Use of interstitial hyperthermia to produce homogeneous heat distribution patterns.

The preliminary experience of the use of a prototype hyperthermia unit (Astro 200) for tumor regression in Howard University Hospital's Department of Radiotherapy is described. The purpose of this study was to produce homogeneous heat distribution patterns within a 5-cm cylinder in the middle of a phantom (ground beef) using radio frequency conducted through electrodes implanted in the medium. Homogeneous heat distribution was achieved by finding the optimal spatial distribution of electrodes within the phantom and by sequencing the radio frequency in the electrodes. Monitored observation revealed a steady state homogeneous temperature of 42.5 °C within a 4-cm diameter. There was a temperature difference of 0.5 °C within 1 cm of the periphery.Heat in the clinical range of 42 to 43 °C has caused tumor regression, and was found to be most effective when combined with another modality of radiation. At Howard University Hospital, hyperthermia is used in conjunction with conventional modalities-surgery, radiotherapy, and chemotherapy-in the treatment of tumors.