UWB RSS-Based Localization for Capsule Endoscopy Using a Multilayer Phantom and In Vivo Measurements

Abstract

In recent years, localization for capsule endoscopy applications using Ultra-Wideband (UWB) technology has become an attractive field of investigation due to its potential benefits for patients. Literature concerning performance analysis of RF-based localization techniques for in-body applications at UWB frequencies is very limited. Available studies mainly rely on Finite Difference Time Domain (FDTD) simulations, using digital human models and on experimental measurements by means of homogeneous phantoms. Nevertheless, no realistic analysis based on multilayer phantom measurements or through in vivo experiment has been reported yet. This paper investigates the performance of RSS-based approach for two-dimensional (2D) and three-dimensional localization (3D) in the UWB frequency band. For 2D localization, experimental laboratory measurements using a two-layer phantom based setup have been conducted. For 3D localization, data from a recently conducted in vivo experiment have been used. Localization accuracy using path loss (PL) models, under ideal and not ideal channel estimation assumptions, are compared. Results show that under not ideal channel assumption the relative localization error slightly increases for the 2D case but not for the in vivo 3D case. Impact of receivers selection on the localization accuracy has also been investigated for both, 2D and 3D, cases. Index Terms-Wireless capsule endoscopy (WCE), Ultra-Wideband (UWB), in-body localization, heterogeneous phantom, in vivo measurements.

Impact of Receivers Location on the Accuracy of Capsule Endoscope Localization

“…In-vivo measurements for one on-body position (a) and grid of all on-body position (top view) (b)[21] …”

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

“…Multiple antennas were arranged outside the body for localization to sense the RF signal from the capsule. The achieved position error by Khan et al [ 12 ], as well as Barbi et al [ 36 ] by using RF-based methods was for both studies approximately 10 mm. The main source of error for the RF-based methods is the inhomogeneous permittivity of human tissue, which differs for different patients.…”

Characterization of Wearable and Implanted Antennas: Test Procedure and Range Design

“…In terms of realization complexity this is another benefit of the proposed measurement approach, as only a flat phantom is needed, compared to the complex body shapes used for in-situ measurements. A two-layer (fat and muscle) flat phantom, as required for the proposed measurement approach, has already been presented in [25]. Furthermore, for any application scenario considered, the body surface in the direct vicinity of the antenna must be sufficiently flat to correctly characterize the on-body gain.…”