SHORTWAVE AND MICROWAVE DIATHERMY FOR DEEP-TISSUE HEATING

A theory is developed to describe the heating of a planary skin-fat-muscle tissue combination by electromagnetic wave diathermy. Both shortwaves and microwaves are treated. All mechanisms of heat dissipation are taken into account. The effects of wave frequency, power input, ambient conditions, vasodilation and core boundary conditions on the thermal distributions in the tissues are determined. The theoretical results agree well with in vivo temperatures recorded in human thighs. It is concluded that (a) microwaves at 2450 MHz yield peak temperatures in the skin layer, a superficial heating agent, (b) 900MHz radiation has a pronounced temperature rise and the highest peak value in the musculature, most attractive for deep issue heating, and (c) shortwaves at 27·12 MHz produce a wide plateau of elevated temperature in the muscle layer using a high power intensity. © 1979 IFMBE.