Development and evaluation of a multi-applicator system of endocavitary radiothermotherapy of gynecologic tumors

An applicator system for the radiothermotherapy of gynecological tumors has been developed. The concept is based on combining high-dose rate afterloading therapy with local hyperthermia (27.12 MHz). The main applicator, the rf-gamma applicator consists of a guide tube for the gamma source, an electrode system and a cooling system. Isodoses and isotherms can be adapted to the individual anatomical-pathological situation presenting. For therapy planning the interaction between the applicators and the perfused tissue was investigated in a theoretical FEM model. In the first step, the SAR-function in the vicinity of the rf-applicator was determined by means of a 2D FEM calculation. In a second step, the 3D temperature fields was determined using linear shape functions. The results of these calculations showed that in every case the hot spots shifted from the applicator surface into the depths of the tissue. With the aid of an infrared camera and a split phantom the calculations were examined in a homogeneous non-perfused tissue model. Thermometry confirmed the accuracy of the results obtained. The radiothermotherapy system described here was tested in animal experiments, and is presently being used in a clinical pilot study.