The Study of Standardization of Temperature Distribution of Interstitial Hyperthermia: In Phantoms and Living cat's brain tissue (Normal Tissue)

Koh, Kyoung Hwan; Cho, Chul Koo; Park, Young Hwan; Park, Woo Yoon; Yoo, Seong Yul; Kim, Jong Hyun; Lee, Seung Hoon

Abstract

The ultimate objective of our experiment is to obtain the precise distribution of temperature in malignant tumors occurring in cerebral parenchyma of human beings when we will carry out interstitial hyperthermia in the near future. To achieve this purpose, first of all, it is necessary to make an attempt at performing interstitial hyperthermia in vivo under the similar condition of human beings. Moreover, it is also necessary to get the basic data from dynamic phantom in order to standardize and compare results obtained from interstitial hyperthermia carried out in cats. By having performed these experiments we got the following results. 1) On doing interstitial hyperthermia with 915 MHz microwave, the possible treated volume was 2cm by 2cm by 6cm according to 50% specific absorption rate (SAR). 2) The distribution of temperature within non-circulated static phantom was much the same as power density in air, but we observed that the temperature, within 5~10 minutes, rose to more higher than 55degrees C not measure with ga-As fiberoptic termistor which was not impeded by microwave after performing interstitial hyperthermia. 3) Within dynamic phantom in which normal saline was circulating, temperature reached steady state which was maintained for more than 45 minutes through transit period in 5 minutes after starting interstitial hyperthermia. 4) When we interrupted circulation in the dynamic phantom, we observed that temperature rose to the same level as in the static phantom. 5) We could carry out interstitial hyperthermia safely when we used the generating power below 5 watts. Abrupt interruption of circulation caused a rapid increase in temperature. Times taking to rise to maximum 55degrees C were 15.2 minutes (SE 0.4), 9.7 minutes (SE 0.3), and 6.3 minutes (SE 0.4) respectively with generating powers of 5, 10, and 15 watts.