南京“5．7”^192Ir放射事故患者三种生物剂量估算指标的衰变规律探讨

Dynamic analysis on three indexes of biological dose estimation of the victim exposed to ^192Ir radiation source at ＂5.7＂ accident in Nanjing

目的 观察南京＂5.7＂ 192Ir放射事故患者受照后不同采血时间对生物剂量估算的影响,探讨3种生物剂量估算指标在体内的自然衰减规律。方法 事故后5、40和280 d,采集患者的外周血,分别进行外周血淋巴细胞染色体＂双着丝粒＋环＂（＂dic＋r＂）畸变分析、胞质分裂阻滞微核（CBMN）分析、核质桥＋融合＋马蹄形＋环（NPB ＋FHC）分析。观察受照后不同时间染色体＂dic＋r＂畸变、微核、NPB ＋FHC衰变情况及对生物剂量估算结果的影响。结果 与事故后5 d的估算剂量相比,在40和280 d,染色体＂dic＋r＂畸变分析估算的剂量分别下降34%和49%, CBMN的估算结果分别下降48%和79%,NPB ＋FHC的估算结果分别下降48%和75%。结论 本例事故患者受照后3种生物剂量估算指标在体内呈进行性下降,染色体＂dic＋r＂/细胞的半衰期为40 d,3个指标在40 d时剂量估算结果与5 d时比较,相对偏差 〉 20%。

Objective To explore the natural attenuation pattern of three biological dose estimation indexes in vivo by investigating the effect on biological dosimetry of peripheral blood sampling at different time points from the victim partially exposed to 192Ir radiation source at ＂5.7＂ accident in Nanjing.Methods Peripheral blood of the patient was collected on days 5, 40 and 280 after exposure, respectively. The yields of dicentrics plus rings chromosomes （＂dic＋r＂）, cytokinesis-block micronuclei （CBMN） and nucleoplasmic bridge＋fusion＋horse shoe＋circular（NPB＋FHC） were analyzed. The dynamic reduction and dose estimation were both observed using the biomarkers mentioned above after exposure. Results Compared to the estimates on days 5 after exposure, the dose values estimated on days 40 and 280 decreased by 34% and 49% for ＂dic＋r＂ method, 48% and 79% for the CBMN assay, and 48% and 75% for NPN＋FHC method, respectively. Conclusions Three biological dose estimation indexes show a progressive decrease in vivo, with the half-life of ＂dic＋r＂/cell being 40 days. The doses estimated using these three indexes on days 40 after exposure showed a relative deviation more than 20% compared with those on days 5 after exposure.