My main research interest are real-time physically-based simulation, high-performance and massively-parallel computing, virtual and augmented reality, haptic interfaces as well as aspects of software engineering and architecture of simulation software. My current work concentrates on virtual reality medical simulators for surgical training, specifically, on simulation of Endovascular Interventions and Natural Orifice Transluminal Endoscopic Surgery (NOTES).
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NOTES is an experimental surgical technique whereby "scarless" abdominal operations can be performed with an endoscope passed through a natural orifice, then through an internal incision in the stomach, vagina, bladder or colon, thus avoiding any external incisions or scars. A key aspect of this technique is the innovative use of sophisticated flexible endoscopes. NOTES creates many new challenges and produces extremely steep learning curve for clinicians. Very little work has been done so far in training for this new type of surgical interventions. VR simulation of NOTES can contribute to surgical training without putting patients at risk, popularizing NOTES and keeping practitioners up to date with new methods. To our current knowledge there are no other VR simulators, either commercial or experimental, aimed specifically at this novel technique.
Transgastric (left), transvaginal (middle) and transrectal (right) NOTES procedures
The main objective of this project is to build and validate a novel virtual reality simulator for NOTES surgery. This involves iterative software and hardware development as well as rigorous validation and testing. Trans-gastric cholecystectomy (gallbladder removal through the mouth) was chosen as a simulated procedure. The procedure consists of the three main tasks: navigation via stomach to the abdomen, clipping and cutting of the Calots triangle and gallbladder dissection using the diathermy tool and the grasper. The procedure finishes when the operator pulls out the gallbladder through the throat.
NOViSE - a first VR simulator for NOTES procedures training
The simulator set-up consists of a real-time software simulation and a physical, force feedback human-computer-interface (a haptic device). The software can efficiently run on a standard mid-range PC or laptop. The generated display is divided into two parts. On the right there is a view from the endoscopic camera. On the left the user can see an external, optional aerial view which can be freely manipulated. The simulator presently supports a complete trans-gastric hybrid cholecystectomy procedure. The behaviour of virtual flexible endoscope is modelled on a solid theoretical footing - the Cosserat rod. This model allows realistic recreation of all deformations of the endoscope, such as bending and twisting, as well as guarantees immediate response to user manipulations. The operator can choose from four types of actuators to clip and dissect the gallbladder: grasper, clipper, scissors and diathermy tool. The physical parameters of the virtual endoscope can be adjusted to match the behaviour of different models of real endoscopes. The operator interacts with the virtual endoscope via custom built haptic device.
Effective and safe performance of cardiovascular interventions requires excellent catheter / guidewire manipulation skills. These skills are currently mainly gained through an apprenticeship on real patients, which may not be safe or cost-effective. Computer simulation offers an alternative for core skills training.
Virtual Catheterisation Simulator (VCSim3) is a prototype VR simulator for cardiovascular interventions. The behaviour of the virtual catheter and guidewire is based on the inextensible Cosserat rod implementation. The model allows for efficient modelling of bending, stretching and twisting phenomena, as well as guaranteeing almost immediate response to user manipulations, even for long instruments. The mechanical parameters of six guidewires and three catheters were optimised with respect to their real counterparts scanned in a silicone phantom using CT. The virtual instruments exhibit near sub-millimetre accuracy. The implementation allows the simulator to run efficiently on an off-the-shelf PC or laptop, significantly exceeding the minimum required haptic interactive rate.