Performance Optimization of a Differential Method for Localization of Capsule Endoscopes

Wireless capsule endoscopy is a promising medical application and a potential alternative to conventional endoscopy. A small capsule with an integrated camera for recording a video is swallowed by a patient allowing gastrointestinal diagnosis. It is of particular interest for doctors that a certain video frame is correlated to the precise location of the capsule within the gastrointestinal tract. Static magnetic localization is well-established for that purpose and the localization method is based on the magnetic dipole model. Generally, the dipole model is only valid for sufficiently large distances from the magnet. In this paper, simulations in which the magnetic flux density generated by different-sized permanent magnets and different sized computational domains was compared to the magnetic dipole model by simulations in COMSOL Multiphysics ®. The computational domain dimensions, as well as the ratio of the length and diameter of the magnet, were optimized to fit the magnetic flux density generated by the magnet with the dipole mode. The distance from the magnet, for which the dipole model is sufficiently accurate, was determined. Subsequently, the standard static magnetic localization method was applied to the proposed empirical data-based localization setup with different parameters. The results revealed, that the localization performance was significantly improved by applying the optimized parameters.