Research On Key Technologies Of Virtual Endoscopic Surgery Training System

Digestive endoscopy is an important way to diagnose and treat gastrointestinal diseases.With the increasing number of endoscopists,the training of endoscopists has become a hot spot in clinical education and research in recent years.Virtual surgery simulation provides a solution to this problem.Compared with traditional training methods,virtual surgery has the advantages of saving training time and cost,standardizing the training process and reducing medical risks,which can improve the success rate of surgery.Based on the above background and purpose,this paper studies and implements the key technologies of virtual endoscopic surgery training design,including geometric modeling technology,collision detection technology,tactile feedback technology,deformation modeling and soft tissue cutting,and virtual surgical platform design.The main research contents are as follows:(1)In order to improve the real-time performance of the system,the method of surface model for rendering and display and volume model for deformation calculation are proposed to jointly establish the soft tissue geometric model.Using real CT data to reconstruct the surface model of the digestive tract tissue for rendering and display in the virtual scene;Delaunay tetrahedral meshing is performed after the surface model mesh is optimized to generate a volume mesh,which is used for surgical tools and digestive tract.Deformation cutting calculation of soft tissue when soft tissue interacts.It not only ensures that the soft tissue model has real texture details,but also has a good deformation effect.(2)According to the characteristics of endoscopic surgical tools,design a corresponding collision detection algorithm,and calculate and detect the collision state through the spatial position relationship of points,lines,surfaces,and bodies.When a collision occurs,it can respond in real time and return the coordinates of the collision point;in order to enhance the immersion of training,a haptic feedback algorithm is designed based on the spring-damping model,and a force feedback device is connected to realize haptic sensing during surgical training.(3)Realize soft tissue deformation based on position dynamics(PBD)algorithm,propose a data grouping method solved by backtracking algorithm,solve the constraint conflict problem of PBD constraints in the process of GPGPU accelerated calculation,and realize real-time Gaussian Seidel iteration of PBD algorithm;According to the shape characteristics of mucous membrane and internal tissue,the vertex replication and split surface cutting algorithm of Bezier curve optimization incision and the volume mesh removal method suitable for electric knife cutting were designed respectively,and the details of mesh reconstruction and update were solved.(4)Finally,the algorithms are integrated in Unity3D,the points of attention for the combination of each algorithm are explained and solutions are proposed;the improved model-view-controller(MVC)framework is used to design software-related software such as UI interface,establish a virtual operating environment,and Connect the Omega.7 force feedback device and the HTC Vive head display device to build a virtual endoscopic surgery training system.