Equivalency of the quality of sublethal lesions after photons and high-linear energy transfer ion beams

• Published in: Journal of radiation research 2017-11, Vol.58 (6), p.803-808
• Main Authors: Furusawa, Yoshiya, Nakano-Aoki, Mizuho, Matsumoto, Yoshitaka, Hirayama, Ryoichi, Kobayashi, Alisa, Konishi, Teruaki
• Format: Article
• Language: English
• Subjects: Animals; Biology; Cell Line; Cell Survival - radiation effects; Cricetinae; Dose-Response Relationship, Radiation; Humans; Ions; Kinetics; Linear Energy Transfer; Photons
• ISSN: 0449-3060; 1349-9157
• DOI: 10.1093/jrr/rrx030

Abstract The quality of the sublethal damage (SLD) after irradiation with high–linear energy transfer (LET) ion beams was investigated with low-LET photons. Chinese hamster V79 cells and human squamous carcinoma SAS cells were first exposed to a priming dose of different ion beams at different LETs at the Heavy Ion Medical Accelerator in the Chiba facility. The cells were kept at room temperature and then exposed to a secondary test dose of X-rays. Based on the repair kinetics study, the surviving fraction of cells quickly increased with the repair time, and reached a plateau in 2–3 h, even when cells had received priming monoenergetic high-LET beams or spread-out Bragg peak beams as well as X-ray irradiation. The shapes of the cell survival curves from the secondary test X-rays, after repair of the damage caused by the high-LET irradiation, were similar to those obtained from cells exposed to primary X-rays only. Complete SLD repairs were observed, even when the LET of the primary ion beams was very high. These results suggest that the SLD caused by high-LET irradiation was repaired well, and likewise, the damage caused by the X-rays. In cells where the ion beam had made a direct hit in the core region in an ion track, lethal damage to the domain was produced, resulting in cell death. On the other hand, in domains that had received a glancing hit in the low-LET penumbra region, the SLD produced was completely repaired.