In an attempt to understand radiobiological basis for targeted radiotherapy in oncology

the cell cycle perturbations have studied in Hela cell lines after exposed to different doses and dose-rate of 32 P radiation. Asynchronous Hela cells

cultured in vitro

were exposed to β radiation from radioactive filter papers (absorbed 32 P) which were put close under culture plate of growing monolayer of Hela cells. The characteristic radiation response to different dose

dose-rate and radiation time was evaluated through cell cycle perturbation studied by flow cytometry. Cell cycle status showed G2 phase blockage in a way of dose dependence

a plateau of G2 block can be recognized at about 24h. Interestingly

the G2 phase declined even though the accumulated doses increased as the time of radiation prolonged. This result suggested that the cell cycle progress could not be inhibited completely when exposed to continuous radiation

rather it seems to be controlled somehow by the nature of cell cycle itself for a certain cell line. G2 blockage

one of the major changes caused by β radiation

is dose-dependent

but the time reaching the plateau of G2 phase blockage is most likely related with the intrinsic nature of cell cycle.