A FEM simulation study of the optimization of the imaging attributes of a microwave radiometry system with possible functional imaging capabilities

Abstract

Microwave radiometry is a measurement technique which detects natural-thermal radiation emitted by matter. The human brain having certain temperature and specific electromagnetic properties emits chaotic radiation throughout the whole electromagnetic spectrum. A novel Microwave Radiometry Imaging System (MiRaIS) comprising an ellipsoidal conductive wall cavity and sensitive radiometric receivers, operating at low microwave frequencies (1-4GHz), has been used the past four years in various experiments to assess its value as a potential intracranial imaging device. With this view, current research aims at the improvement of the system's focusing properties using matching layers made of dielectric and left handed materials that are placed around a double layered human head model. Another approach tested, included filling of the whole ellipsoidal with a lossless dielectric material in conjunction with reduction of the ellipsoid's volume. The results show better focusing properties in the brain areas of interest and improvement of the system's spatial resolution. Future research including mainly phantom and human experiments implementing the above ideas will illustrate the value of the present simulation study.

Passive multi-frequency brain imaging and hyperthermia irradiation apparatus: the use of dielectric matching materials in phantom experiments

“…Previous simulation results indicated a 30-40% increase in the electric field values and energy absorption inside the head model [31,32]. The experimental results presented in this paper indicate indeed an increase of about 30-50% in all frequencies when the dielectric layer of ε r = 6 is present.…”

“…The scope of the present research focuses mainly on the experimental use of dielectric matching materials to improve the system focusing properties, in terms of detection/penetration depth and spatial resolution, during radiometric monitoring and hyperthermia experiments with phantoms, verifying at the same time previous theoretical results [30][31][32].…”

Contactless passive diagnosis for brain intracranial applications: A study using dielectric matching materials

“…In an effort to overcome these issues, extensive electromagnetic analysis has been performed using various simulation setups, including low loss dielectric materials as filling inside the entire ellipsoidal volume [Karanasiou et al, 2008; Gouzouasis et al, 2009b; Karathanasis et al, 2009b] or as matching layers in conjunction with left‐handed materials (metamaterials) [Karathanasis et al, 2007a; Karanasiou et al, 2008]. The results elicited from these studies showed that in both cases a stepped refraction index on the head–air boundary is achieved, resulting in reduced reflection of the electromagnetic waves and, consequently, an increase of the system's sensing capability and detection depth.…”

“…The results elicited from these studies showed that in both cases a stepped refraction index on the head–air boundary is achieved, resulting in reduced reflection of the electromagnetic waves and, consequently, an increase of the system's sensing capability and detection depth. Also, in the first case, improvement of the spatial sensitivity in relative movements of the subject around the focal point was observed [Karanasiou et al, 2008; Karathanasis et al, 2009b].…”

Συμβολή Στην Ανάπτυξη Μεθόδων Μη-Ιοντιζουσών Ακτινοβολιών Για Την Ανίχνευση Του Καρκίνου Και Τη Μελέτη Νευροφυσιολογικών Λειτουργιών

“…Σύμφωνα με προηγούμενες θεωρητικές αναλύσεις η τομή δεν επηρεάζει τις ιδιότητες εστίασης του συστήματος [140]- [144].…”