Dose-effect relationship of chromosome aberrations induced by different LET rays at low doses / 中华放射医学与防护杂志

Objective To establish the dose-effect curves of chromosome aberrations in human peripheral blood lymphocytes induced by different LET rays,including 60Co γ-rays,252Cf neutrons,14MeV neutrons and 12C heavy ions at low doses,respectively,in order to assess radiation-induced damages after occupational and accidental exposure.Methods Heparinized whole blood samples were irradiated with the various radiation devices and doses ranged from 0 to 1 Gy with the interval of 0.25 Gy.Conventional chromosome culture method was applied with adding colchicines at the beginning and chromosome specimens were prepared after 48 h incubation.The Metafer scanning system was used for automatical finder of chromosome metaphases.The mathematic models were fitted according to aberration data obtained.Results At the dose range of 0 - 1 Gy,the math models of dic + r were linear for 60 Co γrays and linear-quadratics for 252 Cf neutrons,14 MeV neutrons and 12 C heavy ions.The models of ace were linear-quadratic for 60Co γ-rays and 12C heavy ion beams,and linear for 252Cf and 14 MeV neutrons.The models of total aberrations were linear-quadratic for all types of radiation.Conclusions High LET rays have higher biological effects in inducing chromosome aberrations yields compared with low LET rays.Moreover,the severity of damage is 252Cf ＞ 14 MeV neutrons ＞ 12C heavy ions ＞ 60Co γ-rays in turn.Therefore,in the range of low doses,the dic + r may be a better target of radiation damage for high LET radiation.

A dose-effect curve of premature condensation chromosome ring in lymphocytes of human peripheral blood exposed to high dose of 60Co γ-rays in vitro / 中华放射医学与防护杂志

Objective To establish a dose-effect curve of premature condensation chromosome ring (PCC-R)in lymphocytes of human peripheral blood after exposed to high doses of Y-rays. Methods Peripheral blood samples was drawn from three healthy individuals, and exposed to 60Co γ-rays with doses between 0 and 30 Gy. The frequencies of PCC-R in premature condensation chromosome (PCC) cells obtained by Okadaic acid (OA) induction were calculated, and a dose-effect curve was fitted. Results PCC index tapered with dose. Frequencies of PCC-R per cell increased until 20 Gy, and then saturation was observed. The results were fitted to a lineal model up to 20 Gy: y = - 0.020 + 0.052D ,where y was the frequencies of PCC-R per cell, D was the radiation dose (Gy). Conclusins The highest dose could be estimated is 20 Gy by the dose-effect curve established with PCC-R method. Its utility and validity will be verified in the future application of radiation accident.