Treatment planning for ferromagnetic seed heating.

Computer simulations of ferromagnetic seed heating have been performed for the case of a single constant-temperature ferromagnetic seed. Results obtained from both 2-dimensional and 3-dimensional thermal models are compared to determine the appropriate use and limitations of the 2-dimensional model for the case of array implants. It has been determined that the 2-dimensional model that assumes infinite extent of the ferromagnetic seed(s) is applicable for calculating the thermal distribution in any plane perpendicular to the axes of the implant(s) up to 1 cm from the ends of the seed(s). The feasibility of spatially interspersed ferromagnetic and radioactive seeds for concurrent hyperthermia and brachytherapy has also been studied. The steady-state temperature distribution within an array of ferromagnetic seed implant has been examined as a function of implant spacing and blood perfusion rate. The results have been quantified in generalized histograms that are readily applicable to pre-treatment planning.