Simulation of bleeding in endoscopic procedures using virtual reality

Background and Purpose: An image-based approach has been developed to represent bleeding in a simulator for transurethral resection of the prostate (TURP). Whereas previous groups attempted to simulate bleeding mathematically over tissue surfaces or in blood vessels, our approach focused on macroscopic visualization of bleeding in a fluid environment. The TURP is an ideal procedure for simulator-based training because of its importance as a skill to acquire as well as its long learning curve. The most challenging step in creating a realistic TURP simulator is simulated bleeding. Materials and Methods: We took an image-based approach in which we generated blood flow movies of bleeding vessels having different severity and position under variable fluid flow conditions and processed them to separate the blood flow from the background anatomy. We then organized the movies into a parametric database. During the running of the simulation, resection systematically triggers the playback of a blood flow movie (bleeding event). The movie is texture mapped onto a virtual surface that is positioned, oriented, morphed, composited, and looped into the virtual scene. Results and Conclusion: The technique produced an accurate depiction of bleeding vessels one would encounter during a TURP. The image changes readily according to the fluid flow state.