An image registration system and method for femoral surgery

Abstract

The present invention relates to an image registration system and method for femoral surgery, belonging to the field of surgical image registration. Before the surgery, DRR projections of the three-dimensional femoral CT image are performed at various angles. The femoral coordinate system and femoral feature points are generated and selected on the two-dimensional DRR projection image and the two-dimensional X-ray image respectively. According to the femoral coordinate system and femoral feature points, the two-dimensional DRR projection image and the two-dimensional X-ray image are registered, improving the accuracy of image registration. It can accurately obtain the two-dimensional DRR projection image with the same femoral pose as when the two-dimensional X-ray image is scanned, and then a real surgical path can be obtained for surgical navigation, ensuring the accuracy of surgical assisted navigation, and thus improving the surgical quality.

Description

Technical Field

[0001] The present invention relates to the field of surgical image registration, and particularly to an image registration system and method for femoral surgery. Background Art

[0002] The femoral neck needs to bear the movement and support functions during most activities of the human body, and the treatment effect of its fracture will directly affect the quality of life of patients after surgery. At present, femoral neck fractures have accounted for 3.6% of all body fractures and half of hip fractures, mostly occurring in middle-aged and elderly people with osteoporosis. With the serious aging of society, its incidence rate increases year by year. The surgical navigation system assisting femoral neck fracture surgery is of great significance.

[0003] Currently, the commonly used navigation methods in different femoral surgeries based on medical imaging data on the market are mainly divided into the following four types: 1) preoperative navigation system based on CT data; 2) intraoperative imaging navigation system based on C-arm X-ray machine; 3) navigation system based on intraoperative three-dimensional reconstruction; 4) navigation system based on three-dimensional-two-dimensional image registration.

[0004] The preoperative navigation system based on CT data cannot perform intraoperative spatial positioning due to the lack of intraoperative information support. The intraoperative imaging navigation system based on C-arm X-ray machine is not intuitive enough, and the intraoperative three-dimensional reconstruction system has a high price and low popularity. The navigation system based on three-dimensional-two-dimensional image registration can effectively avoid the above disadvantages, and the difficulty lies in the accurate registration of three-dimensional images and two-dimensional images. Summary of the Invention

[0005] The purpose of the present invention is to provide an image registration system and method for femoral surgery, which improves the accuracy of image registration, can ensure the accuracy of surgical assistant navigation, and thus improves the surgical quality.

[0006] To achieve the above purpose, the present invention provides the following solutions:

[0007] An image registration system for femoral surgery, comprising: a projection module, a preprocessing module, and a registration module;

[0008] The projection module is used to perform DRR projections of a three-dimensional femoral CT image at different angles to obtain a plurality of two-dimensional DRR projection images;

[0009] The preprocessing module is used to preprocess the femoral images in each two-dimensional DRR projection image and each two-dimensional X-ray image to generate a femoral coordinate system and femoral feature points; the two-dimensional X-ray images include a plurality of X-ray planar images taken of the femoral part at different angles;

[0010] The registration module is configured to determine, from the plurality of two-dimensional DRR projection images, a two-dimensional DRR projection image having the same femoral pose as that in the two-dimensional X-ray image according to the femoral coordinate systems and femoral feature points of the two-dimensional DRR projection image and the two-dimensional X-ray image, so as to obtain a plurality of target DRR projection images.

[0011] Optionally, the femur includes a femoral head, a femoral neck, and a femoral shaft, and the preprocessing module includes a femoral contour line generation unit, a femoral head fitting unit, a femoral neck feature line selection unit, a femoral coordinate system establishment unit, a femoral feature circle generation unit, a femoral feature line selection unit, and a femoral feature point selection unit;

[0012] The femoral contour line generation unit is configured to automatically extract the outer contour of the femur to obtain a femoral contour line;

[0013] The femoral head fitting unit is configured to fit the femoral head into a circle to obtain a femoral head fitting circle;

[0014] The femoral neck feature line selection unit is configured to select, between two femoral contour lines at the femoral neck, a line segment connecting two points with the shortest distance as the femoral neck feature line;

[0015] The femoral coordinate system establishment unit is configured to establish a femoral coordinate system with a line connecting the center of the femoral head fitting circle and the midpoint of the femoral neck feature line as one coordinate axis of the femoral coordinate system;

[0016] The femoral feature circle generation unit is configured to, with the radius of the femoral head fitting circle as the radius, select two points on the extension line of the line connecting the center of the femoral head fitting circle and the midpoint of the femoral neck feature line as the centers, and respectively generate a first feature circle and a second feature circle; the first feature circle is tangent to the femoral head fitting circle, and the center of the first feature circle is on the edge line of the second feature circle;

[0017] The femoral feature line selection unit is configured to select a plurality of femoral feature lines perpendicular to the line connecting the center of the femoral head fitting circle and the midpoint of the femoral neck feature line;

[0018] The femoral feature point selection unit is configured to take the intersection points of each femoral feature line and the femoral contour line as femoral feature points.

[0019] Optionally, the femoral feature line selection unit includes: a first femoral feature line selection subunit, a second femoral feature line selection subunit, a third femoral feature line selection subunit, a fourth femoral feature line selection subunit, and a fifth femoral feature line selection subunit;

[0020] The first femoral feature line selection subunit is configured to select a first femoral feature line; the first femoral feature line is a line segment passing through the tangent point of the femoral head fitting circle and the first feature circle;

[0021] The second femoral feature line selection subunit is configured to select the second femoral feature line; the second femoral feature line is a line segment passing through the center of the first feature circle.

[0022] The third femoral feature line selection subunit is configured to select the third femoral feature line; the third femoral feature line is a line segment passing through the center of the second feature circle.

[0023] The fourth femoral feature line selection subunit is configured to select the fourth femoral feature line; the fourth femoral feature line is a line segment parallel to the second femoral feature line and tangent to the second feature circle.

[0024] The fifth femoral feature line selection subunit is configured to select the fifth femoral feature line; the fifth femoral feature line is a line segment passing through the midpoint of the line connecting the center of the femoral head fitting circle and the midpoint of the femoral neck feature line and the midpoint of the line connecting the intersection points of the third femoral feature line and the fourth femoral feature line.

[0025] Optionally, the registration module includes: a femoral coordinate system coincidence unit and a femoral feature point registration unit;

[0026] The femoral coordinate system coincidence unit is configured to coincide the femoral coordinate systems of the two-dimensional DRR projection image and the two-dimensional X-ray image.

[0027] The femoral feature point registration unit is configured to match the positions of the femoral feature points of the two-dimensional DRR projection image and the two-dimensional X-ray image one by one.

[0028] Optionally, the preprocessing module further includes: a region of interest selection unit;

[0029] The region of interest selection unit is configured to select a region of interest composed of line segments and arcs at the positions of the femoral head contour line and the two femoral neck contour lines of the femoral contour line.

[0030] On the other hand, for the aforementioned image registration system, the present invention also provides an image registration method for femoral surgery, including the following steps:

[0031] Perform DRR projections of the three-dimensional femoral CT image at different angles to obtain a plurality of two-dimensional DRR projection images;

[0032] Preprocess the femoral images in each two-dimensional DRR projection image and each two-dimensional X-ray image to generate a femoral coordinate system and femoral feature points; the two-dimensional X-ray image includes a plurality of X-ray planar images taken of the femoral part at different angles.

[0033] Based on the femoral coordinate system and femoral feature points of the two-dimensional DRR projection images and the two-dimensional X-ray images, determine the two-dimensional DRR projection images with the same femoral pose as that in the two-dimensional X-ray images from the several two-dimensional DRR projection images, and obtain multiple target DRR projection images.

[0034] Optionally, the femur includes the femoral head, femoral neck and femoral shaft. The preprocessing of the femoral images in each two-dimensional DRR projection image and each two-dimensional X-ray image to generate a femoral coordinate system and femoral feature points specifically includes:

[0035] Automatically extract the outer contour of the femur to obtain the femoral contour line;

[0036] Fit the femoral head into a circle to obtain the femoral head fitting circle;

[0037] Select the line connecting the two points with the shortest distance between the two femoral contour lines at the femoral neck as the femoral neck feature line;

[0038] Take the line connecting the center of the femoral head fitting circle and the midpoint of the femoral neck feature line as one coordinate axis of the femoral coordinate system to establish the femoral coordinate system;

[0039] With the radius of the femoral head fitting circle as the radius, select two points on the extension line of the line connecting the center of the femoral head fitting circle and the midpoint of the femoral neck feature line as the centers, and generate the first feature circle and the second feature circle respectively; the first feature circle is tangent to the femoral head fitting circle, and the center of the first feature circle is on the edge line of the second feature circle;

[0040] Generate multiple femoral feature lines perpendicular to the line connecting the center of the femoral head fitting circle and the midpoint of the femoral neck feature line;

[0041] Take the intersection points of each femoral feature line and the femoral contour line as femoral feature points.

[0042] Optionally, the generating of multiple femoral feature lines perpendicular to the line connecting the center of the femoral head fitting circle and the midpoint of the femoral neck feature line specifically includes:

[0043] Select the line segment passing through the tangent point of the femoral head fitting circle and the first feature circle as the first femoral feature line;

[0044] Select the line segment passing through the center of the first feature circle as the second femoral feature line;

[0045] Select the line segment passing through the center of the second feature circle as the third femoral feature line;

[0046] Select the line segment parallel to the second femoral feature line and tangent to the second feature circle as the fourth femoral feature line;

[0047] Select the line segment connecting the midpoint of the extension line of the line connecting the center of the fitting circle of the femoral head and the midpoint of the femoral neck feature line and the midpoint of the line connecting the intersection points of the third femoral feature line and the fourth femoral feature line as the fifth femoral feature line.

[0048] Optionally, the method for determining the two-dimensional DRR projection image with the same femoral pose as the two-dimensional X-ray image from the plurality of two-dimensional DRR projection images according to the femoral coordinate system and femoral feature points of the two-dimensional DRR projection image and the two-dimensional X-ray image, to obtain a plurality of target DRR projection images, specifically includes:

[0049] Coincide the femoral coordinate systems of the two-dimensional DRR projection image and the two-dimensional X-ray image;

[0050] Match the positions of the femoral feature points of the two-dimensional DRR projection image and the two-dimensional X-ray image one by one.

[0051] Optionally, the method further includes:

[0052] Select a region of interest composed of line segments and arcs at the positions of the femoral head contour line and the two femoral neck contour lines of the femoral contour line;

[0053] Identify the contour lines in each region of interest to generate the fitting curves of the femoral head contour line and the two femoral neck contour lines;

[0054] Automatically generate a fitting circle of the femoral head according to the fitting curve of the femoral contour line at the femoral head;

[0055] Select the line segment connecting the two points with the shortest distance between the fitting curves of the two femoral contour lines at the femoral neck as the femoral neck feature line.

[0056] According to the specific embodiments provided by the present invention, the following technical effects are disclosed: An image registration system and method for femoral surgery provided by the present invention include: a projection module, a preprocessing module, and a registration module; the projection module is used to perform DRR projections of a three-dimensional femoral CT image at different angles to obtain several two-dimensional DRR projection images; the preprocessing module is used to preprocess the femoral images in each two-dimensional DRR projection image and each two-dimensional X-ray image to generate a femoral coordinate system and femoral feature points; the two-dimensional X-ray images include multiple X-ray planar images taken of the femoral part at different angles; the registration module is used to determine, according to the femoral coordinate system and femoral feature points of the two-dimensional DRR projection images and the two-dimensional X-ray images, the two-dimensional DRR projection image with the same femoral pose as that in the two-dimensional X-ray image from several two-dimensional DRR projection images to obtain multiple target DRR projection images. Before the surgery, the present invention performs DRR projections of the three-dimensional femoral CT image at various angles, generates and selects the femoral coordinate system and femoral feature points on the two-dimensional DRR projection images and the two-dimensional X-ray images respectively, and registers the two-dimensional DRR projection images and the two-dimensional X-ray images according to the femoral coordinate system and femoral feature points, improving the accuracy of image registration, accurately obtaining the two-dimensional DRR projection image with the same femoral pose as that during the two-dimensional X-ray image scanning, and thus being able to obtain a real surgical path for surgical navigation, ensuring the accuracy of surgical assistant navigation, and further improving the surgical quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the following described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0058] Figure 1 It is a structural block diagram of an image registration system for femoral surgery provided by the present invention;

[0059] Figure 2 It is a structural block diagram of a femoral feature line selection unit in the image registration system provided by the present invention;

[0060] Figure 3 It is a flowchart of an image registration method for femoral surgery provided by the present invention;

[0061] Figure 4 It is a specific flowchart of step S2 in the image registration method provided by the present invention;

[0062] Figure 5 It is a specific flowchart of step S26 in the image registration method provided by the present invention;

[0063] Figure 6 The three-dimensional femoral CT image reconstructed in the image registration method provided by the present invention;

[0064] Figure 7 The schematic diagram of the femoral contour line generated for the two-dimensional DRR projection image in the image registration method provided by the present invention;

[0065] Figure 8 The schematic diagram of the femoral feature points generated for the two-dimensional DRR projection image in the image registration method provided by the present invention;

[0066] Figure 9 The two-dimensional X-ray image scanned in the image registration method provided by the present invention;

[0067] Figure 10 The schematic diagram of the femoral contour line generated for the two-dimensional X-ray image in the image registration method provided by the present invention;

[0068] Figure 11 The schematic diagram of the femoral feature points generated for the two-dimensional X-ray image in the image registration method provided by the present invention.

[0069] In the figure: 1: Projection module; 2: Preprocessing module; 3: Registration module; 21: Femoral contour line generation unit; 22: Femoral head fitting unit; 23: Femoral neck feature line selection unit; 24: Femoral coordinate system establishment unit; 25: Femoral feature circle generation unit; 26: Femoral feature line selection unit; 27: Femoral feature point selection unit; 28: Region of interest selection unit; 261: First femoral feature line selection sub-unit; 262: Second femoral feature line selection sub-unit; 263: Third femoral feature line selection sub-unit; 264: Fourth femoral feature line selection sub-unit; 265: Fifth femoral feature line selection sub-unit; 31: Femoral coordinate system coincidence unit; 32: Femoral feature point registration unit. Detailed implementation manners

[0070] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0071] The purpose of the present invention is to provide an image registration system and method for femoral surgery, which improves the accuracy of image registration, can ensure the accuracy of surgical assisted navigation, and thus improves the surgical quality.

[0072] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0073] Embodiment 1:

[0074] The present invention provides an image registration system for femoral surgery. As Figures 1 - 2 shown, the image registration system for femoral surgery of the present invention includes: a projection module 1, a preprocessing module 2, and a registration module 3;

[0075] The projection module 1 is configured to perform DRR projections of a three-dimensional femoral CT image at different angles to obtain a plurality of two-dimensional DRR projection images;

[0076] The preprocessing module 2 is configured to preprocess the femoral images in each two-dimensional DRR projection image and each two-dimensional X-ray image to generate a femoral coordinate system and femoral feature points; the two-dimensional X-ray images include a plurality of X-ray planar images taken of the femoral part at different angles;

[0077] The registration module 3 is configured to determine, according to the femoral coordinate system and femoral feature points of the two-dimensional DRR projection image and the two-dimensional X-ray image, a two-dimensional DRR projection image having the same femoral pose as that in the two-dimensional X-ray image from the plurality of two-dimensional DRR projection images to obtain a plurality of target DRR projection images.

[0078] The femur includes a femoral head, a femoral neck, and a femoral shaft. In this embodiment, the preprocessing module 2 includes a femoral contour line generation unit 21, a femoral head fitting unit 22, a femoral neck feature line selection unit 23, a femoral coordinate system establishment unit 24, a femoral feature circle generation unit 25, a femoral feature line selection unit 26, and a femoral feature point selection unit 27;

[0079] The femoral contour line generation unit 21 is configured to automatically extract the outer contour of the femur to obtain a femoral contour line;

[0080] The femoral head fitting unit 22 is configured to fit the femoral head into a circle to obtain a femoral head fitting circle;

[0081] The femoral neck feature line selection unit 23 is configured to select a line connecting two points with the shortest distance between two femoral contour lines at the femoral neck as the femoral neck feature line;

[0082] The femoral coordinate system establishment unit 24 is configured to establish a femoral coordinate system with the line connecting the center of the femoral head fitting circle and the midpoint of the femoral neck feature line as one coordinate axis of the femoral coordinate system;

[0083] The femoral feature circle generation unit 25 is configured to select two points on the extension line of the line connecting the center of the femoral head fitting circle and the midpoint of the femoral neck feature line as the centers with the radius of the femoral head fitting circle as the radius, and respectively generate a first feature circle and a second feature circle; the first feature circle is tangent to the femoral head fitting circle, and the center of the first feature circle is on the edge line of the second feature circle;

[0084] The femoral feature line selection unit 26 is configured to select multiple femoral feature lines perpendicular to the line connecting the center of the fitted circle of the femoral head and the midpoint of the femoral neck feature line;

[0085] The femoral feature point selection unit 27 is configured to take the intersection points of each femoral feature line and the femoral contour line as femoral feature points.

[0086] In this embodiment, the femoral feature line selection unit 26 includes: a first femoral feature line selection subunit 261, a second femoral feature line selection subunit 262, a third femoral feature line selection subunit 263, a fourth femoral feature line selection subunit 264, and a fifth femoral feature line selection subunit 265;

[0087] The first femoral feature line selection subunit 261 is configured to select the first femoral feature line; the first femoral feature line is a line segment passing through the tangent point of the fitted circle of the femoral head and the first feature circle;

[0088] The second femoral feature line selection subunit 262 is configured to select the second femoral feature line; the second femoral feature line is a line segment passing through the center of the first feature circle;

[0089] The third femoral feature line selection subunit 263 is configured to select the third femoral feature line; the third femoral feature line is a line segment passing through the center of the second feature circle;

[0090] The fourth femoral feature line selection subunit 264 is configured to select the fourth femoral feature line; the fourth femoral feature line is a line segment parallel to the second femoral feature line and tangent to the second feature circle;

[0091] The fifth femoral feature line selection subunit 265 is configured to select the fifth femoral feature line; the fifth femoral feature line is a line segment passing through the midpoint of the extension line of the line connecting the center of the fitted circle of the femoral head and the midpoint of the femoral neck feature line and the intersection point of the third femoral feature line and the fourth femoral feature line.

[0092] Specifically in this embodiment, the registration module 3 includes: a femoral coordinate system coincidence unit 31 and a femoral feature point registration unit 32;

[0093] The femoral coordinate system coincidence unit 31 is configured to coincide the femoral coordinate systems of the two-dimensional DRR projection image and the two-dimensional X-ray image;

[0094] The femoral feature point registration unit 32 is configured to match the positions of the femoral feature points of the two-dimensional DRR projection image and the two-dimensional X-ray image one by one.

[0095] In order to reduce the computational amount, in this embodiment, the preprocessing module 2 further includes: a region of interest selection unit 28;

[0096] The region of interest selection unit 28 is configured to select a region of interest composed of line segments and arcs at the positions of the femoral head contour line and the two femoral neck contour lines of the femoral contour line. The selection template composed of line segments and arcs is used to select the region of interest at the femoral head and femoral neck, so that it is not necessary to perform contour recognition on the entire X-ray film, thereby achieving the effect of reducing the calculation amount.

[0097] Embodiment 2:

[0098] Corresponding to the image registration system for femoral surgery in Embodiment 1, the present invention also provides an image registration method for femoral surgery, as Figure 3 shown, the image registration method includes the following steps:

[0099] S1. Perform DRR projections of the three-dimensional femoral CT image at different angles to obtain a plurality of two-dimensional DRR projection images;

[0100] S2. Preprocess the femoral images in each two-dimensional DRR projection image and each two-dimensional X-ray image to generate a femoral coordinate system and femoral feature points; the two-dimensional X-ray images include a plurality of X-ray planar images taken of the femoral part at different angles;

[0101] S3. According to the femoral coordinate system and femoral feature points of the two-dimensional DRR projection image and the two-dimensional X-ray image, determine the two-dimensional DRR projection image with the same femoral pose as that in the two-dimensional X-ray image from the plurality of two-dimensional DRR projection images to obtain a plurality of target DRR projection images. Step S3 specifically includes:

[0102] S31. Coincide the femoral coordinate systems of the two-dimensional DRR projection image and the two-dimensional X-ray image;

[0103] S32. Match the positions of the femoral feature points of the two-dimensional DRR projection image and the two-dimensional X-ray image one by one.

[0104] The femur includes the femoral head, femoral neck and femoral shaft, and only a part of the femoral shaft can be shown by CT or X-ray film. In order to perform accurate registration between the CT image and the X-ray image, in this embodiment, as Figure 4 shown, step S2 specifically includes:

[0105] S21. Automatically extract the outer contour of the femur to obtain the femoral contour line;

[0106] S22. Fit the femoral head into a circle to obtain the femoral head fitting circle;

[0107] S23. Select the line connecting the two points with the shortest distance between the two femoral contour lines at the femoral neck as the femoral neck feature line;

[0108] S24. Take the line connecting the center of the fitted circle of the femoral head and the midpoint of the femoral neck feature line as one coordinate axis of the femoral coordinate system, and establish the femoral coordinate system;

[0109] S25. With the radius of the fitted circle of the femoral head as the radius, select two points on the extension line of the line connecting the center of the fitted circle of the femoral head and the midpoint of the femoral neck feature line as the centers, and generate the first feature circle and the second feature circle respectively; the first feature circle is tangent to the fitted circle of the femoral head, and the center of the first feature circle is on the edge line of the second feature circle;

[0110] S26. Generate multiple femoral feature lines perpendicular to the line connecting the center of the fitted circle of the femoral head and the midpoint of the femoral neck feature line;

[0111] S27. Take the intersection points of each femoral feature line and the femoral contour line as femoral feature points.

[0112] Regarding the selection rules of each femoral feature line, in this embodiment, as Figure 5 shown, step S26 specifically includes:

[0113] S261. Select the line segment passing through the tangent point of the fitted circle of the femoral head and the first feature circle as the first femoral feature line;

[0114] S262. Select the line segment passing through the center of the first feature circle as the second femoral feature line;

[0115] S263. Select the line segment passing through the center of the second feature circle as the third femoral feature line;

[0116] S264. Select the line segment parallel to the second femoral feature line and tangent to the second feature circle as the fourth femoral feature line;

[0117] S265. Select the line segment passing through the midpoint of the line connecting the intersection points of the extension line of the line connecting the center of the fitted circle of the femoral head and the midpoint of the femoral neck feature line with the third femoral feature line and the fourth femoral feature line as the fifth femoral feature line.

[0118] To reduce the computational amount, the image registration method of this embodiment further includes:

[0119] A1. Select a region of interest composed of line segments and arcs at the positions of the femoral head contour line and two femoral neck contour lines of the femoral contour line; the selection template composed of line segments and arcs is used to select the region of interest at the femoral head and femoral neck, so that it is not necessary to perform contour recognition on the entire X-ray film, thereby achieving the effect of reducing the computational amount.

[0120] A2. Identify the contour lines in each region of interest and generate the fitted curves of the femoral head contour line and two femoral neck contour lines.

[0121] A3. Automatically generate the fitted circle of the femoral head according to the fitted curve of the femoral contour line at the femoral head.

[0122] A4. Between the fitting curves of the two femoral contour lines at the femoral neck, select the two points with the shortest distance to connect as the femoral neck feature line.

[0123] The following combines a specific example to further elaborate on the image registration method for femoral surgery provided by the present invention, including the following steps:

[0124] 1) Before the surgery starts, obtain the patient's femoral image data through a CT imaging device, and process and reconstruct to generate a three-dimensional femoral CT image, such as Figure 6 , and plan the surgical path on it.

[0125] 2) Perform multiple projections on the three-dimensional femoral CT image in the Z direction of the lateral single view according to the surgical requirements, such as Figure 7 As shown on the left, O is the center of the fitting circle of the femoral head. OY passes through the femoral neck feature line and intersects the central axis of the femoral shaft at O1. OZ is perpendicular to OY and lies in the OO1Y1 plane. The OX axis conforms to the right-hand rule.

[0126] 3) Rotate around the X and Y axes at intervals of a preset rotation angle. Both α and β are in the range of 1° - 2°. Generate multiple DRR images from the Z-axis projection, and obtain the corresponding pose parameters P = (θ x , θ y , θ z , P x , P y , P <s z ), θ x , θ y , θ z respectively represent the rotation angles in the reference coordinate system, and P x , P y , P z respectively represent the translation amounts along the three main axes in the reference coordinate system; similarly, perform multiple projections in the X direction of the anterior single view, such as Figure 7 As shown on the right, obtain multiple two-dimensional DRR projection images.

[0127] 4) Process each two-dimensional DRR projection image, such as Figure 8 , automatically extract the femoral contour line, automatically generate the fitting circle of the femoral head, with the center O2. O3 is the midpoint of the femoral neck feature line. Make the first feature circle O4 and the second feature circle O5 on the extension line of O2O3. Select five femoral feature lines to intersect the femoral contour line at femoral feature points A1, A2, A3, A4, A5, A6, A7, A8, A9, and A10.

[0128] 5) When the patient lies on the operating table for surgery, obtain two-dimensional X-ray images taken by the C-arm X-ray machine at different angles, such as Figure 9, the shooting angle between the two two-dimensional images is 90°, Figure 9 As shown on the left is the anteroposterior X-ray image, that is, the X-ray taken vertically when the patient lies flat, Figure 9 As shown on the right is the lateral X-ray image, that is, the X-ray taken horizontally when the patient lies flat.

[0129] 6) As Figure 10 shown, taking the anteroposterior X-ray image as an example, in the femoral head area, the region of interest C1 is delimited to automatically generate the fitted circle C2 of the femoral head, or three points are manually selected within the region C1 to generate the fitted circle C2 of the femoral head, and the center is O6. Manually select the regions of interest C3 and C5 of the femoral neck, automatically generate the fitted curves C4 and C6 of the outer contour of the femoral neck, manually select the two fitted curves at the narrowest part of the femoral neck, calculate the minimum distance between the two fitted curves, or manually select two points at the visually estimated narrowest part of the femoral neck, take the minimum distance as the characteristic line of the femoral neck, and generate the minimum circle C7 of the femoral neck with the characteristic line of the femoral neck as the diameter, and the center is O7. Refer to the operation steps 4), automatically generate the femoral coordinate system, femoral characteristic circle, femoral characteristic line and femoral characteristic points for the two-dimensional X-ray image, as Figure 11 .

[0130] 7) Automatically register each anteroposterior two-dimensional DRR projection of the femur with the anteroposterior two-dimensional X-ray image, overlap the femoral coordinate systems of the two-dimensional DRR projection image and the two-dimensional X-ray image, calculate the distances of all corresponding femoral characteristic points, and perform the similarity comparison of the characteristic points. If there is a match between the two-dimensional DRR projection image and the two-dimensional X-ray image within the error range, obtain the projection pose parameters of the two-dimensional DRR projection image. If there is more than one set of registration results, select the set with the minimum error to complete the registration of the three-dimensional femoral CT image of the femur and the two-dimensional X-ray image.

[0131] 8) According to the projection pose parameters of the two-dimensional DRR projection image and the surgical planning path information, use the biplane method to output the accurately registered surgical path.

[0132] In this article, specific examples are used to elaborate on the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. An image registration system for femoral surgery, wherein the femur includes a femoral head, a femoral neck, and a femoral shaft, characterized in that, The image registration system includes: a projection module, a preprocessing module, and a registration module; The projection module is configured to perform DRR projections of the three-dimensional femoral CT image at different angles to obtain a plurality of two-dimensional DRR projection images; The preprocessing module is configured to preprocess the femoral images in each two-dimensional DRR projection image and each two-dimensional X-ray image to generate a femoral coordinate system and femoral feature points; the two-dimensional X-ray images include a plurality of X-ray planar images taken of the femoral region at different angles; the preprocessing module includes a femoral contour line generation unit, a femoral head fitting unit, a femoral neck feature line selection unit, a femoral coordinate system establishment unit, a femoral feature circle generation unit, a femoral feature line selection unit, and a femoral feature point selection unit; The femoral contour line generation unit is configured to automatically extract the outer contour of the femur to obtain a femoral contour line; The femoral head fitting unit is configured to fit the femoral head into a circle to obtain a femoral head fitting circle; The femoral neck feature line selection unit is configured to select the line connecting the two points with the shortest distance between the two femoral contour lines at the femoral neck as the femoral neck feature line; The femoral coordinate system establishment unit is configured to establish a femoral coordinate system with the line connecting the center of the femoral head fitting circle and the midpoint of the femoral neck feature line as one coordinate axis of the femoral coordinate system; The femoral feature circle generation unit is configured to select two points on the extension line of the line connecting the center of the femoral head fitting circle and the midpoint of the femoral neck feature line as the centers of circles, and respectively generate a first feature circle and a second feature circle with the radius of the femoral head fitting circle; the first feature circle is tangent to the femoral head fitting circle, and the center of the first feature circle is on the edge line of the second feature circle; The femoral feature line selection unit is configured to select a plurality of femoral feature lines perpendicular to the line connecting the center of the femoral head fitting circle and the midpoint of the femoral neck feature line; The femoral feature point selection unit is configured to take the intersection points of each femoral feature line and the femoral contour line as femoral feature points; The registration module is configured to determine, according to the femoral coordinate system and femoral feature points of the two-dimensional DRR projection image and the two-dimensional X-ray image, a two-dimensional DRR projection image with the same femoral pose as that in the two-dimensional X-ray image from the plurality of two-dimensional DRR projection images to obtain a plurality of target DRR projection images.

2. The image registration system according to claim 1, wherein The femoral feature line selection unit includes: a first femoral feature line selection subunit, a second femoral feature line selection subunit, a third femoral feature line selection subunit, a fourth femoral feature line selection subunit, and a fifth femoral feature line selection subunit; The first femoral feature line selection subunit is configured to select a first femoral feature line; the first femoral feature line is a line segment passing through the tangent point of the femoral head fitting circle and the first feature circle; The second femoral feature line selection subunit is configured to select a second femoral feature line; the second femoral feature line is a line segment passing through the center of the first feature circle; The third femoral feature line selection subunit is configured to select a third femoral feature line; the third femoral feature line is a line segment passing through the center of the second feature circle; The fourth femoral feature line selection subunit is used to select the fourth femoral feature line; the fourth femoral feature line is a line segment parallel to the second femoral feature line and tangent to the second feature circle. The fifth femoral feature line selection subunit is used to select the fifth femoral feature line; the fifth femoral feature line is a line segment passing through the midpoint of the extension line of the connection between the center of the fitted circle of the femoral head and the midpoint of the femoral neck feature line and the midpoint of the connection between the intersection points of the third femoral feature line and the fourth femoral feature line.

3. The image registration system according to claim 2, wherein The registration module includes: a femoral coordinate system coincidence unit and a femoral feature point registration unit. The femoral coordinate system coincidence unit is used to make the femoral coordinate systems of the two-dimensional DRR projection image and the two-dimensional X-ray image coincide. The femoral feature point registration unit is used to match the positions of the femoral feature points of the two-dimensional DRR projection image and the two-dimensional X-ray image one by one.

4. The image registration system according to claim 1, wherein The preprocessing module further includes: a region of interest selection unit. The region of interest selection unit is used to select a region of interest composed of line segments and arcs at the positions of the femoral head contour line and the two femoral neck contour lines of the femoral contour line respectively.

5. An image registration method for femoral surgery, wherein the femur includes a femoral head, a femoral neck, and a femoral shaft, characterized in that, The image registration method includes the following steps: Performing DRR projections of the three-dimensional femoral CT image at different angles to obtain a plurality of two-dimensional DRR projection images. Preprocessing the femoral images in each two-dimensional DRR projection image and each two-dimensional X-ray image to generate a femoral coordinate system and femoral feature points; the two-dimensional X-ray images include a plurality of X-ray planar images taken of the femoral part at different angles. According to the femoral coordinate system and femoral feature points of the two-dimensional DRR projection image and the two-dimensional X-ray image, determining the two-dimensional DRR projection image with the same femoral pose as that in the two-dimensional X-ray image from the plurality of two-dimensional DRR projection images to obtain a plurality of target DRR projection images. Preprocessing the femoral images in each two-dimensional DRR projection image and each two-dimensional X-ray image to generate a femoral coordinate system and femoral feature points, specifically including: Automatically extracting the outer contour of the femur to obtain the femoral contour line. Fitting the femoral head into a circle to obtain the fitted circle of the femoral head. Selecting the line segment connecting the two points with the shortest distance between the two femoral contour lines at the femoral neck as the femoral neck feature line. Taking the connection line between the center of the fitted circle of the femoral head and the midpoint of the femoral neck feature line as one coordinate axis of the femoral coordinate system to establish the femoral coordinate system. Taking the radius of the fitted circle of the femoral head as the radius, selecting two points on the extension line of the connection line between the center of the fitted circle of the femoral head and the midpoint of the femoral neck feature line as the centers respectively to generate a first feature circle and a second feature circle; the first feature circle is tangent to the fitted circle of the femoral head, and the center of the first feature circle is on the edge line of the second feature circle. Generating a plurality of femoral feature lines perpendicular to the connection line between the center of the fitted circle of the femoral head and the midpoint of the femoral neck feature line. Taking the intersection points of each femoral feature line and the femoral contour line as femoral feature points.

6. The image registration method according to claim 5, wherein The generating a plurality of femoral feature lines perpendicular to the connection line between the center of the fitted circle of the femoral head and the midpoint of the femoral neck feature line specifically includes: Selecting the line segment passing through the tangent point of the fitted circle of the femoral head and the first feature circle as the first femoral feature line. Select the line segment passing through the center of the first characteristic circle as the second femoral characteristic line; Select the line segment passing through the center of the second characteristic circle as the third femoral characteristic line; Select the line segment parallel to the second femoral characteristic line and tangent to the second characteristic circle as the fourth femoral characteristic line; Select the line segment passing through the midpoint of the extension line connecting the center of the fitted circle of the femoral head and the midpoint of the femoral neck characteristic line and the midpoint of the line connecting the intersection points of the third femoral characteristic line and the fourth femoral characteristic line as the fifth femoral characteristic line.

7. The image registration method according to claim 5, wherein Determine the 2D DRR projection image with the same femoral pose as the 2D X-ray image from the several 2D DRR projection images according to the femoral coordinate system and femoral characteristic points of the 2D DRR projection image and the 2D X-ray image, and obtain multiple target DRR projection images, specifically including: Coincide the femoral coordinate systems of the 2D DRR projection image and the 2D X-ray image; Match the positions of the femoral characteristic points of the 2D DRR projection image and the 2D X-ray image one by one.

8. The image registration method according to claim 5, characterized in that, The image registration method further includes: Select a region of interest composed of line segments and arcs at the positions of the femoral head contour line and the two femoral neck contour lines of the femoral contour line; Identify the contour lines in each of the regions of interest to generate the fitted curves of the femoral head contour line and the two femoral neck contour lines; Automatically generate a fitted circle of the femoral head according to the fitted curve of the femoral contour line at the femoral head; Select the line connecting the two points with the shortest distance between the fitted curves of the two femoral contour lines at the femoral neck as the femoral neck characteristic line.

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