In vivo and in situ measurement and modelling of intra‐body effective complex permittivity. Issue 6 (30th November 2015)

• Record Type: Journal Article
• Authors: Nadimi, Esmaeil S.; Blanes‐Vidal, Victoria; Harslund, Jakob L.F.; Ramezani, Mohammad H.; Kjeldsen, Jens; Johansen, Per Michael; Thiel, David; Tarokh, Vahid
• Is Part Of: Healthcare technology letters. Volume 2:Issue 6(2015)
• Page Start: 135
• Page End: 140
• Publication Date: 2015-11-30
• Subjects: permittivity -- bioelectric phenomena -- biomedical measurement -- biological organs -- biomechanics -- statistical analysis -- radiofrequency measurement -- microrobots -- medical robotics -- electromagnetic wave refraction -- electromagnetic wave absorption -- electromagnetic wave attenuation; in vivo measurement -- in situ measurement -- intrabody effective complex permittivity -- radiofrequency tracking -- medical microrobots -- minimally invasive medicine -- homogeneous propagation medium -- refraction -- absorption -- gastrointestinal tract organs -- oesophagus -- stomach -- small intestine -- large intestine -- porcine abdominal wall -- irregular unsynchronised contractions -- simulated peristaltic movements -- abdominal cavity -- multilayer inhomogeneous medium -- wave attenuation -- GI tract morphometric variables -- statistical based models; Biomedical engineering -- Periodicals; Medical technology -- Periodicals; 610.28
• DOI: 10.1049/htl.2015.0024
• Languages: English
• ISSNs: 2053-3713

Abstract

Abstract : Radio frequency tracking of medical micro‐robots in minimally invasive medicine is usually investigated upon the assumption that the human body is a homogeneous propagation medium. In this Letter, the authors conducted various trial programs to measure and model the effective complex permittivity ε in terms of refraction ε′, absorption ε″ and their variations in gastrointestinal (GI) tract organs (i.e. oesophagus, stomach, small intestine and large intestine) and the porcine abdominal wall under in vivo and in situ conditions. They further investigated the effects of irregular and unsynchronised contractions and simulated peristaltic movements of the GI tract organs inside the abdominal cavity and in the presence of the abdominal wall on the measurements and variations of ε′ and ε′′. They advanced the previous models of effective complex permittivity of a multilayer inhomogeneous medium, by estimating an analytical model that accounts for reflections between the layers and calculates the attenuation that the wave encounters as it traverses the GI tract and the abdominal wall. They observed that deviation from the specified nominal layer thicknesses due to non‐geometric boundaries of GI tract morphometric variables has an impact on the performance of the authors' model. Therefore, they derived statistical‐based models for ε′ and ε′′ using their experimental measurements.