| Research Abstract |
The body temperature is a physical parameter that provides the body with the fundamental background condition for its life, activities and functions. Temperature measured at the axilla, for example, is usually taken as the body temperature. Actually, it is not uniform in a body. It takes different values at various parts of body and it also changes with the time, reflecting changes in physiological conditions, for instance. However, the knowledge of temperature distribution in a living body is limited due to the lack of non-invasive temperature measurement technique. In the hyperthermia treatment of cancer, tissue temperatures at several points in the treatment region are measured invasively by inserting thermometer probes, such as thermocouples. Development of non-invasive temperature measurement techniques is strongly desired.
The microwave radiometry is investigated to develop a non-invasive temperature measurement technique. In our method, the brightness temperature of a biological
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object is measured at five different microwave frequencies to obtain a set of data, and a temperature-versus-depth profile is retrieved from the set of data. Results obtained during the 1989-1990 period can be summarized as follows : (1) It was shown theoretically and experimentally that the radiometric temperature measurement was possible from above a water-filled bolus which was required for the surface cooling during the heating for hyperthermic treatment, (2) a method was developed using the Monte Carlo technique to calculate the precision of tissue temperature measurement along the temperature profile, (3) it became possible to calculate the precision of tissue temperature measurement from the brightness temperature resolution of the radiometer, (4) numerical simulation indicated that the precision of about +/-0.4 k at 2 cm and about +/-0.7 k at 4 cm from surface was to be expected at an integration time of 5 seconds for a new radiometer which was under construction in our laboratory. Less
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