2018 Fiscal Year Final Research Report

Investigation of 124Sb-Be neutron source for BNCT

Research Project

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Project/Area Number	16K15584
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Multi-year Fund
Research Field	Radiation science
Research Institution	Hiroshima University
Principal Investigator	Tanaka Kenichi 広島大学, 工学研究科, 准教授 (70363075)
Co-Investigator(Kenkyū-buntansha)	遠藤暁広島大学, 工学研究科, 教授 (90243609) 梶本剛広島大学, 工学研究科, 助教 (70633759) 櫻井良憲京都大学, 複合原子力科学研究所, 准教授 (20273534)
Project Period (FY)	2016-04-01 – 2019-03-31
Keywords	中性子捕捉療法 / 照射場設計 / 同位体線源 / 放射線治療物理学 / 放射線科学 / 放射線技術学
Outline of Final Research Achievements	As third neutron source, following reactors and accelerators, isotopes have advantages such as stability of the neutron production and ease in controlling. Among them, the combination of gamma ray source 124Sb and 9Be target produces neutrons with about 24 keV. The neutron yield was calculated using Monte Carlo calculations with the PHITS code. Be was set with varied thickness around 124Sb. Through this, the required activity was also estimated for a standard of beam quality as an epithermal neutron beam by IAEA-tecdoc-1223. For an apithermal neutron beam, Be with the thickness of about 13 mm is required. In this case, the required activity is in the order of ten to the fifteenth Bequrel. In this case, the contamination of gamma rays is about four orders higher than the standard. By combining 30 cm thick Bi and 30 cm thick Pb, the beam quality satisfies the satandard. In this case, the required activity is about ten to the sixteenth Bequrell.
Free Research Field	医学物理学
Academic Significance and Societal Importance of the Research Achievements	本研究の特色は、原子炉・加速器に続く第3の中性子源として、放射性同位元素をBNCTに適用する点にある。本研究で扱う中性子源が治療に用いられることとなれば、高エネルギー中性子の混入が少なく、従って正常組織被曝がより少ないBNCT照射場の実現が予想される。これは、患者に優しいBNCTの実現、適用腫瘍種拡大や臨床数増加による研究進展、更にはがんの撲滅に寄与することで社会に貢献する点で意義がある。本課題で得られた124Sb-Be中性子についての知見は、ラジオグラフィをはじめとする中性子利用の高度化に寄与し、広く放射線計測学、中性子科学の発展に貢献すると期待される。