Pedicle screw path planning method

Abstract

The invention discloses a pedicle screw path planning method. The pedicle screw path planning method comprises the steps of S1, performing image segmentation on a spine structure model to obtain a 3D voxel map of a target vertebral body and a pedicle; s2, determining an initial screw radial direction and an initial screw radius by combining the 3D voxel maps of the target vertebral body and the vertebral pedicle; s3, optimizing the initial screw radial direction and the initial screw radius in combination with the vertebral pedicle point cloud to obtain a screw radial parameter and a screw radius parameter; s4, calculating coordinates of a screw inlet point and a screw outlet point of the pedicle screw based on the radial parameters of the screw in combination with the centroid coordinates of the pedicle; and S5, simulating the swinging range of the universal nail head based on the coordinates of the nail outlet point to judge whether the nail rod penetrates through all the pedicle screws on the same side or not, if so, determining a planned path, and if not, iteratively executing the steps S3 to S5 until the nail rod penetrates through all the pedicle screws on the same side. According to the scheme, the problems of low efficiency and low success rate of pedicle screw placement and rod penetration operations are solved.

Description

Technical Field

[0001] The invention relates to the field of medical technology, and in particular to a pedicle screw path planning method. Background Art

[0002] Spinal pedicle screws are used to treat various spinal traumas, deformities, tumors and other degenerative diseases. The screws are accurately placed in the appropriate position of two or more narrow pedicle channels, and then the screw heads are fixed to the fusion hardware to stabilize the spine. The vertebral foramen on the inner side of the pedicle are filled with a large number of nerves and blood vessels. Improper placement of screws will cause serious neurological complications. Traditional manual screw placement requires surgeons to have rich clinical experience and energy. The existing pedicle screw automatic planning scheme does not consider the rod insertion process after optimizing the screw position. In actual surgery, doctors often need to further fine-tune the screw position manually, which affects the efficiency of screw placement and rod insertion, increases the complexity of the operation, and further affects the efficiency and success rate of the operation. Summary of the invention

[0003] The main purpose of the present invention is to provide a pedicle screw path planning method to at least solve the problem of low surgical efficiency and success rate caused by the need to manually fine-tune the screw position during pedicle screw placement and rod insertion.

[0004] According to one aspect of the present invention, a pedicle screw path planning method is provided, comprising:

[0005] Step S1: performing image segmentation on the spinal structure model to obtain a 3D voxel image of the target vertebral body and pedicle;

[0006] Step S2: Determine an initial screw radial direction and an initial screw radius by combining the 3D voxel image of the target vertebral body and the pedicle;

[0007] Step S3: optimizing the initial screw radial direction and the initial screw radius in combination with the pedicle point cloud to obtain screw radial parameters and screw radius parameters;

[0008] Step S4: Calculating the screw entry point coordinates and the screw exit point coordinates of the pedicle screw based on the screw radial parameters and the pedicle centroid coordinates;

[0009] Step S5: Simulate the swingable range of the universal screw head of the pedicle screw based on the screw exit point coordinates to determine whether the screw rod passes through all the pedicle screws on the same side. If so, determine the planned path in combination with the screw entry point coordinates and the screw exit point coordinates. If not, iterate steps S3 to S5 until the screw rod passes through all the pedicle screws on the same side.

[0010] Optionally, the step S1 includes:

[0011] Step S11: Acquire a historical spine image dataset and a patient's spine three-dimensional image;

[0012] Step S12: training 3D U-Net with the historical spine image dataset to obtain an image segmentation model, wherein the image segmentation model includes a vertebral body segmentation model and a pedicle segmentation model;

[0013] Step S13: performing image segmentation on the three-dimensional image of the spine based on the vertebral body segmentation model and the pedicle segmentation model to obtain a 3D voxel image of the target vertebral body and pedicle.

[0014] Optionally, step S2 includes:

[0015] Step S21: acquiring a target vertebral point cloud and a pedicle point cloud based on the 3D voxel map of the target vertebral body and pedicle;

[0016] Step S22: Initializing the screw radial direction and screw radius of the pedicle screw by combining the target vertebral point cloud and the pedicle point cloud to obtain an initial screw radial direction and an initial screw radius.

[0017] Optionally, the step S21 includes:

[0018] Step S211: converting the 3D voxel image of the target vertebral body and the pedicle into a 3D point cloud model;

[0019] Step S212: extracting vertebral lamina plane parameters of the target vertebra based on the 3D point cloud model.

[0020] 5. The pedicle screw path planning method according to claim 4, characterized in that the step S22 comprises:

[0021] Step S221: calculating the centroid coordinates of the pedicle based on the 3D point cloud model corresponding to the pedicle;

[0022] Step S222: calculating a lamina plane vector based on the lamina plane parameters of the target vertebra;

[0023] Step S223: Initializing the angle between the radial direction of the pedicle screw and the line connecting the centroids of the left and right pedicles;

[0024] Step S224: Initializing the lamina plane vector according to the angle between the screw radial direction and the line connecting the left and right pedicle centroids to obtain an initial screw radial direction.

[0025] Optionally, step S3 includes:

[0026] Step S31: Calculate the equation of the straight line where the screw is located according to the coordinates of the centroid of the pedicle and the initial screw radial direction. Step S32: Calculate the distance from the pedicle point cloud to the straight line where the screw is located according to the equation of the straight line where the screw is located.

[0027] Step S33: calculating the angle between the initial screw radial direction and the plane normal vector of the upper lamina;

[0028] Step S34: establishing an optimization objective function based on the distance from the pedicle point cloud to the straight line where the screw is located, the angle between the initial screw radial direction and the plane normal vector of the upper lamina, and the angle between the initial screw radial direction and the line connecting the centroids of the left and right pedicles, combined with the initial screw radius;

[0029] Step S35: Obtaining optimized screw radial parameters and screw radius parameters according to the optimization objective function.

[0030] Optionally, step S4 includes:

[0031] Step S41: Calculate the intersection of the straight line equation where the screw is located and the vertebral bone surface to obtain the three-dimensional coordinates of the pedicle screw entry point and the three-dimensional coordinates of the initial exit point;

[0032] Step S42: Calculating the three-dimensional coordinate distance between the nail entry point and the initial nail exit point;

[0033] Step S43: determining the planned screw length corresponding to the pedicle screw, and calculating the three-dimensional coordinates of the final screw exit point based on the proportion of the planned screw length to the three-dimensional coordinate distance.

[0034] Optionally, step S5 includes:

[0035] Step S51: determining the movable range of the screw exit point coordinates corresponding to the pedicle screw;

[0036] Step S52: calculating the radius of the swing range corresponding to the center of mass of the swing range of the universal nail head of the pedicle screw according to the movable range;

[0037] Step S53: calculating the distance from the center of mass to the screw rod used to fix the pedicle screw;

[0038] Step S54: determining whether the distance from the center of mass to the screw rod for fixing the pedicle screw is within the swingable range of the center of mass, if so, the planning is completed, and the planning path is determined according to the screw entry point coordinates and the screw exit point coordinates; if not, executing step S55;

[0039] Step S55: adding the distance from the center of mass to the screw rod for fixing the pedicle screws to be no greater than the radius of the swingable range as a penalty term to the optimization function, and optimizing the screw position based on the updated optimization function to ensure that all automatically planned screws can meet the rod insertion requirements;

[0040] Step S56: iteratively execute steps S3 to S5 until the distance from the center of mass to the screw rod for fixing the pedicle screws is no greater than the swingable range radius, that is, the screw rod can pass through all target screws on the same side.

[0041] Optionally, the step S52 includes:

[0042] Step S521: Obtaining the length of the movable part and the maximum swingable angle of the universal nail head;

[0043] Step S522: simulating the swing range of the universal nail head by combining the length of the movable part and the maximum swing angle;

[0044] Step S523: Calculate the distance from the center of mass of the swingable range of the universal nail head to the nail insertion point;

[0045] Step S524: Calculate the swingable range radius corresponding to the center of mass based on the distance from the center of mass to the nail entry point and the movable radius of the nail exit point.

[0046] In the present invention, when performing the path planning of the pedicle screw, the swingable range of the universal nail head of the pedicle screw is simulated according to the coordinates of the determined nail exit point, and it is judged whether the nail rod used to fix the screw passes through all the pedicle screws on the same side. When the nail rod passes through all the pedicle screws on the same side, the final planning path is obtained, otherwise the screw parameters and coordinates are recalculated to optimize the planning path, taking into account the process of placing the nail and passing the rod of the pedicle screw, and it is possible to avoid the need to fine-tune the screw position during the operation, thereby improving the efficiency of the operation and further improving the success rate of the operation. The present application takes into account the diversity of the actual morphology of the pedicle, and initializes the screw radial direction by using the angle between the screw radial direction and the upper lamina and the angle between the left and right pedicle centroids to improve the accuracy of the initial screw radial direction, enhance the stability of the optimization process, and make the final screw path more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0048] Figure 1 A flow chart of a pedicle screw path planning method disclosed in an embodiment of the present invention;

[0049] Figure 2 A flowchart of step S1 disclosed in an embodiment of the present invention;

[0050] Figure 3 A flowchart of step S2 disclosed in an embodiment of the present invention;

[0051] Figure 4 A flowchart of step S3 disclosed in an embodiment of the present invention;

[0052] Figure 5 A flowchart of step S4 disclosed in an embodiment of the present invention;

[0053] Figure 6 A flowchart of step S5 disclosed in an embodiment of the present invention;

[0054] Figure 7 The target vertebral point cloud disclosed in the embodiment of the present invention;

[0055] Figure 8 The vertebral disc point cloud disclosed in the embodiment of the present invention;

[0056] Fig. 9 The left pedicle point cloud disclosed in the embodiment of the present invention;

[0057] Fig.10 The right pedicle point cloud disclosed in the embodiment of the present invention;

[0058] Fig.11 A schematic diagram of the angle between the radial direction of the screw and the centroid of the pedicle disclosed in an embodiment of the present invention;

[0059] Fig.12 A schematic diagram of the angle between the radial direction of the screw and the upper lamina plane disclosed in an embodiment of the present invention;

[0060] Fig.13 The invention discloses a universal screw head of a pedicle screw that can swing. DETAILED DESCRIPTION

[0061] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0062] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0063] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0064] like Figure 1 Shown is the flow chart of this application, such as Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 The sub-step flow charts of step S1, step S2, step S3, step S4, and step S5 of the embodiment of the application are respectively provided. According to the embodiment of the application, a pedicle screw path planning method is provided, comprising:

[0065] Step S1: Perform image segmentation on the spinal structure model to obtain a 3D voxel image of the target vertebral body and pedicle.

[0066] Specifically, step S1 includes:

[0067] Step S11: Acquire a historical spine image dataset and a patient's spine three-dimensional image;

[0068] Step S12: training 3D U-Net using a historical spine image dataset to obtain an image segmentation model, where the image segmentation model includes a vertebral body segmentation model and a pedicle segmentation model;

[0069] Step S13: performing image segmentation on the three-dimensional image of the spine based on the vertebral body segmentation model and the pedicle segmentation model to obtain a 3D voxel image of the target vertebral body and pedicle.

[0070] Furthermore, firstly, spinal CT images of different patients are collected from the hospital's historical medical database to obtain a historical spinal image data set, and a CT scanner is used to collect a three-dimensional spinal image of a patient to be operated on, and the vertebrae and pedicles in the spinal CT images in the obtained historical spinal image data set are respectively annotated, and the spinal CT images after the vertebrae and pedicles are annotated are used as the input of the 3D U-Net model for model training to obtain an image segmentation model. The three-dimensional spinal image is segmented by the trained image segmentation model to obtain a 3D voxel map of the target vertebrae and pedicles, including voxel-by-voxel classification of the three-dimensional spinal image by the image segmentation model, distinguishing the vertebrae, pedicles and other background areas and outputting a probability map of each category, obtaining an initial segmentation result from the obtained probability map by a probability threshold, and then performing optimization operations such as cavity filling and edge smoothing on the initial segmentation result to obtain the final 3D voxel map of the target vertebrae and pedicles, and using the 3D voxel map of the pedicles to separate the 3D voxel map of the vertebral disc from the 3D voxel map of the vertebral body. The pedicle 3D voxel map includes a left pedicle 3D voxel map and a right pedicle 3D voxel map, such as Figure 7 , Figure 8 , Fig. 9 , Fig.10 Shown are the target vertebral 3D point cloud, vertebral disc 3D point cloud, left pedicle 3D point cloud, and right pedicle 3D point cloud. In this embodiment, the target vertebra and pedicle are segmented by image segmentation technology based on the 3DU-Net model. The 3D U-Net model can efficiently process a large number of three-dimensional images of the spine, achieving fast and accurate segmentation. Based on the accurate segmentation results, doctors can develop more personalized treatment plans for patients. For example, in spinal surgery planning, accurate vertebral models and pedicle models can help doctors choose appropriate surgical paths and internal fixation devices, thereby improving the success rate and safety of the operation.

[0071] Step S2: Determine the initial screw radial direction and initial screw radius by combining the 3D voxel map of the target vertebral body and pedicle.

[0072] Further, step S2 includes:

[0073] Step S21: acquiring a target vertebral point cloud and a pedicle point cloud based on the 3D voxel map of the target vertebral body and pedicle;

[0074] Step S22: Initializing the screw radial direction and screw radius of the pedicle screw by combining the target vertebral point cloud and the pedicle point cloud to obtain an initial screw radial direction and screw radius.

[0075] Further, step S21 includes:

[0076] Step S211: converting the 3D voxel image of the target vertebral body and pedicle into a 3D point cloud model;

[0077] Step S212: extracting vertebral lamina plane parameters of the target vertebra based on the 3D point cloud model.

[0078] In this embodiment, the plane fitting algorithm is first used to process the vertebral plate point cloud of the target vertebra to find the best vertebral plate plane point cloud, and the plane equation is extracted from the vertebral plate plane point cloud, such as Figure 8 The screw radius is initialized according to clinical experience, such as the diameter of cervical screws is usually 3.5mm, the diameter of thoracic screws is 4mm, and the diameter of lumbar screws is 7mm.

[0079] Further, step S22 includes:

[0080] Step S221: Calculating the centroid coordinates of the pedicle based on the 3D point cloud model corresponding to the pedicle;

[0081] Step S222: calculating the lamina plane vector based on the lamina plane parameters of the target vertebra;

[0082] Step S223: Initializing the angle between the radial direction of the pedicle screw and the line connecting the centroids of the left and right pedicles;

[0083] Step S224: Initializing the lamina plane vector according to the angle between the screw radial direction and the line connecting the left and right pedicle mass centers to obtain an initial screw radial direction.

[0084] In this embodiment, the coordinates of the centroids of the left and right pedicles are first calculated using the 3D point cloud model of the pedicles, and then the plane normal vector n0 of the upper lamina is rotated 90° along the line connecting the centroids of the left and right pedicles as the rotation axis to obtain a vector α0 parallel to the plane of the upper lamina, and the angle between the radial direction of the left and right pedicle screws and the line connecting the centroids of the left and right pedicles is initialized to β0. Fig.11 The figure shows the angle between the radial direction of the screw and the centroid of the pedicle. The angle β between the vector a0 and the vector RL and the vector LR is calculated. R and β L , let the vector a0 rotate along the vector n0 to obtain the initial screw radial direction of the left and right pedicle screws, where β = β R -β0 or β=β L -β0.

[0085] In the above embodiment, by calculating the centroid coordinates of the pedicle, the center position of the pedicle can be accurately located. By calculating the lamina plane vector in combination with the plane normal vector of the target vertebra, the direction of screw insertion can be further determined to ensure that the screw can enter the pedicle along the correct path to avoid damaging the surrounding important structures. By initializing the angle between the screw radial of the pedicle screw and the line connecting the centroid coordinates of the pedicle, and then initializing the lamina plane vector by the obtained angle to obtain the initial screw vector, it is helpful to improve the stability of the subsequent optimization process of the screw.

[0086] Step S3: Optimize the initial screw radial direction and initial screw radius in combination with the pedicle point cloud to obtain screw radial parameters and screw radius parameters.

[0087] Further, step S3 includes:

[0088] Step S31: Calculate the equation of the straight line where the screw is located according to the coordinates of the centroid of the pedicle and the initial screw radial direction;

[0089] Step S32: Calculate the distance from the pedicle point cloud to the straight line where the screw is located according to the equation of the straight line where the screw is located;

[0090] Step S33: calculating the angle between the initial screw radial direction and the plane normal vector of the upper lamina;

[0091] Step S34: establishing an optimization objective function based on the distance from the pedicle point cloud to the straight line where the screw is located, the angle between the initial screw radial direction and the plane normal vector of the upper lamina, and the angle between the initial screw radial direction and the line connecting the centroids of the left and right pedicles, combined with the initial screw radius;

[0092] Step S35: Obtaining optimized screw radial parameters and screw radius parameters according to the optimization objective function.

[0093] In this embodiment, the distance D from the pedicle point cloud to the straight line is calculated based on the straight line where the screw is located, such as Fig.12 As shown in the figure, the angle θ between the initial screw radial direction and the upper lamina plane is calculated, and the angle β between the left and right screw axis vectors and the line connecting the left and right pedicles is calculated. L and β R , the optimization objective function is as follows:

[0094] (Dr) e -r +(θ-θ0)·m+(β i -β init )·m, where D is the distance from the pedicle point cloud to the straight line where the screw is located, r is the screw radius; θ is the angle between the screw radial direction and the upper lamina plane, θ init The ideal angle between the screw radial direction and the superior lamina (the recommended value is 0-3°); is the angle between the radial direction of the screw and the vector connecting the left and right pedicles, is the ideal angle between the screw radial direction and the line connecting the left and right pedicles, and the recommended value is 80°; m is the weight parameter.

[0095] In the above embodiment, the relevant distance and angle are calculated based on the initial screw radial direction, which fully considers the individual pedicle morphology and anatomical characteristics of the patient, and can ensure that the screw insertion path and size are more in line with the patient's actual situation, thereby improving the surgical effect. The distance from the plane point cloud of the pedicle to the straight line where the screw is located is considered during the optimization process, which helps to avoid the screw from colliding with or penetrating the pedicle wall during the insertion process. By establishing an optimization objective function and solving it, the optimal screw radial parameters and screw radius parameters can be obtained, which can significantly improve the accuracy of spinal surgery and ensure the accuracy and stability of the screw insertion position.

[0096] Step S4: Calculate the entry point coordinates and exit point coordinates of the pedicle screw based on the radial parameters of the screw and the coordinates of the centroid of the pedicle.

[0097] Specifically, step S4 includes:

[0098] Step S41: Calculate the intersection of the equation of the straight line where the screw is located and the surface of the vertebral bone to obtain the three-dimensional coordinates of the pedicle screw entry point and the three-dimensional coordinates of the initial exit point;

[0099] Step S42: Calculate the three-dimensional coordinate distance between the nail entry point and the initial nail exit point;

[0100] Step S43: determining the planned screw length corresponding to the pedicle screw, and calculating the three-dimensional coordinates of the final screw exit point based on the proportion of the planned screw length in the three-dimensional coordinate distance.

[0101] In this embodiment, the intersection point P of the screw with the surface of a single vertebral bone is calculated according to the equation of the straight line where the screw is located. entry and P exit ', where P entry Indicates the entry point of the pedicle screw. Calculate the length of the entry point and the exit point, assuming that the planned screw length is 80% of the length of the line segment between the entry point and the exit point at this time. Then calculate the three-dimensional coordinates of the actual pedicle screw exit point based on the entry point and the screw length. The obtained coordinates of the pedicle screw exit point are P exit =0.8·|P exit -P entry |·a i +P entry By accurately calculating the coordinates of the entry and exit points, the insertion path and length of the pedicle screw can be ensured to be in line with the surgical plan, avoiding collision or penetration of the screw with the pedicle wall or other important structures during the insertion process, thereby improving the accuracy of the operation and reducing surgical risks.

[0102] Step S5: Simulate the swingable range of the universal screw head of the pedicle screw based on the screw exit point coordinates to determine whether the screw rod passes through all the pedicle screws on the same side. If so, determine the planned path by combining the screw entry point coordinates and the screw exit point coordinates. Otherwise, iterate steps S3 to S5 until the screw rod passes through all the pedicle screws on the same side.

[0103] Specifically, step S5 includes:

[0104] Step S51: determining the movable range of the screw exit point coordinates corresponding to the pedicle screw;

[0105] Step S52: Calculate the radius of the swing range corresponding to the center of mass of the swing range of the universal screw head of the pedicle screw according to the movable range;

[0106] Step S521: Obtain the length of the movable part and the maximum swing angle of the universal nail head;

[0107] Step S522: simulating the swing range of the universal nail head by combining the length of the movable part and the maximum swing angle;

[0108] Step S523: Calculate the distance from the center of mass of the swingable range of the universal nail head to the nail insertion point;

[0109] Step S524: Calculate the swingable range radius corresponding to the center of mass based on the distance from the center of mass to the nail entry point and the movable radius of the nail exit point;

[0110] Step S53: calculating the distance from the center of mass to the screw rod used to fix the pedicle screw;

[0111] Step S54: determine whether the distance from the center of mass to the screw rod for fixing the pedicle screw is within the swingable range of the center of mass. If so, the planning is completed, and the planning path is determined according to the coordinates of the screw entry point and the screw exit point; if not, execute step S55;

[0112] Step S55: adding the distance from the center of mass to the screw rod for fixing the pedicle screws to be no greater than the radius of the swingable range as a penalty term to the optimization function, and optimizing the screw position based on the updated optimization function to ensure that all automatically planned screws can meet the rod insertion requirements;

[0113] Step S56: iteratively execute steps S3 to S5 until the distance from the center of mass to the screw rod for fixing the pedicle screws is no greater than the radius of the swingable range, that is, the screw rod can pass through all target screws on the same side.

[0114] In this embodiment, it is assumed that the movable range radius of the pedicle screw corresponding to the screw exit point coordinate is r exitThe length of the swingable part of the universal nail head of the pedicle screw is L, and the maximum angle of the swingable part is σ, that is, the range of motion of the swingable part of the universal nail head can be simulated as a cone with a vertex angle of σ and a generatrix length of L, such as Fig.13 As shown, calculate the length from the center of mass of the cone to the vertex The movable range of the cone mass center is calculated based on the movable range radius of the nail point coordinates: Calculate the distance D from the centroid coordinates of all target cones to the nail rod stick If there is D stick ≤r stick , then the screw rod can pass through all planned pedicle screws on the same side, the planning is completed, and the final pedicle planning path is obtained; otherwise, the screw planning position needs to be adjusted further to establish an optimization function with the distance from the swingable range of the center of mass to the screw rod used to fix the pedicle screws not greater than the swingable range radius as the constraint condition. The obtained optimization function is as follows:

[0115]

[0116] Where N is the number of ipsilateral screws that need to be planned, and m and n are weight parameters.

[0117] Furthermore, based on the constraint that the distance from the center of mass to the nail rod is not greater than the range of motion of the center of mass, a new optimization function is established, and the process returns to step S3 to re-optimize the initial screw radial direction and the initial screw radius, and then further calculates the coordinates of the nail entry point and the nail exit point based on the optimized initial screw radial direction and the initial screw radius, and recalculates the distance from the swingable range of the center of mass to the nail rod used to fix the pedicle screws, until the distance from the center of mass to the nail rod used to fix the pedicle screws is no greater than the swingable range radius, the planning is completed, and the final pedicle planning path is obtained.

[0118] In the above embodiment, by accurately simulating the swingable range of the universal screw head of the pedicle screw, it can be ensured that the screw rod can smoothly pass through all pedicle screws on the same side during the implantation process, avoiding manual readjustment due to position deviation, and improving the efficiency of screw placement and rod insertion.

[0119] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pedicle screw path planning method, characterized in that: include: Step S1: performing image segmentation on the spinal structure model to obtain a 3D voxel image of the target vertebral body and pedicle; Step S2: Determine an initial screw radial direction and an initial screw radius by combining the 3D voxel image of the target vertebral body and the pedicle; Step S3: optimizing the initial screw radial direction and the initial screw radius in combination with the pedicle point cloud to obtain screw radial parameters and screw radius parameters; Step S4: calculating the screw entry point coordinates and the screw exit point coordinates of the pedicle screw based on the screw radial parameters and the pedicle centroid coordinates; Step S5: Simulate the swingable range of the universal screw head of the pedicle screw based on the screw exit point coordinates to determine whether the screw rod passes through all the pedicle screws on the same side. If so, determine the planned path in combination with the screw entry point coordinates and the screw exit point coordinates. If not, iterate steps S3 to S5 until the screw rod passes through all the pedicle screws on the same side.

2. The pedicle screw path planning method according to claim 1, characterized in that: The step S1 comprises: Step S11: Acquire a historical spine image dataset and a patient's spine three-dimensional image; Step S12: training 3D U-Net with the historical spine image dataset to obtain an image segmentation model, wherein the image segmentation model includes a vertebral body segmentation model and a pedicle segmentation model; Step S13: performing image segmentation on the three-dimensional image of the spine based on the vertebral body segmentation model and the pedicle segmentation model to obtain a 3D voxel image of the target vertebral body and pedicle.

3. The pedicle screw path planning method according to claim 1, characterized in that: The step S2 comprises: Step S21: acquiring a target vertebral point cloud and a pedicle point cloud based on the 3D voxel map of the target vertebral body and pedicle; Step S22: Initializing the screw radial direction and screw radius of the pedicle screw by combining the target vertebral point cloud and the pedicle point cloud to obtain an initial screw radial direction and an initial screw radius.

4. The pedicle screw path planning method according to claim 3, characterized in that: The step S21 comprises: Step S211: converting the 3D voxel image of the target vertebral body and the pedicle into a 3D point cloud model; Step S212: extracting vertebral lamina plane parameters of the target vertebra based on the 3D point cloud model.

5. The pedicle screw path planning method according to claim 4, characterized in that: The step S22 comprises: Step S221: calculating the centroid coordinates of the pedicle based on the 3D point cloud model corresponding to the pedicle; Step S222: calculating a lamina plane vector based on the lamina plane parameters of the target vertebra; Step S223: Initializing the angle between the radial direction of the pedicle screw and the line connecting the centroids of the left and right pedicles; Step S224: Initializing the lamina plane vector according to the angle between the screw radial direction and the line connecting the left and right pedicle centroids to obtain an initial screw radial direction.

6. The pedicle screw path planning method according to claim 1, characterized in that: The step S3 comprises: Step S31: calculating the equation of the straight line where the screw is located according to the coordinates of the centroid of the pedicle combined with the initial screw radial direction; Step S32: calculating the distance from the pedicle point cloud to the straight line where the screw is located according to the equation of the straight line where the screw is located; Step S33: calculating the angle between the initial screw radial direction and the plane normal vector of the upper lamina; Step S34: establishing an optimization objective function based on the distance from the pedicle point cloud to the straight line where the screw is located, the angle between the initial screw radial direction and the plane normal vector of the upper lamina, and the angle between the initial screw radial direction and the line connecting the centroids of the left and right pedicles, combined with the initial screw radius; Step S35: Obtaining optimized screw radial parameters and screw radius parameters according to the optimization objective function.

7. The pedicle screw path planning method according to claim 6, characterized in that: The step S4 comprises: Step S41: calculating the intersection of the straight line equation where the screw is located and the vertebral bone surface to obtain the three-dimensional coordinates of the pedicle screw entry point and the three-dimensional coordinates of the initial exit point; Step S42: Calculating the three-dimensional coordinate distance between the nail entry point and the initial nail exit point; Step S43: determining the planned screw length corresponding to the pedicle screw, and calculating the three-dimensional coordinates of the final screw exit point based on the proportion of the planned screw length to the three-dimensional coordinate distance.

8. The pedicle screw path planning method according to claim 1, characterized in that: The step S5 comprises: Step S51: determining the movable range of the screw exit point coordinates corresponding to the pedicle screw; Step S52: calculating the radius of the swing range corresponding to the center of mass of the swing range of the universal nail head of the pedicle screw according to the movable range; Step S53: calculating the distance from the center of mass to the screw rod used to fix the pedicle screw; Step S54: determining whether the distance from the center of mass to the screw rod for fixing the pedicle screw is within the swingable range of the center of mass, if so, the planning is completed, and the planning path is determined according to the screw entry point coordinates and the screw exit point coordinates; if not, executing step S55; Step S55: adding the distance from the center of mass to the screw rod for fixing the pedicle screws to be no greater than the radius of the swingable range as a penalty term to the optimization function, and optimizing the screw position based on the updated optimization function to ensure that all automatically planned screws can meet the rod insertion requirements; Step S56: iteratively execute steps S3 to S5 until the distance from the center of mass to the screw rod for fixing the pedicle screws is no greater than the swingable range radius, that is, the screw rod can pass through all target screws on the same side.

9. The pedicle screw path planning method according to claim 8, characterized in that: The step S52 comprises: Step S521: Obtaining the length of the movable part and the maximum swingable angle of the universal nail head; Step S522: simulating the swing range of the universal nail head by combining the length of the movable part and the maximum swing angle; Step S523: Calculate the distance from the center of mass of the swingable range of the universal nail head to the nail insertion point; Step S524: Calculate the swingable range radius corresponding to the center of mass based on the distance from the center of mass to the nail entry point and the movable radius of the nail exit point.

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