Inter-species Extrapolation of Skin Heating Resulting from Millimeter Wave Irradiation: Modeling and Experimental Results

• Main Authors: Nelson, D A, Walters, T J, Ryan, K L, Emerton, K B, Hurt, W D, Ziriax, J M, Johnson, L R, Mason, P A
• Format: Report
• Language: English
• Subjects: ABDOMEN; ABSORPTION; ARMS(ANATOMY); BLOOD CIRCULATION; CLINICAL MEDICINE; DAMAGE CONTROL; DOSAGE; DOSE ASSESSMENT; EVAPORATION; EXPOSURE(PHYSIOLOGY); HEAT STRESS(PHYSIOLOGY); HEAT TRANSFER; HPM(HIGH POWER DENSITY MICROWAVES); IRRADIATION; LOCALIZED IRRADIATION; LPM(LOW POWER DENSITY MICROWAVES); MATHEMATICAL MODELS; Medicine and Medical Research; MILLIMETER WAVES; MODELING; MONKEYS; NON-IONIZING; PERSPIRATION; PHYSIOLOGICAL EFFECTS; RADIATION DAMAGE; RATS; RESPONSE(BIOLOGY); SKIN DOSE; SKIN(ANATOMY); Stress Physiology; TEMPERATURE CONTROL; THERMOREGULATORY RESPONSE; TISSUES(BIOLOGY); VARIABLES

This study reports measurements of the skin surface temperature elevations during localized irradiation (94 GHz) of three species: rat (irradiated on lower abdomen), rhesus monkey (posterior forelimb), and human (posterior forearm). Two exposure conditions were examined: prolonged, low power density microwaves (LPM) and short-term, high power density microwaves (HPM). Temperature histories were compared with calculations from a bio-heat transfer model. The mean peak surface temperature increase was approximately 7.0 degrees C for the short-term HPM exposures for all three species/locations, and 8.5 degrees C (monkey, human) to 10.5 degrees C (rat) for the longer-duration LPM exposures. The HPM temperature histories are in close agreement with a one-dimensional conduction heat transfer model with negligible blood flow. The LPM temperature histories were compared with calculations from the bio-heat model, evaluated for various (constant) blood flow rates. Results suggest a variable blood flow model, reflecting a dynamic thermoregulatory response, may be more suited to describing skin surface temperature response under long duration MMW irradiation. Published in Health Physics, v84 n5 p608-615, May 2003.