Non-Invasive Measurements in Hyperthermia: Radiometry and Previsional Thermometry
The development of Hyperthermia as a therapeutic method is closely related to the possibilty to control and quantify hyperthermic treatment in the portion of a biological body heated. For this purpose, the thermometer would have resolution and precision between 0.1°C and 0.2°C, because of the great dependence of the biological response to the temperature increase; suitable spatial resolution, between 5 and 10 mm, cause of the necessity to work in large temperature gradients; ability to follow the temporal variations of temperature with a temporal resolution of 1 second and a dimensions below 16 gauge to minimize trauma for patients. Actually the thermometry system used in the routine consist of thermistors, thermocouples and optical fibers. All these system are invasive: they give punctual temperature measurements in the whole tissue area and are traumatic for the patient.To avoid these disadvantages in our institute two non invasive methods have been tested: they’re a microwave radiometer, which measures the emitted intensity of bodies, that is directly related to their temperature and a simulation program, which calculates the temperature behavior of an heated tissue by the solution of the bio-heat equation. The results of our tests show that the thermometric technique, based on radiometer, gives temperature measurements that are to be considered as a mean among the ones obtained in the whole tissue area and not global at all; on the other hand the calculation of the heat produced by metabolism and over all of the heat taken away by the blood flow. With the intent to verify the goodness of the program we have simulated 22 hyperthermic treatments comparing the real temperature, obtained by optical fibers inserted in the tissue area during heating, with the simulated one. In parallel it was made a comparison between invasive measurements, with optical fibers, and non invasive ones, revealed by radiometer.
KeywordsSimulation Program Good Correspondence Tissue Area Microwave Radiometer Heated Tissue
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