A Monte Carlo dosimetry?based evaluation of the reaction near threshold for accelerator boron neutron capture therapy

Authors:   Lee C.L., Zhou X.L. Kudchadker R.J., Harmon F., Harker Y.D.
Journal: Medical Physics
https://doi.org/10.1118/1.59888
Abstract: Advanced methods of boron neutron capture therapy (BNCT) use an epithermal neutron beam in conjunction with tumor?targeting boron compounds for irradiation of glioblastomas and metastatic melanomas. A common neutron?producing reaction considered for accelerator?based BNCT is whose cross section increases very rapidly within several tens of keV of the reaction threshold at 1.88 MeV. Operation in the proton energy region near threshold will have an appreciable thick target neutron yield, but the neutrons produced will have relatively low energies that require little moderation to reach the epithermal range desirable for BNCT. Because of its relatively low projected accelerator cost and the portability of the neutron source/target assembly, BNCT based on the near?threshold technique is considered an attractive candidate for widespread hospital use. A systematic Monte Carlo N?Particle (MCNP) investigation of the dosimetric properties of near?threshold neutron beams has been performed. Results of these studies indicate that accelerator proton energies between 1.93 and 1.99 MeV, using 5 cm of moderator followed by thin and Pb shields, can provide therapeutically useful beams with treatment times less than one hour and accelerator currents less than 5 mA.