Local Ionizing Radiation with and without Microwave Induced Hyperthermia in Superficial Malignant Tumors in Brain
In order to generate local hyperthermia in superficial malignant tumor in man a computerized system using a 2 450 MHz microwave generator connected to a circular direct contact applicator (diameter 90 mm) has been constructed. The automatic control system uses a pulsed irradiation technique and reads the tumor and normal tissue temperature via thermistor probes. The microcomputer regulates the output power of the microwave generator and maintains the preset temperature in the centre of the tumor with a maximum temperature ripple of ± 0.3°C. Superficial tumors of less than 7 cm diameter and of less than 3 cm depth have been accepted for treatment. The ionizing radiation beams have been conventional X-ray, electrons and 137Cs gama rays. Ionizing radiation has been given with 3.00 Gy for 10 fractions (5 fractions per week) to a total dose of 30.0 Gy. The hyperthermial level has been 42.5°C–43.5°C ± 0.3°C during 45 minutes once or twice a week for 2 weeks with at least 72 hours between each hyperthermia treatment. In case of more than one superficial tumor in the same patient a comparison between the effect of radiation alone, hyperthermia alone and the combination of those two modalities has been performed according to a prescribed protocol. The time gap between radiation and hyperthermia has been 1 or 4 hours in different schedules in order to compare the effect on normal tissue and tumor according to timing and fraction.