Relative Biological Effectiveness (RBE) of 131 I Radiation Relative to 60 Co Gamma Rays

Objective: To assess relative biological effectiveness (RBE) of I radiation relative to Co gamma rays in glioblastoma spheroid cells. Materials and Methods: In this experimental study, glioblastoma spheroid cells were exposed to 131 I radiation and Co gamma rays. Radiation induced DNA damage was evaluated by alkaline comet assay. Samples of spheroid cells were treated by radiation from 131 60 I for four different periods of time to find the dose-response equation. Spheroid cells were also exposed by 200 cGy of Co gamma rays as reference radiation to induce DNA damage as endpoint. Results: Resulted RBE of 131 60 I radiation relative to Co gamma rays in 100 µm giloblastoma spheroid cells was equal to 1.16. Conclusion: The finding of this study suggests that 60 I photons and electrons can be more effective than 60 131 Co gamma rays to produce DNA damage in glioblastoma spheroid cells.