Finite difference time domain modelling of hyperthermia applicators for cancer therapy

An enhanced version of the finite-difference-time-domain (FDTD) method is used to calculate the field penetration and specific absorption rate (SAR) pattern for a current sheet applicator used in hyperthermia treatment. The FDTD method uses modified equations to rigorously model three-dimensional dielectric boundaries and a nonuniform grid for computational efficiency. Results obtained using the FDTD method are compared with experimental measurements made on phantoms, and excellent agreement is obtained. It is found both experimentally and theoretically that at low phantom conductivities the penetration depth is almost independent of conductivity due to the presence of circulating currents. In addition, the SAR pattern (calculated and measured) shows two null spots whose positions are correctly predicted by the FDTD method and match experimental measurements.<>