A comparison study on of tumor cell-killing effects between low-dose-rate β-irradiation of ~(32)Pand γ-irradiation of~(60)Co

The paoer is to elucidate radiobiological charicateristics and radiobiological mechanism in killing tumor cells with low dose rate β?rays and high dose rate γ-rays. HeLa cells were exposed to low?rate β?irradiation of 32P or high?dose?rate γ?irradiation of 60Co. Cell response?patterns were compared between two the types of radiations in terms of their inhibition of cell proliferation and cell cycle blockage, evaluated by typanblue excluded method and flow cytometry, respectively. Results show that there is a different way in growth inhibition effect on HeLa cells between low?dose?rate irradiation of P and high?dose?rate irradiation of Coγ. In exposure to P, the 32 60 32 inhibition of cell proliferation in HeLa cell was a prolong course, whereas and the effect was in a more serious and quick way in Co irradiation. Cell cycle arrest in G2 phase induced by P was lower and more prolong than that 60 32 induced by Co. The inhibition effect on tumor cells between the two types of radiations is different. Impaired DNA 60 repair system by continuous low?dose?rate radiation might contribute to the final radiation effect of P. 32