Localization of Wireless Capsule Endoscopes Using the Receiver Selection Algorithm and a Modified Capsule Antenna

Wireless capsule endoscopes capture and transmit images of the human gastrointestinal tract for use in medical diagnosis. The localization of the capsule makes it possible to precisely identify areas with lesions detected during the examination. The antenna is an important element of the endoscopic capsule that is used for the transmission of the signal containing the recorded image of the inside of the digestive system. Antenna parameters influence also the performance of algorithms that are locating capsule endoscopes based on the analysis of the received signal. The zig-zag conformal antenna for the endoscope capsule is presented in this paper. It was examined both in simulation and tissue simulant liquid. It is then applied to an improved localization system that is based on phase difference analysis of received signals. In this new approach, the algorithm selects five external receivers from the predefined set and uses an adaptive estimation of human body model permittivity. The localization algorithm was verified with computer simulations. Remcom XFdtd software and both simplified and heterogeneous human body models were applied in simulations. The technique which uses automatic selection of the external receiver together with proposed antenna enhanced localization accuracy by about 15% compared with the previous version of this algorithm.