Analysis of matching media effect on microwave brain stroke imaging via a spherically symmetrical head model

The effect of using a matching medium in the brain imaging via the microwave tomography technique has been investigated using a three-dimensional multi-layered sphere as a head model. By modelling the human head as a spherically symmetrical piecewise homogeneous sphere, the related scattering problem can be transformed into a one-dimensional form. As a result, the computational complexity of the problem can be significantly reduced. This scattering problem is then solved via the discretization of the one-dimensional integral equations, and through the dyadic Green's function related to the layered spherical structures. In order to test the effect of the matching medium for the brain stroke detection, the scattered electric fields for the healthy brain model and the stroke-affected one have been compared. The results show that in the absence of a matching medium the variation in the scattered field between two cases is too small to enable a successful stroke detection mechanism based on microwave imaging. On the other hand, in the presence of the matching medium, a noticeable difference in the scattered field has been observed. However, further tests employing more realistic models must be used to evaluate the applicability of the microwave tomography in the brain stroke detection.