Near-field microwave radiometric temperature monitoring of heated and cooled living tissues

Using the dependence of the shaping depth of the received thermal radio emission on the apertures of small contact probes used as antennas in microwave radiometers, the temperature profile dynamics in subcutaneous human tissues subjected to heating and cooling have been retrieved according to the measured dynamics of the received signal. For the experiment, a human hand was heated (or cooled) in water, and temperature variations in hot (or cold) water with subsequent relaxation in air were measured using contact antennas with sizes of 0.5, 1, 2, and 3 cm and a radiometer at 31 cm wavelength. Antennas were matched both to water and living tissues. Similar radiometric measurements in air and the recovery of the temperature relaxation processes in the human body following a 100-second heating are presented. The results show that relaxation processes in the near-surface layer commence immediately, while with deeper layers, the heating still continues for some time. The developed single-wave technique of subcutaneous temperature profile recovery might prove efficient for medical applications in monitoring internal body temperatures during microwave hyperthermia treatment.