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Microdosimetric evaluation of the 400 MeV ∕ nucleon carbon beam at HIMAC
Author(s) -
Endo Satoru,
Tanaka Kenichi,
Ishikawa Masayori,
Hoshi Masaharu,
Onizuka Yoshihiko,
Takada Masashi,
Yamaguchi Hiroshi,
Hayabuchi Naofumi,
Maeda Naoko,
Shizuma Kiyoshi
Publication year - 2005
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 - 10.1118/1.2133719
Subject(s) - imaging phantom , bragg peak , beryllium , beam (structure) , proton , carbon fibers , relative biological effectiveness , linear energy transfer , materials science , scintillation , physics , optics , nuclear physics , irradiation , detector , composite number , composite material
Microdosimetric single event spectra were determined as a function of depth in an acrylic phantom for the carbon beam at HIMAC using a tissue equivalent proportional counter (TEPC) coupled to a scintillation counter system. The fragments produced by the carbon beam were identified by the Δ E ‐time of flight distribution obtained from two scintillation counters which were positioned at the up‐ and down‐stream of the TEPC. Lineal energy distribution for the carbon beam and its five fragments, namely, proton, helium, lithium, beryllium, and boron ions, were measured in the lineal‐energy range of 5 – 1000 keV ∕ μ m at five phantom depths between 0 and 230 mm . The dose distribution for the carbon beam and its fragments were obtained separately. The relative biological effectiveness (RBE) of the carbon beam in the phantom was calculated using a response function. The maximum RBE for the carbon beam was found to be about 5 near the Bragg peak. It was observed to rapidly decrease for Bragg peaks occurring at deeper positions in the phantom. The dose from the beam fragments accounted for about 30% to the total dose, however, its contribution to the RBE was less than 17%.