Interstitial radiofrequency hyperthermia for brain tumors--preliminary laboratory studies and clinical application

An interstitial radiofrequency (RF) hyperthermia system for brain tumor was evaluated in cranial phantoms and cat brains. An intracranial RF applicator and thermocouple microprobes were emplaced in the brain and a headband-type flexible extracranial electrode fixed over the scalp. An 8 MHz RF capacitive-type heating machine provided power. The temperature distribution was measured by thermography. In phantom and animal studies, the RF power had good penetration into the tissue and generated uniform and easily controllable high-temperature fields within the intracranial cavity. There was little change in temperature near or in the cranium itself. Six cases of human malignant glioma were treated with this interstitial RF hyperthermia system, achieving therapeutic temperature without adverse effects.