A novel BNCT irradiation system with an on-line monitor using 7Li(P,N) 7Be near threshold neutrons

• Published in: Radiation measurements 2011-12, Vol.46 (12), p.2000-2002
• Main Authors: Kobayashi, Tooru, Bengua, Gerard, Tanaka, Kenichi, Hayashizaki, Noriyosu, Katabuchi, Tatsuya, Hattori, Toshiyuki, Aritomi, Masanori
• Format: Article
• Language: English
• Subjects: 7Li(p,n) 7Be reaction; Accelerator; Direct neutron usage; Earth sciences; Earth, ocean, space; Exact sciences and technology; Geochronology; Isotope geochemistry. Geochronology; Liquid lithium target; Near-threshold
• ISSN: 1350-4487; 1879-0925
• DOI: 10.1016/j.radmeas.2011.08.024

A neutron irradiation system for boron neutron capture therapy using accelerators with an online dose monitoring system was studied for the possible practical implementation of hospital-based BNCT. For this purpose the neutrons produced by the near threshold 7Li(p,n) 7Be reaction, i.e. an incident proton energy of around 1.90 MeV, have suitable properties. Such as the maximum energy below 100 keV and mostly forward-directed. A good candidate material to shield gamma rays from the Li-target was Lead and the suitable boron-dose enhancer was polyethylene. The optimum physical dimensions and configuration of the irradiation system was determined using the concept of treatbale protocol depth as figures of merit. For the online monitor system, the single photon emission computed tomography using prompt gamma-ray was studied to provide an ideal dose estimation system. A neutron producing target system with a liquid lithium jet flow of about 30 m/s at a thickness of 1 mm and a cross-sectional area of 50 mm × 50 mm is proposed.