Skin temperature increase during local exposure to high-power RF levels in humans

The local temperature response of the skin on heating due to prolonged exposure to RF radiation by a surface coil was investigated in five healthy volunteers. Temperature changes induced by RF radiation were measured at the skin of the calf muscle by a fluoroptic probe. Exposure to superficial specific absorption rate (SAR) levels of 6.5, 12 and 22 W/kg resulted in skin temperature increases, the highest temperature recorded was 38.3 degrees C. Although the maximum values of each temperature curve correlated with the applied superficial SAR levels, these values did not exceed the recommended temperature limit for the extremities such as given by the Food and Drug Administration (FDA).