Research On Modeling And Application Of Mass Spring Model In Virtual Surgery

In recent years,virtual reality technology has opened up a new path for surgical training.As a new cross-disciplinary research field,virtual surgery can save training costs and improve training efficiency.The soft tissue model is the research emphasis of virtual surgery system.Mass Spring Model(MSM)is one of the mainstream soft tissue models,which has the advantages of fast calculation and simple modeling.However,the stability and accuracy of MSM is relatively poor.Therefore,this paper studies on the basis of the existing MSM,and three MSM based modeling methods are designed as follows to simulate three common scenes in surgery:(1)Since the accuracy and structure of MSM cannot well satisfy the demand of tumor simulation,an Equal Pitch Conical Coil Spring Model for tumor modeling is designed.The shear modulus of soft tissue was controlled by a similarity algorithm based on the Fréchet distance to express the heterogeneity of clinical tumor.Also,a deformation calculation method for multi-layer springs is utilized to calculate the deformation of soft tissue.(2)Since the accuracy and stability of MSM cannot well satisfy the demands of suture surgery simulation,a MSM-based modeling method for suture simulation is designed.The method involves three kinds of MSMs,which are optimized by a mass nodes constraint algorithm in term of limiting the moving range of mass nodes around suture point.Also,a suture control strategy is designed to supervise the stability of suture procedure.(3)MSM cannot well satisfy the demands of puncture simulation such as accurate positioning of suture point.While MSM can be utilized as an assistant model to help other model calculate force during puncture simulation.Therefore,a soft tissue resumption modeling method based on MSM force mesh is designed.The spherical harmonic function(SHF)is used to construct the three-layer soft tissue body.The MSM-based force mesh is used to compensate for the lack of SHF in term of force calculation.A deformation resumption algorithm based on shape matching algorithm is used to simulate the resumption phenomenon of soft tissue surface during the puncture process.By constructing a tumor perception system,a suture surgery system and a puncture simulation system,the proposed modeling methods are applied to virtual surgery.Evaluation experiments are designed to study their application.The experimental results show that the three proposed virtual modeling methods in this paper promote the accuracy and stability of MSM,and can well simulate tumor,suture surgery and puncture operation,and have good performance in practical applications and surgery training.