The Research Of Tissue Deformation Based On Mass-Spring Model

Along with unceasing consummation and development of the modem medical technology, the perfect combination of virtual reality technology and surgery formed the important application in medical field—Virtual Surgery. The virtual surgery provides the true reappearance of surgical scene in vision and touch for the users, it can applied in surgeon training, surgical evaluation of the result and surgical navigation etc. Virtual surgery plays an important role in extending surgery training and complicated operation. As a result of the doctors contact most is the soft tissue in surgery, so the simulation of soft tissue deformation is one of the key technologies in virtual surgery, and it regulates the development of virtual surgery. During the simulation of soft tissue deformation, the system must satisfy the stability and the precision when it generates deformation. At the same time, as the simulation system of virtual surgery must guarantee the real-time interaction, so real-time became one of the most important requirements in soft tissue deformation. So, the deformation of soft tissue in virtual surgery must meet the requirement of stability, precision and real-time. In this paper, it has a research on the technology of soft tissue deformation in virtual surgery simulation based on the three aspects above.In stability, this paper compares and analyses the physical models of soft tissue deformation, and chooses the mass-spring model to build the system. By improved regular hexagon topology based on mass-spring model, it guarantees the stability in deforming. In precision, by establishing and analyzing the dynamics model of the soft tissue deformation, we choose mid-point method as the numerical algorithm, and comparing with other methods, this method performs better in precision and real-time. In real-time, this paper promotes an improving method of searching for the nearest neighbor mass. This method can reduce computational time, improve the efficiency of soft tissue deformation and maximal meet the requirement of real-time.A good virtual surgery simulation system must meet the requirements in vision and sense of touch at the same time. In rendering of vision, this paper uses OpenGL build the surface model of virtual human soft tissue. In haptic interaction, this paper uses PHANToM Omni haptic device to implement the interaction between virtual surgical instruments and soft tissue model, and uses the spring-damper model as the calculation model of force feedback in tissue deformation. At last, this paper gives some simulation experiments of soft tissue deformation.