval, and the transit time differences within the interval are determined as valid transit time differences.

[0038] By presetting the numerical interval, this embodiment can effectively exclude those obviously unreasonable or disturbed transit time differences. For example, when the received waveform is affected by noise interference and flow field disturbance, the transit time is prone to shift forward or backward by one cycle. By setting a reasonable interval, these abnormal values ​​can be excluded, thereby improving the accuracy of the measurement results.

[0039] Step 4: determine a two-dimensional velocity matrix according to the velocity reconstruction value vector, determine a two-dimensional temperature value matrix according to the two-dimensional velocity matrix, and determine a two-dimensional pixel map of the target to be measured based on the two-dimensional temperature value matrix.

[0040] In this embodiment, the velocity reconstruction value vector is mapped into a two-dimensional space to realize two-dimensionalization, forming a two-dimensional velocity matrix, and then each velocity value in the two-dimensional velocity matrix is ​​converted into a temperature value according to the temperature-sound velocity characteristic relationship of the target to be measured. The relationship between the sound velocity and the temperature can be described by the following formula: v(T)=v0+k*(T-T0), where v0 is the velocity at the reference temperature T0. For example, at 20°C, the sound velocity in water is 1482 m / s, and k is the coefficient of the sound velocity varying with temperature. For each velocity value v in the above two-dimensional velocity matrix, j , use the following formula to calculate the corresponding temperature T j :T j =(v j -v0) / k+ T0. Each temperature value T j Put it into a new two-dimensional matrix T to form a temperature value matrix. Then use a third-party tool such as MATLAB to map each temperature value in the temperature matrix to the color or grayscale value of the pixel to generate a two-dimensional pixel map, so that each pixel in the two-dimensional pixel map corresponds to the temperature value. Through the above method, the velocity values ​​in the two-dimensional velocity matrix can be converted into temperature values, thereby realizing the visualization and analysis of the temperature distribution.

[0041] Step 5, reading the newly collected pulse signal in the register of each sound channel, and executing steps 3 and 4 until the transmitting array element of the annular ultrasonic array stops transmitting the ultrasonic pulse.

[0042] During the continuous emission of ultrasonic pulses, the pulse signals collected by the multi-channel ultrasonic array are first stored in a register. After imaging through the Nth pulse signal, the N+1th pulse signal is read for imaging, thereby realizing real-time generation of a two-dimensional pixel image of the target to be measured.

[0043] Furthermore, the storage status of the register can be detected. When the register reaches a certain threshold, its value is regularly cleared or archived to a larger storage space, such as an external memory or a database, so as to avoid overflow of the register after long-term operation.

[0044] So far, completed Figure 1 The process shown.

[0045] In the above embodiment, for the target to be ultrasonically detected, ultrasonic pulses are emitted to it, and after the pulse signals passing through the target to be detected are collected, the initial transit time and the initial velocity reconstruction value vector are determined according to the first pulse signal; the transit time difference of each adjacent pulse signal is calculated and determined by the orthogonal digital phase-locked method, and the velocity reconstruction value vector corresponding to each pulse signal is determined by the transit time difference and the initial velocity reconstruction value vector, and finally the two-dimensional pixel map of the target to be detected is determined according to the velocity reconstruction value vector, and each pixel in the two-dimensional pixel map corresponds to the temperature value. Compared with the prior art, this method has the characteristics of accurate results, small calculation amount, and good real-time performance.

[0046] In another embodiment, the ultrasonic detection device further includes inner and outer ring confocal therapeutic ultrasonic transducers and a multi-channel annular ultrasonic array; the method further includes: The inner and outer ring confocal transducers transmit two beams of high-frequency ultrasonic waves of different frequencies (f1 and f2) to the target to be measured, so that the target to be measured is acted upon by the acoustic radiation force to emit a low-frequency (△f=|f1-f2|) vibration acoustic signal outward; The vibration sound signal is collected by the multi-channel ultrasonic array and monitored in real time. When it is determined that the amplitude of the vibration sound signal has a transition, the transition moment of the vibration sound signal collected on different sound channels is detected, and the position of the ultrasonic cavitation is calculated by reverse calculation.

[0047] In this embodiment, if Figure 5 As shown, the bottom of the device is an inner and outer double-ring confocal transducer. The inner and outer confocal transducers are driven to emit two ultrasonic beams of different frequencies (f1 and f2) confocal to the target to be measured, and the two ultrasonic beams are controlled to be generated and stopped at the same time, so that the target to be measured is acted upon by the radiation force and emits a vibration sound signal Δf (equal to the difference between f1 and f2) outward, and the signal is collected by a multi-channel annular ultrasonic array. The confocal transducer is also the target area, and the temperature rises due to the acoustic thermal effect.

[0048] When cavitation occurs, the amplitude of the detection signal changes significantly, and the data is captured by accessing the registers of all channels through the acquisition card. The specific steps are as follows: 1. Signal collection: When the confocal transducer is working, the membrane medium in the acoustic focal area is heated and the vibration and acoustic signals are excited at the same time. The program monitors the amplitude of the vibration and acoustic signals in real time.

[0049] 2. Amplitude transition detection: Identify the moment when cavitation occurs by setting a threshold or analyzing the mutation characteristics of the signal.

[0050] 3. Data capture: When a transition in the amplitude of the vibration sound signal is detected, the acquisition card captures the data of all channels.

[0051] After acquiring the data, a set of equations is constructed based on the signal sound path received by multiple array elements and the corresponding signal transition time to calculate the transit time on different sound channels. Then, combined with each spatial position and transit time, the cavitation position can be reversely located through a geometric inversion algorithm, such as the TDOA algorithm.

[0052] In the above embodiment, the traditional single-frequency therapeutic ultrasonic transducer is replaced by the inner and outer ring confocal transducers, and the cavitation position in the ultrasonic imaging process is determined in conjunction with the multi-channel ultrasonic array. Cavitation detection is achieved while the treatment is performed to solve the problem that the position of the microbubbles generated during the ultrasonic treatment process cannot be determined, thereby suppressing the interference of the microbubbles on the imaging accuracy.

[0053] The present application also provides an ultrasonic imaging device, which is applied to ultrasonic detection equipment, such as Figure 6 As shown, the device comprises: The data acquisition unit 601 is used to transmit focused ultrasonic pulses to the target to be measured from different angles at a certain pulse repetition frequency through the transmitting array elements of the annular ultrasonic array, and collect the pulse signals passing through the target to be measured, wherein the pulse signals include a plurality of periods of sinusoidal signals; The initial time and speed determination unit 602 is used to determine the initial transit time, discretize the imaging area into spatial grids according to the number of acoustic channels, and determine the path length of the ultrasonic pulse through each grid in combination with the propagation path of the ultrasonic pulse in the medium to obtain the path vector of the ultrasonic pulse; determine the initial velocity reconstruction value vector according to the initial transit time and path vector corresponding to each acoustic channel, wherein the initial transit time is the transit time of the first pulse signal; and the acoustic channel is the path of the ultrasonic pulse propagating in the medium during the process of the ultrasonic pulse being emitted from the array element to the receiving array element; The speed reconstruction value vector determining unit 603 is used to determine the difference in flight time between each adjacent pulse signal, and determine the speed reconstruction value vector of each pulse signal according to the difference in flight time, the path vector and the initial speed reconstruction value vector; An imaging unit 604 is used to determine a two-dimensional velocity matrix according to the velocity reconstruction value vector, determine a two-dimensional temperature value matrix according to the two-dimensional velocity matrix, and determine a two-dimensional pixel map of the target to be measured based on the two-dimensional temperature value matrix; The circular imaging unit 605 is used to read the newly collected pulse signal in the register of each sound channel, and execute the steps in the velocity reconstruction value vector determination unit and the imaging unit until the transmitting array element of the annular ultrasonic array stops transmitting the ultrasonic pulse.

[0054] In another embodiment, the ultrasonic detection device further includes inner and outer ring confocal transducers and a multi-channel ultrasonic array; the device further includes: The cavitation position determination unit 606 is used to transmit two beams of high-frequency ultrasonic waves of different frequencies to the target to be measured through the inner and outer ring confocal transducers, so that the target to be measured is acted upon by the acoustic radiation force to emit low-frequency vibration acoustic signals outward; The vibration sound signal is collected by the multi-channel ultrasonic array and monitored in real time. When it is determined that the amplitude of the vibration sound signal has a transition, the sound path and transition time of the pulse signal on different sound channels are calculated to determine the cavitation position.

[0055] In another embodiment, determining the initial transit time in the initial time and speed determination unit comprises: Determine the initial value of the transit time of the first pulse signal by a double threshold method, and then correct the initial value of the transit time by a digital phase-locked method to obtain a corrected value of the first transit time; The initial value and the corrected value are combined to obtain the initial time of flight TOF1.

[0056] In another embodiment, determining the difference in transit time between adjacent pulse signals in the velocity reconstruction value vector determining unit comprises: For the pulse signal 1 of the same array element and the subsequent pulse signal 2 adjacent in time sequence, the first maximum amplitude point of the sinusoidal signal contained in the pulse signal 1 is t 1_first The starting point of the matching window is the time t at the last maximum amplitude of the pulse signal. 1_last The length w of the matching window and the first window data W1 in the matching window are determined as the end point of the matching window, and at the time t of the pulse signal 2 1_first A second window data W2 with a length of w is intercepted at the position of the first window data and the second window data, a time delay is determined by performing phase-locked calculation through the first window data and the second window data, and the time delay is determined as a difference between the transit times of the pulse signal 1 and the pulse signal 2; The above steps are respectively performed between adjacent pulse signals to obtain the difference in transit time between each adjacent pulse signal.

[0057] In another embodiment, the speed reconstruction value vector determining unit determines the speed reconstruction value vector of each pulse signal according to the difference in the transit time, the path vector and the initial speed reconstruction value vector, including: For the first pulse signal 1 and the corresponding initial velocity reconstruction value vector, and the adjacent pulse signal 2, the velocity reconstruction value vector difference between the pulse signals 1 and 2 is determined by the transit time difference between the pulse signal 1 and the pulse signal 2 and the grid path of the imaging area, and the velocity reconstruction value vector 2 of the pulse signal 2 is determined by the velocity reconstruction value vector difference between the pulse signals 1 and 2 and the initial velocity reconstruction value vector; For a pulse signal 3 other than the first pulse signal and the corresponding velocity reconstruction value vector 3, as well as an adjacent pulse signal 2, the velocity reconstruction value vector difference between the pulse signals 2 and 3 is determined by the transit time difference between the pulse signal 2 and the pulse signal 3 and the path vector of the imaging area, and then the velocity reconstruction value vector 3 of the pulse signal 3 is determined by the velocity reconstruction value vector difference between the pulse signals 2 and 3 and the velocity reconstruction value vector 2; The above steps are performed on each pulse signal respectively to obtain a velocity reconstruction value vector of each pulse signal.

[0058] In the above embodiment of the present invention, an ultrasonic imaging method is provided, and an ultrasonic imaging device is provided based on the method. Through the above method and device, not only the problem of the existing ultrasonic imaging method being unstable and having a large amount of calculation is solved, but also the problem of the microbubbles generated during the ultrasonic treatment process being unable to be determined is solved, thereby reducing the interference of the microbubbles on the imaging.

[0059] This embodiment also discloses a computer device, such as Figure 7 As shown, the computer device includes a processor and a memory, wherein the memory stores at least one instruction, and the at least one instruction is loaded and executed by the processor to implement any of the above-mentioned ultrasound imaging methods.

[0060] In addition, in the implementation of the ultrasonic imaging device in the above-mentioned example, the logical division of each program module is only an example. In actual application, the above-mentioned functions can be assigned to different program modules as needed, for example, for the configuration requirements of the corresponding hardware or the convenience of software implementation. That is, the internal structure of the ultrasonic imaging device is divided into different program modules to complete all or part of the functions described above.

[0061] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. An ultrasonic imaging method, characterized in that: Applied to ultrasonic testing equipment, the method comprises: Step 1, transmitting focused ultrasonic pulses to the target to be measured from different angles at a certain pulse repetition frequency through the transmitting array elements of the annular ultrasonic array, and collecting the pulse signal passing through the target to be measured, wherein the pulse signal includes a sinusoidal signal of several cycles; Step 2, determine the initial transit time, discretize the imaging area into spatial grids according to the number of acoustic channels, determine the path length of the ultrasonic pulse through each grid in combination with the propagation path of the ultrasonic pulse in the medium, so as to obtain the path vector of the ultrasonic pulse; determine the initial velocity reconstruction value vector by the initial transit time and path vector corresponding to each acoustic channel, wherein the initial transit time is the transit time of the first pulse signal; the acoustic channel is the path of the ultrasonic pulse propagating in the medium during the process of the ultrasonic pulse being emitted from the array element to the receiving array element; Step 3, determining the difference in transit time between adjacent pulse signals, and determining the velocity reconstruction value vector of each pulse signal according to the transit time difference, the path vector and the initial velocity reconstruction value vector; Step 4, determining a two-dimensional velocity matrix according to the velocity reconstruction value vector, determining a two-dimensional temperature value matrix according to the two-dimensional velocity matrix, and determining a two-dimensional pixel map of the target to be measured based on the two-dimensional temperature value matrix; Step 5, reading the newly collected pulse signal in the register of each sound channel, and executing steps 3 and 4 until the transmitting array element of the annular ultrasonic array stops transmitting the ultrasonic pulse.

2. The method according to claim 1, characterized in that The ultrasonic detection device also includes inner and outer ring confocal therapeutic ultrasonic transducers and an annular multi-channel ultrasonic array; the method also includes: The inner and outer confocal transducers emit two beams of high-frequency ultrasonic waves of different frequencies to the target to be measured, so that the target to be measured emits low-frequency vibration sound signals outward under the effect of acoustic radiation force. The inner and outer confocal transducers also serve as therapeutic ultrasonic transducers to increase the temperature of the target area to be measured. The vibration sound signal is collected by the multi-channel ultrasonic array and monitored in real time. When it is determined that the amplitude of the vibration sound signal has a transition, the sound path and transition time of the vibration sound signal collected on different sound channels are calculated to determine the cavitation position. The frequency of the vibration sound signal is different from that of the pulse signal, so the annular ultrasonic array can be divided into different frequency bands to collect and analyze the vibration sound signal and the ultrasonic pulse signal at the same time.

3. The method according to claim 1, characterized in that Determining the initial transit time comprises: Determine the initial value of the transit time of the first pulse signal by a double threshold method, and then correct the initial value of the transit time by a digital phase-locked method to obtain a corrected value of the first transit time; The initial value and the corrected value are combined to obtain the initial time of flight TOF1.

4. The method according to claim 1, characterized in that: Determining the difference in transit time between adjacent pulse signals comprises: For a pulse signal 1 emitted by the same array element and a subsequent pulse signal 2 that is adjacent in time sequence, the first maximum amplitude point of the sinusoidal signal contained in the pulse signal 1 is t 1_first The starting point of the matching window is the time t at the last maximum amplitude of the pulse signal 1. 1_last为匹配窗终点，确定所述匹配窗的长度w以及所述匹配窗内的第一窗数据W1 , and at the time t of the pulse signal 2 1_first A second window data W2 with a length of w is intercepted at the position of the first window data and the second window data, a time delay is determined by performing phase-locked calculation through the first window data and the second window data, and the time delay is determined as a difference between the transit times of the pulse signal 1 and the pulse signal 2; The above steps are respectively performed between adjacent pulse signals to obtain the difference in transit time between each adjacent pulse signal.

5. The method according to claim 1, characterized in that Determining the velocity reconstruction value vector of each pulse signal according to the difference in the transit time, the path vector and the initial velocity reconstruction value vector comprises: For the first pulse signal 1 and the corresponding initial velocity reconstruction value vector emitted by the same array element, as well as the adjacent pulse signal 2, the velocity reconstruction value vector difference between the pulse signals 1 and 2 is determined by the transit time difference between the pulse signal 1 and the pulse signal 2 and the path vector corresponding to the pulse signal, and the velocity reconstruction value vector 2 of the pulse signal 2 is determined by the velocity reconstruction value vector difference between the pulse signals 1 and 2 and the initial velocity reconstruction value vector; For a pulse signal 3 other than the first pulse signal and the corresponding speed reconstruction value vector 3, the speed reconstruction value vector difference between the pulse signals 2 and 3 is determined by the transit time difference between the pulse signal 2 and the pulse signal 3 and the path vector corresponding to the pulse signal, and then the speed reconstruction value vector 3 of the pulse signal 3 is determined by the speed reconstruction value vector difference between the pulse signals 2 and 3 and the speed reconstruction value vector 2; The above steps are performed on each pulse signal respectively to obtain a velocity reconstruction value vector of each pulse signal.

6. An ultrasonic imaging device, characterized in that: Applied to ultrasonic testing equipment, the device comprises: A data acquisition unit transmits focused ultrasonic pulses to a target to be measured from different angles at a certain pulse repetition frequency through the transmitting array elements of the annular ultrasonic array, and collects pulse signals passing through the target to be measured, wherein the pulse signals include a plurality of cycles of sinusoidal signals; An initial time and speed determination unit determines an initial transit time, discretizes the imaging area into spatial grids according to the number of acoustic channels, and determines the path length of the ultrasonic pulse through each grid in combination with the propagation path of the ultrasonic pulse in the medium to obtain the path vector of the ultrasonic pulse; determines an initial velocity reconstruction value vector according to the initial transit time and path vector corresponding to each acoustic channel, wherein the initial transit time is the transit time of the first pulse signal; and the acoustic channel is the path of the ultrasonic pulse propagating in the medium during the process of the ultrasonic pulse being emitted from the array element to the receiving array element; A speed reconstruction value vector determining unit, used to determine the difference in transit time between adjacent pulse signals, and determine the speed reconstruction value vector of each pulse signal according to the difference in transit time, the path vector and the initial speed reconstruction value vector; An imaging unit, used to determine a two-dimensional velocity matrix according to the velocity reconstruction value vector, determine a two-dimensional temperature value matrix according to the two-dimensional velocity matrix, and determine a two-dimensional pixel map of the target to be measured based on the two-dimensional temperature value matrix; The circular imaging unit is used to read the newly collected pulse signal in the register of each sound channel and execute the steps in the velocity reconstruction value vector determination unit and the imaging unit until the transmitting array element of the annular ultrasonic array stops transmitting the ultrasonic pulse.

7. The device according to claim 6, characterized in that The ultrasonic detection equipment also includes an inner and outer ring confocal therapeutic ultrasonic transducer and a multi-channel annular ultrasonic array; the device also includes: A cavitation position determination unit, used for transmitting two beams of high-frequency ultrasonic waves of different frequencies to the target to be measured through the inner and outer ring confocal transducers, so that the target to be measured is acted upon by the acoustic radiation force to emit a low-frequency vibration acoustic signal outward; The vibration sound signal is collected by the multi-channel ultrasonic array and monitored in real time. When it is determined that the amplitude of the vibration sound signal has a transition, the sound path and transition time of the vibration sound signal on different sound channels are calculated to determine the cavitation position.

8. The device according to claim 6, characterized in that Determining the initial transit time in the initial time and speed determination unit comprises: Determine the initial value of the transit time of the first pulse signal by a double threshold method, and then correct the initial value of the transit time by a digital phase-locked method to obtain a corrected value of the first transit time; The initial value and the corrected value are combined to obtain the initial time of flight TOF1.

9. The device according to claim 6, characterized in that Determining the difference in transit time between adjacent pulse signals in the speed reconstruction value vector determination unit includes: For a pulse signal 1 emitted by the same array element and a subsequent pulse signal 2 that is adjacent in time sequence, the first maximum amplitude point of the sinusoidal signal contained in the pulse signal 1 is t 1_first The starting point of the matching window is the time t at the last maximum amplitude of the pulse signal. 1_last为匹配窗终点，确定所述匹配窗的长度w以及所述匹配窗内的第一窗数据W1 , and at the time t of the pulse signal 2 1_first A second window data W2 with a length of w is intercepted at the position of the first window data and the second window data, a time delay is determined by performing phase-locked calculation through the first window data and the second window data, and the time delay is determined as a difference between the transit times of the pulse signal 1 and the pulse signal 2; The above steps are respectively performed between adjacent pulse signals to obtain the difference in transit time between each adjacent pulse signal.

10. The device according to claim 1, characterized in that Determining the speed reconstruction value vector of each pulse signal according to the difference in the transit time, the path vector and the initial speed reconstruction value vector in the speed reconstruction value vector determination unit includes: For the first pulse signal 1 and the corresponding initial velocity reconstruction value vector emitted by the same array element, as well as the adjacent pulse signal 2, the velocity reconstruction value vector difference between the pulse signals 1 and 2 is determined by the transit time difference between the pulse signal 1 and the pulse signal 2 and the path vector of the pulse signal, and the velocity reconstruction value vector 2 of the pulse signal 2 is determined by the velocity reconstruction value vector difference between the pulse signals 1 and 2 and the initial velocity reconstruction value vector; For a pulse signal 3 other than the first pulse signal and the corresponding velocity reconstruction value vector 3, the velocity reconstruction value vector difference between the pulse signals 2 and 3 is determined by the transit time difference between the pulse signal 2 and the pulse signal 3 and the path vector of the imaging area, and then the velocity reconstruction value vector 3 of the pulse signal 3 is determined by the velocity reconstruction value vector difference between the pulse signals 2 and 3 and the velocity reconstruction value vector 2; The above steps are performed on each pulse signal respectively to obtain a velocity reconstruction value vector of each pulse signal.

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