A real-time ultrasound simulation method based on echo event map and spatiotemporal coherent speckle field reconstruction

Abstract

This invention relates to the fields of medical ultrasound simulation, medical image processing, and computer-aided medical teaching and training. Specifically, it relates to a real-time ultrasound simulation method based on echo event maps and spatiotemporal coherent speckle field reconstruction. This invention constructs a three-dimensional tissue acoustic parameter field, establishes a probe transmit / receive beam model and echo event map, and physically models boundary echoes and volume scattering echoes respectively. It introduces a spatiotemporal coherent speckle field to constrain the continuous evolution of speckle, eliminating speckle jumps and flicker during continuous scanning. It simulates shadows and post-enhancement effects through an artifact modulation model, and generates highly realistic ultrasound images through RF signal synthesis, system response processing, logarithmic compression, and scan transformation. This effectively meets the high-simulation requirements of medical ultrasound teaching and skills training.

Description

Technical Field

[0001] This invention relates to the fields of medical ultrasound simulation, medical image processing, and computer-aided medical teaching and training, specifically a real-time ultrasound simulation method based on echo event spectrum and spatiotemporal coherent speckle field reconstruction. Background Technology

[0002] Ultrasound imaging is widely used in medical settings such as obstetrics, cardiology, abdominal surgery, interventional procedures, emergency medicine, breast surgery, and urology due to its advantages such as real-time imaging, non-invasiveness, radiation-free imaging, and relatively low cost. Unlike static imaging such as CT and MRI, the quality of ultrasound images is highly dependent on the operator's real-time control of the probe position, posture, pressure, scanning direction, and anatomical sections. Therefore, ultrasound training and teaching have a strong demand for high-fidelity simulation technology. Existing ultrasound simulation methods mainly include: methods based on 2D / 3D medical image slice interpolation; image generation methods based on deep learning and generative adversarial networks; physical modeling methods based on ray tracing or statistical ray propagation approximation; and real-time integration methods based on specific engines, platforms, or visualization systems. The existing technology has the following shortcomings: 1. It is difficult to balance image realism and physical interpretability. Methods based on slice interpolation or pure image generation lack explicit modeling of the formation mechanisms of boundary reflection, volume scattering, shadows, post-enhancement, depth attenuation, and speckle texture, resulting in insufficient clinical interpretability and training transferability. 2. Poor consistency in the timing of continuous scanning, with independent random perturbation or independent generation processes used between frames, resulting in abrupt changes, flickering, and discontinuities in speckle texture and local echoes; 3. It is difficult to optimize tissue contours and speckle textures at the same time. If the focus is too much on contours, the texture will be missing, and if the focus is too much on textures, the structure and artifacts will be insufficient. 4. There is a contradiction between real-time performance and complex physical processes. High-precision full-path simulation is costly, while oversimplification reduces realism. 5. It lacks a unified underlying framework for multiple organs and scenarios, resulting in insufficient versatility and making it difficult to promote as a platform-level underlying algorithm; Therefore, there is a need in this field for an ultrasound image simulation method that does not rely on a specific platform, does not overly depend on pure data-driven methods, and combines physical interpretability, spatiotemporal continuity, speckle realism, and real-time computability. To address the aforementioned shortcomings, a technical solution is provided. Summary of the Invention

[0003] To address the aforementioned shortcomings of existing technologies, this invention provides a real-time ultrasonic simulation method based on echo event maps and spatiotemporal coherent speckle field reconstruction. This method effectively solves the problems of insufficient realism in ultrasonic simulation, poor temporal consistency, discontinuous speckle texture, difficulty in simultaneously considering structure and texture, and insufficient real-time performance in existing technologies.

[0004] To achieve the above objectives, the present invention can be implemented through the following technical solutions: This invention provides a real-time ultrasound simulation method based on echo event spectra and spatiotemporal coherent speckle field reconstruction, comprising the following steps: S1: Construct a three-dimensional tissue acoustic parameter field for the region to be simulated based on CT and MRI segmentation data, three-dimensional digital phantoms, or manual modeling results. S2: Establish the probe transmit and receive beam model in the scan line coordinate system; S3: Abstract the key physical events of ultrasonic echo generation into echo events and construct an echo event map; S4: Based on acoustic impedance differences and propagation path characteristics, establish a boundary echo event model to generate tissue contour and interface structure information; S5: A statistical stochastic model is used to establish a volume scattering echo model and generate ultrasonic speckle texture; S6: Construct a spatiotemporally coherent speckle field to constrain the continuous spatiotemporal evolution of speckle and eliminate speckle jumps and flicker during continuous scanning; S7: Establish an artifact modulation and non-uniform propagation model to simulate shadows and post-enhanced ultrasound artifacts; S8: Superimpose boundary echo, volume scattering echo, artifact signal and system noise to synthesize the final RF echo signal, and perform system response convolution and envelope detection on the RF echo signal to simulate the response of the ultrasound imaging system; S9: Logarithmic compression, time gain compensation, and scan transformation are performed on the envelope signal to generate the final ultrasound image.

[0005] Furthermore, the construction of the three-dimensional tissue acoustic parameter field is as follows: Assuming the region to be simulated is a three-dimensional spatial region, specifically expressed as:

[0006] For any point in space Define the tissue acoustic parameter vector field as:

[0007] in: It is a three-dimensional spatial region; It is a three-dimensional real number space; Spatial location; This is a vector of acoustic parameters; The density of the medium; Local sound velocity; This is the frequency-dependent attenuation coefficient; Ultrasonic frequency; Acoustic impedance; Boundary echo intensity factor; Volume scattering intensity factor; These are the statistical parameters for organizing texture.

[0008] Furthermore, the probe's transmit and receive beam model is established as follows: Let the origin of the probe be... , No. The direction of each scan line is a unit vector. Then the spatial point The axial distance in this scan line coordinate system is:

[0009] The corresponding lateral offset is:

[0010] Based on the above parameters, the joint transmit-receive beam weighting function is defined as follows:

[0011] in: Number the scan lines; This indicates the probe position; The unit vector is the direction of the scan line; This is the axial distance; This is a horizontal offset; It is the Euclidean norm; Beam weighting; For lateral beamwidth function; For focus depth; This refers to the axial focus width. It is an exponential function.

[0012] Furthermore, the event caching and incremental update method is as follows: when the probe moves continuously, the event map of the previous moment is mapped to the current coordinate system through coordinate mapping, and the new field of view event set is incrementally updated.

[0013] Furthermore, the echo event spectrum is defined as:

[0014] Event nodes are defined as follows:

[0015] in: Echo event map; A collection of event nodes; A set of event relationships; This is a property mapping function; For the first One event node; Location of the event; This refers to the echo arrival time; For the event range; For the duration of transmission; The interface normal vector; These are local texture spectrum parameters.

[0016] Furthermore, the boundary echo event model is constructed as follows: The reflectance coefficient at the interface is defined as:

[0017] When considering the effects of the incident angle and the refraction angle, the reflection coefficient is extended to:

[0018] The boundary echo propagation time is defined as:

[0019] The attenuation term along the propagation path is defined as:

[0020] Finally, the boundary echo signal is represented as:

[0021] in: The reflection coefficient; and The acoustic impedance on both sides of the interface; Angle of incidence; The angle of refraction; This is the two-way travel time; For the propagation path; For path infinitesimal elements; Local sound velocity; It is the attenuation factor; The attenuation coefficient; This is a boundary echo signal; Boundary weights; Beam weighting; The system impulse response function; It is a time variable.

[0022] Furthermore, the volume scattering echo model is established using a statistical stochastic model as follows: Define spatial location The microscattering random variable at point is:

[0023] The volume-scattered echo signal is represented as:

[0024] in: Represents a three-dimensional tissue region; Indicates a point in space; Indicates position Random scattering variables at the location; This indicates that the mean is 0 and the variance is 0. Gaussian distribution; The variance parameter representing the scattering intensity; Indicates the first Volume scattered echo signal of each scan line; Represents a time variable; Indicates the weight of volume scattering intensity; This represents the beam weighting function (definition see step S2); Represents the system impulse response function; Indicates the propagation time (see step S4 for definition); Represents a volume differential element; Integral symbol This indicates that the integral is performed over the entire volume region.

[0025] Furthermore, a spatiotemporally coherent speckle field is constructed to constrain the continuous spatiotemporal evolution of speckle, thereby eliminating speckle jumps and flicker during continuous scanning. Define the speckle field recursive model as follows:

[0026] in: Indicates position At any moment The speckle field value; Indicates spatial location; Indicates a discrete-time index; Indicates the time coherence coefficient; This represents the local displacement field caused by probe movement or tissue deformation. This represents the speckle value after displacement at the previous moment; Represents a random disturbance term; This represents zero-mean Gaussian noise; Indicates the intensity of the disturbance; Define the space-time correlation function as follows:

[0027] in: Represents the relevant function; Indicates the difference in spatial distance; Indicates a time interval; Indicates Euclidean distance; Indicates spatially related length; Represents the time-dependent constant; Represents an exponential function; Simultaneously, the speckle field is decomposed into multi-scale components:

[0028] in: This is a large-scale structure modulation term; For mesoscale texture items; It is a high-frequency micro-speckled term.

[0029] Furthermore, the method for establishing the artifact modulation and non-uniform propagation model is as follows: Define path cumulative decay as:

[0030] The shadow modulation factor is:

[0031] The post-enhancement modulation factor is:

[0032] The modulated scattering signal is:

[0033] in: Indicates cumulative path decay; Indicates the propagation path; Indicates position Attenuation coefficient at the location; Represents the path element; Indicates the shading factor; Indicates the post-enhancement factor; Indicates the shadow modulation coefficient; Indicates the enhancement modulation coefficient; Indicates the reference attenuation; This represents the signal after artifact modulation; This indicates the volume-scattered echo.

[0034] Furthermore, this method is adaptable to simulation scenarios in obstetrics, cardiology, abdominal surgery, breast surgery, interventional procedures, and intracavitary ultrasound. The underlying algorithm can be reused simply by replacing the tissue parameter field, case model, and probe configuration.

[0035] The technical solution provided by this invention has the following advantages compared with the known prior art: 1. This invention, by constructing a three-dimensional tissue acoustic parameter field and echo event spectrum, explicitly physical models the boundary reflection, volume scattering, path attenuation, and speckle formation mechanism, thus overcoming the limitations of purely data-driven generation methods. This enables the simulated image to simultaneously possess clear anatomical contours, realistic speckle textures, and typical clinical artifacts, significantly improving the clinical interpretability and training transferability of ultrasound simulation. 2. This invention introduces a spatiotemporal coherent speckle field recursive model to strongly constrain the spatial correlation and temporal continuity of speckle, so that when the probe is continuously moved, rotated, and pressed, the speckle texture evolves smoothly without jumps or flickering, significantly improving the temporal consistency of continuous scanning. 3. This invention incorporates boundary echo, volume scattering echo, and artifact modulation into the same framework, simultaneously achieving tissue contour clarity and speckle texture realism. It can fully simulate typical artifacts such as shadows, post-enhancement, and non-uniform attenuation, balancing the structural recognition required for teaching with the visual realism required for training. 4. This invention employs an event caching and incremental update mechanism, reuses historical calculation results, and performs incremental calculations only on newly added field-of-view areas. While ensuring high-precision physical simulation, it significantly reduces computational overhead and can stably achieve high frame rate real-time interaction, meeting the real-time requirements of ultrasonic training equipment. 5. This invention forms a unified underlying algorithm framework that does not rely on specific hardware, graphics engines, or dedicated platforms. It can quickly adapt to various ultrasound simulation scenarios such as abdominal, obstetric, cardiac, breast, interventional, and endoscopic ultrasound simply by changing the tissue parameter field, case model, and probe configuration. It has strong scalability and platform reuse value. 6. This invention can dynamically couple probe pressure with tissue deformation and acoustic parameter fields, so that the simulated image changes with the pressure applied, resulting in tissue compression, structural displacement and echo changes, which is closer to the actual clinical operation experience and effectively improves the realism and effectiveness of ultrasound skills training. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is an overall flowchart of the present invention; Figure 2 This is a schematic diagram of the three-dimensional tissue acoustic parameter field of the present invention; Figure 3 This is a schematic diagram of the probe scanning lines and beam model of the present invention; Figure 4 This is a schematic diagram of the echo event spectrum structure of the present invention; Figure 5 This is a schematic diagram illustrating the layering of boundary events and volume scattering events in this invention; Figure 6 This is a schematic diagram illustrating the recursive derivation of the spatiotemporal coherent speckle field of the present invention; Figure 7 This is a flowchart illustrating the RF synthesis, envelope detection, and scan transformation processes of the present invention. Figure 8 This is a comparison diagram of the speckle continuity of the present invention and the conventional method during continuous scanning. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] In this embodiment, the simulated object is human abdominal tissue. The probe is a convex array ultrasound probe with a center frequency of 3.5MHz, 128 scan lines, and an imaging depth of 12cm. The system frame rate is maintained at more than 30 fps, realizing continuous scanning without flicker and with high realism in real-time ultrasound image simulation.

[0040] like Figure 1-8 As shown, a real-time ultrasonic simulation method based on echo event spectrum and spatiotemporal coherent speckle field reconstruction includes the following steps: S1: Based on CT and MRI segmentation data, 3D digital phantoms, or manual modeling results, construct a 3D tissue acoustic parameter field for the region to be simulated. The specific implementation method is as follows: Based on the results of abdominal CT and MRI segmentation data, 3D digital phantoms or artificial modeling, a 3D tissue acoustic parameter field covering tissues such as skin, fat, muscle, liver, kidney, gallbladder, blood vessels, and blood is established to describe the acoustic property distribution of different tissue types in space and to provide unified basic physical parameters for subsequent echo generation. Assuming the region to be simulated is a three-dimensional spatial region, specifically expressed as:

[0041] For any point in space Define the tissue acoustic parameter vector field as:

[0042] in: It is a three-dimensional spatial region; It is a three-dimensional real number space; Spatial location; This is a vector of acoustic parameters; The density of the medium; Local sound velocity; This is the frequency-dependent attenuation coefficient; Ultrasonic frequency; Acoustic impedance; Boundary echo intensity factor; Volume scattering intensity factor; These are the statistical parameters for organizing texture.

[0043] S2: Establish a probe transmission and reception beam model in the scan line coordinate system to characterize the probe's transmission and reception characteristics in space, so that the contribution of different spatial points to the current scan line has directionality and focusing characteristics. The specific implementation method is as follows: Let the origin of the probe be... , No. The direction of each scan line is a unit vector. Then the spatial point The axial distance in this scan line coordinate system is:

[0044] The corresponding lateral offset is:

[0045] Based on the above parameters, the joint transmit-receive beam weighting function is defined as follows:

[0046] in: Number the scan lines; This indicates the probe position; The unit vector is the direction of the scan line; This is the axial distance; This is a horizontal offset; It is the Euclidean norm; Beam weighting; For lateral beamwidth function; For focus depth; This refers to the axial focus width. It is an exponential function; It should be noted that the above beam weighting means that only tissue points that fall within the beam range and are close to the focal region can effectively contribute to the echo of the current scan line. To improve the real-time performance of continuous scanning, during continuous probe movement, the event map nodes from the previous moment can be mapped to the current probe coordinate system through rigid body transformation or local pose update. The mapping relationship is as follows:

[0047] in: For event graph coordinate mapping operators; This represents the change in probe pose. This is the set of incremental events that have recently entered the field of view. Event caching and incremental updates can reduce redundant calculations and improve real-time performance. If the probe is equipped with a pressure sensor, the probe pressure can be measured. Coupled to local tissue deformation and acoustic parameter fields, the coupling relationship is as follows:

[0048] in:

[0049] To organize the pressure response field, This is the pressure coupling coefficient; This implementation method allows images to undergo tissue compression, structural displacement, and texture changes as the pressure applied changes, thereby improving the realism of the training.

[0050] S3: Abstract the key physical events of ultrasonic echo generation into echo events, and construct an echo event map to express the spatial adjacency and temporal propagation relationships between various echo events. The specific implementation method is as follows: Define the echo event spectrum as follows:

[0051] Define the event node as:

[0052] in: Echo event map; A collection of event nodes; A set of event relationships; This is a property mapping function; For the first One event node; Location of the event; This refers to the echo arrival time; For the event range; For the duration of transmission; The interface normal vector; These are local texture spectrum parameters.

[0053] S4: Based on acoustic impedance differences and propagation path characteristics, a boundary echo event model is established to generate tissue contour and interface structure information. The specific implementation method is as follows: The reflectance coefficient at the interface is defined as:

[0054] When considering the effects of the incident angle and the refraction angle, the reflection coefficient is extended to:

[0055] The boundary echo propagation time is defined as:

[0056] The attenuation term along the propagation path is defined as:

[0057] Finally, the boundary echo signal is represented as:

[0058] in: The reflection coefficient; and The acoustic impedance on both sides of the interface; Angle of incidence; The angle of refraction; This is the two-way travel time; For the propagation path; For path infinitesimal elements; Local sound velocity; It is the attenuation factor; The attenuation coefficient; This is a boundary echo signal; Boundary weights; Beam weighting; The system impulse response function; It is a time variable.

[0059] S5: A statistical stochastic model is used to model the volume scattering echo to simulate random scattering generated by the microstructure inside the tissue, generating ultrasound speckle textures that conform to clinical real-world characteristics. The specific implementation method is as follows: Define spatial location The microscattering random variable at point is:

[0060] The volume-scattered echo signal is represented as:

[0061] in: Represents a three-dimensional tissue region; Indicates a point in space; Indicates position Random scattering variables at the location; This indicates that the mean is 0 and the variance is 0. Gaussian distribution; The variance parameter representing the scattering intensity; Indicates the first Volume scattered echo signal of each scan line; Represents a time variable; Indicates the weight of volume scattering intensity; This represents the beam weighting function (definition see step S2); Represents the system impulse response function; Indicates the propagation time (see step S4 for definition); Represents a volume differential element; Integral symbol This indicates that the integral is performed over the entire volume region.

[0062] S6: Construct a spatiotemporally coherent speckle field to constrain the continuous spatiotemporal evolution of speckle and eliminate speckle jumps and flicker during continuous scanning. The specific implementation method is as follows: Define the speckle field recursive model as follows:

[0063] in: Indicates position At any moment The speckle field value; Indicates spatial location; Indicates a discrete-time index; Indicates the time coherence coefficient; This represents the local displacement field caused by probe movement or tissue deformation. This represents the speckle value after displacement at the previous moment; Represents a random disturbance term; This represents zero-mean Gaussian noise; Indicates the intensity of the disturbance.

[0064] The space-time correlation function is further defined as follows:

[0065] in: Represents the relevant function; Indicates the difference in spatial distance; Indicates a time interval; Indicates Euclidean distance; Indicates spatially related length; Represents the time-dependent constant; Represents an exponential function; To further enhance the sense of depth and visual distinction of the texture, the speckle field is decomposed into multi-scale components:

[0066] in: This is a large-scale structure modulation term; For mesoscale texture items; For high-frequency micro-spots; Multi-scale modeling can enhance the texture hierarchy and visual differences in different tissue regions.

[0067] S7: Establish an artifact modulation and non-uniform propagation model to simulate shadows and post-enhanced ultrasound artifacts in real ultrasound images. The specific implementation method is as follows: Define path cumulative decay as:

[0068] The shadow modulation factor is:

[0069] The post-enhancement modulation factor is:

[0070] The modulated scattering signal is:

[0071] in: Indicates cumulative path decay; Indicates the propagation path; Indicates position Attenuation coefficient at the location; Represents the path element; Indicates the shading factor; Indicates the post-enhancement factor; Indicates the shadow modulation coefficient; Indicates the enhancement modulation coefficient; Indicates the reference attenuation; This represents the signal after artifact modulation; This indicates the volume-scattered echo.

[0072] S8: Superimpose boundary echo, volume scattering echo, artifact signal, and system noise to synthesize the final RF echo signal. Then, perform system response convolution and envelope detection on the RF echo signal to simulate the response of the ultrasound imaging system. The specific implementation method is as follows: The various echo signals are superimposed to obtain the final radio frequency signal.

[0073]

[0074] in: This represents the final RF echo signal; Indicates boundary echo; Indicates volume-scattered echo; Indicates artifact signal; Indicates system noise; Indicates Gaussian white noise; Indicates the noise variance; The synthesized RF echo signal is processed to simulate the actual ultrasound imaging system. Axial convolution:

[0075] Lateral convolution:

[0076] Envelope extraction:

[0077] in: This represents the signal after axial convolution; This represents the convolution operation; Represents the axial impulse response function; Represents the lateral point spread function; Represents a two-dimensional image signal; Represents the Hilbert transform; Indicates the envelope signal; This indicates the modulo operation.

[0078] S9: Logarithmic compression, time gain compensation, and scan transformation are performed on the envelope signal to generate the final ultrasound image. The specific implementation method is as follows: Logarithmic compression:

[0079] Time gain compensation:

[0080] Scan transformation:

[0081] in: This represents the result of logarithmic compression; Represents the natural logarithm function; Indicates the envelope signal; This represents the time gain compensation function; Indicates the signal after compensation; Indicates the scan transformation operator; This represents the final ultrasound image; Represents image coordinates.

[0082] This invention is not limited to a specific organ or platform. It can be used for obstetric ultrasound simulation, cardiac ultrasound simulation, abdominal ultrasound simulation, breast ultrasound simulation, interventional puncture ultrasound simulation, and transvaginal or intracavitary ultrasound simulation. Only the tissue parameter field, case model, and probe configuration need to be replaced to reuse the same underlying algorithm framework.

[0083] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A real-time ultrasonic simulation method based on echo event spectrum and spatiotemporal coherent speckle field reconstruction, characterized in that, Includes the following steps: S1: Construct a three-dimensional tissue acoustic parameter field for the region to be simulated based on CT and MRI segmentation data, three-dimensional digital phantoms, or manual modeling results. S2: Establish the probe transmit and receive beam model in the scan line coordinate system; S3: Abstract the key physical events of ultrasonic echo generation into echo events and construct an echo event map; S4: Based on acoustic impedance differences and propagation path characteristics, establish a boundary echo event model to generate tissue contour and interface structure information; S5: A statistical stochastic model is used to establish a volume scattering echo model and generate ultrasonic speckle texture; S6: Construct a spatiotemporally coherent speckle field to constrain the continuous spatiotemporal evolution of speckle and eliminate speckle jumps and flicker during continuous scanning; S7: Establish an artifact modulation and non-uniform propagation model to simulate shadows and post-enhanced ultrasound artifacts; S8: Superimpose boundary echo, volume scattering echo, artifact signal and system noise to synthesize the final RF echo signal, and perform system response convolution and envelope detection on the RF echo signal to simulate the response of the ultrasound imaging system; S9: Logarithmic compression, time gain compensation, and scan transformation are performed on the envelope signal to generate the final ultrasound image.

2. The real-time ultrasonic simulation method based on echo event spectrum and spatiotemporal coherent speckle field reconstruction according to claim 1, characterized in that, The construction of the three-dimensional tissue acoustic parameter field is as follows: Assuming the region to be simulated is a three-dimensional spatial region, specifically expressed as: For any point in space Define the tissue acoustic parameter vector field as: in: For a three-dimensional spatial region, For three-dimensional real space, For spatial location, For acoustic parameter vectors, For the density of the medium, For local sound speed, This is the frequency-dependent attenuation coefficient. For ultrasonic frequency, Acoustic impedance, Boundary echo intensity factor For volume scattering intensity factor, These are the statistical parameters for organizing texture.

3. The real-time ultrasonic simulation method based on echo event spectrum and spatiotemporal coherent speckle field reconstruction according to claim 1, characterized in that, The probe's transmit and receive beam model is established as follows: Let the origin of the probe be... , No. The direction of each scan line is a unit vector. Then the spatial point The axial distance in this scan line coordinate system is: The corresponding lateral offset is: Based on the above parameters, the joint transmit-receive beam weighting function is defined as follows: in: For scan line numbering, This indicates the probe position. The unit vector is the direction of the scan line. It is the axial distance. For horizontal offset, It is the Euclidean norm. For beam weights, For the lateral beamwidth function, For focus depth, The axial focus width, It is an exponential function.

4. The real-time ultrasonic simulation method based on echo event spectrum and spatiotemporal coherent speckle field reconstruction according to claim 3, characterized in that, The event caching and incremental update method is as follows: when the probe moves continuously, the event map of the previous moment is mapped to the current coordinate system through coordinate mapping, and the new field of view event set is incrementally updated.

5. The real-time ultrasonic simulation method based on echo event spectrum and spatiotemporal coherent speckle field reconstruction according to claim 1, characterized in that, The echo event spectrum is defined as: Event nodes are defined as follows: in: For echo event patterns, For a set of event nodes, For a set of event relationships, This is a property mapping function. For the first Each event node For the location of the event, For echo arrival time, For the magnitude of the event, For the time of dissemination, For the interface normal vector, These are local texture spectrum parameters.

6. The real-time ultrasonic simulation method based on echo event spectrum and spatiotemporal coherent speckle field reconstruction according to claim 1, characterized in that, The boundary echo event model is constructed as follows: The reflectance coefficient at the interface is defined as: When considering the effects of the incident angle and the refraction angle, the reflection coefficient is extended to: The boundary echo propagation time is defined as: The attenuation term along the propagation path is defined as: Finally, the boundary echo signal is represented as: in: The reflection coefficient, and The acoustic impedance on both sides of the interface. Angle of incidence For the angle of refraction, For two-way travel time, For the propagation path, For path infinitesimal elements, For local sound speed, As the attenuation factor, The attenuation coefficient is... For boundary echo signals, For boundary weights, For beam weights, Let be the system impulse response function. It is a time variable.

7. The real-time ultrasonic simulation method based on echo event spectrum and spatiotemporal coherent speckle field reconstruction according to claim 1, characterized in that, The method for establishing the volume scattering echo model using a statistical stochastic model is as follows: Define spatial location The microscattering random variable at point is: The volume-scattered echo signal is represented as: in: Represents a three-dimensional tissue region. Represents a point in space. Indicates position Random scattering variables at that location, This indicates that the mean is 0 and the variance is 0. Gaussian distribution, The variance parameter representing the scattering intensity. Indicates the first Volume scattered echo signal of each scan line, Represents a time variable. Indicates the weight of volume scattering intensity. Represents the beam weighting function. Represents the system impulse response function. Indicates the time of transmission. Represents a volume differential element, with the integral symbol. This indicates that the integral is performed over the entire volume region.

8. The real-time ultrasonic simulation method based on echo event spectrum and spatiotemporal coherent speckle field reconstruction according to claim 1, characterized in that, The method for constructing a spatiotemporally coherent speckle field, constraining the continuous spatiotemporal evolution of speckle, and eliminating speckle jumps and scintillation during continuous scanning is as follows: Define the speckle field recursive model as follows: in: Indicates position At any moment The speckle field value, Indicates spatial location, Represents a discrete-time index. Represents the time coherence coefficient. This represents the local displacement field caused by probe movement or tissue deformation. This represents the speckle value after displacement at the previous moment. Represents the random disturbance term. This represents zero-mean Gaussian noise. Indicates the intensity of the disturbance; Define the space-time correlation function as follows: in: Represents the relevant function, Indicates the difference in spatial distance. Indicates time interval, Represents Euclidean distance. Indicates spatially related length. Represents the time-dependent constant. Represents an exponential function; Simultaneously, the speckle field is decomposed into multi-scale components: in: This is a large-scale structure modulation term. For mesoscale texture items, It is a high-frequency micro-speckled term.

9. The real-time ultrasonic simulation method based on echo event spectrum and spatiotemporal coherent speckle field reconstruction according to claim 1, characterized in that, The method for establishing the artifact modulation and non-uniform propagation model is as follows: Define path cumulative decay as: The shadow modulation factor is: The post-enhancement modulation factor is: The modulated scattering signal is: in: Indicates cumulative path decay. Indicates the propagation path, Indicates position Attenuation coefficient at that point Represents the path element. Represents the shading factor. Indicates the post-enhancement factor, Represents the shadow modulation coefficient. Indicates the enhancement modulation coefficient, Indicates the reference attenuation. This represents the signal after artifact modulation. This indicates the volume-scattered echo.

10. The real-time ultrasonic simulation method based on echo event spectrum and spatiotemporal coherent speckle field reconstruction according to claim 1, characterized in that, The method is adaptable to simulation scenarios in obstetrics, cardiology, abdomen, breast, interventional procedures, and intracavitary ultrasound. The underlying algorithm can be reused simply by replacing the tissue parameter field, case model, and probe configuration.

Images