阅读说明：本技术 基于全波形反演的医学成像方法、计算机设备及存储介质 (Medical imaging method based on full waveform inversion, computer equipment and storage medium ) 是由 佟小龙 张家豹 葛勇 马国栋 于 2021-01-13 设计创作，主要内容包括：本申请涉及一种基于全波形反演的医学成像方法、计算机设备及存储介质,本申请的技术方案通过确定初始速度模型；获取高频超声波换能器获取人体部位的实际观测数据；并根据所述实际观测数据和所述初始速度模型进行反演得到目标速度模型；最后基于所述目标速度模型进行人体部位的医学成像,把石油勘探中近年来热门FWI(Full Waveform Inversion)全波形反演的技术引入超声医学影像领域,采集的超声波数据,进行反演,得到目标介质的物理属性(例如速度、密度),该属性可以进行相关的医学分析,为目标介质的准确成像奠定基础。(The application relates to a medical imaging method, computer equipment and a storage medium based on full waveform inversion, and the technical scheme of the application determines an initial velocity model; acquiring actual observation data of a human body part acquired by a high-frequency ultrasonic transducer; performing inversion according to the actual observation data and the initial velocity model to obtain a target velocity model; and finally, performing medical imaging of human body parts based on the target velocity model, introducing the recent popular FWI (full wave form inversion) full Waveform inversion technology in petroleum exploration into the field of ultrasonic medical images, and performing inversion on acquired ultrasonic data to obtain physical attributes (such as velocity and density) of a target medium, wherein the attributes can be used for performing related medical analysis and lay a foundation for accurate imaging of the target medium.)

1. A method of medical imaging based on full waveform inversion, comprising:

determining an initial velocity model;

acquiring actual observation data of a human body part acquired by a high-frequency ultrasonic transducer;

carrying out inversion according to the actual observation data and the initial velocity model to obtain a target velocity model;

medical imaging of the body part is performed based on the target velocity model.

2. The method of claim 1, wherein the inverting from the actual observation data and the initial velocity model to obtain a target velocity model comprises:

acquiring forward data generated by the simulation of the initial velocity model, and recording simulated wave field data U at all moments;

calculating wave field residual errors of the simulated wave field data and the actual observation data at the corresponding receiving point positions: d ═ d_obs-d_modWherein d is_obsRepresenting actual observed data, d_modRepresenting simulated wavefield data, Δ d representing wavefield residual;

calculating an instantaneous gradient field according to the wave field residual error;

determining a whole-region gradient according to the instantaneous gradient field;

and updating the initial speed model according to the full-area gradient to obtain a target speed model.

3. The method of claim 2, wherein said computing instantaneous gradient fields from the wavefield residuals comprises:

and carrying out continuation back transmission on the wave field residual error to obtain a residual wave field at each moment: | d_obs-S×d_mod|；

Wherein S represents: coefficient of amplitude, d_obsRepresenting actual observed data, d_modRepresenting simulated wavefield data;

calculating second-order partial derivative of forward wave field

Two quantities are inner-integrated to obtain the instantaneous gradient:

4. the method of claim 3, wherein determining the full-area gradient from the instantaneous gradient field comprises:

superposing instantaneous gradient fields at all the moments to obtain a single shot gradient;

and superposing all the single shot gradients to obtain a full-area gradient.

5. The method of claim 4, wherein updating an initial velocity model to obtain a target velocity model based on the full-zone gradient comprises:

regularizing the whole-region gradient;

updating the initial velocity model with the regularized full-region gradient.

6. The method of claim 5, wherein after updating the initial velocity model with the regularized full-region gradients, further comprising:

judging whether the wave field residual meets the target function of the updated initial velocity model;

if yes, outputting the updated initial speed model as a target speed model;

if not, the initial velocity model continues to be updated.

7. The method of claim 2, wherein said obtaining forward data generated from said initial velocity model simulation comprises:

acquiring actual observation data;

performing reverse time migration imaging on the actual observation data on an initial speed model to obtain an imaging result;

carrying out reverse offset on the imaging result to obtain reverse offset data;

using the reverse offset data as the forward data.

8. A computer device comprising a memory and a processor, the memory storing a computer program, wherein the processor implements the steps of the method of any one of claims 1 to 7 when executing the computer program.

9. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the method according to any one of claims 1 to 7.

Technical Field

The present application relates to the field of medical imaging technologies, and in particular, to a medical imaging method based on full waveform inversion, a computer device, and a storage medium.

Background

In the field of modern medical imaging, imaging technologies mainly include nuclear Magnetic Resonance (MRI), CT, ultrasonic and other means, wherein the nuclear magnetic resonance has high cost and large equipment volume (many millions of counterfeits are frequently generated, hundreds of tons of steel and iron shield a strong magnetic field, and a magnetic field iron core also frequently moves dozens of tons or even hundreds of tons), and special requirements (such as no metal content) are also provided for a detection target; although the CT has high precision, the radiation dose is large, the equipment volume is large, and the cost is relatively high; the ultrasonic wave has small volume and low cost, but only utilizes simple reflected wave imaging, has the defects of insufficient precision, incapability of penetrating through special parts, incapability of accurately imaging disordered wave fields of the special parts and the like (for example, the skull has weak ultrasonic wave penetrating capability, wave fields oscillate back and forth in the skull, difficult reflection identification and multiple clutter interference, and incapability of accurately imaging.

Disclosure of Invention

In view of the above, it is necessary to provide a technical solution to solve the problem of insufficient precision in the prior art. To this end, the application provides a medical imaging method, a computer device and a storage medium based on full waveform inversion.

The application provides a medical imaging method based on full waveform inversion, which comprises the following steps: a method of medical imaging based on full waveform inversion, comprising: determining an initial velocity model; acquiring actual observation data of a human body part acquired by a high-frequency ultrasonic transducer; carrying out inversion according to the actual observation data and the initial velocity model to obtain a target velocity model; medical imaging of the body part is performed based on the target velocity model.

Optionally, said determining of said actual viewThe data measurement and the initial velocity model are inverted to obtain a target velocity model, and the inversion comprises the following steps: acquiring forward data generated by the simulation of the initial velocity model, and recording simulated wave field data U at all moments; calculating wave field residual errors of the simulated wave field data and the actual observation data at the corresponding receiving point positions: d ═ d_obs-d_modWherein d is_obsRepresenting actual observed data, d_modRepresenting simulated wavefield data, Δ d representing wavefield residual; calculating an instantaneous gradient field according to the wave field residual error; determining a whole-region gradient according to the instantaneous gradient field; and updating the initial speed model according to the full-area gradient to obtain a target speed model.

Optionally, said computing an instantaneous gradient field from said wavefield residual comprises: and carrying out continuation back transmission on the wave field residual error to obtain a residual wave field at each moment: | d_obs-S×d_modWhere, S represents: coefficient of amplitude, d_obsRepresenting actual observed data, d_modRepresenting simulated wavefield data; calculating second-order partial derivative of forward wave fieldTwo quantities are inner-integrated to obtain the instantaneous gradient:

optionally, the determining the full-area gradient from the instantaneous gradient field comprises: superposing instantaneous gradient fields at all the moments to obtain a single shot gradient; and superposing all the single shot gradients to obtain a full-area gradient.

Optionally, the updating the initial velocity model according to the full-region gradient to obtain the target velocity model includes: regularizing the whole-region gradient; updating the initial velocity model with the regularized full-region gradient.

Optionally, after the updating the initial velocity model with the regularized full-region gradient, the method further includes: judging whether the wave field residual meets the target function of the updated initial velocity model; and if so, outputting the updated initial speed model as the target speed model.

Optionally, the obtaining forward data generated by the initial velocity model simulation comprises: acquiring actual observation data; performing reverse time migration imaging on the actual observation data on an initial speed model to obtain an imaging result; carrying out reverse offset on the imaging result to obtain reverse offset data; using the reverse offset data as the forward data.

The present application further provides a computer device comprising a memory storing a computer program and a processor implementing the steps of the method of any preceding claim when the processor executes the computer program.

The present application also provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements a method as claimed in any one of the above.

The present application further provides a computer device comprising a memory storing a computer program and a processor implementing the steps of any of the above methods when the processor executes the computer program.

The present application further provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the method of any of the above.

The technical scheme of the application determines an initial speed model; acquiring actual observation data of a human body part acquired by a high-frequency ultrasonic transducer; performing inversion according to the actual observation data and the initial velocity model to obtain a target velocity model; and finally, performing medical imaging of human body parts based on the target velocity model, introducing the recent popular FWI (full wave form inversion) full Waveform inversion technology in petroleum exploration into the field of ultrasonic medical images, and performing inversion on acquired ultrasonic data to obtain physical attributes (such as velocity and density) of a target medium, wherein the attributes can be used for performing related medical analysis and lay a foundation for accurate imaging of the target medium.

Drawings

FIG. 1 is a schematic flow diagram of a medical imaging method based on full waveform inversion according to an embodiment;

FIG. 2 is a schematic flow chart diagram of a method for determining a target velocity model in one embodiment;

FIG. 3 is a diagram illustrating an internal structure of a computer device according to an embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

The following description, with reference to the accompanying drawings, is provided to facilitate a comprehensive understanding of various embodiments of the application as defined by the claims and their equivalents; these embodiments include various specific details for ease of understanding, but these are to be considered exemplary only. Accordingly, those skilled in the art will appreciate that various changes and modifications may be made to the various embodiments described herein without departing from the scope and spirit of the present application. In addition, descriptions of well-known functions and constructions will be omitted herein for brevity and clarity.

The terms and phrases used in the following specification and claims are not to be limited to the literal meaning, but are merely for the clear and consistent understanding of the application. Accordingly, it will be appreciated by those skilled in the art that the description of the various embodiments of the present application is provided for illustration only and not for the purpose of limiting the application as defined by the appended claims and their equivalents.

The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the accompanying drawings in some embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It is to be understood that the terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only, and is not intended to be limiting of the application. As used in the examples of this application and the appended claims, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. The expressions "first", "second", "the first" and "the second" are used for modifying the corresponding elements without regard to order or importance, and are used only for distinguishing one element from another element without limiting the corresponding elements.

As shown in fig. 1, the present application provides a medical imaging method based on full waveform inversion, comprising:

determining an initial velocity model;

acquiring actual observation data of a human body part acquired by a high-frequency ultrasonic transducer;

carrying out inversion according to the actual observation data and the initial velocity model to obtain a target velocity model;

medical imaging of the body part is performed based on the target velocity model.

Full wave inversion, also called Full waveform inversion, was proposed in the 80 s by scientists such as Albert Tarandola, where waves propagate and receive in a medium and are subject to various properties of the medium (e.g., velocity, density, interface wave impedance, quality factor, anisotropy, etc.). Full waveform inversion starts with observed waveform data, correlates it to multiple properties of the propagation medium by inversion, and derives detailed data of the medium properties. Full waveform inversion has extremely high precision, and the wavelet wavelength precision of a wave field can be theoretically achieved. With respect to offset imaging, imaging is used to delineate highly accurate reflected impedance boundaries, and full-wave inversion can yield more accurate media properties. The main operations mainly include:

defining a data space D and a model space m, and a mapping relation between the model space and the data space, and a function f: d_mod＝f(m)1-1

Where f is the positive operator, d is an n-dimensional vector for the M-response of the model space, and M is the M-dimensional vector of the model space. For the nonlinear inverse problem of actual data, the nonlinear problem can be converted into a linear problem to be solved, and 1-1 Taylor expansion is approximated to obtain:

formula 1-2, d_jobsRepresenting j components of the actual data, d_jmodRepresents the jth component of the analog data,representing the partial derivative of the simulation data with respect to the model, Δ m_iIs the correction of the i model parameters. For each excitation point and reception point, by the difference of ten data and the simulation data, N can be defined as a spatial error vector:

Δd＝d_obs-d_mod1-3

where d is_modA vector representing the simulated wavefield.

The inversion process is a process that an initial model gradually approaches an actual model, and simulated data gradually approaches observed data. We establish a suitable objective function measure of the degree of approximation, from L₁Norm to L_∞Finding the minimum under norm, where the optimal model for finding least squares, i.e., L, is chosen₂Is measured.

On the time domain raw data, the wavefield error can be sorted from 1-4 into the following situations:

from the initial model m₀Start ofAnd each iteration is corrected to be delta m, and a new model m is obtained after one iteration of the model₀+Δm。

Carrying out linearization treatment on the target function, and carrying out Taylor expansion on a formula 1-5 to obtain:

in the vicinity of the initial model, to minimize the objective function, the right derivative of the formula 1-5 is 0, so as to obtain the model perturbation amount:

whereinIs a first order disturbance quantity of the model, -H^-1Is the model second order perturbation quantity.

In combination with the above, one round of full waveform inversion is described as the following steps (i.e., the step of obtaining a target velocity model by performing inversion according to the actual observation data and the initial velocity model):

as shown in fig. 2, includes: acquiring forward data generated by the simulation of the initial velocity model, and recording simulated wave field data U at all moments;

calculating wave field residual errors of the simulated wave field data and the actual observation data at the corresponding receiving point positions: d ═ d_obs-d_modWherein d is_obsRepresenting actual observed data, d_modRepresenting simulated wavefield data, Δ d representing wavefield residual; calculating an instantaneous gradient field according to the wave field residual error; determining a whole-region gradient according to the instantaneous gradient field; and updating the initial speed model according to the full-area gradient to obtain a target speed model. Said computing instantaneous gradient fields from the wavefield residual comprises: and carrying out continuation back transmission on the wave field residual error to obtain a residual wave field at each moment: | d_obs-S×d_modL, |; wherein S represents: coefficient of amplitude, d_obsRepresenting actual observationsData, d_modRepresenting simulated wavefield data; calculating second-order partial derivative of forward wave fieldTwo quantities are inner-integrated to obtain the instantaneous gradient:wherein the determining the full-area gradient from the instantaneous gradient field comprises: superposing instantaneous gradient fields at all the moments to obtain a single shot gradient; superposing all single shot gradients to obtain a whole-region gradient, and carrying out regulation on the whole-region gradient; updating the initial velocity model with the regularized full-region gradient.

The single shot refers to the concept of a shot in seismic exploration, and here, after one transducer is transmitted, all data recorded by the received transducer is a shot, namely a single shot.

As an alternative embodiment, after updating the initial velocity model with the regularized full-region gradient, the method further includes:

judging whether the wave field residual meets the target function of the updated initial velocity model;

if yes, outputting the updated initial speed model as a target speed model;

and if not, continuously updating the initial speed model, namely returning to the step of obtaining the target speed model by carrying out inversion according to the actual observation data and the initial speed model until the target function is met.

As an alternative embodiment, the obtaining forward data generated from the initial velocity model simulation comprises:

acquiring actual observation data;

performing reverse time migration imaging on the actual observation data on an initial speed model to obtain an imaging result;

carrying out reverse offset on the imaging result to obtain reverse offset data;

using the reverse offset data as the forward data.

According to another aspect of the present application, there is also provided a computer device comprising a memory and a processor, the memory storing a computer program, wherein the processor implements the steps of any of the above methods when executing the computer program.

According to yet another aspect of the application, a computer-readable storage medium, on which a computer program is stored, characterized in that the program, when executed by a processor, implements the method as defined in any of the above.

As shown in fig. 3, the present application further provides a computer device, which includes a memory and a processor, where the memory stores a computer program, and the processor implements the steps of the method when executing the computer program. In one embodiment, a computer device is provided, which may be a terminal, and its internal structure may be a diagram. The computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device comprises a nonvolatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The communication interface of the computer device is used for carrying out wired or wireless communication with an external terminal, and the wireless communication can be realized through WIFI, an operator network, NFC (near field communication) or other technologies. The computer program is executed by a processor to implement a velocity model determination method. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment can be a touch layer covered on the display screen, a key, a track ball or a touch pad arranged on the shell of the computer equipment, an external keyboard, a touch pad or a mouse and the like.

Those skilled in the art will appreciate that the architecture shown in fig. 3 is merely a block diagram of some of the structures associated with the disclosed aspects and is not intended to limit the computing devices to which the disclosed aspects apply, as particular computing devices may include more or less components than those shown, or may combine certain components, or have a different arrangement of components.

The present application also provides a computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method as described above.

According to the technical scheme, an initial velocity model is established according to seismic data, a plurality of parameter adjusting velocities are obtained, the initial velocity model is iterated based on the seismic data and the parameter adjusting velocities to obtain a plurality of groups of stacking sections and energy spectrums, each group of stacking sections and energy spectrums correspond to different velocity adjusting parameters, a target velocity model is determined according to the plurality of groups of stacking sections and energy spectrums, multiple iterations are performed through the plurality of parameter adjusting velocities, the multi-solution performance of the velocity model in imaging is eliminated, an objective and correct underground velocity model is obtained through mass calculation, and accurate objective bases are provided for underground structure imaging.

It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database or other medium used in the embodiments provided herein can include at least one of non-volatile and volatile memory. Non-volatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical storage, or the like. Volatile Memory can include Random Access Memory (RAM) or external cache Memory. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM), among others.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.