title: Graphic and haptic simulation for transvaginal cholecystectomy training in NOTES.
abstract: BACKGROUND
  Natural Orifice Transluminal Endoscopic Surgery (NOTES) provides an emerging surgical technique which usually needs a long learning curve for surgeons. Virtual reality (VR) medical simulators with vision and haptic feedback can usually offer an efficient and cost-effective alternative without risk to the traditional training approaches. Under this motivation, we developed the first virtual reality simulator for transvaginal cholecystectomy in NOTES (VTEST™).
  
  
  METHODS
  This VR-based surgical simulator aims to simulate the hybrid NOTES of cholecystectomy. We use a 6DOF haptic device and a tracking sensor to construct the core hardware component of simulator. For software, an innovative approach based on the inner-spheres is presented to deform the organs in real time. To handle the frequent collision between soft tissue and surgical instruments, an adaptive collision detection method based on GPU is designed and implemented. To give a realistic visual performance of gallbladder fat tissue removal by cautery hook, a multi-layer hexahedral model is presented to simulate the electric dissection of fat tissue.
  
  
  RESULTS
  From the experimental results, trainees can operate in real time with high degree of stability and fidelity. A preliminary study was also performed to evaluate the realism and the usefulness of this hybrid NOTES simulator.
  
  
  CONCLUSIONS
  This prototyped simulation system has been verified by surgeons through a pilot study. Some items of its visual performance and the utility were rated fairly high by the participants during testing. It exhibits the potential to improve the surgical skills of trainee and effectively shorten their learning curve.
authors.affiliation: State Key Laboratory of Virtual Reality Technology and Systems, Beihang University, Beijing, China; Center for Modeling, Simulation and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, USA. Electronic address: pan_junjun@hotmail.com.
authors.forename: Jun J
authors.initials: JJ
authors.lastname: Pan
authors.affiliation: Center for Modeling, Simulation and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, USA.
authors.forename: Woojin
authors.initials: W
authors.lastname: Ahn
authors.affiliation: Center for Modeling, Simulation and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, USA.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Dargar
authors.affiliation: Computer Science Department, University of Central Arkansas, Conway, USA.
authors.forename: Tansel
authors.initials: T
authors.lastname: Halic
authors.affiliation: Center for Modeling, Simulation and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, USA.
authors.forename: Bai C
authors.initials: BC
authors.lastname: Li
authors.affiliation: Center for Modeling, Simulation and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, USA.
authors.forename: Ganesh
authors.initials: G
authors.lastname: Sankaranarayanan
authors.affiliation: Gastrointestinal Surgery, Yale School of Medicine, Yale University, New Heaven, USA.
authors.forename: Kurt
authors.initials: K
authors.lastname: Roberts
authors.affiliation: Department of Surgery, Cambridge Health Alliance, Harvard Medical School, Boston, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Schwaitzberg
authors.affiliation: Center for Modeling, Simulation and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, USA.
authors.forename: Suvranu
authors.initials: S
authors.lastname: De
keywords: Dissection; GPU; Inner-sphere; NOTES; Transvaginal cholecystectomy; Virtual reality