[Mutation induction by heavy ion beams and X-rays: analysis with cultured cell line].
This study was performed to determine the biological effects of heavy ion beams on cultured cells. V79 cells were irradiated with carbon or neon beams or X-rays, and cell survivals was calculated by the colony assay method. The Do values for 150 kVp X-rays, 20 keV/micron and 80 keV/micron carbon beams, and 80 keV/micron neon beams were 2.2Gy, 1.8Gy, 1.0Gy and 1.4Gy, respectively. After 7-10 day expression periods, the mutation frequencies at the hypoxanthine-guanine phosphribosyl transferase (hprt) locus were analyzed from the numbers of colonies formed in media supplemented with 6-thioguanine. An extremely higher frequency of mutation was observed with heavy ion beams compared with X-rays. Both cell killing effect and the mutation induction were enhanced when the LET of carbon beams was increased from 20 to 80 keV/micron. These results mean that carbon beams had a stronger cell-killing effect than X-rays, but also carried a high risk of mutation induction. On the other hand, neon beams yielded cell survival curves similar to those of carbon beams, but they had a smaller mutation induction effect than carbon beams. The effect of fractionated irradiation (3 hr interval) on cell survival and mutation frequency were also examined. When cells were irradiated with X-rays, cell survival was increased by fractionation, but the mutation frequency was not modified. Irradiating cells with fractionated carbon beams, survival curves were not affected, but mutation frequency was reduced.
Toya
K
K
Department of Radiology, Keio University School of Medicine.
Shigematsu
N
N
Ito
H
H
Yamashita
S
S
Kubo
A
A
Kanai
T
T
D000818:Animals; D002244:Carbon; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D009154:Mutation / Q000528:radiation effects*; D009356:Neon; D014965:X-Rays
D009356:Neon; D002244:Carbon; D007041:Hypoxanthine Phosphoribosyltransferase