Research On Cutting Simulation Of Soft Tissue In A Virtual Liver Surgery System

With the development of modern medicine, more and more high-tech technique has been applied to clinical surgery. However it ushered a new problem which is the surgeon’s skills training are getting more and more complex and the cost the training is increasing too. The rise of the virtual reality technology since 1990 s gives the doctors a totally new way to solve these problems. The virtual surgery system is able to help to train the doctors which can save the train costs and shorten the train time.Virtual surgery system was initially a simple multimedia technology, and only used as an auxiliary tool which can help them during the surgery. As the technology advances, and the computer are becoming more and more powerful, people began to try to the virtual surgery system to simulate a whole surgery in reality. The virtual endoscopic surgery and the virtual micrographic surgery are relatively successful in this field, but the simulation of major surgery, such as liver cutting surgery, is not good enough at present. There are two main reasons for this problem, the first one is that there is no suitable interaction device available for the system and the second one is that there is not a good simulation algorithm for the deformation and cutting operation of the soft issue.To address this problem, we have done a lot of research work on the simulation for the deformation and cutting operation of the soft issue and built a virtual liver resection surgery system consists of two PHANToM devices and one PC. For the body’s soft tissues and organs variety, the physical properties of them are different. Therefore, the deformation model cannot be single in the system. And we need to give the organs with different physical properties with different deformation models. After all of these works done, the users can interact with our system by touch feeling and vision.There are three main methods can simulate the soft tissues, mass spring system method, finite element method and position based dynamics method. We have done a deep research on the mass spring system method and position based dynamics method. And there are four main contributions of our work:1) Based on these two methods above, we develop two improved algorithms to simulate the different soft tissues and organs. We present a lattice-based isomerism modeling method, and solve the contradiction between the performance and efficiency in the traditional methods.2) Based on the lattice-based isomerism modeling method, we develop a novel cutting simulation of the soft tissues. We use the replica of the cut elements instead of subdivide them to reduce the silvers would appear in the simulation.3) We design an improved adaptive Delaunay algorithm to solve the two main drawbacks of the traditional one, and we applied this algorithm into the reconstruction step of the cutting simulation.4) We design the simulation algorithms of soft tissues deformation and cutting based on the need of the virtual liver surgery system. Our methods have advantages on robust and efficiency, and the accuracy of our methods is also stand out. We have applied these algorithms in the virtual liver surgery system, and they did a good job on the simulation of the liver and other organs. The result shows that our methods are good at robust and efficiency, and can be qualified a virtual major surgery system.