Effects of continuous and pulsed microwave irradiation on distribution of heat in the gluteal region of minipigs. A comparative study

Eleven experiments were conducted on minipigs for the purpose of determining heat distribution in tissue exposed to therapeutic doses of microwaves. Temperatures were measured by means of coated thermocouples from the cutis, subcutis, musculature, and periost. Irradiation was applied to intensities of 10 W, 40 W and 60 W by means of a "Radarmed 12 S 251" circular emitter and to 60 W, 100 W and 140 W, using a trough emitter. Maximum temperature in superficial tissue layers was reached after five to ten minutes of microwave exposure. The temperature rise in the cutis and subcutis was steeper and at a higher rate than that in the muscles. Continuation of microwave irradiation did not cause any further rise in temperature, which was attributed to induction of hyperaemia. No difference regarding heat distribution was found to exist between pulsed and continuous irradiation at equal wattage.