Capacitive heating of phantom and human tumors with an 8 MHz radiofrequency applicator (Thermotron RF-8)

Abstract

The thermal profile was investigated in agar phantoms and in human tumors heated capacitively with 8 MHz RF. Deep and homogeneous heating could be achieved in a large homogeneous phantom of 25 cm diameter and 24 cm thick when heated with a pair of 25 cm diameter electrodes, coupled to both bases of the phantom. When the size of the two electrodes was not the same, the region near the smaller electrode was preferentially heated. It was, therefore, possible to control the depth of heating by choosing properly sized electrodes. Therapeutic temperature (greater than 42 degrees C) could be obtained in 7 out of 9 small, as well as, bulky superficial human tumors as large as 8 X 8 X 10 cm. Indications are that heating of some deep-seated human tumors might be achieved by the capacitive method, provided that subcutaneous fat layer is cooled by temperature controlled bolus and large electrodes are used. The effect of the anatomical structure on the power deposition in the human body during capacitive heating should be further investigated.