Pedicle screw path planning method

Abstract

The present invention discloses a pedicle screw path planning method, comprising: step S1: performing image segmentation on a spinal structure model to obtain a 3D voxel map of the target vertebra and pedicle; step S2: determining an initial screw radial direction and an initial screw radius based on the 3D voxel map of the target vertebra and pedicle; step S3: optimizing the initial screw radial direction and the initial screw radius based on the pedicle point cloud to obtain screw radial parameters and screw radius parameters; step S4: calculating the entry point and exit point coordinates of the pedicle screw based on the screw radial parameters and the pedicle centroid coordinates; step S5: simulating the swing range of the universal screw head based on the exit point coordinates to determine whether the screw rod passes through all pedicle screws on the same side, and if so, determining a planned path, and if not, iteratively executing steps S3 to S5 until the screw rod passes through all pedicle screws on the same side. This solution solves the problems of low efficiency and low success rate in pedicle screw placement and rod insertion.

Description

Technical Field

[0001] The present 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 is full 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 automatic planning scheme for pedicle screws does not take into account 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 for manual fine-tuning of 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 images 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 coordinates of the entry point and exit point of the pedicle screw based on the screw radial parameters and the coordinates of the pedicle centroid;

[0009] Step S5: Based on the coordinates of the screw exit point, simulate the swingable range of the universal screw head of the pedicle screw to determine whether the nail 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. Otherwise, iterate steps S3 to S5 until the nail rod passes through all the pedicle screws on the same side.

[0010] Optionally, step S1 includes:

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

[0012] Step S12: training a 3D U-Net using 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, 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] The step S22 includes:

[0021] Step S221: calculating the coordinates of the centroid 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 based on 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 based on 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 superior lamina;

[0028] Step S34: establishing an optimization objective function based on the distance from the pedicle point cloud to the screw line, 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 left and right pedicle centroids, 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: calculating the intersection of the equation of the straight line 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 pedicle screw corresponding to the screw exit point coordinate;

[0036] Step S52: calculating the swing range radius 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 planned path is determined according to the coordinates of the screw entry point and the screw exit point; if not, executing step S55;

[0039] Step S55: The distance from the center of mass to the screw rod used to fix the pedicle screws is not greater than the swing range radius, which is added as a penalty term to the optimization function. The screw positions are optimized based on the updated optimization function to ensure that all automatically planned screws can meet the rod insertion requirements.

[0040] Step S56: iteratively executing 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, step S52 includes:

[0042] Step S521: Obtain the length of the movable portion and the maximum swing 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 portion and the maximum swing angle;

[0044] Step S523: Calculating 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 swing 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 pedicle screw path planning, the swingable range of the universal nail head of the pedicle screw is simulated according to the coordinates of the determined screw 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 planned path is obtained, otherwise the screw parameters and coordinates are recalculated to optimize the planned path, taking into account the pedicle screw placement and rod insertion process, which can avoid the need to fine-tune the screw position during the operation, improve the efficiency of the operation, and further improve the success rate of the operation. This application takes into account the diversity of the actual morphology of the pedicles, and initializes the screw radial direction by using the angle between the screw radial direction and the upper lamina and the angle between the screw radial direction and the center of mass of the left and right pedicles, thereby improving the accuracy of the initial screw radial direction, enhancing the stability of the optimization process, and making 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 This is a flow chart of the pedicle screw path planning method disclosed in an embodiment of the present invention;

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

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

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

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

[0053] Figure 6 This is 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] Figure 9 The left pedicle point cloud disclosed in the embodiment of the present invention;

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

[0058] Figure 11 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] Figure 12 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] Figure 13 The swing range of the universal screw head of the pedicle screw disclosed in the embodiment of the present invention is shown. DETAILED DESCRIPTION

[0061] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention 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 the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate 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, numerical expressions and numerical values ​​set forth in these embodiments 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 drawings are not drawn according to actual proportional relationships. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorized specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as being merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0064] like Figure 1 Shown is the flow chart of this application, as Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 The flowcharts of the sub-steps 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 column 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 the 3D U-Net using the 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, spinal CT images of different patients are first collected from the hospital's historical medical database to obtain a historical spinal image dataset, and a CT scanner is used to collect three-dimensional spinal images of patients undergoing surgery. The vertebrae and pedicles in the spinal CT images in the obtained historical spinal image dataset are respectively annotated. The spinal CT images with annotated vertebrae and pedicles are used as input for model training to obtain an image segmentation model. The trained image segmentation model is used to segment the three-dimensional spinal images to obtain 3D voxel maps of the target vertebrae and pedicles, including voxel-by-voxel classification of the three-dimensional spinal images using the image segmentation model to distinguish the vertebrae, pedicles, and other background areas and output a probability map for each category. An initial segmentation result is obtained from the obtained probability map using a probability threshold, and then the initial segmentation result is optimized by performing operations such as void filling and edge smoothing to obtain the final 3D voxel map of the target vertebrae and pedicles. The 3D voxel map of the pedicles is used 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 、 Figure 9 、 Figure 10 Shown are the 3D point cloud images of the target vertebra, the 3D point cloud image of the vertebral disc, the 3D point cloud image of the left pedicle, and the 3D point cloud image of the right pedicle, respectively. In this embodiment, the target vertebra and pedicle are segmented using image segmentation technology based on the 3D U-Net model. The 3D U-Net model is capable of efficiently processing large amounts of three-dimensional spinal images, achieving fast and accurate segmentation. Based on the precise segmentation results, doctors can develop more personalized treatment plans for their patients. For example, during spinal surgery planning, accurate vertebral and pedicle models can help doctors select the appropriate surgical path and internal fixation device, improving the success rate and safety of the surgery.

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

[0072] Furthermore, 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] Furthermore, 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 the 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] Furthermore, 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 centroids to obtain an initial screw radial direction.

[0084] In this embodiment, the coordinates of the left and right pedicle mass centers are first calculated using the 3D point cloud model of the pedicle. Then, the plane normal vector n0 of the upper lamina is rotated 90° along the line connecting the left and right pedicle mass centers as the rotation axis to obtain a vector α0 parallel to the plane of the upper lamina. The angle between the radial direction of the left and right pedicle screws and the line connecting the left and right pedicle mass centers is initialized to β0. Figure 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 vector a0 rotate along 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 placement can be further determined, ensuring that the screw can enter the pedicle along the correct path and avoid damaging surrounding important structures. By initializing the angle between the screw radial direction of the pedicle screw and the line connecting the centroid coordinates of the pedicle, and then initializing the lamina plane vector using the obtained angle to obtain the initial screw vector, it helps to improve the stability of the subsequent screw optimization process.

[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] Furthermore, step S3 includes:

[0088] Step S31: Calculate the equation of the straight line where the screw is located based on 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 superior lamina;

[0091] Step S34: establishing an optimization objective function based on the distance from the pedicle point cloud to the screw line, 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 left and right pedicle centroids, combined with the initial screw radius;

[0092] Step S35: Obtain 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, as shown in FIG. Figure 12 As shown, calculate the angle θ between the initial screw radial direction and the upper lamina plane, and calculate the angle β between the left and right screw axis vectors and the line connecting the left and right pedicles. 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 screw line, 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 (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, with a recommended value of 80°; m is the weight parameter.

[0095] In the above embodiment, the relevant distances and angles are calculated based on the initial screw radial direction, fully considering the individual patient's pedicle morphology and anatomical characteristics, ensuring that the screw insertion path and size are more consistent with the patient's actual situation, thereby improving the surgical effect. The distance from the pedicle's plane point cloud to the straight line where the screw is located is taken into account during the optimization process, which helps to prevent the screw from colliding with or penetrating the pedicle wall during insertion. By establishing and solving the optimization objective function, 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 pedicle centroid.

[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 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;

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

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

[0101] In this embodiment, the intersection point P of the screw with the surface of a single vertebral body is calculated based on 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 exit point, assuming that the planned screw length is 80% of the length of the line segment between the entry point and exit point at this time. Then calculate the three-dimensional coordinates of the actual pedicle screw exit point based on the entry point and 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 pedicle screw insertion path and length can be ensured to conform to the surgical plan, preventing the screw from colliding with or penetrating the pedicle wall or other important structures during insertion, thereby improving surgical accuracy and reducing surgical risks.

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

[0105] Step S52: Calculating 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: Calculating the swing 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 screws;

[0111] Step S54: Determine whether the distance from the center of mass to the screw rod for fixing the pedicle screws is within the swingable range of the center of mass. If so, the planning is completed and the planned 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: The distance from the center of mass to the screw rod used to fix the pedicle screws is not greater than the swing range radius, which is added as a penalty term to the optimization function. The screw positions are optimized 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 swing range radius, that is, the screw rod can pass through all target screws on the same side.

[0114] In this embodiment, it is assumed that the radius of the movable range of the pedicle screw corresponding to the screw exit point 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, as shown in Figure 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 further adjusted. The optimization function is established with the constraint that the distance from the swing range of the center of mass to the screw rod used to fix the pedicle screws is not greater than the swing range radius. 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. Then, the coordinates of the entry point and the exit point are further calculated based on the optimized initial screw radial direction and the initial screw radius. The distance from the swingable range of the center of mass to the nail rod for fixing the pedicle screw is recalculated until the distance from the center of mass to the nail rod for fixing the pedicle screw is not 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 nail head of the pedicle screw, it is possible to ensure that the nail 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 nail placement and rod insertion.

[0119] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the 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 images 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 coordinates of the entry point and the exit point of the pedicle screw based on the radial parameters of the screw and the coordinates of the centroid of the pedicle screw; Step S5: Based on the coordinates of the screw exit point, simulate the swingable range of the universal screw head of the pedicle screw to determine whether the nail 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. Otherwise, iterate steps S3 to S5 until the nail 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 a 3D U-Net using 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 includes: 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 includes: Step S221: calculating the coordinates of the centroid 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 and 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 superior lamina; Step S34: establishing an optimization objective function based on the distance from the pedicle point cloud to the screw line, 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 left and right pedicle centroids, 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 equation of the straight line 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 pedicle screw corresponding to the screw exit point coordinate; Step S52: calculating the swing range radius 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 planned path is determined according to the coordinates of the screw entry point and the screw exit point; if not, executing step S55; Step S55: The distance from the center of mass to the screw rod used to fix the pedicle screws is not greater than the swing range radius, which is added as a penalty term to the optimization function. The screw positions are optimized based on the updated optimization function to ensure that all automatically planned screws can meet the rod insertion requirements. Step S56: iteratively executing 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 includes: Step S521: Obtain the length of the movable portion and the maximum swing angle of the universal nail head; Step S522: simulating the swing range of the universal nail head by combining the length of the movable portion and the maximum swing angle; Step S523: Calculating 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 swing 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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