title: Dose point kernel for boron-11 decay and the cellular S values in boron neutron capture therapy.
abstract: The study of the radiobiology of boron neutron capture therapy is based on the cellular level dosimetry of boron-10's thermal neutron capture reaction 10B(n,alpha)7Li, in which one 1.47 MeV helium-4 ion and one 0.84 MeV lithium-7 ion are spawned. Because of the chemical preference of boron-10 carrier molecules, the dose is heterogeneously distributed in cells. In the present work, the (scaled) dose point kernel of boron-11 decay, called 11B-DPK, was calculated by GEANT4 Monte Carlo simulation code. The DPK curve drops suddenly at the radius of 4.26 microm, the continuous slowing down approximation (CSDA) range of a lithium-7 ion. Then, after a slight ascending, the curve decreases to near zero when the radius goes beyond 8.20 microm, which is the CSDA range of a 1.47 MeV helium-4 ion. With the DPK data, S values for nuclei and cells with the boron-10 on the cell surface are calculated for different combinations of cell and nucleus sizes. The S value for a cell radius of 10 microm and a nucleus radius of 5 microm is slightly larger than the value published by Tung et al. [Appl. Radiat. Isot. 61, 739-743 (2004)]. This result is potentially more accurate than the published value since it includes the contribution of a lithium-7 ion as well as the alpha particle.
authors.affiliation: Research Center for Tumor Diagnosis and Radiotherapy Physics and Laboratory of Medical Physics and Engineering, Peking University, Beijing 100871, People's Republic of China.
authors.forename: Yunzhi
authors.initials: Y
authors.lastname: Ma
authors.forename: JinPeng
authors.initials: J
authors.lastname: Geng
authors.forename: Song
authors.initials: S
authors.lastname: Gao
authors.forename: Shanglian
authors.initials: S
authors.lastname: Bao
mesh_terms: D001895:Boron / Q000737:chemistry / Q000627:therapeutic use*; D016754:Boron Neutron Capture Therapy / Q000379:methods*; D003198:Computer Simulation; D007477:Ions; D008094:Lithium / Q000737:chemistry; D015233:Models, Statistical; D009010:Monte Carlo Method; D009502:Neutrons; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation / Q000379:methods*; D011879:Radiotherapy Dosage; D012984:Software
chemical_list: D007477:Ions; D008094:Lithium; D001895:Boron