低剂量氚水β射线对人体外周血淋巴细胞染色体的影响

Induction of Chromosome Aberrations in Human Lymphocytes by Irradiation With ~ Particles From Low-Doses Tritiated Water

通过染色体非稳定性畸变来研究低剂量氚水β射线的生物效应。将人体外周血与氚水混合培养24h和48h，共培养72h后获细胞得到与氚水作用后染色体畸变的频率并与相同剂量下^60Coγ射线的细胞效应对比。将实验结果进行回归方程拟合，得到HTOB射线的最佳回归方程Y=（0．001±0．004）＋（0．062±0．018）D＋（0．053±0．010）D^2（n=3，r^2=0．995，P〈0．01）；通过比较HTO与7射线的最佳回归方程可知，方程系数的主要区别在b值，提示在低剂量的情况下β射线诱发畸变的能力更强。将^60Coγ射线作为参考可得HTOB射线的相对生物效能（RBE）最大值出现在0．06Gy，为2．17，RBE值随着剂量的增大而减小。

The yield of unstable chromosome aberration induced in human lymphocytes by β particles from low-doses HTO has been measured. 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 60 Co 7 radiation. Using a linear-quadratic dose-effect relation to fit the experimental data, a significant linear contribution Y= （0. 001 ± 0. 004） ＋ （0. 062 ± 0. 018）D＋（0. 053±0. 010）D2 （n=3,r2=0. 995, P〈0.01） was found. The main difference between the coefficients for β and γ radiation is in the b values, indicating that HTO ~ 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. 17 at 0.06 Gy and decreases with increasing dose.