Contrast aided blind focusing of the electromagnetic field for microwave hyperthermia

The paper presents a novel approach of focused microwave hyperthermia based on the use of contrast agents. The idea is to induce a detectable and localized contrast change in the target and exploit this variation for the synthesis of the excitations of the antenna array employed for the focusing. In particular, the excitations are determined through a fast and effective processing of the differential scattering matrix, obtained by the difference of two scattering matrixes measured, by the same antenna array used for the focusing, before and after the contrast change in the target. As a result, the approach is computationally effective and totally blind, not requiring any a priori knowledge of the electric and geometric features of the region to be treated, as well as of its spatial position with respect to the antenna array.