title: Modeling the biological response of normal human cells, including repair processes, to fractionated carbon beam irradiation.
abstract: To understand the biological response of normal cells to fractionated carbon beam irradiation, the effects of potentially lethal damage repair (PLDR) and sublethal damage repair (SLDR) were both taken into account in a linear-quadratic (LQ) model. The model was verified by the results of a fractionated cell survival experiment with normal human fibroblast cells. Cells were irradiated with 200-kV X-rays and monoenergetic carbon ion beams (290 MeV/u) at two irradiation depths, corresponding to linear energy transfers (LETs) of approximately 13 keV/μm and 75 keV/μm, respectively, at the Heavy Ion Medical Accelerator in Chiba of the National Institute of Radiological Sciences. When we only took into account the repair factor of PLDR, γ, which was derived from the delayed assay, the cell survival response to fractionated carbon ion irradiation was not fully explained in some cases. When both the effects of SLDR and PLDR were taken into account in the LQ model, the cell survival response was well reproduced. The model analysis suggested that PLDR occurs in any type of radiation. The γ factors ranged from 0.36-0.93. In addition, SLD was perfectly repaired during the fraction interval for the lower LET irradiations but remained at about 30% for the high-LET irradiation.
authors: Medical Physics Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555, Japan.
authors: Mami
authors: M
authors: Wada
authors: Masao
authors: M
authors: Suzuki
authors: Cuihua
authors: C
authors: Liu
authors: Yumiko
authors: Y
authors: Kaneko
authors: Shigekazu
authors: S
authors: Fukuda
authors: Koichi
authors: K
authors: Ando
authors: Naruhiro
authors: N
authors: Matsufuji
mesh_terms: D002250:Carbon Radioisotopes; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects*; D003198:Computer Simulation; D004249:DNA Damage / Q000502:physiology* / Q000528:radiation effects; D004260:DNA Repair / Q000502:physiology*; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects*; D063193:Heavy Ion Radiotherapy / Q000379:methods*; D020450:Heavy Ions; D006801:Humans; D008954:Models, Biological; D011827:Radiation
chemical_list: D002250:Carbon Radioisotopes
keywords: PLDR; SLDR; fractionated carbon beam irradiation; modeling