Cell-killing Effecacy of ~(32) P β-irradiation in Hela Cell Line

Objective To study the response patterns of Hela cell lines after exposing to different doses and dose rate radiation of 32 P.Methods Hela cells were exposed to β radiation from radioactive filter papers(absorbed 32 P) which were put closely under culture plate of Hela cells monolayer.The radiation response to different dose,dose rate and radiation time were evaluated through cell proliferation assessed by the colony forming assay and total population size.Results Data showed that the cell killing effects were related to dose,dose rate and radiation time with seemingly threshold characteristics.Irradiation time 2h,dose rate 2.78 MBq·h and dose 148.00 MBq·h might be the threshold respectively for the effective cell killing.Comparison of the cell killing effects between the single and fractionated pattern showed that the fractionation schedules led to increased tumor responses,the intervals of 4 h seemed to be more efficient than the others,possibly due to the combining effects of cell cycle,repair and repopulation.Conclusion The cell killing effect in Hela cells exposed to β radiation of 32 P has the threshold characteristics in terms of dose,dose rate and radiation time;Under the same total doses and a certain dose rate,the more prolonged radiation time,the more efficient cell killing;The low dose fractionation can produce the similar,if not more,effect on cell killing than a single high dose radiation.