量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum and Radiological Science and Technology.
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Purpose: To investigate the biological effects of combining carbon-beam and X-ray in vitro. Methods and Materials: Cultured cells from human salivary gland cancer (HSGc-C5 cells) were irradiatied with a single source of carbon-beam (320 MeV/nucleon) or X-ray (4 MV), or with a combination of the two. Cell survivals were evaluated by clonogenic assay and survival curves were fitted using the LQ model. Sensitivity with long interval (72 hours) irradiation was also assessed. Theoretical survival curve of the combination was proposed with estimation of the cytotoxicity using actual carbon-beam and X-ray curves. Results: Carbon-beam showed the strongest effect, X-ray the weakest, and the combination intermediate for physical doses. The sequence of combination of carbon-beam and X-ray did not affect clonogenic survival. For biological equivalent doses, carbon-beam, X-ray, and the combination of both had equal effects. The theoretical survival curves corresponded well to the actual curves of the combination. The same results were observed with long interval irradiation. Conclusions: The biological effects of combining carbon-beam and X-ray were additive but not synergistic in vitro. These results may provide important and novel information about the combination of carbon-beam and X-ray irradiation.
Combination of carbon-beam and X-ray: biologically synergistic or additive?
