Evaluation of the 3D time reversal method for hyperthermia treatment planning in head and neck tumors

The goal of the hyperthermia treatment is to heat up tumors to temperatures above 42°C while keeping healthy tissues at normal temperatures. To reach this goal, accurate hyperthermia treatment planning is necessary. This demands finding the optimal excitation amplitudes and phases of the antenna applicator to heat the tumor. The aim of this paper is to evaluate the 3D time reversal focusing method for hyperthermia treatment planning application. This method which is based on the constructive wave interference at the tumor site, is implemented in our code. The code makes use of finite-difference time-domain (FDTD) to solve Maxwell´s equations. The effect of different parameters as the input settings of our 3D code, has been studied for optimal heating of two tumor models in a head and neck phantom. Performance indicators have been calculated to give a rough estimate of the best input settings. Based on our presented results, for laryngeal tumor with relatively small size, the computed power density in our 3D code is comparable with that obtained in the commercial software. Despite the difference between CST and 3D code results for the tongue tumor, which is mainly due to different applied antennas, the tumor coverage qualifiers for both tumors are very promising. Further improvements in the quality of treatment outcomes can be achieved by e.g. combination of different treatment plannings and hot-spot reduction techniques.