Heat production in microwave-irradiated thermocouples.
It has been known for some time that the irradiation of metallic thermometers by microwaves during clinical hyperthermia can lead to artifactual readings. We describe here a series of measurements in which this effect has been quantitatively studied. In particular, the data yield values for the conversion coefficient describing the rate of heat production per unit length of a thermocouple array per watt applied power which can be compared with the rate of heat production in the same volume of tissue. The degree of artifact in the temperature recording depends on the thermal resistance of the protective materials surrounding the array, and this thermal resistance has also been determined. It has been shown that measures taken to reduce the temperature artifact do not compromise the response time of the probe.
D006801:Humans; D006979:Hyperthermia, Induced / Q000295:instrumentation; D008872:Microwaves; D013816:Thermodynamics; D013821:Thermometers