Ferromagnetic implants in hyperthermia: An analytical, numerical and experimental study

Abstract

Power deposition in ferromagnetic implants of cylindrical and spherical shape from an externally applied uniform time harmonic radio-frequency magnetic field has been investigated by means of quasi-static analysis. Inductive heating efficiency is related to the relative permeability and temperature dependence of permeability can be exploited to limit the maximum temperature rise to the desired value by proper choice of Curie point of ferromagnetic material. It is found that theoretically calculated power absorption versus orientation of the cylindrical implant with the direction of magnetic field is in good agreement with the experimental results. The parametric studies are based on a two-dimensional finite difference model for calculating temperature distribution in perfused tissues due to induction heating of an array of implants. An approximate analytical model was developed for a large regular array of implants in perfused tissues. The results of the analytical model are compared with those of the numerical model. (Abstract shortened with permission of author.)