A fast algorithm to find optimal controls of multiantenna applicators in regional hyperthermia.

The goal of regional hyperthermia is to heat up deeply located tumours to temperatures above 42 C while keeping the temperatures in normal tissues below tissue-dependent critical values. The aim of this paper is to describe and analyse functions which can be used for computing hyperthermia treatment plans in line with these criteria. All the functionals considered here can be optimized by efficient numerical methods. We started with the working hypothesis that maximizing the quotient of integral absorbed power inside the tumour and a weighted energy norm outside the tumour leads to clinically useful power distributions which also yield favourable temperature distributions. The presented methods have been implemented and tested with real patient data from the Charité Berlin. Campus Virchow-Klinikum. The results obtained by these fast routines are comparable with those obtained by relatively expensive global optimization techniques. Thus the described methods are very promising for online optimization in a hybrid system for regional hyperthermia where a fast response to MR-based information is important.