13.56 MHz hyperthermia temperature distribution in phantoms, and clinical results of therapy.

Hyperthermia with 13.56 MHz was studied experimentally and clinically. Experimental studies revealed the following. To spare the surface electrodes greater than half of the phantom in diameter should be employed preferably. By cooling the electrodes, the surface is additionally spared, which is important in patients with thick subcutaneous fat. The application of different electrode sizes induces higher temperature in the vicinity of the smaller electrode. Relatively homogeneous heat distribution occurred in the brain. In contrast, thorax mediastinum and hilar areas do show much temperature increase, whereas lung parenchyma shows a high increase. Pelvis generally demonstrates a uniform temperature increase. High frequency currents do hardly penetrate bones but it achieves higher temperature by convection sequence. The best clinical results were obtained in superficial tumors; for example, breast carcinoma showed an 80% remission rate. ENT tumors responded well, with a remission rate of 73%. Glioblastoma showed no improvement with hyperthermia. Hyperthermia is well tolerated. Therefore, this treatment mode is highly recommended to be used as an adjunct to radiotherapy in palliative treatment.