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Our concept of boron neutron capture therapy (BNCT) is selective destruction of tumor cells using the heavy-charged particles yielded through 10B(n, alpha)7 Li reactions. To design a new protocol that employs epithermal neutron beams in the treatment of glioma patients, we examined the relationship between the radiation dose, histological tumor grade, and clinical outcome. Since 1968, 183 patients with different kinds of brain tumors were treated by BNCT; for this retrospective study, we selected 105 patients with glial tumors who were treated in Japan between 1978 and 1997. In the analysis of side effects due to radiation, we included all the 159 patients treated between 1977 and 2001. With respect to the radiation dose (i.e. physical dose of boron n-alpha reaction), the new protocol prescribes a minimum tumor volume dose of 15 Gy or, alternatively, a minimum target volume dose of 18 Gy. The maximum vascular dose should not exceed 15 Gy (physical dose of boron n-alpha reaction) and the total amount of gamma rays should remain below 10 Gy, including core gamma rays from the reactor and capture gamma in brain tissue. The outcomes for 10 patients who were treated by the new protocol using a new mode composed of thermal and epithermal neutrons are reported.

: The purpose of this study was to evaluate the clinical outcome of boron neutron capture therapy (BNCT) and conventional treatment in patients with newly diagnosed glioblastoma. Since 1998 we treated 23 newly-diagosed GBM patients with BNCT without any additional chemotherapy. Their median survival time was 19.5 months ; the 2-, 3-, and 5-year survival rates were 31.8% %, 22.7% %, and 9.1% %, respectively. The clinical results of BNCT in patients with GBM are similar to those of recent conventional treatments based on radiotherapy with concomitant and adjuvant temozolomide.

No abstract

A calculation method for the dosage of neutrons by near-threshold 7Li(p, n)7Be and gamma rays by 7Li(p, p'gamma)7Li was validated through experiments with variable distance between the Li target and the phantom, focusing on large angular dependence. The production of neutrons and gamma rays in the Li target was calculated by Lee's method and their transport in the phantom was calculated using the MCNP-4B code. The dosage in intra-operative boron neutron capture therapy (BNCT) using near-threshold 7Li(p, n)7Be direct neutrons was evaluated using the validated calculation method. The effectiveness of the usage of the direct neutrons was confirmed from the existence of the region satisfying the requirements of the protocol utilized in intra-operative BNCT for brain tumours in Japan. The boron-dose enhancer (BDE) introduced in this paper to increase the contribution of the 10B(n, alpha)7Li dose in the living body was effective. The void utilized to increase the dose in deep regions was also effective with BDE. For the investigation of 1.900 MeV proton beams, for example, it was found that intraoperative BNCT using near-threshold 7Li(p, n)7Be direct neutrons is feasible.