A new type of neutron capture therapy against malignant tumors using medical nuclear reactor

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[Basic Physics Study] Before using epi-thermal neutron to the patients, basic studies for neutron beam characterization have been performed. We used water phantom, cultured cells for measurement. The RBE of the each beam component has been calculated, which can be applied to the clinical dose evaluation. Besides, the treamtne planning system (so called JCDS system) has been also developed for JRR-4 boron neutron capture therapy (BNCT) project.[Basic Oncology Study] To improve the boron delivery to the tumor cells, we have developed a new boronated porphyrin and have examined using in vitro cultured glioma cells and have shown that this compound effectively accumulate in the tumor cells and show cytotoxic effect after neutron irradiation. We have also analyzed the boron uptake in two boronated compounds currently used in clinical trial by means of the cell cycle dependency. Both compound showed different behavior and based on this result we may use two compounds simultanesouly for clinical trial since they cover different cell population in the cell cycle.[Clinical Study] Since October 1999, a new clinical phase I/II trial using mixed thermal-epithermal beam with open craniotomy has been conducted at the new JRR-4 reactor with full medical equipment installed. So far, there have been 9 patients treated and the phase I/II finished. The median survival of Glioblastoma cases is 15.4 months and 16months for anaplastic astrocytomas. This result is favorable for phase I/II study and merits for further new protocol using pure epithermal beam.