title: Characteristics of boron-dose enhancer dependent on dose protocol and 10B concentration for BNCT using near-threshold 7Li(p,n)7Be direct neutrons.
abstract: The dependence of boron-dose enhancer (BDE) characteristics on dose protocol and 10B concentration was evaluated for BNCT using near-threshold 7Li(p,n)7Be direct neutrons. The treatable protocol depth (TPD) was utilized as an evaluation index. MCNP calculations were performed for near-threshold 7Li(p,n)7Be at a proton energy of 1.900 MeV and for a polyethylene BDE. The effect of dose protocol on BDE characteristics was reflected in terms of the optimum BDE thickness needed for maximum TPD which was found to be independent of the treatable dose but was observed to vary for different combinations of the tolerance doses for heavy charged particles and gamma rays. For the 10B concentration dependence, the TPD was increased by increasing the T/N ratio, i.e., the ratio of the 10B concentration in the tumour (10B(Tumour)) to that in the normal tissue (10B(Normal)), and by increasing 10B(Tumour) and 10B(Normal) at constant T/N ratio. It was found that the use of BDE becomes unnecessary from the viewpoint of increasing the TPD, when 10B(Tumour) is over a certain level which is decided by the conditions of the dose protocol.
authors.affiliation: Research Institute for Radiation Biology and Medicine, Hiroshima University, Kasumi, Minami-ku, Hiroshima 734-8553, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Tanaka
authors.forename: Tooru
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Gerard
authors.initials: G
authors.lastname: Bengua
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Nakagawa
authors.forename: Satoru
authors.initials: S
authors.lastname: Endo
authors.forename: Masaharu
authors.initials: M
authors.lastname: Hoshi
mesh_terms: D001895:Boron; D016754:Boron Neutron Capture Therapy / Q000379:methods*; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D006801:Humans; D008094:Lithium / Q000737:chemistry; D008962:Models, Theoretical; D009502:Neutrons; D010315:Particle Accelerators; D019047:Phantoms, Imaging; D017785:Photons; D020959:Polyethylene / Q000737:chemistry; D011522:Protons; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*
chemical_list: D011522:Protons; D020959:Polyethylene; D008094:Lithium; D001895:Boron