インプラントヒーティングシステム (IHS) を用いた悪性脳腫瘍の組織内温熱療法とその将来展望

抄録

Interstitial hyperthermia of brain tumors has been developed and made by an implant heating system (IHS) using ferromagnetic implant (Fe-Pt alloy) with low Curie temperature. Induction heating of the implants which are stereotactically placed in a tumor is obtained by eddy current under high frequency (240 kHz) magnetic field. The whole tumor is heated by heat conduction from the implant.
Safe, repeated and longterm treatments of 35 cases of malignant brain tumor have been made using IHS. The effectiveness of combined treatment with interstitial hyperthermia and external irradiation was confirmed by repeated CT and pathological examination. Over all response rate was 31.4%, while those of metastatic tumor and deep-seated, malignant glioma were 50% and 36.4% respectively. The characteristic and common pathological finding of treated tumor was circumscribed, ellipoid shape of coagulation necrosis around the implant. Regarding the future prospects of IHS, following projects have been on going. A large induction coil (φ 60 cm) has been developed and been used for the malignancies of other systemic organs. Three dimentional arrangement of implants in a tumor to cover whole tumor properly and effectively will be made by computer simulation. The combination treatment of interstitial hyperthermia by IHS and brachytherapy with isotope seeds using common after loading catheter will be promissing. The developement of new implant which is not influenced by the direction of magnetic field and also of ultra-small grain (powder) implant for the intracellular hyperthermia are possible.