Present status of Accelerator-Based BNCT

Authors:   Kreiner A.J., Berqueiro J., Cartelli D., Baldo M., Castell W., Gomez Asoia J., Padulo J., Suárez Sandín J.C., Igarzabal M., Erhardt J., Mercuri D., Valda A.A., Minsky D.M., Debray M.E., Somacal H.R., Capoulat M.E., Herrera M.S., del Grosso M.F., Gegetti L., Suarez Anzorena M., Canepa N., Real N., Gun M., Tacca H.
Journal: Reports of Practical Oncology & Radiotherapy
https://doi.org/10.1016/j.rpor.2014.11.004
Abstract: Aim: This work aims at giving an updated report of the worldwide status of Accelerator-Based BNCT (AB-BNCT). Background: There is a generalized perception that the availability of accelerators installed in hospitals, as neutron sources, may be crucial for the advancement of BNCT. Accordingly, in recent years a significant effort has started to develop such machines. Materials and methods: A variety of possible charged-particle induced nuclear reactions and the characteristics of the resulting neutron spectra are discussed along with the worldwide activity in suitable accelerator development. Results: Endothermic 7Li(p,n)7Be and 9Be(p,n)9B and exothermic 9Be(d,n)10B are compared. In addition to having much better thermo-mechanical properties than Li, Be as a target leads to stable products. This is a significant advantage for a hospital-based facility. 9Be(p,n)9B needs at least 4–5 MeV bombarding energy to have a sufficient yield, while 9Be(d,n)10B can be utilized at about 1.4 MeV, implying the smallest possible accelerator. This reaction operating with a thin target can produce a sufficiently soft spectrum to be viable for AB-BNCT. The machines considered are electrostatic single ended or tandem accelerators or radiofrequency quadrupoles plus drift tube Linacs. Conclusions: 7Li(p,n)7Be provides one of the best solutions for the production of epithermal neutron beams for deep-seated tumors. However, a Li-based target poses significant technological challenges. Hence, Be has been considered as an alternative target, both in combination with (p,n) and (d,n) reactions. 9Be(d,n)10B at 1.4 MeV, with a thin target has been shown to be a realistic option for the treatment of deep-seated lesions.