Hyperthermic therapy of deep seated tumors: comparison of the heating efficiencies of an annular array applicator and a capacitively coupled radiofrequency system.

Among 82 cases of deep seated tumors treated by hyperthermia with an annular array applicator (AA) and/or a capacitively coupled 8 mHz system (CCS) combined with radiation therapy, 13 cases were treated by both devices. The efficiencies of tumor heating were compared in terms of the time required to attain 42 degrees C, the duration of heating time and the thermal dose as determined by a biological iso-effect formula for equivalent minutes at 42.5 degrees C. Temperature profiles and percent of temperature levels greater than 42 degrees C were better in the cases treated by the AA, but higher thermal doses were obtained with the CCS because longer treatment times were tolerated with the CCS than with the AA. Methods are necessary to prevent excess elevation of body temperature in the case of the AA, and to reduce superficial pain where the applicators contact the skin in the case of the CCS.