Soft Tissue Modeling And Its Application In Virtual Surgery System

The development of virtual reality technology has been extended to the field of medicine,among which virtual surgery simulation technology is one of its typical applications,which plays an important role in the training of novice doctors before surgery and in the practice of solving various situations that may be faced in real surgery.There are some problems in the virtual surgery system,such as the lack of accuracy of 3D reconstruction of soft tissue,the lack of accuracy of mechanical parameters and deformation model of soft tissue,and the reappearance of force and touch in the virtual surgery system.A set of virtual surgery simulation system is developed,which includes nephroscope and renal branch abdominal aorta exhaust needle compression.It solves the problems existing in the virtual surgery system,greatly improves the visual fidelity and force touch authenticity of the virtual surgery environment,and provides an efficient surgery training platform for doctors.Firstly,aiming at the inaccuracy of the traditional 3D reconstruction model of blood vessel and kidney and the lack of consideration of human anatomical structure,the software of Mimics was used to reconstruct and optimize the 3D reconstruction of renal branch,abdominal aorta and kidney in abdominal CT image.For example,threshold selection and regional growth are used to segment the abdominal aorta and renal tissue from the image.The method of cavity filling was used to solve the problem that the information of renal artery and renal mask was incomplete because of the uneven flow of contrast agent with blood.Through the mask editing function,the abdominal aorta and kidney were reconstructed after edge enhancement.At the same time,the reconstruction model was covered and smoothed.Secondly,aiming at the inaccuracy of traditional soft tissue mechanics model parameters,the spring mass model is improved to simulate the nonlinear characteristics of different soft tissue contact stages.In order to verify the accuracy of the improved spring mass model,different soft tissues were measured.According to the analysis of the biomechanical characteristics of the soft tissue,the pig kidney and the abdominal aorta of the pig kidney were selected as the experimental objects.According to the corresponding operation in modern medical operation,the empty tube puncture experiment similar to the nephroscope for the pig kidney and the exhaust needle puncture experiment for the abdominal aorta of the pig kidney were determined.The real mechanical data of the puncture of the pig kidney and the abdominal aorta of the pig kidney were measured,such as shape variable,interaction force,etc.Then MATLAB software is used to process and fit the data in the touch stage.Finally,based on the phantom Omni device,the force touch interactive virtual surgery simulation system is built.In the built virtual surgery force touch interactive system,the renal abdominal aorta and the kidney are pressed.The results show that the developed operation system based on the improved spring mass model of the kidney and the renal abdominal aorta has a more real force touch.