Objective To investigate the effects of high-energy X-rays irradiation at different dose rates on the plating efficiency, survival fraction and radiobiological parameters of cervical cancer HeLa cell line.
Methods Human cervical cancer Hela cell line in exponential growth phase were treated with 0, 1, 2, 4, 6, 8Gy at 2, 6, 10Gy/min dose rates. After irradiation for 12 days in the incubator, 0.5% crystal violet staining was fixed, and the number of clones larger than 50 cells was counted. The data was analyzed and dose-survival curves were plotted following the standard linear-quadratic model using GraphPad Prism 5.0 software to get the values of radiobiological parameters. Differences of survival fraction with different dose rates were tested with analysis of variance by SPSS19.0 software.
Results After 2, 6, 10 Gy/min of high-energy X-rays irradiation, the differences between the plating efficiency and survival fraction of HeLa cells were statistically significant (P=0.03 and 0.04). The average α/β values were 3.28Gy, 3.35Gy, 3.93Gy, SF2 were 0.79, 0.78, 0.75. Three dose rates showed no statistically significant difference in the biological parameters, α/β, D0, Dq or SF2 (P > 0.05).
Conclusion With the increasing dose rate of high-energy X-rays (2, 6, 10Gy/min), the survival rate of HeLa cells gradually decreases while the biological effect gradually increases.
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