NONINVASIVE MICROWAVE MULTIFREQUENCY RADIOMETRY USED IN MICROWAVE HYPERTHERMIA FOR BIDIMENSIONAL RECONSTRUCTION OF TEMPERATURE PATTERNS

Microwave radiometry, used routinely since 1984 for non invasive tempe rature measurements during hyperthermia sessions for superficial tumou rs treatment has proven its efficiency for temperature control. From r adiometric temperature measurements in two frequency ranges (around 1 and 3 GHz) and superficial (or cutaneous) temperature measurements ach ieved during hyperthermia sessions, a numerical method to obtain the t wo-dimensional thermal profile has been developed and implemented. Thi s method is based on hyperthermia simulation from the bioheat equation , the absorbed microwave power calculation in the medium taking into a ccount the radiative diagram of the applicator, and the calculation of radiometric temperatures. From these experimental measurements (radio metric and superficial temperatures, heating power, dielectric and the rmal characteristics), a program to determine the bidimensional distri bution of temperature during the hyperthermia session has been develop ed, tested and used during and after clinical treatments.