The increased risk of thyroid cancer among individuals exposed during childhood and adolescence to Iodine-131 (¹³¹I) is the main statistically significant long-term effect of the Chornobyl accident. Several radiation epidemiological studies have been carried out or are currently in progress in Ukraine, to assess the risk of radiation-related health effects in exposed populations. About 150,000 measurements of ¹³¹I thyroid activity, so-called ‘direct thyroid measurements’, performed in May–June 1986 in the Ukrainian population served as the main sources of data used to estimate thyroid doses to the individuals of these studies. However, limitations in the direct thyroid measurements have been recently recognized including improper measurement geometry and unknown true values of calibration coefficients for unchecked thyroid detectors. In the present study, a comparative analysis of ¹³¹I thyroid activity measured by calibrated and unchecked devices in residents of the same neighboring settlements was conducted to evaluate the correct measurement geometry and calibration coefficients for measuring devices. As a result, revised values of ¹³¹I thyroid activity were obtained. On average, in Vinnytsia, Kyiv, Lviv and Chernihiv Oblasts and in the city of Kyiv, the revised values of the ¹³¹I thyroid activities were found to be 10–25% higher than previously reported, while in Zhytomyr Oblast, the values of the revised activities were found to be lower by about 50%. New sources of shared and unshared errors associated with estimates of ¹³¹I thyroid activity were identified. The revised estimates of thyroid activity are recommended to be used to develop an updated Thyroid Dosimetry system (TD20) for the entire population of Ukraine as well as to revise the thyroid doses for the individuals included in post-Chornobyl radiation epidemiological studies: the Ukrainian-American cohort of individuals exposed during childhood and adolescence, the Ukrainian in utero cohort and the Chornobyl Tissue Bank.

切尔诺贝利事故在统计上显着的主要长期影响是儿童期和青春期接触碘 131 ( ¹³¹ I) 的个体患甲状腺癌的风险增加。乌克兰已经开展或目前正在进行多项辐射流行病学研究，以评估暴露人群中与辐射相关的健康影响的风险。 1986 年 5 月至 6 月在乌克兰人群中进行了约 150,000 次¹³¹ I 甲状腺活性测量，即所谓的“直接甲状腺测量”，这是用于估计这些研究个体的甲状腺剂量的主要数据来源。然而，最近已经认识到直接甲状腺测量的局限性，包括不正确的测量几何形状和未经检查的甲状腺探测器的校准系数的真实值未知。在本研究中，对同一邻近住区居民使用校准设备和未经校准设备测量的¹³¹ I 甲状腺活性进行了比较分析，以评估测量设备的正确测量几何形状和校准系数。结果，获得了¹³¹ I 甲状腺活性的修正值。平均而言，在文尼察、基辅、利沃夫和切尔尼戈夫州以及基辅市， ¹³¹ I 甲状腺活性的修正值比之前报告的高出 10-25%，而在日托米尔州，修订后的活动减少了约 50%。确定了与¹³¹ I 甲状腺活性估计相关的共享和非共享错误的新来源。 建议将修订后的甲状腺活性估计值用于为乌克兰全体人口开发更新的甲状腺剂量测定系统（TD20），并修订切尔诺贝利核电站辐射后流行病学研究中所包括个体的甲状腺剂量：乌克兰-美国儿童和青少年时期暴露的个体队列、乌克兰子宫内队列和切尔诺贝利组织库。