Kiani Nasab Mitra, Rafat Motavalli Laleh, Miri Hakimabad Hashem
Physics Department, Factually of Sciences, Ferdowsi University of Mashhad, Vakilabad Boulevard, Mashhad, 91775-1436, Iran.
J Environ Radioact. 2018 Jan;181:62-69. doi: 10.1016/j.jenvrad.2017.10.013. Epub 2017 Nov 1.
In this paper, the dose assessment for the iodine inhalation exposure in 19 aerosol sizes and three gas/vapor forms at three levels of thyroid uptake, was performed. Two different modes of work (light vs. heavy) and breathing (nose vs. mouth) for aerosol inhalation were investigated. In order to calculate the cumulated activities per unit of inhaled activity, a combined model which included the latest models of both human respiratory and alimentary tract was developed. The S values for I were computed based on the ICRP adult male and female reference voxel phantoms by the Monte Carlo method. Then, the committed equivalent and committed effective dose coefficients were obtained (The data are available at http://www.um.ac.ir/∼mirihakim). In general, for the nonzero thyroid uptakes, the maximum cumulated activity was found in the thyroid. When the thyroid is blocked, however, the maximum depends on the work and breathing mode and radioisotope form. Overall, the maximum CED coefficient was evaluated for the inhalation of elemental iodine at thyroid uptake of ∼27% (2.8 × 10 Sv/Bq). As for the particle inhalation per se, mouth breathing of 0.6 nm and 0.2 μm AMTD particles showed to have the maximum (2.8 × 10 Sv/Bq) and minimum (6.4 × 10 Sv/Bq) CED coefficients, respectively. Compared to the reference CED coefficients, the authors found an increase of about 58% for inhalation of the aerosols with AMAD of 1 μm and 70% for 5 μm.
本文针对19种气溶胶粒径、三种气体/蒸汽形态在三种甲状腺摄取水平下的碘吸入暴露进行了剂量评估。研究了气溶胶吸入的两种不同工作模式（轻度与重度）和呼吸方式（经鼻与经口）。为了计算每单位吸入活度的累积活度，开发了一个综合模型，该模型包含了人类呼吸道和消化道的最新模型。基于国际放射防护委员会（ICRP）成年男性和女性参考体素模型，通过蒙特卡罗方法计算了碘的S值。然后，获得了待积当量剂量系数和待积有效剂量系数（数据可在http://www.um.ac.ir/∼mirihakim获取）。一般来说，对于非零甲状腺摄取情况，甲状腺中的累积活度最高。然而，当甲状腺被阻断时，最大值取决于工作和呼吸模式以及放射性同位素形态。总体而言，对于甲状腺摄取约27%（2.8×10 Sv/Bq）的元素碘吸入，评估得到了最大的待积有效剂量系数。就颗粒物吸入本身而言，经口呼吸0.6 nm和0.2 μm AMTD颗粒的待积有效剂量系数分别显示为最高（2.8×10 Sv/Bq）和最低（6.4×10 Sv/Bq）。与参考待积有效剂量系数相比，作者发现吸入空气动力学直径为1 μm的气溶胶时增加了约58%，吸入5 μm的气溶胶时增加了70%。
