低剂量氚水对人体外周血淋巴细胞的影响

目的 研究低剂量水平下氚水β射线的生物效应。方法 人体外周血与氚水混合,分别培养24 h和48 h,72 h后收获细胞。通过染色体非稳定性畸变的变化,得到与氚水作用后染色体畸变的频率,以⁶⁰Co γ射线照射后的细胞效应作为参照,得到相同剂量下氚水的相对生物效应值。结果 拟合实验结果得到氚水β射线的最佳回归方程是Y=0.001+0.062D+0.053D²;比较氚水与γ射线的最佳回归方程可知,方程系数的主要区别在a值,氚水β射线的RBE最大值为2.21出现在0.06 Gy,随着剂量的增大RBE值先减小而后稳定。低剂量情况下淋巴细胞微核剂量-效应关系符合线性拟合方程Y=C+αD,得到⁶⁰Co γ射线对HTO β射线诱发微核的RBE值在1.46~2.17之间,与染色体畸变所得RBE值及变化趋势一致。结论 在低剂量情况下,β射线诱发畸变的能力更强,HTO β射线在一个电离辐射径迹上使两个染色单体各产生一个损伤的效率更高。

Cytogenetic Effects of Low Dose Tritiated Water in Human Peripheral Blood Lymphocytes

Objective The yield of unstable chromosome aberration induced in human lymphocytes by β particles from low-doses HTO have been measured.Methods HTO was mixed with heparinised blood in various amounts so that dose of 6.24×10^-4 Gy to 1.23 Gy were delivered in 24 h and 48 h. After culturing for 72 h, the dicentric yield was measured as a function of dose to the blood and compared with data from ⁶⁰Co γ-radiation.Results Using a linear-quadratic dose-effect relation to fit the experimental data, a significant linear contribution Y=0.001+0.062D+0.053D² was found. The main difference between the coefficients for β and γ radiation is in the a values, indicating that HTO β rays are more efficient, particularly at low doses. In accord with the theory of dual radiation, the RBE of HTO β-particles relative to γ rays is 2.21 at 0.06 Gy and decreases with increasing dose. Micronucles yield at low doses could be fitted to a linear equation Y=C+αD and the indicated RBE value of MN for HTO β-rays irradiation is between 1.46 and 2.17 which is similar in shape to the chromosome aberrations experiments.Conclusion Hence β-rays are found to be more efficient in producing two lesions with sigle ioniziong tracks at low dose.