Host: The Japan Radiation Research Society
Lewis lung carcinoma cells were exposed to 89.63MeV/u carbon ion and 6MV X-ray irradiations respectively, and cell reproductive death and DNA damage were examined. Lewis lung carcinoma cells were shown to be more sensitive to the carbon ion beam from the measured survival data using clonogenic assay. The relative biological effectiveness (RBE) value of the carbon ion beam at 10% survival level was up to 1.77, indicating that the damage induced by the carbon ion irradiation was more remarkable than that induced by the low linear energy transfer (LET) X-rays. The dose response curves of "Tail DNA (%)" (TD) and "Olive tail moment" (OTM) detected with comet assay for the carbon ion irradiation showed a saturated effect beyond about 8 Gy, while it was not found in the case of the X-ray irradiation. There was an inverse correlation that the high-LET carbon ion beam produced a lower survival fraction at 2 Gy (SF2) value and a higher initial Olive tail moment at 2 Gy (OTM2) than those for the X-ray irradiation. In conclusion, carbon ion beams having high LET values produced more severe cell reproductive death and DNA damage in Lewis lung carcinoma cell in comparison with X-rays and comet assay could be a predictive assay solely applied or combining with clonogenic assay to assess the radiosensitivity of cancerous cells prior to clinical therapy.
