Research On The Technology For Endoscopic Surgery Simulation Based On 3D Virtual Reality

With the development of computer technology, the virtual technology is playing an important role in the medical field, the virtual surgery (also known as surgery simulation) has been accepted by the medical field step by step, and the virtual surgery has become a very important branch of the medical informatics.The endoscopic surgery is very complicated, so the clinicians must need a long period of training to gain the capacity of good hand-eye coordination. Using virtual reality technology to build up virtual surgery environment and to implement endoscopic surgery simulation training, can solve the defects of high cost and unable-duplicating in the traditional training mode, which currently has become a very important issue.According to the current research results of virtual surgery, most reseach focuse ong the medical image segmentation, reconstruction, physical model, the study of force-feedback model is in the initial stage.This paper focuses on the key algorithm of collision detection, soft tissue deformation, cutting and suturing-line knotting in the three-dimensional virtual reality simulation of endoscopic surgery, and the construction the training system for endoscopic surgery has been also discussed.In collision detection, according to the characteristics of endoscopic surgery, the mixing collision detection models of surgical instruments and soft tissue were build, a detection algorithm based on mixed-level bounding box was brought up. Based on analysis of experiment results, this algorithm can improved bounding tightness of the bounding box for the surgical instruments and the soft tissue, increase the speed of collision detection and the accuracy of the collision point.To improve the computing speed of the soft tissue deformation simulation, according to the biomechanical characteristics of the abdominal organs, an improved force-point addressing algorithm and the neighboring points query algorithm based on triangle area matching were brought up. According to the experiment result, these algorithms can improve the response speed of deformation simulation, the real-time characteristics and the accuracy of deformation simulation computing.In the realization of soft tissue cutting simulation, to consider the defects in current cutting simulation algorithm, a new cutting-splitting algorithm based on vertex replication and a new cutting-fining algorithm based on vertex moving were proposed. Comparing the experiment results, these algorithms can reduce the increase number of the grid cell after cutting, and improve the cut surface of the smooth sophistication, increase the speed of cutting simulation response.In the realization of suturing-line knotting similation, to conside the characteristics of suturing-line, the 3-D model of suturing-line was build, a transformating algorithm of the suturing-line's position based on continuous control points and a collision detection algorithm based on sphere bounding were proposed, the simulation of suturing-line's knotting process was achieved.