Electromagnetic Analysis of a Non Invasive Microwave Radiometry Imaging System Emphasizing on the Focusing Sensitivity Optimization

Abstract

Abstract-A Green's function based methodology has been developed and implemented with the view to optimize the focusing properties and thus the performance of a Microwave Radiometry Imaging System (MiRaIS). The system consists of an ellipsoidal conductive wall cavity and a sensitive radiometric receiver and its operation principal is based on the convergence of the radiation from one focal point, where the subject or phantom is placed, on the other, where the receiver antenna is positioned. A two-layered cylinder is used to model the human head with the semi-analytical Green's function technique. The imaging configuration is enhanced by different matching structures of various materials which are placed on the surface of both the human head model and the antenna inside the ellipsoidal. Numerical code executions have been realized and the results for the electric field distribution inside the head are presented for materials of various dielectric properties and for left handed materials at two different frequencies (0.5 GHz and 1.0 GHz). Increased sensitivity of the system focusing properties is observed using particular matching structures.

Enhancement of a Microwave Radiometry Imaging System's Performance Using Left Handed Materials

“…In order to solve this problem, a Green's function technique is adopted [1,16,17]. According to the Reciprocity theorem, a response of a system to a source is unchanged when source and measurer are interchanged.…”

“…Towards the enhancement of the system's focusing properties, in previous recent work carried out by our group, various setups have been investigated aiming to improve the transition of the diffraction index from air to the head and vice versa. Specifically, initially the receiving antenna was covered by two layers of different dielectric properties, then a thin lossless dielectric layer was placed on the surface of the human head model [1] and various configurations using lossless dielectric materials placed around the head models/phantoms or used as filling material inside the ellipsoidal cavity were also implemented [4,5]. With appropriate adaptation of values of the dielectric properties and the thicknesses of each layer, a stepped change of the refraction index on the scattering objects-air interface has been achieved, hence a better radiation focusing inside the brain has been observed.…”

“…A Microwave Radiometry Imaging System (MiRaIS) has been developed and it mainly consists of an ellipsoidal conductive cavity which ensures the focusing on the brain areas of interest and a multifrequency sensitive radiometric receiver [1][2][3][4][5] (Fig. 1).…”

A Trust Region Subproblem for 3d Electrical Impedance Tomography Inverse Problem Using Experimental Data

“…In this method the regularized solution was obtained using a parameterized trust region approach to estimate the region of maximum curvature of the L-curve. Method proposed here can be used in other imaging techniques [17][18][19][20][21].…”

Non-Invasive Microwave Radiometric System for Intracranial Applications: A Study Using the Conformal L-Notch Microstrip Patch Antenna

“…Microwave radiometry was proposed approximately 30 years ago to be used as a diagnostic imaging method to noninvasively measure temperature distributions inside the human body. Since then numerous research results have been reported regarding the clinical practical value of this passive imaging methodology which exhibits unique capabilities [7,8]. The applications of microwave radiometry in clinical medicine aim mainly at obtaining information about internal in-depth body temperature patterns by the non-traumatic measurement of natural thermal radiation from body tissues at low microwave frequencies.…”