Monte Carlo simulation for assessing absorbed dose effects of low-dose β-radiation (⁹⁰Sr/⁹⁰Y) on cytotoxicity and apoptotic death in K562 cells

Objective: Most studies suggest that dose-specific radiation regimens are essential for optimal induction of cancer cell response. This study focused on determining β-radiation-absorbed dose (rad) effects on the cell viability, cytotoxicity, hypersensitivity, and cell death of K562 cells using experimental methods and Monte Carlo simulation (MCS).

Materials and methods: The K562 cells were cultured and irradiated with β-particles emitted from a strontium source in vitro, with the estimated daily activity of 1.238 μCi. The treated cells were radiated at least three times every day for 3 consecutive days. The cell viability and apoptosis were investigated in treated cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, DNA electrophoresis, Hoechst dye, and inverted microscope. The average absorbed doses were obtained by MCS (MCNPX code). To verify simulation and experimental results, we used a Geiger-Muller counter and estimated a scaling factor.

Results: The cytotoxic effects and cell death were induced in the treated groups via rad in a time-dependent manner. The highest apoptotic and cytotoxic effects were observed in cells after irradiation with β-particles for 120 min per day in 3 consecutive days. rads were determined using MCNPX code and cell survival rates were significantly reduced during irradiation periods. No significant hyper-radiosensitivity was found based on experimental and theoretical results.

Conclusion: Despite the difficult calculation of the rad in the target cells and the scant information in this field, fortunately we have achieved significant theoretical data consistent with the experimental results. Our findings also introduced MCS as a better choice for evaluating of rad effects under different cellular conditions with high accuracy.