The Construction Of The Physical Model And The Deformation Algorithm Of The Soft Issue In Virtual Surgery Of The Anterior Segment

Computer virtual surgery is simulating surgery operations on biological tissues or organs,the core part of which is the building of model of tissues or organs and the algorithm needed for model deformation,cutting and other operations.In this paper,we study the virtual surgery of anterior segment,which mainly involves the soft tissue such as cornea,so the main part of the study is the construction of deformation model and deformation algorithm of the soft tissues.We used optical coherence tomography(OCT)to get three-dimensional image data of the anterior segment of pig eyes.The methods of mass-spring model and position-based dynamic were used as the basic when a software of the virtual surgery on anterior segment is established.The OCT system was constructed to scan several pig eyes for a series of 2-D images of real pig eyes.After the step of three-dimensional reconstruction,the 3-D graphics of pig eyes is got.In order to study the physical properties of soft tissues in the pig eyes such as corneal,the deformation of the pig eyes under different forces was recorded when different loads to pig eyeball during real-time scanning in the experiment.Based on the scanning data got in the experiment,the models of the corneal are established by using the two methods of mass-spring model and position-based dynamic.The mass-spring model is composed of a series of mass particles and springs which connecting the mass particles to simulate the internal interaction of objects;the position-dynamics method constructs a series of mass particles as a whole model by establishing the constraints between particles.These simulations are the key modules of the anterior segment virtual surgery software.The deformational simulation is the core part of the virtual surgery software of anterior segment,based on which a virtual surgery software of the surgery is completed by adding the modules of collision detection,graphics rendering using Open GL and GPU accelerated computing controlled by CUDA.In this paper,we obtained three-dimensional images reconstructed from the optical coherence tomography scanning data of the anterior segment of real pig eyes.Deformable models of the corneal is established by two different methods.The virtual surgery software finished in this paper can be used to find the changes of the eyeball under different pressures.