title: [Biological effect of carbon beams on cultured human cells].
abstract: This study was performed to determine the biological effect of carbon beams on 13 human tumor cells, in comparison with 200 KVp X-rays. Carbon beams were generated by the Riken Ring Cyclotron. The RBE (relative biological effectiveness) values were distributed from 1.46 to 2.20 for LET of 20 ke V/micron, and 2.29-3.54 for 80 keV/micron. The RBEs were increased in all cell lines as the LET of carbon beams was increased from 20 to 80 keV/micron. There was no significant difference in radiosensitivity between cells from adenocarcinoma and those from squamous cell carcinoma. The relationship between the radiosensitivity of cells to X-rays and RBE was analyzed, but no significant correlation was suggested. Several survival curves of 20-40 keV/micron carbon beam irradiation showed the initial shoulders and the recovery ratios between two split doses were determined. Recovery was observed for LET of 20 keV/micron but not for that of 40 keV/micron. Furthermore, recovery ratios were 1.0-1.8, smaller than those for X-rays (1.5-2.4).
authors.affiliation: Department of Radiology, Keio University School of Medicine.
authors.forename: W J
authors.initials: WJ
authors.lastname: Ka
authors.forename: H
authors.initials: H
authors.lastname: Ito
authors.forename: N
authors.initials: N
authors.lastname: Shigematsu
authors.forename: S
authors.initials: S
authors.lastname: Yamashita
authors.forename: A
authors.initials: A
authors.lastname: Kubo
authors.forename: T
authors.initials: T
authors.lastname: Kanai
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D002244:Carbon; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D002470:Cell Survival / Q000528:radiation effects*; D017357:Cyclotrons; D006801:Humans; D018499:Linear Energy Transfer; D012062:Relative Biological Effectiveness; D014407:Tumor Cells, Cultured; D014965:X-Rays
chemical_list: D002244:Carbon