An alternating projections algorithm for optimizing electromagnetic fields in regional hyperthermia

Regional hyperthermia in cancer treatment is often performed by targeting tumours with electromagnetic radiation that is produced by an antenna array. In order to focus the electromagnetic energy in the tumour area, the amplitudes and phases of the antennas have to be carefully chosen. In this work we propose an algorithm for finding suitable excitations of an antenna array in a hyperthermia applicator. The proposed algorithm is based on the alternating projections method and is an adaptation of a similar method used in array beamforming. We apply the algorithm to a simplified simulated scenario (tumor in the lower leg area) and compare its results with two other eigenvalue-based algorithms from the literature. It is found that the proposed algorithm achieves a lower level of hotspots in the healthy tissues, but also lower heating contrast than the algorithms we compared it with.