低剂量电离辐射与放射工作人员甲状腺激素的剂量-反应关系

目的 探究低剂量辐射与甲状腺激素水平的剂量-反应关系，为放射工作人员防护工作重点提供理论依据。方法 采用前瞻性队列研究设计，收集1237名放射工作人员健康体检报告及个人剂量监测数据。以辐射累积有效剂量作为观察指标并按照四分位间距分0～2.586 mSv、2.586～3.757 mSv、3.758～31.272 mSv 3组，低剂量组为参照，比较不同累积辐射剂量组放射工作人员甲状腺激素变化情况。采用广义线性模型和限制性立方样条模型分别估计累积有效剂量与甲状腺激素变化的关联及剂量反应关系。结果 1237名放射工作人员的甲状腺素T4、FT3水平变化在不同剂量组间的差异有统计学意义(P < 0.05)。调整性别、年龄、工龄、职业、医疗等级和吸烟后，广义线性模型分析显示，2.586～3.757 mSv (β = 3.514, 95%CI: 0.900～6.128)与放射工作人员T4水平变化显著相关，而累积有效剂量与FT3水平变化无关(P > 0.05)。限制性立方样条分析结果显示，累积有效剂量连续变化与T4水平变化呈非线性剂量反应关系(P = 0.023)。结论 长期低剂量电离辐射对放射工作人员甲状腺功能造成一定的损伤，辐射累积有效剂量与T4水平变化存在剂量-反应关系。

The dose-response relationship between low-dose ionizing radiation and thyroid hormone of medical workers

Objectives To explore the dose-response relationship between low-dose ionizing radiation and thyroid hormone levels of radiation medical workers and provide theoretical basis for occupational health protection to this population.Methods Using a prospective cohort study design, we collected health examination reports on employees that worked on jobs with occupational exposure to radiation at hospital with individually dose monitoring data for 1 237 workers. The effective cumulative radiation dose was divided into three groups: 0～2.586 mSv, 2.586～3.757 mSv, 3.758～31.272 mSv by the interquartile range. The low-dose group was used as a reference to compare the changes in thyroid hormones of medical workers in different cumulative radiation dose groups. The generalized linear models and restricted cubic spline model were used to examine the association and dose-response relationship between the cumulative effective dose and changing thyroid hormones.Results There were statistically significant differences in changing thyroxine (T4) and Free triiodothyronine (FT3) levels among three different dose groups of 1237 subjects (P < 0.05). The results of generalized linear models analysis revealed that 2.586～3.757 mSv was a significant risk factors of changing T4, with β of 3.514 (95% confidence interval 95% CI]: 0.900～6.128) after adjusting for gender, age, working duration, occupation, medical level and smoking, while the association with changing FT3 was not observed (P > 0.05). The restrictive cubic spline (RCS) model analysis indicated a non-linear dose-response correlation between cumulative radiation dose with changing T4 (P = 0.023).Conclusion Long-term exposure to low-dose ionizing radiation could induce the thyroid damage among medical occupational population. And there is a dose-response relationship between cumulative radiation dose and changing thyroxine.