Experimental and clinical evaluation of a prototype hyperthermia system.

In order to achieve better thermal distribution, a high output radiofrequency capacitive heating system was developed for hyperthermia and operated at a frequency of 13.56 MHz with an output of 1,000 watts (Inter Nova Inc., IH-1000). With use of this equipment, an agar phantom study, an animal experiment, and a clinical trial have been performed. This unit has made it possible to use large applicators with large electrodes. The phantom study revealed homogeneous, deep-heating capability. In the animal study using a miniature pig, good thermal distribution within the body was obtained, but the problem of overheating the subcutaneous fat layer remained. In the clinical application, some limiting factors remained unsolved in spite of our attempts to eliminate them; however, the problem of insufficient power supply was solved.