A surgical instrument calibration and visual tracking method for optical navigation surgery

Abstract

The present invention discloses a surgical instrument calibration and visual tracking method for optical navigation surgery, comprising the following steps: establishing data communication between an optical navigation positioning device and a computer, obtaining the position and posture data of different optical tracers; performing point instrument calibration based on the position and posture data; performing linear instrument calibration based on the position and posture data of the optical tracer; performing plane instrument calibration based on the position and posture data of the optical tracer; and performing visual tracking of surgical instruments. The present invention uses calibration tools and optical positioning devices with point, line, and surface geometric structures to achieve preoperative calibration of different surgical instruments, improve the calibration accuracy and time required for surgical instruments, and improve efficiency. The present invention classifies and transmits position information internally, reducing the difficulty of operation for doctors; the visualization module provides an intuitive display of the spatial position of surgical instruments, realizes the calibration process and visual tracking of surgical instruments after calibration, and improves the accuracy of the calibration process.

Description

Technical Field

[0001] The present invention belongs to the technical field of surgical instrument calibration and tracking, and in particular relates to a surgical instrument calibration and visualization tracking method for optical navigation surgery. Background Art

[0002] Traditional surgical operation methods, whether preoperative planning or intraoperative execution, are highly dependent on the doctor's experience, and often have defects such as low precision, large trauma, and long recovery period. With the rapid development of digital image processing, computer vision, network communication and other technologies, surgical navigation system (SNS) has become a research hotspot. It uses image processing technology and visual positioning technology to combine the patient's preoperative CT image, magnetic resonance imaging (MRI) image information, the patient's lesion location obtained during surgery, and the spatial position information of surgical instruments during surgical preparation or during the process, track and display the relative position relationship between the patient's anatomical structure and the surgical instruments, and perform real-time navigation for the operation to meet the requirements of modern surgery with precision and minimally invasiveness.

[0003] Accurate and efficient positioning and tracking of surgical instruments are the prerequisites for the effective execution of navigation surgery. During surgical navigation, the spatial positioning system tracks the optical tracer attached to the surgical instrument. Based on the calibration relationship between the optical tracer and the instrument working terminal, the navigation system calculates the spatial position of the surgical instrument working terminal and displays the relative position relationship between the surgical instrument and the patient's anatomical structure. Therefore, how to obtain the calibration information of the surgical instrument and accurately display the tracking position of the surgical instrument is a key issue for the surgical navigation system.

[0004] In surgical navigation surgery, commonly used surgical instruments include optical probes, surgical puncture needles, scalpels, etc., and their working terminals can be simplified into simple geometric structures such as spatial sharp points, straight lines, and planes. The optical tracer connected to the surgical instrument serves as the reference coordinate system of the instrument. The problem to be solved in surgical instrument calibration is to calculate the spatial position of the working terminal (point, line, surface) of the surgical instrument in the reference coordinate system.

[0005] Traditional surgical instrument calibration uses surgical instrument assembly models and vernier calipers to measure calibration information, and then inputs the calibration information into surgical navigation software to complete the calibration work, which has the defects of low efficiency, high measurement difficulty, and low measurement accuracy. At the same time, visually observing the calibration process and evaluating the correctness of the calibration results can avoid erroneous results due to misoperation and save time. Therefore, for different surgical instruments, it is a prerequisite for the effective execution of navigation surgery to propose accurate and efficient calibration methods and visual tracking methods, and integrate a class of surgical instrument rapid calibration and visual tracking systems.

[0006] Among the existing navigation surgical instrument calibration systems and calibration methods, the most representative one is the American Stryker surgical navigation system. The calibration platform of this system has a positioning axis hole for fixing the surgical instrument and a pit for placing the tip of the surgical instrument, and an optical tracer is fixedly connected. During calibration, the navigator is first used to track the surgical instrument and the optical tracer on the calibration platform to establish the instrument reference coordinate system and the calibration platform reference coordinate system; then, the tip of the surgical instrument is placed straight in the pit, and while keeping the tip of the surgical instrument fixed, the surgical instrument is shaken around the tip facing the navigator, and the navigator collects all the optical tracer position information and calculates the calibration data of the surgical instrument tip; finally, the surgical instrument is inserted into the positioning axis hole of the calibration platform, locked and fixed, keeping the axial direction of the surgical instrument unchanged, and the surgical instrument is rotated facing the navigator, and the navigator collects all the optical tracer position information and calculates the calibration data of the axial vector.

[0007] This calibration technology has certain applicability and versatility, and has been widely used in surgical instrument calibration before navigation begins, such as the navigation surgical instrument calibration system and method described in patents CN109171962B and CN112022350A.

[0008] The system has the following deficiencies:

[0009] First, it can only calibrate the tip position and axial vector of the surgical probe, and cannot be adapted to surgical instruments such as scalpels and bone saws.

[0010] Second, the calibration algorithm uses a numerical approximation algorithm based on the least squares principle, which requires multiple acquisitions of reference marker images, making the process time-consuming and labor-intensive.

[0011] Third, it is impossible to visualize the calibration process and track the calibrated surgical instruments, and it is impossible to discover the wrong results caused by incorrect operations in time, which may lead to repeated operations and affect efficiency. Summary of the invention

[0012] The present invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a surgical instrument calibration and visualization tracking method for optical navigation surgery.

[0013] The technical solution of the present invention is: a surgical instrument calibration and visual tracking method for optical navigation surgery, the following steps:

[0014] ⅰ. Establish data communication between the optical navigation and positioning equipment and the computer to obtain the position and posture data of different optical tracers;

[0015] ⅱ. Calibrate the sharp-point instrument based on the position and posture data of the optical tracer;

[0016] ⅲ. Calibrate linear instruments based on the position data of the optical tracer;

[0017] ⅳ. Calibrate planar instruments based on the position and posture data of the optical tracer;

[0018] v. Perform visual tracking of surgical instruments.

[0019] Furthermore, step i establishes data communication between the optical navigation positioning and the computer to obtain the position data of different optical tracers. The specific process is as follows:

[0020] 1a. Initialize and establish a connection between the optical navigation positioning and the data communication thread and the main thread between the computer;

[0021] 1b. According to the optical tracer number connected to different surgical instruments, correctly load the rigid body file of the corresponding optical tracer, activate the tool handle, and obtain the position information of the loaded optical tracer;

[0022] 1c. Using the data request function in the main thread to call the dynamic link library of the optical positioning system, the data in the data buffer is transferred to the main thread;

[0023] 1d. According to the optical tracer posture information data, the optical tracer posture matrix is ​​calculated.

[0024] Furthermore, step 1b also includes caching processing of the position information, that is, storing the acquired position information in a data buffer and waiting for the main thread to call the data.

[0025] Furthermore, step 1c also includes the following process:

[0026] With the help of QTTimer, the data request function in the main thread is called at fixed time intervals to achieve real-time data transmission.

[0027] Furthermore, step ii performs point instrument calibration based on the position and posture data of the optical tracer, and the specific process is as follows:

[0028] First, the sharp-point surgical instrument and the calibration tool are placed within the field of view of the optical positioning device;

[0029] Then, the pose matrix is ​​combined with the vtkAxesActor component in the VTK toolkit to display the spatial position and pose of all optical tracer coordinate systems in the visualization module;

[0030] After that, make sure that the reference coordinate system of the sharp-point surgical instrument and the calibration tool is correctly displayed in the visualization module;

[0031] Finally, the three-dimensional coordinates of the instrument tip in the reference coordinate system are calculated through the tip instrument calibration method.

[0032] Furthermore, in step ii, a method for calibrating a cusp instrument in calibrating a cusp instrument is performed based on the position and posture data of the optical tracer. The specific process is as follows:

[0033] 2a. Place the tip of the instrument at the calibration tool tip geometry to obtain the three-dimensional coordinate expression of the tip of the instrument in the optical positioning system coordinate system;

[0034] 2b. Rotate the sharp-point instrument around the sharp-point geometric structure of the calibration tool so that the trajectory of the reflective marker ball on the instrument falls on a spherical surface with the end of the instrument as the center;

[0035] 2c. Using an optical positioning device to record the spatial position of the optical tracer at n moments, and record the i-th coordinate expression of the geometric structure of the cusp of the calibration tool in the coordinate system of the optical positioning device;

[0036] 2d. Express the least squares method in matrix form to obtain the objective function;

[0037] 2e. Obtain the optimal solution under the condition of minimizing the objective function and complete the calibration of the sharp-point surgical instrument.

[0038] Furthermore, step iii performs linear instrument calibration based on the position data of the optical tracer, and the specific process is as follows:

[0039] First, place the linear surgical instrument and the calibration tool within the field of view of the optical positioning device;

[0040] Then, confirm that the reference coordinate systems of the linear surgical instrument and the calibration tool are correctly displayed in the visualization module;

[0041] Finally, the calibration in the linear instrument reference coordinate system is completed through the linear instrument calibration method.

[0042] Furthermore, in step iii, a linear instrument calibration method is performed in linear instrument calibration based on the position and posture data of the optical tracer, and the specific process is as follows:

[0043] First, the linear surgical instrument is inserted into the linear geometry of the calibration tool to make it fit tightly;

[0044] Then, the conversion relation expression of the linear surgical instrument is obtained;

[0045] Then, according to the conversion relationship expression, the direction vector of the linear surgical instrument in the coordinate system is obtained;

[0046] Then, according to the conversion relationship expression, the coordinates of the end points of the linear surgical instrument in the coordinate system are obtained;

[0047] Then, the obtained direction vector and coordinates are used to obtain the spatial position of the linear instrument in the reference coordinate system to complete the calibration of the linear surgical instrument.

[0048] Furthermore, step iv is to perform planar device calibration based on the pose data of the optical tracer, and the specific process is as follows:

[0049] First, place the planar surgical instrument and calibration tool within the field of view of the optical positioning device;

[0050] Then, confirm that the reference coordinate system of the planar surgical instrument and the calibration tool is correctly displayed in the visualization module;

[0051] Finally, the calibration in the planar instrument reference coordinate system is completed through the planar surgical instrument calibration method.

[0052] Furthermore, step iv is based on the position data of the optical tracer to perform a planar surgical instrument calibration method in a planar instrument calibration, and the specific process is as follows:

[0053] First, a calibration coordinate system of the plane instrument and the plane geometric structure of the calibration tool is established, and the plane surgical instrument is inserted into the plane geometric structure of the calibration tool to make them fit tightly;

[0054] Then, the conversion relation expression of the planar surgical instrument is obtained;

[0055] Then, according to the conversion relationship expression, the homogeneous transformation matrix of the plane structure calibration coordinate system relative to the surgical instrument reference coordinate system is obtained;

[0056] Finally, the homogeneous transformation matrix is ​​used to complete the planar device calibration.

[0057] The beneficial effects of the present invention are as follows

[0058] The present invention can realize preoperative calibration for different surgical instruments by means of calibration tools and optical positioning equipment with point, line and surface geometric structures, and improve the calibration accuracy and required time of surgical instruments, thereby improving efficiency.

[0059] The present invention classifies and transmits the position information involved in the calibration process internally, reducing the difficulty of operation for doctors; the visualization module provides an intuitive display of the spatial position of surgical instruments, realizes the visualization tracking of the calibration process and the surgical instruments after calibration, and improves the accuracy of the calibration process. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a module connection diagram of the present invention;

[0061] Figure 2 It is a data communication flow chart of the present invention;

[0062] Figure 3 It is a schematic diagram of the calibration principle of the sharp point instrument in the present invention;

[0063] Figure 4 It is a schematic diagram of the calibration principle of the linear instrument in the present invention;

[0064] Figure 5 It is a schematic diagram of the calibration principle of the planar device in the present invention;

[0065] Figure 6 It is a flow chart of visual tracking of surgical instruments in the present invention. DETAILED DESCRIPTION

[0066] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and embodiments:

[0067] like Figures 1 to 6 As shown, a surgical instrument calibration and visual tracking method for optical navigation surgery, the following steps:

[0068] ⅰ. Establish data communication between the optical navigation and positioning equipment and the computer to obtain the position and posture data of different optical tracers;

[0069] ⅱ. Calibrate the sharp-point instrument based on the position data of the optical tracer;

[0070] ⅲ. Calibrate linear instruments based on the position data of the optical tracer;

[0071] ⅳ. Calibrate planar instruments based on the position and posture data of the optical tracer;

[0072] v. Perform visual tracking of surgical instruments.

[0073] Step i: Establish data communication between the optical navigation and positioning device and the computer to obtain the position and posture data of different optical tracers. The specific process is as follows:

[0074] 1a. Initialize and establish a connection between the optical navigation positioning and the data communication thread and the main thread between the computer;

[0075] 1b. According to the optical tracer number connected to different surgical instruments, correctly load the rigid body file of the corresponding optical tracer, activate the tool handle, and obtain the position information of the loaded optical tracer;

[0076] 1c. Using the data request function in the main thread to call the dynamic link library of the optical positioning system, the data in the data buffer is transferred to the main thread;

[0077] 1d. According to the optical tracer posture information data, the optical tracer posture matrix is ​​calculated.

[0078] Step 1b also includes caching of the position information, that is, storing the acquired position information in a data buffer and waiting for the main thread to call the data.

[0079] Step 1c also includes the following process:

[0080] With the help of QTTimer, the data request function in the main thread is called at fixed time intervals to achieve real-time data transmission.

[0081] Step ii: Based on the position and posture data of the optical tracer, the sharp point instrument is calibrated. The specific process is as follows:

[0082] First, the sharp-point surgical instrument and the calibration tool are placed within the field of view of the optical positioning device;

[0083] Then, the pose matrix is ​​combined with the vtkAxesActor component in the VTK toolkit to display the spatial position and pose of all optical tracer coordinate systems in the visualization module;

[0084] After that, make sure that the reference coordinate system of the sharp-point surgical instrument and the calibration tool is correctly displayed in the visualization module;

[0085] Finally, the three-dimensional coordinates of the instrument tip in the reference coordinate system are calculated through the tip instrument calibration method.

[0086] Step ii: Based on the position data of the optical tracer, the cusp instrument calibration method is performed. The specific process is as follows:

[0087] 2a. Place the tip of the instrument at the calibration tool tip geometry to obtain the three-dimensional coordinate expression of the tip of the instrument in the optical positioning system coordinate system;

[0088] 2b. Rotate the sharp-point instrument around the sharp-point geometric structure of the calibration tool so that the trajectory of the reflective marker ball on the instrument falls on a spherical surface with the end of the instrument as the center;

[0089] 2c. Using an optical positioning device to record the spatial position of the optical tracer at n moments, and record the i-th coordinate expression of the geometric structure of the cusp of the calibration tool in the coordinate system of the optical positioning device;

[0090] 2d. Express the least squares method in matrix form to obtain the objective function;

[0091] 2e. Obtain the optimal solution under the condition of minimizing the objective function and complete the calibration of the sharp-point surgical instrument.

[0092] Step iii: Based on the position data of the optical tracer, the linear instrument is calibrated. The specific process is as follows:

[0093] First, place the linear surgical instrument and the calibration tool within the field of view of the optical positioning device;

[0094] Then, confirm that the reference coordinate systems of the linear surgical instrument and the calibration tool are correctly displayed in the visualization module;

[0095] Finally, the calibration in the linear instrument reference coordinate system is completed through the linear instrument calibration method.

[0096] Step iii: Based on the position data of the optical tracer, a linear instrument calibration method is performed in the linear instrument calibration. The specific process is as follows:

[0097] First, the linear surgical instrument is inserted into the linear geometry of the calibration tool to make it fit tightly;

[0098] Then, the conversion relation expression of the linear surgical instrument is obtained;

[0099] Then, according to the conversion relationship expression, the direction vector of the linear surgical instrument in the coordinate system is obtained;

[0100] Then, according to the conversion relationship expression, the coordinates of the end points of the linear surgical instrument in the coordinate system are obtained;

[0101] Then, the obtained direction vector and coordinates are used to obtain the spatial position of the linear instrument in the reference coordinate system to complete the calibration of the linear surgical instrument.

[0102] Step iv: Based on the position data of the optical tracer, the planar instrument is calibrated. The specific process is as follows:

[0103] First, place the planar surgical instrument and calibration tool within the field of view of the optical positioning device;

[0104] Then, confirm that the reference coordinate system of the planar surgical instrument and the calibration tool is correctly displayed in the visualization module;

[0105] Finally, the calibration in the planar instrument reference coordinate system is completed through the planar surgical instrument calibration method.

[0106] Step iv: Based on the position data of the optical tracer, a planar surgical instrument calibration method is performed in the planar instrument calibration. The specific process is as follows:

[0107] First, a calibration coordinate system of the plane instrument and the plane geometric structure of the calibration tool is established, and the plane surgical instrument is inserted into the plane geometric structure of the calibration tool to make them fit tightly;

[0108] Then, the conversion relation expression of the planar surgical instrument is obtained;

[0109] Then, according to the conversion relationship expression, the homogeneous transformation matrix of the plane structure calibration coordinate system relative to the surgical instrument reference coordinate system is obtained;

[0110] Finally, the homogeneous transformation matrix is ​​used to complete the planar device calibration.

[0111] Specifically, Figure 1As shown, the optical navigator communication module is connected to the point instrument calibration module, the linear instrument calibration module, and the plane instrument calibration module. The point instrument calibration module, the linear instrument calibration module, and the plane instrument calibration module are connected in parallel. The point instrument calibration module, the linear instrument calibration module, and the plane instrument calibration module are all connected to the information storage module, and the information storage module is connected to the visualization module.

[0112] The optical navigator communication module is used to obtain the position information of the optical tracer in the optical positioning device; the data communication thread in the module establishes data transmission communication with the optical positioning device through the COM serial port, and correctly loads the rigid body file (.rom) of the corresponding optical tracer according to the number of the optical tracer used. After activating the optical tracer used, the optical positioning device transmits the collected posture information of the corresponding optical tracer in the coordinate system of the optical positioning device to the system, and classifies and stores the optical tracer posture information for subsequent calibration and visualization.

[0113] The optical navigator indirectly tracks the spatial position of the optical tracer by tracking the reflective marker balls fixed on the optical tracer: the optical tracer establishes an optical tracer coordinate system according to the distribution of the reflective marker balls thereon, the optical positioning device locates the coordinates of the reflective marker balls in the optical positioning device coordinate system, and uses the coordinates to calculate the position information of the optical tracer coordinate system in the optical positioning device coordinate system, thereby realizing the position tracking of the optical tracer.

[0114] The above calculations are completed in the optical positioning system. After the optical positioning system establishes a connection with the optical navigator communication module, the optical navigator communication module can call the optical tracer position information in the optical positioning system as needed.

[0115] Specifically, the tip instrument calibration module is used to calibrate the probe instrument for collecting marking points during surgery. With the help of the tip groove with known position information on the calibration tool and the tip calibration algorithm, the three-dimensional coordinates of the instrument tip in the instrument reference coordinate system are calculated to complete the tip surgical instrument calibration.

[0116] The pointed instrument reference coordinate system is a coordinate system of an optical tracer fixedly connected to the surgical instrument.

[0117] Specifically, the linear instrument calibration module is used to calibrate linear surgical instruments such as surgical puncture needles and bone screws. With the help of the cylindrical hole structure with known position information on the calibration tool, the endpoint position and axial unit vector of the linear geometric structure on the surgical instrument in the instrument reference coordinate system are calculated based on the knowledge of spatial rigid body transformation to complete the calibration of the linear surgical instrument.

[0118] The linear instrument reference coordinate system is a coordinate system of an optical tracer fixedly connected to the surgical instrument.

[0119] Specifically, the planar instrument calibration module is used to calibrate planar surgical instruments such as scalpels and surgical bone saws. With the help of the planar structure with known position information on the calibration tool, the position of the planar geometric structure on the surgical instrument in the instrument reference coordinate system is calculated based on the knowledge of spatial rigid body transformation to complete the planar surgical instrument calibration.

[0120] The planar instrument reference coordinate system is a coordinate system of an optical tracer fixedly connected to the surgical instrument.

[0121] The calibration tool is used to assist in the calibration process of different surgical instruments. The calibration tool is fixedly connected to an optical tracer, and the optical tracer coordinate system is used as the reference coordinate system of the calibration tool; the calibration tool has geometric structures such as sharp points, cylindrical holes, and planes, which are used to closely cooperate with the ends of different surgical instruments to complete the calibration process; the position information of the geometric structure in the calibration tool coordinate system is obtained through the CAD model of the calibration tool.

[0122] Specifically, the position information storage module is used to classify and store the position information relationships obtained after the calibration is completed, which is subsequently used for tracking and displaying surgical instruments during the operation.

[0123] Specifically, the visualization module is used to build a three-dimensional virtual scene, establish an optical tracer coordinate system model, and establish a surgical instrument surface model. According to the optical tracer position information transmitted by the optical positioning system, real-time posture transformation is applied to the optical tracer coordinate system model and the surgical instrument surface model, and the spatial position of the optical tracer coordinate system and the surgical instrument is displayed in real time, thereby realizing visual observation of the calibration process and visual tracking of the surgical instrument.

[0124] Yet another embodiment

[0125] A surgical instrument calibration and visual tracking method for optical navigation surgery, comprising the following steps:

[0126] ⅰ. Establish data communication between the optical navigation and positioning equipment and the computer to obtain the position and posture data of different optical tracers;

[0127] ⅱ. Calibrate the sharp-point instrument based on the position data of the optical tracer;

[0128] ⅲ. Calibrate linear instruments based on the position data of the optical tracer;

[0129] ⅳ. Calibrate planar instruments based on the position and posture data of the optical tracer;

[0130] v. Perform visual tracking of surgical instruments.

[0131] Step i. Establish data communication between the optical navigation and positioning device and the computer to obtain the position and posture data of different optical tracers. In this stage, the optical positioning device and the computer are connected via a network cable to establish data transmission between the optical positioning system and the computer to obtain the position and posture data of different optical tracers.

[0132] As an implementation method of the present invention, a specific method may be: acquiring the position data of the optical tracer based on the COM serial port, specifically including:

[0133] 1a. In the custom data communication thread, correctly set the IP and port number of the optical positioning system, initialize the system, and establish a connection between the data communication thread and the main thread.

[0134] 1b. According to the optical tracer number connected to different surgical instruments, correctly load the rigid body file (.rom) of the corresponding optical tracer, activate the tool handle, obtain the position information of the loaded optical tracer, store it in the data buffer and wait for the main thread to call the data.

[0135] 1c. Define the data request function in the main thread. The data request function can transfer the data in the data buffer to the main thread by calling the dynamic link library of the optical positioning system. Use the QTTimer timer to call the data request function at fixed time intervals to realize real-time data transmission.

[0136] 1d. According to the optical tracer pose information data obtained in 1c, calculate the pose matrix of the optical tracer:

[0137] q=[q0 q1 q2 q3 q4 q5 q6]

[0138]

[0139] Among them, q represents the optical tracer posture information data, the first four bits are quaternion representing the posture of the optical tracer coordinate system, and the last three bits represent the origin position of the optical tracer coordinate system; T represents the optical tracer posture matrix, which can be used for subsequent calibration and tracking of instruments.

[0140] Specifically, based on the position and posture data of the optical tracer, the sharp-point instrument calibration is performed. Enter the sharp-point instrument calibration module, place the sharp-point surgical instrument and the calibration tool within the field of view of the optical positioning device, and display the spatial position and posture of all optical tracer coordinate systems in the visualization module based on the obtained spatial position and posture of the optical tracer, combined with the vtkAxesActor component in the VTK toolkit. After confirming that the reference coordinate systems of the sharp-point surgical instrument and the calibration tool are correctly displayed in the visualization module, as shown in the attached figure. Figure 3 As shown, the three-dimensional coordinates of the instrument tip in the reference coordinate system are calculated by the tip instrument calibration method. The specific calibration process and principle are as follows:

[0141] First, the tip of the sharp-point instrument is placed at the sharp-point geometry of the calibration tool. At this moment, the three-dimensional coordinates of the tip of the sharp-point instrument in the optical positioning system coordinate system can be expressed as

[0142]

[0143] Wherein, {W} and {B} represent the optical positioning system coordinate system and the cusp instrument reference coordinate system, respectively; B P is the coordinate of the end point of the sharp-point instrument in the coordinate system {B}, which is the parameter to be determined; is the homogeneous transformation matrix of coordinate system {B} relative to coordinate system {W}, obtained by (1). Taking into account factors such as stereoscopic vision positioning error, the least squares method is used to calculate B The optimal solution of P is used as the cusp calibration parameter.

[0144] Then, the sharp-point instrument is rotated around the sharp-point geometric structure of the calibration tool so that the trajectory of the reflective marker ball on the instrument falls on the spherical surface with the end of the instrument as the center. The optical positioning device is used to record the spatial position of the optical tracer at n moments. The i-th coordinate of the sharp-point geometric structure of the calibration tool in the coordinate system of the optical positioning device is recorded as

[0145]

[0146] Where {A} represents the reference coordinate system of the calibration tool, A P is the coordinate of the calibration tool tip geometry in the coordinate system {A}, which is a known parameter; is the homogeneous transformation matrix of the coordinate system {A} relative to the coordinate system {W} at the i-th moment.

[0147] Finally, the least squares method is expressed in matrix form, and the objective function is defined as

[0148]

[0149] in, represents the homogeneous transformation matrix of the coordinate system {B} relative to the coordinate system {W} at the i-th moment, Represents the three-dimensional coordinates of the end point of the cusp instrument at the i-th moment in the optical positioning system coordinate system {W}. Minimize the objective function to obtain the optimal solution B P, complete the calibration of the sharp point surgical instrument.

[0150] Specifically, based on the position data of the optical tracer, the linear instrument calibration is performed. Enter the linear instrument calibration module, place the linear surgical instrument and the calibration tool within the field of view of the optical positioning device, similar to the point instrument calibration method, and confirm that the reference coordinate system of the linear surgical instrument and the calibration tool is correctly displayed in the visualization module, as shown in the attached figure. Figure 4As shown, the linear surgical instrument is inserted into the linear geometric structure of the calibration tool to make it fit tightly, and the following conversion relationship exists:

[0151]

[0152]

[0153] Among them, {W}, {A}, and {C} represent the optical positioning system coordinate system, the calibration tool reference coordinate system, and the linear surgical instrument reference coordinate system, respectively. (u, v, w) T Represents the direction vector of the linear surgical instrument in the coordinate system {C}, which is the parameter to be determined; (x, y, z) T Represents the direction vector of the calibration tool linear geometry in the coordinate system {A}, which is a known parameter. C P represents the coordinates of the endpoints of the linear surgical instrument in the coordinate system {C}, which is the parameter to be determined; A P represents the coordinates of the endpoints of the calibration tool straight line geometry in the coordinate system {A}, which is a known parameter. represents the homogeneous transformation matrix of coordinate system {A} relative to coordinate system {W}, Represents the homogeneous transformation matrix of coordinate system {C} relative to coordinate system {W}.

[0154] Using known parameters to find (u,v,w) T and C P can accurately represent the spatial position of the linear instrument in its reference coordinate system and complete the calibration of the linear surgical instrument.

[0155] Specifically, based on the position data of the optical tracer, the planar instrument calibration is performed. Enter the planar instrument calibration module, place the planar surgical instrument and the calibration tool within the field of view of the optical positioning device, and confirm that the reference coordinate system of the planar surgical instrument and the calibration tool is correctly displayed in the visualization module, as shown in the attached figure. Figure 5 As shown, a calibration coordinate system of the plane instrument and the plane geometric structure of the calibration tool is established, and the plane surgical instrument is inserted into the plane geometric structure of the calibration tool to make it fit tightly, then the following conversion relationship exists:

[0156]

[0157] Among them, {W}, {A}, {D}, and {M} represent the optical positioning system coordinate system, the calibration tool reference coordinate system, the planar surgical instrument reference coordinate system, and the planar structure calibration coordinate system, respectively. represents the homogeneous transformation matrix of the coordinate system {M} relative to the coordinate system {D}, which is the parameter to be determined; Represents the homogeneous transformation matrix of coordinate system {M} relative to coordinate system {A}, which is a known parameter. represents the homogeneous transformation matrix of coordinate system {A} relative to coordinate system {W}, Represents the homogeneous transformation matrix of coordinate system {D} relative to coordinate system {W}. Using known parameters, we can obtain Complete the planar instrument calibration.

[0158] Specifically, step V performs visual tracking of surgical instruments. After the surgical instrument calibration is completed, the visualization module can display the position and posture of the surgical instrument in real time, as shown in the attached figure. Figure 6 As shown, the specific process is as follows:

[0159] 5a. Construct a three-dimensional model of the surgical instrument using the three-dimensional CAD modeling method according to the physical size of the surgical instrument, and convert it into a three-dimensional surface model of the surgical instrument through STL file format conversion for visualization of the surgical instrument.

[0160] 5b. Use the VTK toolkit to create a virtual 3D scene, import the 3D surface model of the surgical instrument into the virtual 3D scene, and use the vtkActor component to realize the visualization of the model.

[0161] In the initial import state, the model coordinate system of each model coincides with the world coordinate system of the three-dimensional virtual scene.

[0162] 5c. The coordinate system of the optical positioning system is considered to coincide with the world coordinate system of the three-dimensional virtual scene. According to the obtained pose matrix of the optical tracer and the above calibration results, the pose matrix of the surgical instrument in the coordinate system of the optical positioning system at a certain moment can be obtained. W T.

[0163] With the help of vtkMatrix4x4 components and vtkTransform components, we can use the above pose matrix W T, transforms the position and posture of the model in the VTK virtual 3D scene so that the virtual model is synchronized with the surgical instrument posture in the real space.

[0164] 5d. Refresh the data every 50ms to update the optical tracer position information and change the position and posture of the surgical instrument model in the virtual scene to achieve real-time visual tracking of the surgical instrument.

[0165] The present invention can realize preoperative calibration for different surgical instruments by means of point, line and surface calibration tools and optical positioning, and improves the calibration accuracy and required time of surgical instruments, thereby improving efficiency.

[0166] The present invention classifies and transmits the position information involved in the calibration process internally, reducing the difficulty of operation for doctors; the visualization module provides an intuitive display of the spatial position of surgical instruments, realizes the visualization tracking of the calibration process and the surgical instruments after calibration, and improves the accuracy of the calibration process.

Claims

1. A surgical instrument calibration and visual tracking method for optical navigation surgery, characterized in that: Follow these steps: (i) establishing data communication between the optical navigation and positioning device and the computer to obtain position and posture data of different optical tracers; (ii) Calibrate the tip instrument based on the position and posture data of the optical tracer; (iii) Calibrate linear instruments based on the position data of the optical tracer; (iv) Planar instrument calibration based on the position data of the optical tracer; (v) Perform visual tracking of surgical instruments; Step (i) establishes data communication between the optical navigation positioning and the computer to obtain the position and posture data of different optical tracers. The specific process is as follows: (1a) Initialization is performed to establish a connection between the data communication thread and the main thread between the optical navigation positioning and the computer; (1b) According to the optical tracer number connected to different surgical instruments, correctly load the rigid body file of the corresponding optical tracer, activate the tool handle, and obtain the position information of the loaded optical tracer; (1c) using the data request function in the main thread to call the dynamic link library of the optical positioning system to transfer the data in the data buffer to the main thread; (1d) calculating the pose matrix of the optical tracer according to the pose information data of the optical tracer; Step (ii) performs point instrument calibration based on the position and posture data of the optical tracer. The specific process is as follows: First, the sharp-point surgical instrument and the calibration tool are placed within the field of view of the optical positioning device; Then, the pose matrix is ​​combined with the vtkAxesActor component in the VTK toolkit to display the spatial position and pose of all optical tracer coordinate systems in the visualization module; After that, make sure that the reference coordinate system of the sharp-point surgical instrument and the calibration tool is correctly displayed in the visualization module; Finally, the three-dimensional coordinates of the instrument cusp in the reference coordinate system are calculated by the cusp instrument calibration method; The three-dimensional coordinates of the instrument tip in the reference coordinate system are calculated by the tip calibration method. The specific calibration process and principle are as follows: First, the tip of the sharp-point instrument is placed at the sharp-point geometry of the calibration tool. At this moment, the three-dimensional coordinates of the tip of the sharp-point instrument in the optical positioning system coordinate system can be expressed as Wherein, {W} and {B} represent the optical positioning system coordinate system and the cusp instrument reference coordinate system, respectively; B P is the coordinate of the end point of the sharp-point instrument in the coordinate system {B}, which is the parameter to be determined; is the homogeneous transformation matrix of coordinate system {B} relative to coordinate system {W}. Taking into account factors such as stereoscopic vision positioning error, the least squares method is used to calculate B The optimal solution of P is used as the cusp calibration parameter; Then, the sharp-point instrument is rotated around the sharp-point geometric structure of the calibration tool, so that the motion trajectory of the reflective marker ball on the instrument falls on the spherical surface with the end of the instrument as the center. The optical positioning device is used to record the spatial position of the optical tracer at n moments, and the i-th coordinate of the sharp-point geometric structure of the calibration tool in the coordinate system of the optical positioning device is recorded as Where {A} represents the reference coordinate system of the calibration tool, A P is the coordinate of the calibration tool tip geometry in the coordinate system {A}, which is a known parameter; is the homogeneous transformation matrix of the coordinate system {A} relative to the coordinate system {W} at the i-th moment; Finally, the least squares method is expressed in matrix form, and the objective function is defined as in, represents the homogeneous transformation matrix of the coordinate system {B} relative to the coordinate system {W} at the i-th moment, Represents the three-dimensional coordinates of the end point of the cusp instrument at the i-th moment in the optical positioning system coordinate system {W}, and minimizes the objective function to obtain the optimal solution B P, complete the calibration of the sharp point surgical instrument.

2. The method for surgical instrument calibration and visual tracking for optical navigation surgery according to claim 1, characterized in that: Step (1b) also includes caching the position information, that is, storing the acquired position information in a data buffer and waiting for the main thread to call the data.

3. The method for surgical instrument calibration and visual tracking for optical navigation surgery according to claim 1, characterized in that: In step (1c), The process includes: With the help of QTTimer, the data request function in the main thread is called at fixed time intervals to achieve real-time data transmission.

4. The method for surgical instrument calibration and visual tracking for optical navigation surgery according to claim 1, characterized in that: Step (ii) performs a cusp instrument calibration method based on the position and posture data of the optical tracer. The specific process is as follows: (2a) placing the tip of the sharp-point instrument at the sharp-point geometric structure of the calibration tool, and obtaining the three-dimensional coordinate expression of the tip of the sharp-point instrument in the coordinate system of the optical positioning system; (2b) rotating the pointed instrument around the pointed geometry of the calibration tool so that the trajectory of the reflective marker ball on the instrument falls on a spherical surface with the tip of the instrument as the center; (2c) using an optical positioning device to record the spatial position of the optical tracer at n moments, and recording the i-th coordinate expression of the geometric structure of the tool tip in the coordinate system of the optical positioning device; (2d) Express the least squares method in matrix form to obtain the objective function; (2e) Obtain the optimal solution under the condition of minimizing the objective function and complete the calibration of the sharp-point surgical instrument.

5. The method for surgical instrument calibration and visual tracking for optical navigation surgery according to claim 1, characterized in that: Step (iii) performs linear instrument calibration based on the position and posture data of the optical tracer. The specific process is as follows: First, place the linear surgical instrument and the calibration tool within the field of view of the optical positioning device; Then, confirm that the reference coordinate systems of the linear surgical instrument and the calibration tool are correctly displayed in the visualization module; Finally, the calibration in the linear instrument reference coordinate system is completed through the linear instrument calibration method.

6. The method for surgical instrument calibration and visual tracking for optical navigation surgery according to claim 5, characterized in that: Step (iii) performs a linear instrument calibration method in a linear instrument calibration based on the position and posture data of the optical tracer. The specific process is as follows: First, the linear surgical instrument is inserted into the linear geometry of the calibration tool to make it fit tightly; Then, the conversion relation expression of the linear surgical instrument is obtained; Then, according to the conversion relationship expression, the direction vector of the linear surgical instrument in the coordinate system is obtained; Then, according to the conversion relationship expression, the coordinates of the end points of the linear surgical instrument in the coordinate system are obtained; Then, the obtained direction vector and coordinates are used to obtain the spatial position of the linear instrument in the reference coordinate system to complete the calibration of the linear surgical instrument.

7. The method for surgical instrument calibration and visual tracking for optical navigation surgery according to claim 1, characterized in that: Step (iv) performs planar instrument calibration based on the position and posture data of the optical tracer. The specific process is as follows: First, place the planar surgical instrument and calibration tool within the field of view of the optical positioning device; Then, confirm that the reference coordinate system of the planar surgical instrument and the calibration tool is correctly displayed in the visualization module; Finally, the calibration in the planar instrument reference coordinate system is completed through the planar surgical instrument calibration method.

8. The method for surgical instrument calibration and visual tracking for optical navigation surgery according to claim 1, characterized in that: Step (iv) performs a planar surgical instrument calibration method based on the position data of the optical tracer. The specific process is as follows: First, a calibration coordinate system of the plane instrument and the plane geometric structure of the calibration tool is established, and the plane surgical instrument is inserted into the plane geometric structure of the calibration tool to make them fit tightly; Then, the conversion relation expression of the planar surgical instrument is obtained; Then, according to the conversion relationship expression, the homogeneous transformation matrix of the plane structure calibration coordinate system relative to the surgical instrument reference coordinate system is obtained; Finally, the homogeneous transformation matrix is ​​used to complete the planar device calibration.

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