Towards Differential Static Magnetic Localization of Commercial Capsule
Endoscopes: An Evaluation Using Different Ring and Cylindrical Magnets
Abstract
Capsule endoscopy is a promising diagnostic tool for the entire
gastrointestinal tract. Since a patient swallows the capsules, their
size must be sufficiently small. The principal built-in components are
cameras, silver-oxide batteries, light emitting diodes, and an antenna
for transmitting the video. For diagnosis and treatment, the precise
localization of the capsules for specific video frames is required.
Recently, static magnetic localization of these apsules with an
integrated permanent magnet showed promising results. However, in the
state-of-the-art, relatively large magnets compared to the small
capsules were used. Therefore, in this extended paper, the localization
performance of a recently proposed optimized differential static
magnetic localization method for different-sized discs and ring magnets
was evaluated. The ring magnets were designed for integration with the
two batteries of commercial capsules. The magnets were evaluated in
static and dynamic scenarios to evaluate the performance of the method
in a patient’s daily life. It was revealed that the mean position and
orientation errors did not exceed 5 mm and 4°, respectively, for all
applied magnets except for the 1.5 mm and 3 mm long disc magnets.
Moreover, the results indicated that the ferromagnetic batteries of
capsule endoscopes increase the localization performance when they are
centered within a diametrical ring magnet. Overall, it was revealed that
the localization performance of the optimized differential method is
significantly better than the state-of-the-art even when the magnet
volume is significantly reduced compared to previous work. Therefore, it
was concluded that a 5 mm long disc magnet or a ring magnet are
excellent candidates for integration into a commercial capsule for
magnetic localization and yield the advantage of being passive magnetic
sources.