Research On Key Technologies Of VR System For Pedicle Screw Insertion Surgery

Accurate placement of pedicle screws is one of the skills that spine surgeons must master,and the procedure is guided by the surgeon's sense of touch through the device.The traditional doctor's training method for this operation is to practice the pedicle screw placement process on the spine specimen or the dummy-based training simulator.Due to the scarcity of the sample and the high cost,it is difficult for interns to have enough opportunities for corresponding surgical training With the rapid development of new technologies,researchers have combined virtual reality(Virtual Reality)technology with clinical medicine to develop a virtual surgery simulation system(Virtual Reality Surgery System,VRSS),which provides a new idea for surgery training.This paper research on the key technologies of the simulation system for pedicle screw placement surgery based on virtual reality,aiming to achieve a more complete surgical system.The main contributions of this paper are as follows:First,this paper analyzes the needs of a complete virtual surgery system,designs the overall framework of a virtual simulation system for pedicle screw placement surgery,and establishes a framework for a dual interactive channel simulation system based on haptics and vision.The system is designed from two aspects:hardware and software.The hardware part includes computer workstation,display,force feedback device and Immersive Virtual Reality Surgery Simulator(IVRSS).The software part uses the OpenGL graphics rendering library to achieve graphics rendering to achieve visual interaction.The OpenHaptics haptic rendering library is used for secondary development to achieve tactile rendering,and a software implementation plan for pedicle screw placement surgery simulation system is designed;Then,in order to better restore the real surgical scene,this paper uses real human CT data for 3D reconstruction.First,pre-process the CT graphics collected by the hospital,then use the technique based on the area growth method and image fusion method to extract the region of interest in the image segmentation process,and finally realize the three-dimensional visualization of the spinal anatomical model based on the MC algorithm.The 3D reconstruction module built in this paper supports rotation,scaling and cropping of arbitrary slices;Next,the tactile feedback model between the high-speed rotating bone drill and bone tissue is derived.Efficient collision detection algorithm performs real-time detection on the virtual surgical instruments and surgical objects in the system.If the collision detection result occurs,the principle of impulse dynamics is used in the pedicle screw placement in the virtual surgery.According to the status information of the bone drill,real-time prediction and update of the force,Then transmitted the information of force to the user through the force feedback device to realize the simulation of the force feedback characteristics of virtual surgery;Finally,this paper uses GPU acceleration technology based on CUD A to realize the operation simulation of bone drilling surgery for pedicle screw placement.CPU and GPU work together to store and transfer information on voxel nodes,which greatly speeds up the response speed of vision and touch,improves the refresh rate and real-time performance,and provides the simulation of pedicle screw operation based on mixed data model.Finally,a simulation system was built to integrate various modules to realize the simulation system.The simulation experiment results show that the pedicle screw placement simulation system built with this technology has a video stream refresh rate above 30 Hz and a tactile response refresh rate above 500 Hz,which can effectively reproduce the virtual operation of pedicle screw placement.