Systematic Performance Evaluation of a Novel Optimized Differential Localization Method for Capsule Endoscopes

Abstract

Capsule endoscopy is a well-established diagnostic tool for the gastrointestinal tract. However, the reliable tracking of capsule endoscopes needs further investigation. Recently, the static magnetic differential method for the localization of capsule endoscopes has shown promising results. This method was experimentally validated by investigating the difference in the measured values of the geomagnetic flux density of a representative sensor pair. In the measurements, it was revealed that misalignment of the sensors and ferromagnetic material near the sensor pair had the most significant impact on the differential approach. Besides, a systematical simulation-based study was conducted. Herein, the position and alignment of all sensors of the localization system were randomly varied. Furthermore, root-mean-squared noise was added to the sensor measurements, and the influence of nearby ferromagnetic material was evaluated. Subsequently, non-idealities were applied simultaneously on the proposed localization system, and the entire system was rotated. The proposed method was significantly better than state-of-the-art geomagnetic compensation methods for the localization of capsule endoscopes with mean position and orientation errors of approximately 2 mm and 1°, respectively.

Tracking the Traveled Distance of Capsule Endoscopes along a Gastrointestinal-Tract Model Using Differential Static Magnetic Localization

“…However, the authors in [ 23 ], revealed that, at the sensor array, the geomagnetic flux density is of the same order as that of the generated magnetic flux density. Thus, in [ 17 , 18 ], a differential static magnetic localisation method was proposed by the authors to compensate for this interference. The differential method groups the sensor array into pairs of equally oriented sensors.…”

“…In our previous work [ 17 , 18 ], a differential static magnetic localisation method for capsule endoscopes was proposed. Simulations [ 17 ] and experiments [ 18 ] showed that the absolute coordinates and orientation of a permanent magnet of size 10 × 10 mm can be determined with accuracy of approx. 3 mm and 2 , respectively.…”

“…Therefore, in this study, the differential static magnetic localisation method proposed by the authors in [ 17 , 18 ] was applied to track the traveled distance and the orientation of permanent magnets that were moved along a 3D curved trajectory within a region that approx. covered the typical size of a GIT.…”