Ultrasound-guided virtual reality isometric cross-sectional dynamic matching system

Abstract

The present application relates to the technical field of dynamic matching, in particular to an ultrasound-guided virtual reality same-azimuth cross-section dynamic matching system, which comprises a probe angle unit, a cross-section virtual unit and a matching update unit.The matching update unit calculates the entropy of the virtual ultrasound cross-section image, carries out combination, obtains the joint entropy, carries out dynamic matching calculation, obtains the similarity measurement of matching and the maximum translation vector, combines the ultrasound probe center point and the rotation matrix from the world coordinate system to the virtual model coordinate system to calculate the new ultrasound probe center point, updates the position of the original ultrasound probe center point, the entropy can reflect the information richness of the image, the joint entropy reflects the associated information between the two images, the similarity measurement calculation is carried out by using the information, the similarity between the virtual image and the actual ultrasound image can be more accurately measured, so that the best matching relationship between the two is found, and the image matching precision is improved.

Description

Technical Field

[0001] This invention relates to the field of dynamic matching technology, and more specifically, to an ultrasound-guided virtual reality co-directional cross-sectional dynamic matching system. Background Technology

[0002] In the medical field, ultrasound-guided virtual reality (US-VR) technology provides strong support for applications such as surgical navigation; however, it currently faces many technical challenges.

[0003] Traditional US-VR technology based on rigid registration has significant limitations. When the ultrasound probe undergoes large-angle movement (pitch or roll greater than 20°), the registration error becomes particularly prominent, exceeding 5 mm. This is mainly because the nonlinear characteristics of the rotation matrix amplify the error when directly processing large-angle rotations. This error amplification not only makes it difficult to accurately register the virtual model with the actual ultrasound image and accurately represent the internal anatomical structure of the human body, but also affects the identification and matching of subtle features in the image, thus affecting the localization and diagnosis of lesions. At the same time, during complex surgical procedures, ultrasound images are also affected by external factors such as the patient's breathing and body movement, further exacerbating the instability of registration and even potentially leading to registration failure, rendering the system unable to function properly.

[0004] Furthermore, when matching virtual ultrasound cross-sectional images with actual ultrasound images, traditional methods struggle to accurately measure the degree of similarity between the two. Due to the lack of effective methods to comprehensively consider the information richness of the images and the correlation between the two images, it is impossible to find the optimal matching relationship between them, resulting in low image matching accuracy. This affects the system's ability to provide doctors with accurate surgical navigation information. To address the above issues, we have provided an ultrasound-guided virtual reality co-directional cross-sectional dynamic matching system. Summary of the Invention

[0005] The purpose of this invention is to provide an ultrasound-guided virtual reality co-directional cross-sectional dynamic matching system to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides an ultrasound-guided virtual reality co-directional cross-sectional dynamic matching system, comprising a probe angle unit, a cross-sectional virtual unit, and a matching update unit;

[0007] The probe angle unit acquires the Euler angles of the ultrasonic probe in the world coordinate system and the ultrasonic probe coordinate system, calculates the homogeneous transformation matrix from the world coordinate system to the ultrasonic probe coordinate system, defines the homogeneous transformation matrix as the ultrasonic probe pose, and detects whether there is large-angle motion of the ultrasonic probe through Euler angles. When large-angle motion of the ultrasonic probe is detected, the ultrasonic image is recorded.

[0008] The transverse virtual unit is used to receive the command from the probe angle unit that the ultrasound probe has a large angle of motion, set the virtual model coordinate system, obtain the normal vector of the transverse plane and fix it, calculate the ultrasound probe pose from the world coordinate system to the virtual model coordinate system, convert it into the transformation matrix from the world coordinate system to the virtual model coordinate system, extract the rotation matrix from the world coordinate system to the virtual model coordinate system and combine it with the normal vector of the transverse plane to calculate the normal vector of the ultrasound transverse plane in the virtual model coordinate system, and then extract the center point of the ultrasound probe to dynamically generate a virtual ultrasound transverse plane image with local coordinates of the transverse plane.

[0009] The matching update unit is used to receive the center point of the ultrasound probe in the transverse virtual unit, the rotation matrix from the world coordinate system to the virtual model coordinate system, and the ultrasound image in the probe angle unit. It calculates the entropy of the virtual ultrasound transverse image and performs joint calculation to obtain the joint entropy and perform dynamic matching calculation to obtain the matching similarity metric and the maximum translation vector. Then, it calculates the new center point of the ultrasound probe by combining the center point of the ultrasound probe and the rotation matrix from the world coordinate system to the virtual model coordinate system, and updates the position of the original center point of the ultrasound probe.

[0010] As a further improvement to this technical solution, when the cross-section module determines that the Z-axis of the ultrasound probe is perpendicular to the cross-section of the ultrasound image, it fixes the normal vector of the cross-section as follows: Here, T refers to the transpose operation, and then the ultrasonic probe pose from the world coordinate system to the virtual model coordinate system is calculated. Homogeneous transformation matrix from world coordinate system to ultrasonic probe coordinate system Transformation matrix from world coordinate system to virtual model coordinate system ;

[0011] Extracting the rotation matrix from the world coordinate system to the virtual model coordinate system Combined with the normal vector of the cross section Calculate the normal vector of the ultrasonic cross-section in the coordinate system of the virtual model, and thus obtain the normal vector of the ultrasonic cross-section. .

[0012] As a further improvement to this technical solution, the virtual section module extracts the center point of the ultrasound probe, and constructs a plane passing through the center point of the ultrasound probe based on the normal vector of the ultrasound cross section and the center point of the ultrasound probe.

[0013] Extract volume data corresponding to data grid points from the virtual model. voxel values Virtual ultrasound cross-sectional images with dynamically generated local coordinates of the cross-section. ,in, This refers to the trilinear interpolation kernel.

[0014] As a further improvement to this technical solution, the matching update unit calculates the entropy of the virtual ultrasound cross-section image and the entropy of the ultrasound image and combines them to obtain the joint entropy. By combining the entropy of the virtual ultrasound cross-section image and the entropy of the ultrasound image with the joint entropy H, dynamic matching calculation is performed to obtain the similarity measure of the match.

[0015] The virtual ultrasound cross-sectional image and the ultrasound image are translated to obtain the translation vector that maximizes the similarity metric of the match. Then, the virtual ultrasound cross-sectional image is translated along the x and y axes from the maximum translation vector. and The unit is used to calculate the new center point of the ultrasound probe by combining the center point of the ultrasound probe and the rotation matrix from the world coordinate system to the virtual model coordinate system. Then, the new center point of the ultrasound probe is fed back to the virtual model coordinate system to update the position of the original center point of the ultrasound probe.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. In this ultrasound-guided virtual reality co-directional cross-sectional dynamic matching system, the matching update unit receives the center point of the ultrasound probe in the cross-sectional virtual unit, the rotation matrix from the world coordinate system to the virtual model coordinate system, and the ultrasound image in the probe angle unit. It calculates the entropy of the virtual ultrasound cross-sectional image and performs joint calculations to obtain the joint entropy. This results in a similarity metric and the maximum translation vector. Then, combining the center point of the ultrasound probe and the rotation matrix from the world coordinate system to the virtual model coordinate system, a new center point of the ultrasound probe is calculated, updating the original position of the ultrasound probe center point. Dynamic matching is performed by calculating the entropy of the virtual ultrasound cross-sectional image, the entropy of the ultrasound image, and their joint entropy. Entropy reflects the richness of information in the image, while joint entropy reflects the correlation information between two images. Using this information for similarity metric calculation allows for a more accurate measurement of the similarity between the virtual image and the actual ultrasound image, thereby finding the optimal matching relationship and improving the accuracy of image matching.

[0018] 2. In this ultrasound-guided virtual reality co-directional cross-sectional dynamic matching system, the cross-sectional virtual unit is used to receive the command from the probe angle unit that the ultrasound probe has a large-angle movement, set the virtual model coordinate system, obtain the normal vector of the cross-section and fix it, calculate the ultrasound probe pose from the world coordinate system to the virtual model coordinate system, and then convert it into the transformation matrix from the world coordinate system to the virtual model coordinate system. The rotation matrix from the world coordinate system to the virtual model coordinate system is extracted and combined with the normal vector of the cross-section to calculate the normal vector of the ultrasound cross-section in the virtual model coordinate system. Then, the center point of the ultrasound probe is extracted to dynamically generate a virtual ultrasound cross-sectional image with local coordinates of the cross-section. The calculated rotation matrix from the world coordinate system to the virtual model coordinate system is combined with the normal vector of the cross-section to calculate the normal vector of the ultrasound cross-section in the virtual model coordinate system. This avoids the error amplification problem caused by the nonlinearity of the rotation matrix when directly handling large-angle rotation, and can better resist the influence of external interference and improve the stability of dynamic matching. Attached Figure Description

[0019] Figure 1 This is a block diagram of the overall system structure of the present invention;

[0020] Figure 2 This is a block diagram of the module units of the present invention.

[0021] The meanings of the labels in the diagram are as follows:

[0022] 10. Probe angle unit; 11. Probe matrix module; 12. Angle motion module;

[0023] 20. Cross-section virtual unit; 21. Cross-section module; 22. Virtual section module; 30. Matching update unit. Detailed Implementation

[0024] The technical solutions in 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1

[0026] This invention provides an ultrasound-guided virtual reality co-orientation cross-sectional dynamic matching system. Please refer to [link / reference]. Figures 1-2 It includes a probe angle unit 10, a transverse virtual unit 20, and a matching update unit 30;

[0027] The probe angle unit 10 acquires the Euler angles of the ultrasonic probe in the world coordinate system and the ultrasonic probe coordinate system, calculates the homogeneous transformation matrix from the world coordinate system to the ultrasonic probe coordinate system, defines the homogeneous transformation matrix as the ultrasonic probe pose, and simultaneously detects whether there is large-angle motion of the ultrasonic probe through Euler angles. When large-angle motion of the ultrasonic probe is detected, the ultrasonic image is recorded. The transverse virtual unit 20 is used to receive the command from the probe angle unit 10 that the ultrasonic probe has detected large-angle motion, sets the virtual model coordinate system, obtains the normal vector of the transverse plane and fixes it, calculates the ultrasonic probe pose from the world coordinate system to the virtual model coordinate system, and then converts it into the transformation matrix from the world coordinate system to the virtual model coordinate system, extracting the transformation matrix from the world coordinate system to the virtual model coordinate system. The rotation matrix is ​​combined with the normal vector of the cross section to calculate the normal vector of the ultrasound cross section in the virtual model coordinate system. Then, the center point of the ultrasound probe is extracted to dynamically generate a virtual ultrasound cross section image with local coordinates of the cross section. The matching update unit 30 is used to receive the center point of the ultrasound probe in the cross section virtual unit 20, the rotation matrix from the world coordinate system to the virtual model coordinate system, and the ultrasound image in the probe angle unit 10. It calculates the entropy of the virtual ultrasound cross section image and performs joint calculation to obtain the joint entropy and perform dynamic matching calculation to obtain the matching similarity metric and the maximum translation vector. Then, it combines the center point of the ultrasound probe and the rotation matrix from the world coordinate system to the virtual model coordinate system to calculate the new center point of the ultrasound probe and update the position of the original center point of the ultrasound probe.

[0028] The following is a detailed breakdown of the above units;

[0029] The probe angle unit 10 includes a probe matrix module 11 and an angle motion module 12;

[0030] High-precision electromagnetic equipment is installed in the surgical environment. Ultrasonic-guided virtual reality technology via probe matrix module 11 is used to acquire in real-time Euler angles (including pitch angle) of the ultrasound probe in the current frame within the world coordinate system W (a global, fixed reference coordinate system) and the ultrasound probe coordinate system U. Roll angle Yaw angle ), where subscript It has no special physical meaning; it is only used for differentiation and to simultaneously acquire the translation vector of the ultrasound probe. , refers to a The column vectors, where Euler angles are the homogeneous transformation matrix. The upper right corner describes the translation of the origin of the ultrasonic probe's coordinate system relative to the origin of the world coordinate system. This translation indicates the position of the ultrasonic probe in the world coordinate system. The rotation angle is calculated based on the pitch, roll, and yaw angles in Euler angles. Basic rotation matrix of axis rotation Then calculate the rotation matrix based on the basic rotation matrix. A rotation matrix is ​​a 3×3 matrix that is a homogeneous transformation matrix. The upper left part, the rotation matrix is ​​used to describe the rotation relationship of the ultrasonic probe coordinate system relative to the world coordinate system W, and is used to reflect the orientation of the ultrasonic probe in space;

[0031] Calculate the winding The basic rotation matrix algorithm formula for axis rotation is:

[0032] ;

[0033] ;

[0034] ;

[0035] Where 0 and 1 are the values ​​of the matrix elements;

[0036] Once the rotation matrix is ​​known, the homogeneous transformation matrix from the world coordinate system to the ultrasound probe coordinate system can be calculated using the translation vector and rotation matrix of the ultrasound probe. The homogeneous transformation matrix is ​​defined as the ultrasonic probe pose (position and orientation).

[0037] The angle motion module 12 is used to receive the Euler angles of the current frame from the probe matrix module 11, obtain the Euler angles of the previous frame from the historical data, extract the pitch and roll angles of the previous frame from the Euler angles of the previous frame, and then extract the pitch and roll angles from the Euler angles of the current frame. Using the pitch and roll angles and the pitch and roll angles of the previous frame, the change in pitch angle between the current frame and the previous frame is calculated. and roll angle change And set the pitch / roll angle change threshold. Then, the absolute values ​​of the pitch and roll angle changes between the current frame and the previous frame are calculated to obtain the pitch angle change. and roll angle change The ultrasonic probe is detected to have large-angle motion by using the absolute values ​​of pitch angle change and roll angle change and pitch and roll angle change thresholds. When the absolute values ​​of pitch angle change and roll angle change are greater than the pitch angle change thresholds, the ultrasonic probe is detected to have large-angle motion, and the ultrasonic image is recorded.

[0038] Historical data includes the Euler angles of the previous frame;

[0039] The transverse virtual unit 20 includes a transverse section module 21 and a virtual section module 22;

[0040] The cross-section module 21 is used to receive commands from the angle motion module 12 indicating a large-angle motion of the ultrasound probe. In the ultrasound probe coordinate system, when it is determined that the Z-axis of the ultrasound probe is perpendicular to the cross-section of the ultrasound image, the normal vector of the cross-section is fixed. Here, T refers to the transpose operation, where the normal vector of the cross section represents the transformation of this row vector into a column vector, becoming... The matrix is ​​of the form of ;

[0041] Once the normal vector of the cross section is known, a virtual model coordinate system M is defined (an abstract 3D spatial reference frame used to construct and represent the virtual model), and the rotation matrix from the world coordinate system to the virtual model coordinate system is obtained. The amount of translation required to align the world coordinate system with the virtual model coordinate system. Calculate the ultrasonic probe pose from the world coordinate system to the virtual model coordinate system. The ultrasonic probe pose is transferred from the world coordinate system to the virtual model coordinate system. Homogeneous transformation matrix from world coordinate system to ultrasonic probe coordinate system Transformation matrix from world coordinate system to virtual model coordinate system .

[0042] Extract the rotation matrix from the world coordinate system to the virtual model coordinate system from the transformation matrix. The rotation matrix from the world coordinate system to the virtual model coordinate system and the normal vector of the cross section Calculate the normal vector of the ultrasonic cross-section in the coordinate system of the virtual model, and thus obtain the normal vector of the ultrasonic cross-section. Among them, the normal vector of the ultrasonic cross section directly represents the orientation of the ultrasonic cross section (e.g., (This indicates the tilt direction of the ultrasonic cross-section in the virtual model coordinate system).

[0043] The virtual section module 22 receives the transformation matrix from the world coordinate system to the virtual model coordinate system and the ultrasonic cross-section normal vector from the cross-section module 21. Because the traditional method of generating the cross-section uses a fixed probe pose, when the probe rotates at a large angle, the orientation of the generated cross-section is inconsistent with the actual ultrasonic cross-section orientation, causing the virtual model and the ultrasonic image to not match accurately, affecting the accuracy of the detection. Therefore, the center point of the ultrasonic probe is first extracted from the transformation matrix from the world coordinate system to the virtual model coordinate system. Based on the normal vector of the ultrasound cross section, a plane passing through the center point of the ultrasound probe is constructed using the center point of the ultrasound probe. The specific algorithm formula is as follows: In this context, the normal vector of the ultrasonic transverse section is perpendicular to the plane, and the center point of the ultrasonic probe is a known point on the plane. For any point P on the plane, the vector... All are perpendicular to the normal vector of the ultrasonic cross-section, and their dot product is 0;

[0044] Once the plane is constructed, since the virtual model (such as CT volume data) is stored in the virtual model coordinate system, the corresponding data grid points of the volume data are extracted from the virtual model. voxel values Then, the local coordinates of the cross section are extracted from the ultrasonic transverse section. Data grid points corresponding to volume data voxel values Virtual ultrasound cross-sectional images with dynamically generated local coordinates of the cross-section ,in, This refers to the trilinear interpolation kernel, which eliminates the co-location difference between the virtual cross-section image and the original ultrasound image;

[0045] The matching update unit 30 is used to receive the virtual ultrasound cross-sectional image from the virtual section module 22, the ultrasound probe center point, and the ultrasound image from the angle motion module 12. It receives the rotation matrix from the world coordinate system to the virtual model coordinate system in the cross-section module 21 and calculates the entropy of the virtual ultrasound cross-section image. and the entropy of ultrasound images Entropy reflects the uncertainty of an image. This is achieved by considering the entropy of a virtual ultrasound cross-section image and the entropy of the ultrasound image. Perform a joint operation to obtain the joint entropy. This reflects the shared uncertainty between the two images. Their similarity metric (mutual information) reaches its maximum when the two images are perfectly aligned, calculated using the entropy of the virtual ultrasound cross-section image and the entropy of the ultrasound image. Combined with joint entropy Dynamic matching calculations are performed to derive a similarity metric for the matches. The specific algorithm formula is as follows: ;

[0046] When the similarity metric for matching is known, the virtual ultrasound cross-sectional image and the ultrasound image are transformed by translation. This allows us to obtain the translation vector that maximizes the similarity metric of the match. , where the symbol This indicates a function composition operation;

[0047] After obtaining the largest translation vector, extract the virtual ultrasound cross-sectional image from the largest translation vector and translate it along the x-axis and y-axis respectively. and The new ultrasonic probe center point is calculated using a unit and the rotation matrix from the world coordinate system to the virtual model coordinate system. Since matching virtual ultrasound cross-sectional images only requires two-dimensional translation, the translation of the virtual ultrasound cross-sectional image along the z-axis is ignored. Each unit then feeds the new ultrasound probe center point back into the virtual model coordinate system, updating the original ultrasound probe center point position. Using this updated ultrasound probe center point position, a virtual cross-sectional image that is more precisely aligned with the ultrasound image can be regenerated, improving registration accuracy.

[0048] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An ultrasound-guided virtual reality co-directional transverse dynamic matching system, characterized in that: It includes a probe angle unit (10), a transverse virtual unit (20), and a matching update unit (30); The probe angle unit (10) acquires the Euler angles of the ultrasonic probe in the world coordinate system and the ultrasonic probe coordinate system, calculates the homogeneous transformation matrix from the world coordinate system to the ultrasonic probe coordinate system, defines the homogeneous transformation matrix as the ultrasonic probe pose, and detects whether the ultrasonic probe has large-angle motion through Euler angles. When large-angle motion of the ultrasonic probe is detected, the ultrasonic image is recorded. The transverse virtual unit (20) is used to receive the command from the probe angle unit (10) that the ultrasonic probe has a large angle of motion, set the virtual model coordinate system, obtain the normal vector of the transverse plane and fix it, calculate the ultrasonic probe pose from the world coordinate system to the virtual model coordinate system, convert it into the transformation matrix from the world coordinate system to the virtual model coordinate system, extract the rotation matrix from the world coordinate system to the virtual model coordinate system and combine it with the normal vector of the transverse plane to calculate the normal vector of the ultrasonic transverse plane in the virtual model coordinate system, and then extract the center point of the ultrasonic probe to dynamically generate a virtual ultrasonic transverse plane image with local coordinates of the transverse plane. The matching update unit (30) is used to receive the center point of the ultrasound probe in the transverse virtual unit (20), the rotation matrix from the world coordinate system to the virtual model coordinate system, and the ultrasound image in the probe angle unit (10), calculate the entropy of the virtual ultrasound transverse image and perform joint calculation to obtain the joint entropy and perform dynamic matching calculation to obtain the matching similarity metric and the maximum translation vector. Then, the new center point of the ultrasound probe is calculated by combining the center point of the ultrasound probe and the rotation matrix from the world coordinate system to the virtual model coordinate system, and the position of the original center point of the ultrasound probe is updated.

2. The ultrasound-guided virtual reality co-directional cross-sectional dynamic matching system according to claim 1, characterized in that: The probe angle unit (10) includes a probe matrix module (11) and an angle motion module (12). The probe matrix module (11) collects the Euler angles of the ultrasonic probe in the world coordinate system and the ultrasonic probe coordinate system in real time, and calculates the basic rotation matrix and the rotation matrix based on the Euler angles; The homogeneous transformation matrix from the world coordinate system to the ultrasonic probe coordinate system is calculated using a rotation matrix, and the homogeneous transformation matrix is ​​defined as the ultrasonic probe pose.

3. The ultrasound-guided virtual reality co-directional cross-sectional dynamic matching system according to claim 2, characterized in that: The angle motion module (12) is used to receive the Euler angles in the probe matrix module (11), obtain the Euler angles of the previous frame in the historical data, calculate the pitch angle change and roll angle change between the current frame and the previous frame and take the absolute value, use the absolute value of the pitch angle change and roll angle change to detect whether there is a large angle motion of the ultrasonic probe, and when the ultrasonic probe is detected to have a large angle motion, record the ultrasonic image.

4. The ultrasound-guided virtual reality co-directional cross-sectional dynamic matching system according to claim 3, characterized in that: The transverse virtual unit (20) includes a transverse section module (21) and a virtual section module (22); The cross-section module (21) is used to receive the command from the angle motion module (12) that the ultrasound probe has a large angle of motion, and when it is determined that the Z-axis of the ultrasound probe is perpendicular to the cross-section of the ultrasound image, it fixes the normal vector of the cross-section as follows: , where T refers to the transpose operation.

5. The ultrasound-guided virtual reality co-directional cross-sectional dynamic matching system according to claim 4, characterized in that: The cross-section module (21) sets the virtual model coordinate system, calculates the ultrasonic probe pose from the world coordinate system to the virtual model coordinate system, and uses the ultrasonic probe pose from the world coordinate system to the virtual model coordinate system. Homogeneous transformation matrix from world coordinate system to ultrasonic probe coordinate system Transformation matrix from world coordinate system to virtual model coordinate system ; Extracting the rotation matrix from the world coordinate system to the virtual model coordinate system Combined with the normal vector of the cross section Calculate the normal vector of the ultrasonic cross-section in the coordinate system of the virtual model, and thus obtain the normal vector of the ultrasonic cross-section. .

6. The ultrasound-guided virtual reality co-directional transverse dynamic matching system according to claim 5, characterized in that: The virtual section module (22) is used to receive the transformation matrix from the world coordinate system to the virtual model coordinate system and the ultrasonic cross section normal vector in the cross section module (21), extract the center point of the ultrasonic probe, and construct a plane passing through the center point of the ultrasonic probe based on the ultrasonic cross section normal vector and the center point of the ultrasonic probe.

7. The ultrasound-guided virtual reality co-directional transverse dynamic matching system according to claim 6, characterized in that: The virtual section module (22) extracts the data grid points corresponding to the volume data from the virtual model. voxel values Virtual ultrasound cross-sectional images with dynamically generated local coordinates of the cross-section. ,in, This refers to the trilinear interpolation kernel.

8. The ultrasound-guided virtual reality co-directional cross-sectional dynamic matching system according to claim 7, characterized in that: The matching update unit (30) is used to receive the virtual ultrasound cross-section image, the center point of the ultrasound probe and the ultrasound image in the angle motion module (12) in the virtual cross-section module (22), receive the rotation matrix from the world coordinate system to the virtual model coordinate system in the cross-section module (21), calculate the entropy of the virtual ultrasound cross-section image and the entropy of the ultrasound image and combine them to obtain the joint entropy. By combining the entropy of the virtual ultrasound cross-section image and the entropy of the ultrasound image with the joint entropy H, dynamic matching calculation is performed to obtain the similarity measure of the match.

9. The ultrasound-guided virtual reality co-directional cross-sectional dynamic matching system according to claim 8, characterized in that: The matching update unit (30) then performs a translation transformation on the virtual ultrasound cross-sectional image and the ultrasound image to obtain a translation vector that maximizes the similarity metric of the match.

10. The ultrasound-guided virtual reality co-directional cross-sectional dynamic matching system according to claim 9, characterized in that: The matching update unit (30) extracts the virtual ultrasound cross-sectional image from the largest translation vector and translates it along the x-axis and y-axis. and The unit is used to calculate the new center point of the ultrasound probe by combining the center point of the ultrasound probe and the rotation matrix from the world coordinate system to the virtual model coordinate system. Then, the new center point of the ultrasound probe is fed back to the virtual model coordinate system to update the position of the original center point of the ultrasound probe.

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