Assessment of radiobiological impacts of threshold doses of alpha particles on A549 human lung cancer cells following direct irradiation exposure

Abstract

Purpose

Investigation of the radiobiological effects of low-doses of alpha particles on the inhibition of human lung cancer cell growth rate.

Materials and methods

To examine whether alpha particles inhibit lung cancer cell growth, human adenocarcinoma A549 cells were irradiated for 10–180 s. The irradiated processes were done during cell culture, using of micro alpha irradiation collimators. The density of accumulated alpha particles is assessed using CR-39NTDs. The MTT cell viability assay was performed on 96-well plates with cell lines seeded at 1 × 10⁴ cells/well to test the cytotoxic effect. The media was removed after 72 h to determine the cytotoxic effect.

Results

Growth Rate Inhibition (GRI%) has been investigated with different irradiation times t_IR ranges (very short: 10–50 s, short: 60–180 s), obtaining the following results: GRI% < 10% for the first range, GRI% increased to over 25% at 60 s, while, for the second range, GRI % increased with a power law relationship. Also, a reduced serum-stimulated growth in the lung cancer cell lines has been observed.

Conclusions

This study investigated that the low doses (i.e. low densities) of accumulated alpha particles) in human lung cancer cells have a significant impact on the Growth Rate Inhibition (GRI%), depending on the irradiation time, showing that there it occurs a critical time of 60 s at which significant changes could start to take place.