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A Monte Carlo dosimetry‐based evaluation of the 7 Li ( p , n ) 7 Be reaction near threshold for accelerator boron neutron capture therapy
Author(s) -
Lee C. L.,
Zhou X.L.,
Kudchadker R. J.,
Harmon F.,
Harker Y. D.
Publication year - 2000
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.598884
Subject(s) - neutron capture , neutron , neutron source , monte carlo method , boron , materials science , dosimetry , proton , nuclear physics , particle accelerator , radiochemistry , neutron temperature , beam (structure) , physics , nuclear medicine , chemistry , optics , medicine , statistics , mathematics
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 is7 Li ( p , n ) 7 Be , 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 H 2 O moderator followed by thin6 Li and Pb shields, can provide therapeutically useful beams with treatment times less than one hour and accelerator currents less than 5 mA.