Experimentally based modeling of field sources for three-dimensional computation of SAR in electromagnetic hyperthermia and treatment planning

This paper presents field source-modeling, for applications to hyperthermia , by utilizing experimental data from the paraxial region of a liquid muscl e-like phantom irradiated by an aperture antenna. The data are used in an o ptimization algorithm, applied to a Gaussian beam model (GBM), to determine the source parameters for GEM-computations of specific absorption rates ev erywhere, accurate to within 1% (relative to the global maximum) of the exp erimental results. This paper also shows how the aperture and incident fiel ds may be determined accurately by the GEM and links them to the electric-f ield integral equation (EFIE), as an example, to improve the accuracy of nu merical computations of the electric or magnetic fields associated with the EFIE, the magnetic-field integral equation, or any other field formulation s. It is further demonstrated that models of plane waves, or approximate so urce fields, predict power levels with significant, unacceptable errors. Fi nally, it is concluded that the GEM is a viable tool for characterizing ape rture antennas used in hyperthermia for cancer therapy.