Ultrasonic plane wave imaging method, device and equipment

Abstract

This article relates to the field of image processing, and in particular to an ultrasonic plane wave imaging method, device and equipment. It includes that each array element of the array ultrasonic linear array probe successively transmits ultrasonic waves to the target tissue according to the first predetermined transmission parameter and receives the reflected ultrasonic waves of the target tissue, generates an initial velocity model, estimates the propagation speed of the ultrasonic waves in the target tissue, and can estimate the sound speed in the layered medium in the variable speed medium. Each array element transmits ultrasonic plane waves to the target tissue according to the second predetermined transmission parameter and multiple deflection angles and receives the reflected ultrasonic plane waves to form a radio frequency signal, and calculates the imaging of the target tissue according to the initial velocity model and the radio frequency signal. Through the embodiments of this article, high-resolution and high-contrast images can be obtained, and the imaging results are more reliable. The problems of low imaging quality and large amount of calculation in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the field of image processing, and in particular to an ultrasonic plane wave imaging method, device and equipment. Background Art

[0002] Ultrasonic imaging has the advantages of being non-invasive, safe, convenient, and highly real-time. It is widely used in fetal, cardiac, and abdominal imaging and is one of the most important imaging modes in clinical diagnosis. Ultrasonic plane wave imaging uses plane wave pulses to image the entire study area at once, replacing the traditional focused beam transmission. Its image frame rate is greatly improved, reaching 4000 to 15000 frames per second, and plays an important role in ultrafast Doppler imaging, shear wave elastic imaging, brain function imaging, and other studies. In order to improve the imaging quality of ultrasonic plane waves, a plane wave coherent composite imaging method (CPWC) was developed. Multiple plane wave pulses are continuously emitted at different deflection angles, and then the imaging results at different angles are combined to form the final reconstructed image. Although this method improves the image quality, it greatly reduces the imaging frame rate. At the same time, plane wave imaging obtains ultrasonic images through point-by-point delay superposition (DAS) wave number synthesis. In the calculation, the speed of the entire medium is assumed to be uniform and the sound wave propagates in a straight line. However, the sound speed in the actual tissue is variable, causing reflection, refraction, and deflection of the sound wave, and the imaging result shows noise reverberation. In addition, real-time processing of ultrasound images at multiple angles (generally 11 to 75 angles) results in a huge amount of calculation, which poses a huge challenge to data processing performance.

[0003] There is an urgent need for an ultrasonic plane wave imaging method to solve the problems of low imaging quality and large amount of calculation in the prior art. Summary of the invention

[0004] To solve the problems in the prior art, the embodiments of this article provide an ultrasonic plane wave imaging method, device and equipment. The method performs imaging based on the reverse time migration of the wave equation, can estimate the sound speed in a layered medium in a variable speed medium, and uses less deflection angle data than the plane wave coherent composite imaging method to achieve images with higher resolution and contrast, and the imaging results are more reliable.

[0005] In order to solve the above technical problems, the specific technical solutions of this article are as follows:

[0006] On the one hand, the embodiments of the present invention provide an ultrasonic plane wave imaging method, comprising:

[0007] Each array element of the array ultrasound linear array probe transmits ultrasound to the target tissue in sequence according to the first predetermined transmission parameter to obtain an original radio frequency signal, rearranges the common reflection point data of the original radio frequency signal, performs energy superposition in the direction of the reflection event axis to obtain a velocity spectrum, and obtains a local velocity model at different depths;

[0008] Each array element of the array ultrasound linear array probe transmits a multi-angle ultrasonic plane wave to the target tissue according to a second predetermined transmission parameter and multiple deflection angles, images the tissue based on the received radio frequency signal combined with the local velocity model, and coherently superimposes the imaging results of the multiple deflection angles to obtain the imaging result of the target tissue.

[0009] Furthermore, the step of obtaining the local velocity model further includes:

[0010] The first predetermined transmission parameter includes the delay time and imaging depth of each array element of the array ultrasound linear array probe for successive transmission, receives multiple reflected ultrasound waves from multiple layers of tissue in the target tissue, forms an original radio frequency signal, rearranges the common reflection point data of the original radio frequency signal, performs energy superposition in the direction of the reflection event axis, obtains a velocity spectrum, calculates the velocity of the original radio frequency signal at different depths based on the velocity spectrum, and obtains the local velocity model.

[0011] Furthermore, the local velocity model describes the velocity relationship between the multiple array elements and the corresponding original radio frequency signals for different layers of tissue.

[0012] Further, the array element includes a transmitting array element and a receiving array element, and the first predetermined transmitting parameter includes an interval time and an imaging depth;

[0013] The local velocity model is the velocity corresponding to the maximum amplitude of velocity spectrum line A1, and the formula is:

[0014]

[0015] Among them, f i，tij is the time delay of the ith array element at t ij The amplitude of the RF signal, A1 represents the velocity spectrum, v j represents the scanning speed, M represents the number of array elements on the array ultrasound linear array probe, and N represents the time window length determined according to the initial time value and the interval time.

[0016] Furthermore, the step of obtaining the imaging result of the target tissue also includes:

[0017] Each array element of the array ultrasound linear array probe transmits an ultrasonic plane wave to the target tissue according to a second predetermined transmission parameter and a plurality of deflection angles, and obtains a radio frequency signal corresponding to each deflection angle, wherein the radio frequency signal includes the transmitted ultrasonic plane wave and the ultrasonic plane wave reflected by multiple layers of tissue in the target tissue;

[0018] Calculating a transmit forward field corresponding to a deflection angle according to the local velocity model and a second predetermined transmit parameter of an ultrasonic plane wave corresponding to the deflection angle, and calculating a receive inversion field of the deflection angle according to a radio frequency signal corresponding to the deflection angle;

[0019] The transmitted forward field and the received inversion field corresponding to a deflection angle are calculated according to the cross-correlation imaging condition to obtain the imaging result of the deflection angle;

[0020] The imaging results of multiple deflection angles are coherently superimposed to obtain the imaging result of the target tissue.

[0021] Furthermore, calculating the transmission forward field corresponding to a deflection angle according to the local velocity model and a second predetermined transmission parameter of an ultrasonic plane wave corresponding to the deflection angle further includes:

[0022] Constructing first and second order partial differential acoustic wave equations at different imaging depths according to the local velocity model and the emission parameters;

[0023] The first second-order partial differential acoustic wave equation is solved by using a staggered grid finite difference time domain method to obtain the extended wave fields at different times as the transmitting forward modeling field.

[0024] Calculating the receiving inversion field of the deflection angle according to the radio frequency signal corresponding to the deflection angle further includes:

[0025] Arranging the radio frequency signals in descending order of data time to obtain a time reverse propagation signal;

[0026] Constructing a second second-order partial differential acoustic wave equation according to the time-backward propagation signal;

[0027] The second second-order partial differential acoustic wave equation is solved using a finite difference method to obtain extended wave fields at different times as the receiving inversion field.

[0028] Furthermore, the transmit forward field and receive inversion field corresponding to a deflection angle are calculated according to the cross-correlation imaging condition, and the formula for obtaining the imaging result of the deflection angle is:

[0029]

[0030] Among them, Image θk represents the kth deflection angle θ k The corresponding imaging result, T represents the total acquisition time in the second predetermined emission sequence, t represents the time, S θ Denotes the deflection angle θ k Corresponding to the launch forward field, R θ Denotes the deflection angle θ kCorresponding to the received inversion field, x = (x, y, z) represents the space vector corresponding to each point in the imaging area.

[0031] Furthermore, the imaging results of multiple deflection angles are coherently superimposed to obtain the imaging result of the target tissue using the formula:

[0032]

[0033] Wherein, Image(x) represents the imaging result of the target tissue, and Θ represents the total number of the deflection angles.

[0034] On the other hand, the embodiments of the present invention also provide an ultrasonic plane wave imaging device, comprising:

[0035] A local velocity model calculation unit is used for each array element of the array ultrasound linear array probe to transmit ultrasound to the target tissue in accordance with the first predetermined transmission parameter one by one to obtain an original radio frequency signal, rearrange the common reflection point data of the original radio frequency signal, perform energy superposition in the direction of the reflection event axis, obtain a velocity spectrum, and obtain local velocity models at different depths;

[0036] The target imaging result calculation unit is used for each array element of the array ultrasound linear array probe to transmit a multi-angle ultrasonic plane wave to the target tissue according to the second predetermined transmission parameter and multiple deflection angles, and to image the tissue according to the received radio frequency signal combined with the local velocity model, and to coherently superimpose the imaging results of the multiple deflection angles to obtain the imaging result of the target tissue.

[0037] On the other hand, an embodiment of the present invention further provides a computer device, including a memory, a processor, and a computer program stored in the memory, and the processor implements the above method when executing the computer program.

[0038] On the other hand, an embodiment of the present invention further provides a computer storage medium on which a computer program is stored. When the computer program is executed by a processor of a computer device, the above method is executed.

[0039] Using the embodiments of this article, first, each array element of the array ultrasound linear array probe successively transmits ultrasound to the target tissue according to the first predetermined transmission parameter, and the transmitted ultrasound and the ultrasound reflected by the multiple layers of tissue in the target tissue form an original radio frequency signal, and then a local velocity model is constructed based on the original radio frequency signal. The local velocity model can estimate the propagation speed of the ultrasound in each layer of tissue, and then each array element of the array ultrasound linear array probe transmits an ultrasound plane wave to the target tissue according to the second predetermined transmission parameter and multiple deflection angles, and the transmitted ultrasound plane wave and the ultrasound plane wave reflected by the multiple layers of tissue in the target tissue form a radio frequency signal corresponding to each deflection angle, and the imaging result of the target tissue is obtained according to the radio frequency signal and the local velocity model. Through the method of the embodiments of this article, high-resolution and high-contrast images can be obtained, and the imaging results are more reliable. The problems of low imaging quality and large amount of calculation in the prior art are solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of this article or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of this article. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 A schematic diagram of an implementation system of an ultrasonic plane wave imaging method in an embodiment of the present invention;

[0042] Figure 2 FIG. 1 is a flow chart of an ultrasonic plane wave imaging method according to an embodiment of the present invention;

[0043] Figure 3 FIG. 1 is a detailed schematic diagram of a method for ultrasonic plane wave imaging according to an embodiment of the present invention;

[0044] Figure 4 Shown is a schematic diagram of a hyperbolic radio frequency signal in the embodiments of this article;

[0045] Figure 5 It shows the steps of calculating the transmission forward field corresponding to a deflection angle according to the local velocity model and the second predetermined transmission parameter of the ultrasonic plane wave corresponding to the deflection angle in the embodiment of this article;

[0046] Figure 6 The figure shows the steps of calculating the receiving inversion field of the deflection angle according to the radio frequency signal corresponding to the deflection angle in the embodiment of this article;

[0047] Figure 7 The figure is a schematic diagram of the structure of an ultrasonic plane wave imaging device according to an embodiment of this invention;

[0048] Figure 8 The figure is a detailed structural schematic diagram of an ultrasonic plane wave imaging device according to an embodiment of this invention;

[0049] Fig. 9 Shown is a schematic diagram of the structure of the computer device of the embodiment of this article.

[0050]

Description of reference numerals

[0051] 101. Terminal;

[0052] 102. Server;

[0053] 701. Local velocity model calculation unit;

[0054] 702, target imaging result calculation unit;

[0055] 7021, radio frequency signal acquisition module;

[0056] 7022. Transmitting forward field and receiving inverse field calculation module;

[0057] 7023, sub-imaging result calculation module;

[0058] 7024, target imaging result calculation module;

[0059] 902. Computer equipment;

[0060] 904. Processing equipment;

[0061] 906. Storage resources;

[0062] 908, driving mechanism;

[0063] 910, input / output module;

[0064] 912. Input device;

[0065] 914. Output device;

[0066] 916. Presentation equipment;

[0067] 918. Graphical user interface;

[0068] 920, network interface;

[0069] 922, communication link;

[0070] 924. Communication bus. DETAILED DESCRIPTION

[0071] The following will be combined with the drawings in the embodiments of this article to clearly and completely describe the technical solutions in the embodiments of this article. Obviously, the described embodiments are only part of the embodiments of this article, not all of the embodiments. Based on the embodiments of this article, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this article.

[0072] It should be noted that the terms "first", "second", etc. in the specification and claims of this article and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of this article described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, device, product or equipment that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0073] It should be noted that the acquisition, storage, use, and processing of data in the technical solution of this application are in compliance with the relevant provisions of national laws and regulations.

[0074] like Figure 1 The diagram is a schematic diagram of an implementation system of an ultrasonic plane wave imaging method according to an embodiment of the present invention, which may include a terminal 101 and a server 102. A communication connection is established between the terminal 101 and the server 102 to enable data interaction. A staff member may input a radio frequency signal obtained by scanning a target tissue with an array ultrasonic linear array probe into the server 102 through the terminal 101, and the server 102 generates an image of the target tissue according to the radio frequency signal input by the terminal 101.

[0075] In the embodiments of this specification, the server 102 can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, content delivery networks (CDN, Content Delivery Network), and big data and artificial intelligence platforms.

[0076] In an optional embodiment, the terminal 101 may include but is not limited to electronic devices such as desktop computers, tablet computers, and laptop computers. Optionally, the operating system running on the electronic device may include but is not limited to Android, IOS, Linux, and Windows.

[0077] In addition, it should be noted that Figure 1 What is shown is only one application environment provided by the present disclosure. In actual application, other application environments may also be included, and this specification does not limit this.

[0078] In order to solve the problems existing in the prior art, the embodiments of this article provide an ultrasonic plane wave imaging method, which performs imaging based on the reverse time migration of the wave equation, can estimate the sound speed in a layered medium in a variable speed medium, and uses less deflection angle data than the plane wave coherent composite imaging method to achieve images with higher resolution and contrast, and the imaging results are more reliable. Figure 2 The figure shows a flow chart of an ultrasonic plane wave imaging method according to an embodiment of the present invention. This figure describes the process of imaging the target tissue, but it may include more or fewer operating steps based on conventional or non-creative work. The order of steps listed in the embodiment is only one way of executing the steps among many orders, and does not represent the only order of execution. When the system or device product is executed in practice, it can be executed in the order or in parallel according to the method shown in the embodiment or the accompanying drawings. Specifically, Figure 2 As shown, the method may be executed by a processor and may include:

[0079] Step 201: each array element of the array ultrasound linear array probe transmits ultrasound to the target tissue in sequence according to the first predetermined transmission parameter to obtain an original radio frequency signal, rearranges the common reflection point data of the original radio frequency signal, performs energy superposition in the direction of the reflection event axis to obtain a velocity spectrum, and obtains a local velocity model at different depths;

[0080] Step 202: Each array element of the array ultrasound linear array probe transmits a multi-angle ultrasonic plane wave to the target tissue according to a second predetermined transmission parameter and a plurality of deflection angles, images the tissue based on the received radio frequency signal in combination with the local velocity model, and coherently superimposes the imaging results of the plurality of deflection angles to obtain an imaging result of the target tissue.

[0081] Using the embodiments of this article, first, each array element of the array ultrasound linear array probe successively transmits ultrasound to the target tissue according to the first predetermined transmission parameter, and the transmitted ultrasound and the ultrasound reflected by the multiple layers of tissue in the target tissue form an original radio frequency signal, and then a local velocity model is constructed based on the original radio frequency signal. The local velocity model can estimate the propagation speed of the ultrasound in each layer of tissue, and then each array element of the array ultrasound linear array probe transmits an ultrasound plane wave to the target tissue according to the second predetermined transmission parameter and multiple deflection angles, and the transmitted ultrasound plane wave and the ultrasound plane wave reflected by the multiple layers of tissue in the target tissue form a radio frequency signal corresponding to each deflection angle, and the imaging result of the target tissue is obtained according to the radio frequency signal and the local velocity model. Through the method of the embodiments of this article, high-resolution and high-contrast images can be obtained, and the imaging results are more reliable. The problems of low imaging quality and large amount of calculation in the prior art are solved.

[0082] Furthermore, the detailed flow chart of the ultrasonic plane wave imaging method described in the embodiment of this invention is as follows: Figure 3 As shown, the specific steps include:

[0083] Step 301: each array element of the array ultrasound linear array probe successively transmits an ultrasonic wave to the target tissue according to a first predetermined transmission parameter, obtains a plurality of reflected ultrasonic waves from multiple layers of tissue in the target tissue, forms an original radio frequency signal according to the transmitted ultrasonic wave and the ultrasonic waves reflected from multiple layers of tissue in the target tissue, rearranges the common reflection point data of the original radio frequency signal, performs energy superposition in the direction of the reflection event axis, obtains a velocity spectrum, calculates the velocity of the original radio frequency signal at different depths according to the velocity spectrum, and obtains a local velocity model;

[0084] Step 302: each array element of the array ultrasound linear array probe transmits an ultrasonic plane wave to the target tissue according to a second predetermined transmission parameter and a plurality of deflection angles, and obtains a radio frequency signal corresponding to each deflection angle, wherein the radio frequency signal includes the transmitted ultrasonic plane wave and the ultrasonic plane wave reflected by multiple layers of tissue in the target tissue;

[0085] Step 303: calculating a transmit forward field corresponding to a deflection angle according to the local velocity model and a second predetermined transmit parameter of an ultrasonic plane wave corresponding to the deflection angle, and calculating a receive inversion field of the deflection angle according to a radio frequency signal corresponding to the deflection angle;

[0086] Step 304: Calculate the transmit forward field and receive inversion field corresponding to a deflection angle according to the cross-correlation imaging condition to obtain an imaging result of the deflection angle;

[0087] Step 305: coherently superimpose the imaging results of multiple deflection angles to obtain the imaging result of the target tissue.

[0088] In the embodiment of the present invention, each array element of the array ultrasound linear array probe is first controlled to transmit ultrasound to the target tissue in a manner that a single array element transmits ultrasound one by one. The first predetermined parameter may include a transmission interval time and an imaging depth. The interval time may be the interval time for each array element to transmit ultrasound one by one. The imaging depth indicates the depth of the ultrasound reflection point in the target tissue. The imaging depth can be controlled by controlling the energy of the ultrasound transducer. Multiple imaging depths correspond to multiple layers of tissue in the target tissue. After the ultrasound emitted by the transmitting array element reaches the corresponding layer of tissue in the target tissue according to the imaging depth, the ultrasound is reflected back and received by the receiving array element. The emitted ultrasound and the reflected ultrasound are used as original radio frequency signals. The channel data that is symmetrical with the transmitting array element about the linear array center is extracted from the original radio frequency signal emitted by each array element, and the original signal is rearranged according to the receiving channel position, and the original data of all array elements are synthesized into a data matrix. Because the ultrasound waves emitted by each transmitting array element at the same imaging depth are reflected back at the same point on the corresponding layer of tissue at the imaging depth, this rearrangement of the original RF signal can be called common reflection point (or common center point) data rearrangement. Then, energy superposition is performed in the direction of the reflection phase axis to obtain a velocity spectrum. The velocities of the original RF signal at different depths are calculated based on the velocity spectrum to obtain a local velocity model.

[0089] Then, each array element of the array ultrasound linear array probe is controlled to transmit an ultrasonic plane wave to the target tissue according to a second predetermined transmission parameter and a plurality of deflection angles, that is, the ultrasonic plane wave is controlled to be transmitted at different deflection angles, and the ultrasonic plane wave transmitted at a deflection angle and the received ultrasonic plane wave are used as the radio frequency signal corresponding to the deflection angle.

[0090] Then, the reverse time migration method based on the wave equation is used to calculate the transmission forward field corresponding to a deflection angle according to the local velocity model and the transmission parameters of the ultrasonic plane wave corresponding to the deflection angle, and the reception inversion field of the deflection angle is calculated according to the radio frequency signal corresponding to the deflection angle. Then, the transmission forward field and the reception inversion field corresponding to the deflection angle are calculated according to the cross-correlation imaging conditions to obtain the imaging result of the deflection angle. The above calculation process is repeated for the radio frequency signals corresponding to different deflection angles to obtain the imaging results of multiple deflection angles. Finally, the imaging results of multiple deflection angles are coherently superimposed to obtain accurate and reliable high-resolution, high-contrast images of the target tissue.

[0091] In the embodiment of this article, the purpose of controlling the single array element of the array ultrasound linear array probe to transmit ultrasound waves one by one is to achieve velocity estimation of the target tissue, and the obtained local velocity model describes the velocity relationship between multiple array elements and the corresponding original radio frequency signal for different layers of tissue. The second predetermined transmission parameters include aperture size, imaging depth, number of plane wave tilt angles, transmission frequency and pulse period. According to the tilt angle sequence of the deflection angle sequence, the delay time of each array element of the ultrasonic transducer under different plane wave tilt angles is determined in sequence, and ultrasonic plane waves are emitted in sequence according to the delay time; and each array element of the ultrasonic transducer is used to sequentially receive the reflected ultrasonic plane waves under different deflection angles.

[0092] Furthermore, the common reflection point data of the original radio frequency signal is rearranged, energy is superimposed in the direction of the reflection event axis to obtain a velocity spectrum, and the velocities at different depths are calculated according to the velocity spectrum to obtain a local velocity model, which includes the following steps:

[0093] Each original radio frequency signal is rearranged in the order of the transmitting array element and the receiving array element being symmetrical about the center of the linear array to obtain a hyperbolic radio frequency signal. In the embodiment of this invention, the deployment relationship between the transmitting array element and the receiving array element can be as follows: Figure 3 As shown. Define the center point of the linear array as O, a certain transmitting array element as S, and its symmetrical point about point O as G. The ultrasonic wave emitted by S is emitted at point R of the target tissue layer and received by G. The horizontal projection point of R is O. This signal arrangement method with a common center point makes the ultrasonic waves emitted by each array element reflect at point R and are received by its symmetrical array element. The horizontal distance between the transmitting S and the receiving G is x, and the depth of the target interface is h0. Then the transit time T of the ultrasonic wave emitted by the array element S is SG It is expressed as formula (1):

[0094]

[0095] Transit time T SG Together with the horizontal spacing x, it forms the equation of a hyperbola. represents the distance between the emission S and the reflection R, Represents the distance between the reflection R and the reception G. For a certain depth h0, the layer velocity is v, and a hyperbolic trajectory is uniquely determined on each data channel of the receiving array element.

[0096] The hyperbolic radio frequency signal on each data channel is a function of time, as shown in formula (2):

[0097] f i (t), (i=1, 2, 3,...,M) (2)

[0098] Among them, f i(t) represents the hyperbolic RF signal corresponding to the i-th array element, t represents time, and M represents the number of array elements on the array ultrasound linear array probe. Figure 4 As shown in (a), point S represents the point of the transmitting element, point R represents the reflection point on the tissue, point G is the point of the receiving element symmetrical to the center of point S of the transmitting element, point O is the calculated center point, and h0 represents the depth, as shown in Figure 4 As shown in (b), X1, X2, ..., Xi, ..., XM represent multiple array elements, t0 corresponds to the reflection time of the round-trip vertical distance (OR) of a certain layer, that is, t0 = 2h0 / v, and t0 corresponds to the vertex position of a hyperbolic RF signal in the above original signal. The initial time values ​​corresponding to the L hyperbolic RF signals are t 01 ,t 02 ,...,t 0L ; For each t0, define the initial value range of velocity [v1,v L ], where v1 represents the starting value of the initial range of velocity, v L Indicates the end value of the initial range of velocity. It is necessary to ensure that the velocity of the target tissue area is within this initial range.

[0099] like Figure 4 As shown in (c), the ordinate represents speed and the abscissa represents time. The time corresponding to the vertex of the hyperbolic RF signal of a layer of tissue corresponding to an array element is taken as the initial time value (that is, Figure 4 The initial time value corresponds to the reflection time of the two-way vertical distance of a layer of tissue in the target tissue (i.e., the round-trip time from point O to point R), and the vertical distance represents the vertical distance between the straight line formed by a transmitting array element and the corresponding receiving array element and the reflection point in the layer of tissue (i.e., the distance from point O to point R).

[0100] For each initial time value, in the range [v1,v L ] scan j times, according to formula (3):

[0101] v j =v B +(jl)Δv(j=1,2,…,J) (3)

[0102] Determine multiple experimental speed values, where v j represents the jth experimental speed value, v B =v1, Δv represents the velocity increment corresponding to the initial time value, and J represents the number of experimental velocity values;

[0103] The hyperbolic RF signal is scanned according to the experimental speed value, and the time delay of the i-th array element is calculated, and the formula is (4):

[0104]

[0105] Among them, t ij represents the time delay corresponding to the jth experimental velocity value of the ith array element, t 0l represents the initial time value, M represents the number of array elements, x i represents the horizontal distance between the receiving array element of the ith array element and its corresponding transmitting array element, v j represents the j-th experimental speed value;

[0106] According to the time delay of multiple experimental velocity values ​​of multiple array elements, according to formula (5),

[0107]

[0108] Calculate the velocity spectrum corresponding to the initial time value of the i-th array element, where A1 represents the velocity spectrum, N represents the time window length determined according to the initial time value and the interval time, and f i represents the initial time value t of the i-th array element 0l Corresponding to the hyperbolic radio frequency signal, Δt0 represents the time interval;

[0109] Change t 0l =t 0B +(l-1)Δt0,l=1,2,…,(t 0E -t 0B ) / Δt0, where t 0B Indicates the starting time of the time range corresponding to the initial time value, t 0E Indicates the end time of the time range corresponding to the initial time value, and calculates the velocity spectrum corresponding to the changed initial time value;

[0110] The velocity spectra corresponding to the multiple initial time values ​​are taken as the velocity spectrum set of the i-th array element;

[0111] Arrange the multiple velocity spectrum sets of multiple array elements according to time to obtain the time-velocity spectrum curve, and obtain the depth-velocity spectrum curve through time-depth conversion. The velocity spectrum calculated by formula (5) is actually the superposition amplitude corrected and superimposed with different speeds. When the correct speed is scanned, the phase axis can be fully leveled to achieve the same phase superposition, so the amplitude value after superposition is the strongest, that is, there is v j So that A1(v j )=A 1max Therefore, the maximum velocity corresponding to A1 at each depth is taken as the local velocity model c=v j .

[0112] According to one embodiment of this article, Figure 5 As shown, calculating the transmission forward field corresponding to a deflection angle according to the local velocity model and a second predetermined transmission parameter of an ultrasonic plane wave corresponding to the deflection angle further includes:

[0113] Step 501: constructing first and second order partial differential acoustic wave equations at different imaging depths according to the local velocity model and the second predetermined transmission parameters;

[0114] In this step, the first and second order partial differential acoustic wave equations at different imaging depths are constructed according to the local velocity model and the second predetermined transmission parameters as formula (6):

[0115]

[0116] In the formula, S θk (x,t) is the position at x at time t. s The sound wave field of the sound source at position x, c(x) is the local velocity model at different positions x, is the Laplace operator. The term is the initial condition of the equation, and f(t) is the value of the point at x at time t. S is the sound source function at , δ is the Kronecker function, and θ is the deflection angle of the plane wave.

[0117] Step 502: Solve the first second-order partial differential acoustic wave equation using a staggered grid finite difference time domain method to obtain extended wave fields at different times as the transmit forward modeling field.

[0118] like Figure 6 As shown, calculating the receiving inversion field of the deflection angle according to the radio frequency signal corresponding to the deflection angle further includes:

[0119] Step 601: Arrange the radio frequency signals in descending order of data time to obtain a time reverse propagation signal P(x R ,t);

[0120] Step 602: construct a second second-order partial differential acoustic wave equation according to the time reverse propagation signal;

[0121] In this step, the second second-order partial differential acoustic wave equation is constructed according to the time back propagation signal as formula (7):

[0122]

[0123] In the formula, R θk (x,t) is the position at x at time t. R The acoustic wave field of the array element at x, P(x R ,t)δ(xx R) is the initial condition of the equation, the inverted RF signal P(x R ,t) as the source term of equation (7).

[0124] Step 603: using a finite difference method to solve the second second-order partial differential acoustic wave equation, and obtaining extended wave fields at different times as the receiving inversion field.

[0125] According to an embodiment of the present invention, the transmit forward field and the receive inversion field corresponding to a deflection angle are calculated according to the cross-correlation imaging condition, and the imaging result of the deflection angle is obtained by formula (8),

[0126]

[0127] Among them, Image θk represents the kth deflection angle θ k The corresponding imaging result, T represents the total acquisition time in the second predetermined emission sequence, t represents the time, S θ The deflection angle θ corresponds to the launch forward field, R θ It indicates that the deflection angle θ corresponds to the received inversion field, and x = (x, y, z) represents the space vector corresponding to each point in the imaging area.

[0128] According to one embodiment of the present invention, the imaging results of multiple deflection angles are coherently superimposed to obtain the imaging result of the target tissue using the formula (9),

[0129]

[0130] Wherein, Image(x) represents the imaging result of the target tissue, and Θ represents the total number of the deflection angles.

[0131] Based on the same inventive concept, the embodiments of this invention also provide an ultrasonic plane wave imaging device, such as Figure 7 As shown, including:

[0132] The local velocity model calculation unit 701 is used for each array element of the array ultrasound linear array probe to transmit ultrasound to the target tissue according to the first predetermined transmission parameter one by one to obtain an original radio frequency signal, rearrange the common reflection point data of the original radio frequency signal, perform energy superposition in the direction of the reflection event axis, obtain a velocity spectrum, and obtain local velocity models at different depths;

[0133] The target imaging result calculation unit 702 is used for each array element of the array ultrasound linear array probe to transmit a multi-angle ultrasonic plane wave to the target tissue according to the second predetermined transmission parameter and multiple deflection angles, and to image the tissue according to the received radio frequency signal combined with the local velocity model, and to coherently superimpose the imaging results of the multiple deflection angles to obtain the imaging result of the target tissue.

[0134] Furthermore, if Figure 8 FIG. 1 is a detailed structural schematic diagram of the ultrasonic plane wave imaging device described in the embodiment of this invention, comprising:

[0135] The local velocity model calculation unit 701 is further used for each array element of the array ultrasound linear array probe to transmit ultrasonic waves to the target tissue in accordance with the first predetermined transmission parameter one by one, obtain multiple reflected ultrasonic waves of multiple layers of tissue in the target tissue, form an original radio frequency signal according to the transmitted ultrasonic waves and the ultrasonic waves reflected by the multiple layers of tissue in the target tissue, rearrange the common reflection point data of the original radio frequency signal, perform energy superposition in the direction of the reflection event axis to obtain a velocity spectrum, calculate the velocity of the original radio frequency signal at different depths according to the velocity spectrum, and obtain a local velocity model;

[0136] The target imaging result calculation unit 702 further includes:

[0137] The radio frequency signal acquisition module 7021 is used for each array element of the array ultrasound linear array probe to transmit an ultrasonic plane wave to the target tissue according to a second predetermined transmission parameter and a plurality of deflection angles, and obtain a radio frequency signal corresponding to each deflection angle, wherein the radio frequency signal includes the transmitted ultrasonic plane wave and the ultrasonic plane wave reflected by multiple layers of tissue in the target tissue;

[0138] The transmit forward field and receive inversion field calculation module 7022 is used to calculate the transmit forward field corresponding to a deflection angle according to the local velocity model and the transmit parameters of the ultrasonic plane wave corresponding to the deflection angle, and calculate the receive inversion field of the deflection angle according to the radio frequency signal corresponding to the deflection angle;

[0139] The sub-imaging result calculation module 7023 is used to calculate the transmission forward field and the reception inversion field corresponding to a deflection angle according to the cross-correlation imaging condition to obtain the imaging result of the deflection angle;

[0140] The target imaging result calculation module 7024 is used to perform coherent superposition on the imaging results of multiple deflection angles to obtain the imaging result of the target tissue.

[0141] Since the principle of solving the problem by the above device is similar to that of the above method, the implementation of the above device can refer to the implementation of the above method, and the repeated parts will not be repeated.

[0142] like Fig. 9The structure diagram of the computer device of the embodiment of the present invention is shown. The apparatus in the present invention can be the computer device in this embodiment, and executes the method of the present invention described above. The computer device 902 may include one or more processing devices 904, such as one or more central processing units (CPUs), and each processing unit may implement one or more hardware threads. The computer device 902 may also include any storage resource 906, which is used to store any kind of information such as code, settings, data, etc. Non-limitingly, for example, the storage resource 906 may include any one or more combinations of the following: any type of RAM, any type of ROM, flash memory device, hard disk, optical disk, etc. More generally, any storage resource can use any technology to store information. Further, any storage resource can provide volatile or non-volatile retention of information. Further, any storage resource can represent a fixed or removable component of the computer device 902. In one case, when the processing device 904 executes an associated instruction stored in any storage resource or a combination of storage resources, the computer device 902 can perform any operation of the associated instruction. The computer device 902 also includes one or more drive mechanisms 908 for interacting with any storage resources, such as a hard disk drive mechanism, an optical disk drive mechanism, and the like.

[0143] The computer device 902 may also include an input / output module 910 (I / O) for receiving various inputs (via input devices 912) and for providing various outputs (via output devices 914). A specific output mechanism may include a presentation device 916 and an associated graphical user interface (GUI) 918. In other embodiments, the input / output module 910 (I / O), the input device 912, and the output device 914 may not be included, and the computer device 702 may be used as a computer device in a network. The computer device 702 may also include one or more network interfaces 920 for exchanging data with other devices via one or more communication links 922. One or more communication buses 924 couple the components described above together.

[0144] The communication link 922 may be implemented in any manner, for example, through a local area network, a wide area network (e.g., the Internet), a point-to-point connection, etc., or any combination thereof. The communication link 922 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc. governed by any protocol or combination of protocols.

[0145] The embodiments of the present invention further provide a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program implements the above method when executed by a processor.

[0146] The embodiments of the present invention also provide a computer-readable instruction, wherein when a processor executes the instruction, the program therein causes the processor to execute the above method.

[0147] It should be understood that in the various embodiments of this document, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this document.

[0148] It should also be understood that in the embodiments of this article, the term "and / or" is only a description of the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0149] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this article.

[0150] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0151] In the several embodiments provided herein, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, or can be electrical, mechanical or other forms of connection.

[0152] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of this article.

[0153] In addition, each functional unit in each embodiment of this invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit may be implemented in the form of hardware or in the form of software functional unit.

[0154] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this article is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of this article. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0155] Specific embodiments are used in this article to illustrate the principles and implementation methods of this article. The description of the above embodiments is only used to help understand the methods and core ideas of this article. At the same time, for general technicians in this field, according to the ideas of this article, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on this article.

Claims

1. An ultrasonic plane wave imaging method, characterized in that: include: Each array element of the array ultrasound linear array probe successively transmits ultrasound to the target tissue according to the first predetermined transmission parameter to obtain an original radio frequency signal, rearranges the common reflection point data of the original radio frequency signal, performs energy superposition in the direction of the reflection event axis to obtain a velocity spectrum, and obtains a local velocity model at different depths; Each array element of the array ultrasound linear array probe transmits a multi-angle ultrasonic plane wave to the target tissue according to a second predetermined transmission parameter and a plurality of deflection angles, images the tissue according to the received radio frequency signal combined with the local velocity model, and coherently superimposes the imaging results of the plurality of deflection angles to obtain an imaging result of the target tissue; The step of obtaining the imaging result of the target tissue also includes: Each array element of the array ultrasound linear array probe transmits an ultrasonic plane wave to the target tissue according to a second predetermined transmission parameter and a plurality of deflection angles, and obtains a radio frequency signal corresponding to each deflection angle, wherein the radio frequency signal includes the transmitted ultrasonic plane wave and the ultrasonic plane wave reflected by multiple layers of tissue in the target tissue; Using a reverse time migration method based on a wave equation, a transmit forward field corresponding to a deflection angle is calculated according to the local velocity model and a second predetermined transmit parameter of an ultrasonic plane wave corresponding to the deflection angle, and a receive inversion field of the deflection angle is calculated according to a radio frequency signal corresponding to the deflection angle; The transmitted forward field and the received inversion field corresponding to a deflection angle are calculated according to the cross-correlation imaging condition to obtain the imaging result of the deflection angle; The imaging results of multiple deflection angles are coherently superimposed to obtain the imaging result of the target tissue.

2. The method according to claim 1, characterized in that The step of obtaining the local velocity model also includes: The first predetermined transmission parameter includes the delay time and imaging depth of each array element of the array ultrasound linear array probe for successive transmission, receives multiple reflected ultrasound waves from multiple layers of tissue in the target tissue, forms an original radio frequency signal, rearranges the common reflection point data of the original radio frequency signal, performs energy superposition in the direction of the reflection event axis, obtains a velocity spectrum, calculates the velocity of the original radio frequency signal at different depths based on the velocity spectrum, and obtains the local velocity model.

3. The method according to claim 1, characterized in that The local velocity model describes the velocity relationship between multiple array elements and corresponding original radio frequency signals for different layers of tissue.

4. The method according to claim 1, characterized in that: The array elements include transmitting array elements and receiving array elements, and the first predetermined transmitting parameters include interval time and imaging depth; The local velocity model is the velocity corresponding to the maximum amplitude of velocity spectrum line A1, and the formula is: in, is the time delay of the ith array element at t ij The amplitude of the RF signal, A1 represents the velocity spectrum, v j represents the scanning speed, M represents the number of array elements on the array ultrasound linear array probe, and N represents the time window length determined according to the initial time value and the interval time.

5. The method according to claim 1, characterized in that Calculating the transmission forward field corresponding to a deflection angle according to the local velocity model and a second predetermined transmission parameter of the ultrasonic plane wave corresponding to the deflection angle further comprises: Constructing first and second order partial differential acoustic wave equations at different imaging depths according to the local velocity model and the second predetermined transmission parameter; Solving the first second-order partial differential acoustic wave equation using a staggered grid finite difference time domain method to obtain extended wave fields at different times as the transmitting forward modeling field; Calculating the receiving inversion field of the deflection angle according to the radio frequency signal corresponding to the deflection angle further includes: Arranging the radio frequency signals in descending order of data time to obtain a time reverse propagation signal; Constructing a second second-order partial differential acoustic wave equation according to the time-backward propagation signal; The second second-order partial differential acoustic wave equation is solved using a finite difference method to obtain extended wave fields at different times as the receiving inversion field.

6. The method according to claim 1, characterized in that According to the cross-correlation imaging condition, the transmit forward field and receive inversion field corresponding to a deflection angle are calculated, and the formula for obtaining the imaging result of the deflection angle is: in, represents the kth deflection angle θ k The corresponding imaging result, T represents the total acquisition time in the second predetermined emission parameter, t represents time, S θ Denotes the deflection angle θ k Corresponding to the launch forward field, R θ Denotes the deflection angle θ k Corresponding to the received inversion field, x = (x, y, z) represents the space vector corresponding to each point in the imaging area.

7. The method according to claim 6, characterized in that The imaging results of multiple deflection angles are coherently superimposed to obtain the imaging result of the target tissue using the formula: Wherein, Image(x) represents the imaging result of the target tissue, and Θ represents the total number of the deflection angles.

8. An ultrasonic plane wave imaging device, characterized in that: include: A local velocity model calculation unit is used for each array element of the array ultrasound linear array probe to transmit ultrasound to the target tissue according to the first predetermined transmission parameter one by one to obtain an original radio frequency signal, rearrange the common reflection point data of the original radio frequency signal, perform energy superposition in the direction of the reflection event axis, obtain a velocity spectrum, and obtain local velocity models at different depths; a target imaging result calculation unit, configured for each array element of the array ultrasound linear array probe to transmit a multi-angle ultrasonic plane wave to the target tissue according to a second predetermined transmission parameter and a plurality of deflection angles, to image the tissue according to the received radio frequency signal in combination with the local velocity model, to coherently superimpose the imaging results of the plurality of deflection angles, and to obtain an imaging result of the target tissue; The target imaging result calculation unit further comprises: A radio frequency signal acquisition module, used for each array element of the array ultrasound linear array probe to transmit an ultrasonic plane wave to the target tissue according to a second predetermined transmission parameter and a plurality of deflection angles, to obtain a radio frequency signal corresponding to each deflection angle, wherein the radio frequency signal includes the transmitted ultrasonic plane wave and the ultrasonic plane wave reflected by multiple layers of tissue in the target tissue; A transmit forward field and receive inversion field calculation module, used to calculate the transmit forward field corresponding to a deflection angle according to the local velocity model and the transmit parameters of the ultrasonic plane wave corresponding to the deflection angle using a reverse time migration method based on the wave equation, and calculate the receive inversion field of the deflection angle according to the radio frequency signal corresponding to the deflection angle; The sub-imaging result calculation module is used to calculate the transmission forward field and the reception inversion field corresponding to a deflection angle according to the cross-correlation imaging condition to obtain the imaging result of the deflection angle; The target imaging result calculation module is used to perform coherent superposition on the imaging results of multiple deflection angles to obtain the imaging result of the target tissue.

9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 7 is implemented.

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