Increase in Irradiation Beam Intensity by Using a Hybrid Target System in Cyclotron-Based Neutron Capture Therapy

• Published in: Journal of nuclear science and technology Vol. 47; no. 7; p. 575
• Main Authors: TAKATA, Takushi, TANAKA, Hiroki, SAKURAI, Yoshinori, MARUHASHI, Akira
• Format: Journal Article
• Language: English
• Published: Tokyo Taylor & Francis Ltd 2010
• Subjects: Assembly; Beryllium; Capture (nuclear); Cyclotrons; Fast neutrons; Generators; Hybrid systems; Therapy; Thin films
• ISSN: 0022-3131; 1881-1248
• DOI: 10.3327/jnst.47.575

A cyclotron-based epithermal neutron generator has been expected to achieve the early realization of hospital-based boron neutron capture therapy. The system using a hybrid target composed of a thin tungsten (W) layer and a thick beryllium (Be) one with 30 MeV protons and a beam-shaping assembly was previously proposed as a better generator candidate than the system using only a thick W or Be layer. In this study, to clearly show that the hybrid target system is more clinically useful than the other two, all three target systems were compared using epithermal neutron intensity as a figure of merit under an equal condition of the harmful effect of fast neutron dose. We found that the hybrid system using a W layer of appropriate thickness increased the epithermal neutron intensity by 107 and 32% compared with systems using only W or Be, respectively, with the same harmful fast neutron component. It is concluded that the hybrid target system is more useful in terms of epithermal neutron intensity than systems with either W or Be as a generator using the 30 MeV proton accelerator and beam-shaping assembly.