System and method for extracting cross section of three-dimensional segmented femur

Abstract

A system for extracting the cross section of a three-dimensional segmented femur. A method for extracting the cross section of a three-dimensional segmented femur comprises: acquiring any 0-degree plane passing through an original femoral long axis, and rotating the 0-degree plane by a preset rotation angle around a vector where the original femoral long axis is located, so as to obtain a rotation plane corresponding to the 0-degree plane and use same as a femoral cross section; synchronously rotating an original three-dimensional image and the femoral cross section, such that the rotated femoral cross section is perpendicular to a coordinate axis of a three-dimensional coordinate system, and acquiring coordinate values of when the femoral cross section is perpendicular to the coordinate axis, and using same as cross-section index values; and in the three-dimensional coordinate system, extracting slice data at the positions of the cross-section index values on the coordinate axis perpendicular to the femoral cross section, wherein the slice data is cross-section data after performing rotation by the preset rotation angle in the 0-degree plane. A 0-degree point which together with two femoral long-axis points defines a 0-degree plane can be customized, a cross section which is obtained by means of rotating by any angle on the basis of the 0-degree plane can be acquired, and numerical data of the cross section can be obtained for subsequent calculation of various parameters.

Description

A system and method for cutting three-dimensional segmented femoral sections Technical Field

[0001] This invention relates to the field of medical image processing technology, and in particular to a system and method for extracting a three-dimensional segmented femoral cross section. Specifically, it involves extracting a three-dimensional segmented femoral cross section by rotating the axis at any angle on a specified 0-degree plane passing through the long axis of the femur. Background Technology

[0002] In image-guided minimally invasive hip surgery, after segmenting the femur, it is usually necessary to plan the area to be removed. This involves measuring various parameters, such as the α angle and eccentricity, to plan the removal area. Since different surgical procedures require different locations to be planned, it is necessary to extract certain sections of the femur along its long axis for processing. That is, based on the 0-degree point specified in the preoperative planning requirements and the two endpoints of the femoral long axis, a 0-degree plane is formed. Based on the 0-degree plane and the femoral long axis as the axis of rotation, the cross-sections after rotating the 0-degree plane by certain angles are obtained, and these cross-sections are used to calculate parameters.

[0003] However, for three-dimensional volumetric data, current methods can only slice the femur using three coordinate axes, and cannot extract the femur cross-section based on arbitrary plane rotation and angle to obtain its data. Therefore, a system is needed to extract a three-dimensional segmented femur cross-section at any rotation angle from a specified 0-degree plane passing through the femur's long axis. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a system and method for extracting three-dimensional segmented femoral cross-sections. This system can define a 0-degree point on the 0-degree plane using two femoral long axis points and can obtain cross-sections that can be rotated at any angle based on the 0-degree plane, and obtain their numerical data for subsequent parameter calculations. This expands the extraction methods of different cross-sectional data from three-dimensional volume data, increases the degree of freedom in preoperative planning, and features novel and direct algorithmic ideas that are easy for programmers to implement.

[0005] The above-mentioned objective of this invention is achieved through the following technical solutions:

[0006] A system for cutting three-dimensional segmented femoral sections, comprising:

[0007] The memory stores the original three-dimensional image containing femoral tissue that needs to be cut into a three-dimensional segmented femoral cross section, as well as the cut cross section data.

[0008] An image acquisition device for acquiring the original three-dimensional image including the femoral tissue before image-guided minimally invasive hip surgery;

[0009] A processor, configured to extract cross-sectional data of the femoral tissue from the preoperatively acquired original three-dimensional image of the femoral tissue during the image-guided minimally invasive hip surgery, through the original femoral long axis, and to extract the cross-sectional data of the femoral tissue using the following modules:

[0010] The femoral section calculation module is used to obtain any 0-degree plane passing through the original femoral long axis, and rotate the 0-degree plane around the vector of the original femoral long axis by a preset rotation angle to obtain a rotation plane corresponding to the 0-degree plane. The rotation plane is used as the femoral section to be cut.

[0011] A three-dimensional image rotation module is used to synchronously rotate the original three-dimensional image and the femoral cross section, so that the rotated femoral cross section is perpendicular to any coordinate axis of the three-dimensional coordinate system, and to obtain the coordinate value of the femoral cross section when it is perpendicular to the coordinate axis as the cross section index value;

[0012] The cross-section data acquisition module is used to acquire slice data at the cross-section index value position on the coordinate axis perpendicular to the femoral cross-section in the three-dimensional coordinate system. The slice data is the cross-section data after rotating by the preset rotation angle below the 0-degree plane.

[0013] Further, in the femoral section calculation module, any 0-degree plane passing through the original femoral long axis is obtained, and the 0-degree plane is rotated around the vector of the original femoral long axis by a preset rotation angle to obtain the rotation plane corresponding to the 0-degree plane. The rotation plane serves as the femoral section to be cut, specifically:

[0014] The original femoral long axis was determined using surface reconstruction and fitting techniques.

[0015] Arbitrarily specify a 0-degree point that is not on the original femoral long axis, and combine it with two points on the original femoral long axis, including the first long axis endpoint and the second long axis endpoint. Based on the principle of determining a plane by three points that are not on a straight line, the 0-degree plane is determined by the 0-degree point, the first long axis endpoint, and the second long axis endpoint.

[0016] The vector of the original femoral long axis pointing to the second long axis endpoint is calculated using the first long axis endpoint and the second long axis endpoint.

[0017] The 0-degree point is obtained by rotating it around the vector containing the original femoral long axis by the preset rotation angle.

[0018] Based on the principle that three points not on a straight line determine a plane, the rotation plane, i.e. the femoral section, is determined by the rotation point, the first major axis endpoint, and the second major axis endpoint.

[0019] Furthermore, in the femoral section calculation module, the original femoral long axis is determined using surface reconstruction and fitting techniques, specifically as follows:

[0020] The femur is segmented from the original three-dimensional image using image segmentation techniques, including threshold segmentation or edge detection, to obtain the three-dimensional region of the femur;

[0021] The three-dimensional region of the femur is reconstructed using surface reconstruction algorithms, including those based on point clouds or voxels, and represented as a continuous three-dimensional femoral surface.

[0022] The three-dimensional femoral surface is fitted using methods including linear fitting or ellipsoidal fitting to obtain the principal axis direction of the femur, i.e., the original femoral long axis.

[0023] The linear fitting involves using a fitting algorithm, including the least squares method, to fit points on the three-dimensional femoral surface to find the best-fitting straight line, which is the direction of the original femoral long axis. The ellipsoid fitting involves fitting an ellipsoid to represent the shape of the femur, and the long axis of the ellipsoid is the original femoral long axis.

[0024] Furthermore, in the femoral section calculation module, the rotation point is obtained by rotating the 0-degree point around the vector containing the original femoral long axis by the preset rotation angle, specifically as follows:

[0025] Assume the vector containing the original femoral long axis is (n x ,n y ,n z The original femoral long axis passes through the point (x0, y0, z0), and the preset rotation angle is α;

[0026] Let K = 1 - cosα, M = n x x0+n y y0+n z If z0, then the rotation matrix is:

[0027] The formula for calculating the coordinates of the rotation point is:

[0028] (x,y,z) new =(x,y,z,1) old ×Rotationrandom_axis

[0029] Where (x,y,z,1) old Let (x, y, z) be the coordinates of the 0-degree point. new Let be the coordinates of the rotation point.

[0030] Furthermore, the three-dimensional image rotation module further includes: taking the y-axis as the coordinate axis perpendicular to the three-dimensional coordinate system after synchronously rotating the original three-dimensional image and the femoral cross-section, specifically:

[0031] Obtain the xoy plane vector of the original femoral long axis vector on the xoy plane, and the x-axis unit vector in the x-axis direction on the xoy plane. Calculate the angle between the xoy plane vector and the x-axis unit vector, and denote it as the xoy plane angle.

[0032] The original three-dimensional image and the femoral cross section are rotated around the z-axis by an angle equal to the angle between the xoy plane and the first major axis endpoint, respectively, to obtain a first rotated three-dimensional image and a first rotated femoral cross section. At this time, the femoral major axis of the first rotated three-dimensional image is perpendicular to the y-axis.

[0033] The angle between the first rotating femoral section and the xoz plane is calculated using the normal vector of the first rotating femoral section and the normal vector of the xoz plane pointing in the negative y-axis direction, and is denoted as the xoz plane angle.

[0034] The first rotated 3D image and the first rotated femoral cross section are rotated around their own femoral long axis through the endpoint of the first long axis by the angle of the xoz plane to obtain a second rotated 3D image and a second rotated femoral cross section. At this time, the second rotated femoral cross section is perpendicular to the y-axis, and the y-coordinate values ​​of the rotation point, the endpoint of the first long axis, and the endpoint of the second long axis are equal. The value of the y-coordinate is the cross section index value of the second rotated femoral cross section on the y-coordinate.

[0035] Further, in the three-dimensional image rotation module, the angle between the xoy plane vector and the x-axis unit vector is calculated and denoted as the xoy plane angle, specifically as follows:

[0036] Wherein, α is the angle between the xoy plane vector and the x-axis unit vector. Let xoy be the vector in the plane. Let x be the unit vector of the x-axis.

[0037] Furthermore, in the three-dimensional image rotation module, when rotating the original three-dimensional image and the femoral cross-section around the z-axis by the angle of the xoy plane through the first major axis endpoint, the module further includes:

[0038] Take the cross product of the xoy plane vector and the x-axis unit vector to calculate the angle between the xoy planes. When the cross product is less than 0, the rotation angle is the opposite of the angle between the xoy planes.

[0039] Furthermore, in the three-dimensional image rotation module, the angle by which the first rotated three-dimensional image and the first rotated femoral section are rotated around their own femoral long axis through the endpoint of the first long axis, by the angle of the xoz plane, further includes:

[0040] The cross product is taken between the normal vector of the first rotated femoral section used to calculate the angle of the xoz plane and the normal vector of the xoz plane pointing in the negative y-axis direction. When the cross product is less than 0, the rotation angle is the opposite of the angle of the xoz plane.

[0041] A method for cutting a three-dimensional segmented femoral section using the system described above, comprising:

[0042] S1: Obtain any 0-degree plane passing through the original femoral long axis, and rotate the 0-degree plane around the vector of the original femoral long axis by a preset rotation angle to obtain a rotation plane corresponding to the 0-degree plane. The rotation plane is used as the femoral section to be cut.

[0043] S2: Simultaneously rotate the original three-dimensional image and the femoral cross section so that the rotated femoral cross section is perpendicular to any coordinate axis of the three-dimensional coordinate system, and obtain the coordinate value of the femoral cross section when it is perpendicular to the coordinate axis as the cross section index value;

[0044] S3: In the three-dimensional coordinate system, take slice data at the position of the cross-section index value on the coordinate axis perpendicular to the femoral cross-section. The slice data is the cross-section data after rotating by the preset rotation angle below the 0-degree plane.

[0045] A computer device includes a memory and one or more processors, the memory storing computer code that, when executed by the one or more processors, causes the one or more processors to perform the method described above.

[0046] A computer-readable storage medium storing computer code that, when executed, performs the method described above.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] A system for extracting three-dimensional segmented femoral cross-sections is provided, comprising: a memory storing an original three-dimensional image of the femoral tissue to be extracted, and the extracted cross-sectional data; an image acquisition device for acquiring the original three-dimensional image of the femoral tissue before image-guided minimally invasive hip surgery; and a processor for extracting the cross-sectional data of the femoral tissue from the pre-acquired original three-dimensional image of the femoral tissue during the image-guided minimally invasive hip surgery, and for extracting the cross-sectional data of the femoral tissue through the original femoral long axis using the following module: a femoral cross-section calculation module for acquiring any cross-sectional data through the original femoral long axis. A 0-degree plane is defined, and this 0-degree plane is rotated around the vector containing the original femoral long axis by a preset rotation angle to obtain a rotation plane corresponding to the 0-degree plane. This rotation plane serves as the femoral cross-section to be extracted. A 3D image rotation module is used to synchronously rotate the original 3D image and the femoral cross-section, so that the rotated femoral cross-section is perpendicular to any coordinate axis of the 3D coordinate system, and obtains the coordinate value of the femoral cross-section when it is perpendicular to the coordinate axis as the cross-section index value. A cross-section data acquisition module is used to extract slice data at the cross-section index value position on the coordinate axis perpendicular to the femoral cross-section in the 3D coordinate system. The slice data is the cross-section data after rotating by the preset rotation angle under the 0-degree plane. The above technical solution expands the method of extracting slices from 3D CT images that can only be done with 3 coordinate axes. In particular, the method of obtaining cross-sections with arbitrary rotation angles based on arbitrarily specified 0-degree planes solves the problem of calculating parameters for femoral segmentation under different custom angle ranges. It also has great reference value for obtaining cross-sections of other 3D CT images to handle other different problems. Attached Figure Description

[0049] Figure 1 is an overall structural diagram of the method for cutting a three-dimensional segmented femoral section according to the present invention;

[0050] Figure 2 is a flowchart of the algorithm for the method of extracting three-dimensional segmented femoral cross-sections according to the present invention;

[0051] Figure 3 is a schematic diagram of the rotational surface result after rotating the 0-degree plane around the long axis of the femur according to the present invention.

[0052] Figure 4 is a schematic diagram of the original three-dimensional image of the present invention after being rotated around the z-axis with the direction pointing in the positive direction and passing through the major axis point;

[0053] Figure 5 is a schematic diagram of the result of rotating the femoral cross section of the present invention around the z-axis, with the direction pointing in the positive direction, through the femoral long axis point, on the same rotated femoral image.

[0054] Figure 6 is a schematic diagram of the femur image used to obtain cross-sectional data after final rotation according to the present invention;

[0055] Figure 7 is a schematic diagram of the cross-sectional data obtained by the present invention;

[0056] Figure 8 is an overall flowchart of the method for cutting three-dimensional segmented femoral cross sections according to the present invention. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0058] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0059] The system for extracting three-dimensional segmented femoral sections disclosed in this invention is summarized as follows: A 0-degree plane is calculated based on an arbitrarily specified 0-degree point and the femoral long axis; a rotation plane is calculated based on an arbitrary rotation angle specified on the 0-degree plane; the angle (movement angle) between the original femoral long axis vector and the x-axis in the xoy plane is calculated; a moving image is obtained by rotating the original image around the z-axis by a movement angle, and a moving plane is obtained by rotating the rotating plane around the z-axis by a movement angle, simultaneously obtaining a new long axis; the angle (rotation angle) between the moving plane and the xoz plane is calculated; a rotated image is obtained by rotating the moving image around the new long axis by a size equal to the rotation angle, and a rotating plane is obtained by rotating the rotating plane around the new long axis by a size equal to the rotation angle, simultaneously obtaining the y-axis index of the long axis at this time; slices are extracted from the rotated image along the y-axis to obtain slice data.

[0060] The system of this invention extends the method of taking slices from three-dimensional CT images that can only be done with three coordinate axes. In particular, it is based on the arbitrary specified 0-degree plane to obtain cross sections with arbitrary rotation angles. This solves the problem of calculating parameters for femoral segmentation under different custom angle ranges. It also has great reference value for obtaining cross sections of other three-dimensional CT images to deal with other different problems.

[0061] First Embodiment

[0062] As shown in Figures 1 and 2, this embodiment provides a system for slicing a three-dimensional segmented femoral cross-section. In Figure 2, pt0 is an arbitrarily specified 0-degree point not on the original femoral long axis, pt1 is the endpoint of the first long axis, pt2 is the endpoint of the second long axis (center of the sphere), and angle_rotate is an arbitrarily specified preset rotation angle based on the 0-degree plane. pt0_rot is the unit vector in the positive x-axis direction on the xoy plane, pt0_rot is the 0-degree point of pt0 after rotating it based on the 0-degree plane by a preset rotation angle, and move_pi is the angle between the x-axis and the major axis vector (pointing to pt2) on the xoy plane. Let pt0_rz be the unit vector in the positive z-axis direction, pt1_rz be the point formed by rotating the first point of the plane of revolution around the z-axis by move_pi, pt2_rz be the point formed by rotating the second point of the plane of revolution around the z-axis by move_pi, and pt2_rz be the point formed by rotating the third point of the plane of revolution around the z-axis by move_pi. pt0_rz.y is the negative y-axis unit vector, bone_image is the original 3D image of the femur segmentation, moved_image is the first rotated 3D image after rotating around the z-axis by move_pi, angle_cross is the angle between the xoz plane and the plane after rotating the first osteotomy plane around the z-axis, rot_image is the second rotated image obtained by rotating moved_image around the new major axis, and pt0_rz.y is the y-axis coordinate of the first endpoint of the new major axis.

[0063] The system for cutting a three-dimensional segmented femoral section according to the present invention specifically includes:

[0064] The memory stores the original three-dimensional image containing femoral tissue that needs to be cut into a three-dimensional segmented femoral cross section, as well as the cut cross section data.

[0065] An image acquisition device for acquiring the original three-dimensional image including the femoral tissue before image-guided minimally invasive hip surgery;

[0066] A processor, configured to extract cross-sectional data of the femoral tissue from the preoperatively acquired original three-dimensional image of the femoral tissue during the image-guided minimally invasive hip surgery, through the original femoral long axis, and to extract the cross-sectional data of the femoral tissue using the following modules:

[0067] The femoral section calculation module is used to obtain any 0-degree plane passing through the original femoral long axis, and rotate the 0-degree plane around the vector containing the original femoral long axis by a preset rotation angle to obtain a rotation plane corresponding to the 0-degree plane. This rotation plane serves as the femoral section to be extracted. Specifically, the original femoral long axis is determined using surface reconstruction and fitting techniques. Specifically, image segmentation techniques, including thresholding or edge detection, are used to segment the femoral bone from the original three-dimensional image to obtain the three-dimensional region of the femoral bone. Surface reconstruction calculations, including those based on point clouds or voxels, are then performed. The method involves reconstructing the three-dimensional region of the femur into a continuous three-dimensional femoral surface. The three-dimensional femoral surface is then fitted using methods including linear fitting or ellipsoidal fitting to obtain the principal axis direction of the femur, i.e., the original femoral long axis. Linear fitting involves using a fitting algorithm, including least squares, to fit points on the three-dimensional femoral surface to find the best-fitting straight line, which represents the direction of the original femoral long axis. Ellipsoidal fitting involves fitting an ellipsoid to represent the shape of the femur, with the long axis of the ellipsoid representing the original femoral long axis.

[0068] Arbitrarily specify a 0-degree point p0 that is not on the original femoral long axis, and combine it with two points on the original femoral long axis, including the first long axis endpoint pt1 and the second long axis endpoint pt2. Based on the principle that three points that are not on a straight line determine a plane, the 0-degree plane zero_plane is determined by the 0-degree point p0, the first long axis endpoint pt1, and the second long axis endpoint pt2.

[0069] The vector org_changzhou, pointing to the original femoral long axis, is calculated using the first long axis endpoint pt1 and the second long axis endpoint pt2.

[0070] The 0-degree point pt0 is rotated around the vector org_changzhou containing the original femoral long axis by the preset rotation angle angle_rotate to obtain the rotation point pt0_rot.

[0071] The formula for the rotation of a point about an axis is:

[0072] Assume the vector containing the original femoral long axis is (n x ,n y ,n z The original femoral long axis passes through the point (x0, y0, z0), and the preset rotation angle is α;

[0073] Let K = 1 - cosα, M = n x x0+n y y0+n z If z0, then the rotation matrix is:

[0074] The formula for calculating the coordinates of the rotation point is: (x, y, z) new =(x,y,z,1) old ×Rotationrandom_axis

[0075] Where (x,y,z,1) old Let (x, y, z) be the coordinates of the 0-degree point. new Let be the coordinates of the rotation point.

[0076] Based on the principle that three points not on a straight line determine a plane, the rotation plane, namely the femoral section rot_plane (as shown in Figure 3), is determined by the rotation point pt0_rot, the first major axis endpoint pt1, and the second major axis endpoint pt2.

[0077] The three-dimensional image rotation module is used to synchronously rotate the original three-dimensional image and the femoral cross section, so that the rotated femoral cross section is perpendicular to any coordinate axis of the three-dimensional coordinate system, and obtains the coordinate value of the femoral cross section when it is perpendicular to the coordinate axis as the cross section index value.

[0078] In this embodiment, the y-axis is used as an example, which is perpendicular to the three-dimensional coordinate system after synchronously rotating the original three-dimensional image and the femoral cross-section. Specifically:

[0079] Obtain the xoy plane vector of the original femoral long axis vector org_changzhou on the xoy plane, and the x-axis unit vector in the x-axis direction on the xoy plane. Calculate the angle between the xoy plane vector and the x-axis unit vector, and denote it as the xoy plane angle move_pi.

[0080] The specific formula for calculating the included angle is as follows:

[0081] Wherein, α is the angle between the xoy plane vector and the x-axis unit vector. Let xoy be the vector in the plane. Let x be the unit vector of the x-axis.

[0082] The original three-dimensional image bone_image and the femoral cross section rot_plane are rotated around the z-axis with the direction pointing in the positive direction, and the angle move_pi is the same as the angle between the xoy plane and the first rotated three-dimensional image moved_image (as shown in Figure 4) and the first rotated femoral cross section moved_plane (as shown in Figure 5). At this time, the femoral long axis of the first rotated three-dimensional image moved_image is perpendicular to the y-axis.

[0083] Furthermore, due to the issue of rotation direction, a cross product is taken between the xoy plane vector and the x-axis unit vector used to calculate the xoy plane angle move_pi. When the cross product is less than 0, the rotation angle is taken as the opposite of the xoy plane angle move_pi.

[0084] The angle between the first rotating femoral section and the xoz plane is calculated using the normal vector of the first rotating femoral section moved_plane and the normal vector of the xoz plane pointing in the negative y-axis direction, and is denoted as the xoz plane angle_cross.

[0085] The first rotated 3D image (moved_image) and the first rotated femoral cross-section (moved_plane) are rotated around their own femoral long axis (new_changezhou) through the first long axis endpoint (pt1_rz) by an angle (angle_cross) of the xoz plane to obtain the second rotated 3D image (rot_image) and the second rotated femoral cross-section, as shown in Figure 6. At this time, the second rotated femoral cross-section is perpendicular to the y-axis, and the y-coordinate values ​​of the rotation point (pt0_rz), the first long axis endpoint (pt1_rz), and the second long axis endpoint (pt2_rz) are equal. The value of the y-coordinate is the cross-section index value (y_index) of the second rotated femoral cross-section on the y-coordinate.

[0086] Furthermore, due to the issue of rotation direction, the cross product is taken between the normal vector of the first rotated femoral section used to calculate the angle of the xoz plane and the normal vector of the xoz plane pointing in the negative y-axis direction. When the cross product is less than 0, the rotation angle is taken as the opposite of the angle of the xoz plane.

[0087] The cross-section data acquisition module is used to acquire slice data at the cross-section index value position on the coordinate axis perpendicular to the femoral cross-section in the three-dimensional coordinate system. The slice data is the cross-section data after rotating by the preset rotation angle below the 0-degree plane.

[0088] Specifically, taking the y-axis as an example in the 3D image rotation module, which is the coordinate axis perpendicular to the 3D coordinate system after synchronously rotating the original 3D image and the femoral cross-section, the cross-section data acquisition module determines the cross-section to be obtained. The cross-section is perpendicular to the y-axis, and the corresponding cross-section index value y_index is the y-coordinate of pt0_rz, pt1_rz, and pt2_rz. Therefore, the slice data is extracted from the second rotated 3D image rot_image at the position y_index, which is the cross-section data under the specified 0-degree plane and the specified rotation angle, as shown in Figure 7.

[0089] Second Embodiment

[0090] As shown in Figure 8, this embodiment provides a method for cutting a three-dimensional segmented femoral section using a system for cutting a three-dimensional segmented femoral section as described in the first embodiment, including:

[0091] S1: Obtain any 0-degree plane passing through the original femoral long axis, and rotate the 0-degree plane around the vector of the original femoral long axis by a preset rotation angle to obtain a rotation plane corresponding to the 0-degree plane. The rotation plane is used as the femoral section to be cut.

[0092] S2: Simultaneously rotate the original three-dimensional image and the femoral cross section so that the rotated femoral cross section is perpendicular to any coordinate axis of the three-dimensional coordinate system, and obtain the coordinate value of the femoral cross section when it is perpendicular to the coordinate axis as the cross section index value;

[0093] S3: In the three-dimensional coordinate system, take slice data at the position of the cross-section index value on the coordinate axis perpendicular to the femoral cross-section. The slice data is the cross-section data after rotating by the preset rotation angle below the 0-degree plane.

[0094] A computer-readable storage medium stores computer code that, when executed, performs the methods described above. Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing related hardware. This program can be stored in a computer-readable storage medium, which may include: read-only memory (ROM), random access memory (RAM), a magnetic disk, or an optical disk, etc.

[0095] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

[0096] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0097] It should be noted that the above embodiments can be freely combined as needed. The above description is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A system for taking a three-dimensional segmented femoral section, characterized in that, The application relates to an image-guided hip arthroplasty system, comprising: a memory for storing an original three-dimensional image of a femoral tissue and cross-section data of a cross-section of the femoral tissue to be cut; an image acquisition device for acquiring the original three-dimensional image of the femoral tissue before an image-guided hip arthroplasty surgery; a processor for cutting the cross-section data of the femoral tissue across a long axis of an original femur in the original three-dimensional image of the femoral tissue acquired before the image-guided hip arthroplasty surgery, and cutting the cross-section data in the femoral tissue by the following modules: a femoral cross-section calculation module for acquiring any 0-degree plane across the long axis of the original femur, rotating the 0-degree plane around a vector of the long axis of the original femur by a preset rotation angle to obtain a rotation plane corresponding to the 0-degree plane, and taking the rotation plane as a femoral cross-section to be cut; a three-dimensional image rotation module for synchronously rotating the original three-dimensional image and the femoral cross-section, so that the rotated femoral cross-section is perpendicular to any coordinate axis of a three-dimensional coordinate system, and acquiring a coordinate value when the femoral cross-section is perpendicular to the coordinate axis as a cross-section index value; a cross-section data acquisition module for taking slice data at a position of the cross-section index value on the coordinate axis perpendicular to the femoral cross-section in the three-dimensional coordinate system, the slice data being cross-section data after the 0-degree plane is rotated by the preset rotation angle.

2. The system for taking three-dimensional sectioned femoral section according to claim 1, characterized in that, In the femoral cross-section calculation module, any 0-degree plane across the long axis of the original femur is acquired, and the 0-degree plane is rotated around a vector of the long axis of the original femur by a preset rotation angle to obtain a rotation plane corresponding to the 0-degree plane, the rotation plane being the femoral cross-section to be cut, specifically as follows: the long axis of the original femur is determined by using a curved surface reconstruction and fitting technology; a 0-degree point not on the long axis of the original femur is arbitrarily designated, two points on the long axis of the original femur including a first long axis end point and a second long axis end point are combined, and the 0-degree plane is determined by the 0-degree point, the first long axis end point and the second long axis end point based on a principle that three points not on a straight line determine a plane; the vector of the long axis of the original femur pointing to the second long axis end point is calculated by the first long axis end point and the second long axis end point; a rotation point is obtained by rotating the 0-degree point around the vector of the long axis of the original femur by the preset rotation angle; the rotation plane, i.e. the femoral cross-section, is determined by the rotation point, the first long axis end point and the second long axis end point based on the principle that three points not on a straight line determine a plane.

3. The system for taking three-dimensional sectioned femoral section according to claim 2, characterized in that, In the femoral cross-section calculation module, the long axis of the original femur is determined by using a curved surface reconstruction and fitting technology, specifically as follows: the femur is segmented from the original three-dimensional image by using an image segmentation technology including threshold segmentation or edge detection to obtain a three-dimensional femur region; a continuous three-dimensional femur curved surface is represented by using a curved surface reconstruction algorithm including a point cloud-based or voxel-based curved surface reconstruction algorithm on the three-dimensional femur region. The three-dimensional femoral surface is fitted using methods including linear fitting or ellipsoidal fitting to obtain the principal axis direction of the femur, i.e., the original femoral long axis. The linear fitting involves using a fitting algorithm, including the least squares method, to fit points on the three-dimensional femoral surface to find the best-fitting straight line, which is the direction of the original femoral long axis. The ellipsoid fitting involves fitting an ellipsoid to represent the shape of the femur, and the long axis of the ellipsoid is the original femoral long axis.

4. The system for taking a three-dimensional segmented femoral section according to claim 2, characterized in that, In the femoral section calculation module, the rotation point is obtained by rotating the 0-degree point around the vector containing the original femoral long axis by the preset rotation angle, specifically as follows: Assuming that a vector where the original femoral long axis is located is (n x ,n y ,n z ), the original femoral long axis passes through point (x0, y0, z0), and the preset rotation angle is α; Let K = 1 - cos a, M = n x x0 + n y y0 + n z z0, then the rotation matrix is: The formula for calculating the coordinates of the rotation point is: (x, y, z) new = (x, y, z, 1) old x Rotation random_axis where (x, y, z, 1) old are the coordinates of the 0-degree point, (x, y, z) new are the coordinates of the rotation point.

5. The system for taking a three-dimensional segmented femoral section according to claim 2, wherein, Also includes: The three-dimensional image rotation module further includes: taking the y-axis as the coordinate axis perpendicular to the three-dimensional coordinate system after synchronously rotating the original three-dimensional image and the femoral cross-section, specifically: Obtain the xoy plane vector of the original femoral long axis vector on the xoy plane, and the x-axis unit vector in the x-axis direction on the xoy plane. Calculate the angle between the xoy plane vector and the x-axis unit vector, and denote it as the xoy plane angle. The original three-dimensional image and the femoral cross section are rotated around the z-axis by an angle equal to the angle between the xoy plane and the first major axis endpoint, respectively, to obtain a first rotated three-dimensional image and a first rotated femoral cross section. At this time, the femoral major axis of the first rotated three-dimensional image is perpendicular to the y-axis. The angle between the first rotating femoral section and the xoz plane is calculated using the normal vector of the first rotating femoral section and the normal vector of the xoz plane pointing in the negative y-axis direction, and is denoted as the xoz plane angle. The first rotated 3D image and the first rotated femoral cross section are rotated around their own femoral long axis through the endpoint of the first long axis by the angle of the xoz plane to obtain a second rotated 3D image and a second rotated femoral cross section. At this time, the second rotated femoral cross section is perpendicular to the y-axis, and the y-coordinate values ​​of the rotation point, the endpoint of the first long axis, and the endpoint of the second long axis are equal. The value of the y-coordinate is the cross section index value of the second rotated femoral cross section on the y-coordinate.

6. The system for taking three-dimensional sectioned femoral section according to claim 5, characterized in that, In the three-dimensional image rotation module, an included angle between the xoy plane vector and the x-axis unit vector is calculated, denoted as an xoy plane included angle, specifically: wherein a is the angle between the xoy plane vector and the x-axis unit vector, for the xoy plane vector, Let x be the unit vector of the x-axis.

7. The system for taking a three-dimensional segmented femoral section according to claim 5, wherein, In the three-dimensional image rotation module, when rotating the original three-dimensional image and the femoral cross-section around the z-axis by an angle equal to the angle between the xoy plane and the first major axis endpoint, the module further includes: Take the cross product of the xoy plane vector and the x-axis unit vector to calculate the angle between the xoy planes. When the cross product is less than 0, the rotation angle is the opposite of the angle between the xoy planes.

8. The system for taking three-dimensional sectioned femoral sectioning according to claim 1, characterized in that, In the three-dimensional image rotation module, the rotation of the first rotated three-dimensional image and the first rotated femoral section around their own femoral long axis through the endpoint of the first long axis by the angle of the xoz plane further includes: The cross product is taken between the normal vector of the first rotated femoral section used to calculate the angle of the xoz plane and the normal vector of the xoz plane pointing in the negative y-axis direction. When the cross product is less than 0, the rotation angle is the opposite of the angle of the xoz plane.

9. A method of taking a three-dimensional segmented femoral section using the system of taking a three-dimensional segmented femoral section according to claims 1 to 8, characterized in that, include: S1: obtaining any 0-degree face of an original femoral long axis, and rotating the 0-degree face around a vector where the original femoral long axis is located by a preset rotation angle to obtain a rotation plane corresponding to the 0-degree face, the rotation plane being a femoral section to be cut off; S2: synchronously rotating the original three-dimensional image and the femoral section, so that the rotated femoral section is perpendicular to any coordinate axis of a three-dimensional coordinate system, and obtaining a coordinate value when the femoral section is perpendicular to the coordinate axis as a section index value; S3: taking slice data at the section index value position on the coordinate axis where the femoral section is perpendicular in the three-dimensional coordinate system, the slice data being section data after the 0-degree face is rotated by the preset rotation angle.

10. A computer-readable storage medium, the computer-readable storage medium storing computer code, when the computer code is executed, the method as claimed in any one of claims 9 is executed.

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