Study Of A Virtual Training System For Mandibular Angle Plastic Surgery

Virtual Reality (VR) is a high-end user interface that requires a synthesis generation of the human factors to investigate all aspects of human performance. VR applications strive to simulate real or imaginary scenes with which users can interact and perceive the effects of their action in real time via all five sensorial channels, including visual, auditory, tactile, smell, and taste. Surgery simulator is one of the perfect applications for virtual reality in medicine area. It presents a realistic and feasible approach to train inexperienced surgeons within a safe environment, plays more and more important role in medical field and also changes the world of surgical training. With the help of the virtual surgery simulator, the surgeon can immerse into the realistic environment to learn and experience how to operate so many kinds of surgical instruments in regular situation and how to handle the urgent happenings in advance.This thesis dissertation is mainly devoted to study the main problems of simulating virtual training system for mandibular angle plastic surgery, especially focuses on establishing interaction model between the virtual burr-bone surgical tool and the bone model, designing a hybrid bone surgery training system based on visual and haptic simulation, and proposing a new haptic rendering model based on Impulse Theorem and Coulomb Law.First, we introduce the surface rendering method of volume data visualization and specify how to create the three-dimensional model of the skull with Marching Cubes method. During the pre-processing stage of three three-dimensional reconstruction of the skull model, a new method using 2-D Gabor filters for edge detection and extraction is presented, and experimental results show it is efficient while extracting the edge of MRI medical images. Then, we realize the algorithm to subdivide the original model of the skull in order to create the force feedback model in the next step. Second, according to the requirement of the virtual surgery for mandibular angle plastic surgery, we design the specified surgical tool model and propose the multi-points collision detection model based on AABB Tree data structure. Considering the rotation of the tool having a huge impact force on the bone and making the bone milled and abraded, we decide to reckon the bone and the tool as rigid body in the simulation process of the virtual surgery. With the former analysis, we simulate the collision process between them and propose a haptic rendering model based on Impulse Theorem and Coulomb Law to calculate the force produced because of the contact between the bone and the tool, which gives prominence to the rotation factor of the tool. Then, a simple surface deformation method needs not to change the topology structure is proposed. Finally, we test the force model from many different kinds of sides, and analyze the key factors which affect the force the most, and give the relation chart of them.