title: Microdosimetry of the full slowing down of protons using Monte Carlo track structure simulations.
abstract: The article investigates two approaches in microdosimetric calculations based on Monte Carlo track structure (MCTS) simulations of a 160-MeV proton beam. In the first approach, microdosimetric parameters of the proton beam were obtained using the weighted sum of proton energy distributions and microdosimetric parameters of proton track segments (TSMs). In the second approach, phase spaces of energy depositions obtained using MCTS simulations in the full slowing down (FSD) mode were used for the microdosimetric calculations. Targets of interest were water cylinders of 2.3-100 nm in diameters and heights. Frequency-averaged lineal energies ([Formula: see text]) obtained using both approaches agreed within the statistical uncertainties. Discrepancies beyond this level were observed for dose-averaged lineal energies ([Formula: see text]) towards the Bragg peak region due to the small number of proton energies used in the TSM approach and different energy deposition patterns in the TSM and FSD of protons.
authors.affiliation: Thailand Institute of Nuclear Technology, Ongkharak, Nakorn Nayok 26120, Thailand thiansinl@tint.or.th.
authors.forename: T
authors.initials: T
authors.lastname: Liamsuwan
authors.affiliation: School of Health Science, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Uehara
authors.affiliation: Radiation Biophysics Group, Department of Oncology-Pathology, Karolinska Institutet, Stockholm 17176, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Nikjoo
mesh_terms: D003198:Computer Simulation; D018499:Linear Energy Transfer; D055616:Microtechnology / Q000379:methods*; D009010:Monte Carlo Method; D011522:Protons; D011874:Radiometry / Q000379:methods*; D014867:Water / Q000737:chemistry
chemical_list: D011522:Protons; D014867:Water