Research On Virtual Surgery Geometrical Modeling And Blood Flow Visualization Simulation

Virtual surgery is a kind of virtual reality system based on medical image data,which builds virtual organ and tissue model through three-dimensional reconstruction technology,and simulates the interaction scene between surgical instruments and virtual tissues and organs in the real operation process through tactile interaction system,thus providing users with real experience and immersion.In the virtual surgery system,a highly realistic geometric model of soft tissue and organs is needed to be established.At the same time,common operations such as cutting,suture and aspiration are often accompanied by bleeding scenes,which is also a difficulty in virtual surgery simulation.Aiming at the problems of low authenticity of geometric model in virtual surgery and inauthenticity of blood flow visualization simulation in virtual surgery,this paper studies the virtual surgery simulation system for gastric aspiration operation,aiming at providing realistic operation simulation and bleeding effect,starting from improving the real presence and real-time of virtual surgery system.First,based on the medical image data,the three-dimensional geometric model of the stomach was reconstructed by using the improved moving cube algorithm.The traditional moving cube algorithm has ambiguity problem,which leads to the empty isosurface,and the generated organ model is not realistic enough.To solve the above problems,an improved moving cube algorithm is proposed in this paper.Without changing the framework of the algorithm,the problem of voids caused by ambiguity is avoided.Surgical instrument modeling adopts agent point modeling to improve the efficiency of collision detection.The experimental results show that the improved moving cube algorithm can effectively solve the void problem on the premise of guaranteeing the reconstruction time,greatly optimize the appearance of the reconstruction organs,and ensure the fidelity of the virtual surgery process.Secondly,the paper completes the blood flow visualization simulation design.Based on N-S(Navier-Stokes)equation,the SPH hydrodynamics model was established.The neighboring particle search algorithm was adopted,and the three-dimensional grid cube search method was selected to improve the performance of finding adjacent particles.The blood flow model was constructed based on the SPH algorithm.In order to improve the fidelity of blood flow to render,in view of the traditional mobile cube algorithm application will appear in the rendering in the fluid flow of information is not complete,at the same time introducing anisotropy accounting method,and time consuming problems of anisotropic accounting method,optimize the anisotropic kernel function,the proposed algorithm can render the fluid surface smooth level off,better retain the information on the surface of the blood,at the same time can also have to ensure real-time performance of virtual surgery.Finally,this paper built a virtual surgical simulation system for gastric aspiration operation,which can realize gastric aspiration operation and present the effect of real bleeding.Users control virtual surgical instruments through a force-feedback device called the Phantom Omni,which simulates suction surgery.The experimental results show that the virtual surgery simulation system developed in this paper with the function of gastric suction operation has good immersion and real-time performance.