A process of determining whether two or more bodies are making contact at one or more points is called collision detection or intersection detection. Collision detection is inseparable part of the computer graphics, surgical simulations, and robotics. There are varieties of methods for collision detection. We will review some of the most common ones. Algorithms for contact determination can be grouped into two general parts: broad-phase and narrow-phase. This paper provides a comprehensive classification of a collision detection literature into the two phases. Moreover, we have attempted to explain some of the existing algorithms which are not easy to interpret. Also, we have tried to keep sections self-explanatory without sacrificing depth of coverage. W 4046 1-4244-0991-8/07/$25.00 ©2007 IEEE

Background-The development of modern surgical simulators is highly challenging as they must support complex simulation environments. The demand for higher realism in such simulators has driven researchers to adopt physics-based models which are computationally very demanding. This poses a major problem since real time interactions must permit graphical updates of 30 Hz and a much higher rate of 1 kHz for force feedback (haptics). Recently several physics engines have been developed which offer multi-physics simulation capabilities including rigid and deformable bodies, cloth and fluids. While such physics engines provide unique opportunities for the development of surgical simulators, their higher latencies, compared to what is necessary for real time graphics and haptics, offer significant barriers to their use in interactive simulation environments.Methods-In this work, we propose solutions to this problem and demonstrate how a multimodal surgical simulation environment may be developed based on NVIDIA's PhysX physics library. Hence, models that are undergoing relatively low frequency updates in PhysX can exist in an environment that demands much higher frequency updates for haptics. We use a collision handling layer to interface between the physical response provided by PhysX and the haptic rendering device to provide both real time tissue response and force feedback.Results-Our simulator integrates a bimanual haptic interface for force-feedback and per-pixel shaders for graphics realism in real time. To demonstrate the effectiveness of our approach, we present the simulation of the Laparoscopic Adjustable Gastric Banding (LAGB) procedure as a case study. Conclusions-To

BackgroundUntil quite recently spinal disorder problems in the U.S. have been operated by fusing cervical vertebrae instead of replacement of the cervical disc with an artificial disc. Cervical disc replacement is a recently approved procedure in the U.S. It is one of the most challenging surgical procedures in the medical field due to the deficiencies in available diagnostic tools and insufficient number of surgical practices For physicians and surgical instrument developers, it is critical to understand how to successfully deploy the new artificial disc replacement systems. Without proper understanding and practice of the deployment procedure, it is possible to injure the vertebral body. Mixed reality (MR) and virtual reality (VR) surgical simulators are becoming an indispensable part of physicians’ training, since they offer a risk free training environment. In this study, MR simulation framework and intricacies involved in the development of a MR simulator for the rasping procedure in artificial cervical disc replacement (ACDR) surgery are investigated. The major components that make up the MR surgical simulator with motion tracking system are addressed. FindingsA mixed reality surgical simulator that targets rasping procedure in the artificial cervical disc replacement surgery with a VICON motion tracking system was developed. There were several challenges in the development of MR surgical simulator. First, the assembly of different hardware components for surgical simulation development that involves knowledge and application of interdisciplinary fields such as signal processing, computer vision and graphics, along with the design and placements of sensors etc . Second challenge was the creation of a physically correct model of the rasping procedure in order to attain critical forces. This challenge was handled with finite element modeling. The third challenge was minimization of error in mapping movements of an actor in real model to a virtual model in a process called registration. This issue was overcome by a two-way (virtual object to real domain and real domain to virtual object) semi-automatic registration method.ConclusionsThe applicability of the VICON MR setting for the ACDR surgical simulator is demonstrated. The main stream problems encountered in MR surgical simulator development are addressed. First, an effective environment for MR surgical development is constructed. Second, the strain and the stress intensities and critical forces are simulated under the various rasp instrument loadings with impacts that are applied on intervertebral surfaces of the anterior vertebrae throughout the rasping procedure. Third, two approaches are introduced to solve the registration problem in MR setting. Results show that our system creates an effective environment for surgical simulation development and solves tedious and time-consuming registration problems caused by misalignments. Further, the MR ACDR surgery simulator was tested by 5 different physicians who found that the MR simulator is effective enough ...

Background Despite the critical importance of cricothyroidotomy (CCT) for patient in extremis, clinical experience with cricothyroidotomy is infrequent, and current training tools are inadequate. The long-term goal is to develop a Virtual Airway Skills Trainer (VAST) that requires a thorough task analysis to determine the critical procedural steps, learning metrics, and parameters for assessment. Methods Hierarchical Task Analysis (HTA) is performed to describe major tasks and subtasks for CCT. A rubric for performance scoring for each task was derived and possible operative errors were identified. Results Time series analyses for seven CCT videos were performed with three different observers. According to Pearson's correlation tests, three of the seven major tasks had a strong correlation between their task times and performance scores. Conclusion The task analysis forms the core of a proposed virtual cricothyroidotomy simulator, and highlights links between performance time and accuracy when teaching individual surgical steps of the procedure.