MODELING TISSUE HEATING WITH FERROMAGNETIC SEEDS

Interstitial hyperthermia using ferromagnetic seeds demands accurate t reatment planning: the seed characteristics and implant geometry must be determined prior to the treatment. A new, finite difference based, seed modelling method is presented. The seed, together with all its su rrounding (non-tissue) layers is described as one unit, independent of the tissue grid. The calculation of the seed-tissue interaction is ba sed on the local seed temperature and several tissue temperature sampl es in the direct vicinity. All the layers between the seed and the sur rounding tissue are taken into account in this interaction calculation . The presented implementation describes the analytical solution of th e modelled steady-state configurations very accurately. The separation between tissue and seed allows easy assessment of the resulting seed temperature profile which is essential to the optimization of the seed characteristics in treatment planning. The thermal effect due to bloo d flow in the modelled tissue volume surrounding the seed can be accou nted for by inclusion of a heat sink term as well as by inclusion of r ealistic discrete vasculature.