Comparing electro-optical and electro-magnetic guidance systems in the preparation of minimal access surgical training environments

Introduction: High quality visual images for virtual environment generation were prepared using two comparative spatial co-ordinate referencing systems, identifying the position of individual frames in the recorded video database. Methodology: A cadaveric shoulder arthroscopy database was recorded and replayed using an ATM Network. An Electro-optical (Optotrak?) spatial reference system is compared with an Electro-magnetic (Flock of Birds?) system, for position tracking of an arthroscope in the virtual environment. Results: 1. Electro–Optical equipment is used safely in the operating theatre environment 2. Electro-Magnetic devices are affected by ferromagnetic environments 3. Electromagnetic devices are inexpensive, and thus more suitable for a training environment 4. It was necessary register the two systems relative to each other using ‘public domain’ algorithms. The precision of the Electro-Optical equipment exceeds the current specification of the video world database matrix granularity and the amplitude of physiological oscillation of the manual operator. Discussion: The dataset may be integrated into a simulated training environment which may then be accessed in a non-critical training environment where it is cost effective to use Electro-magnetic position sensing devices. Interchangeability between such systems, is based upon the mathematical analysis available from our website – www.dcs.ex.ac.uk/evw. Conclusion: The Electro-Optical system allows accurate registration of the frame recording position, and playback, however high capital cost may prohibit widespread use for training. Developing mathematical correlation between the two systems, integrates their specific use in different environments.