准确快速的放射生物剂量估算资料是发生大规模核辐射事故后制定应急策略、指导临床治疗的关键所在，然而目前的生物剂量学指标如染色体畸变、微核、基因表达等均在实际应用中受到限制。细胞组学指标核质桥（NPB）综合了染色体畸变和微核分析的优点，有望实现辐射的特异性和分析的自动化。申请者在前期研究中发现：不同品质射线、不同剂量范围内均可建立良好的剂量效应曲线，并初步分析了部分特定人群外周血淋巴细胞NPB的本底自发率水平。本课题拟在前期研究基础上，在以下几个方面进行探索：NPB标本制备方法的标准化、影响NPB发生的有关因素（射线剂量率、个体敏感性、化学环境诱变剂等）以及整体离体效应的一致性，并在事故受照人员剂量估算进行验证，随访观察NPB水平随时间的变化规律，旨在进一步探明人外周血淋巴细胞NPB作为辐射生物剂量计的可行性。

Accurate, rapid radiation biodosimetry is very important when mass casualty after radiation accident like Fukushima accident and Chernobyl accident, because the biodose assessment of individuals is the key to emergency prepareness and clinical treatment. The current biodosimeters, such as unstable chromosome aberration (dicentric chromosome and centric ring, dic+r), micronucleus (CBMN) and gene expression analysis are limited in practical application. Recently, radiation-induced nucleoplasmic bridges (NPB) in human lymphocytes has the potential to be an ideal radiation biodosimeter, because it combines the advantages of dic+r and CBMN analysis, and its radiation specificity and possibility of autonomous analysis. Our previous study showed that radiation-induced NPB in human peripheral blood lymphocytes (HPBL) has high relevance to the corresponding dic+r. The dose-response curves of Cobalt-60 gamma-rays induced NPB at dose range of 0.04-0.4 Gy, 0.1-1.0Gy and 1-6Gy had established; also for heavy ion carbon-12 at dose range of 0-8Gy. The spontenous NPB level in HPBL of healthy individuals were obtained and the factors were also observed. The present project is to futher investigate the applicability of radiation-induced NPB as a rapid radiation biodosimeter. The studies include the standardization of the preparation of NPB slides, the relative factors affect the NPB levels such as radiation dose-rate, individual sensitivity and environmental mutagen. The individuals exposed to accident radiation will be studied for investigating the consistency of radiation-induced NPB in vitro and in vivo, and the decline of NPB with time will be also observed. The purpose of this project is validation of the possibility of NPB level as the radiation biodosimeter.