Meck R A, Chen M S, Kenny P J
Health Phys. 1985 Feb;48(2):141-57. doi: 10.1097/00004032-198502000-00001.
Scientific data are reviewed to evaluate the risks of radioiodine uptake and to compare those risks with the benefits and risks of low milligram doses of stable potassium iodide (KI). The limit of 25 rad to the thyroid due to radioiodine uptake is adopted as the "break-even" point above which 130-mg KI doses should be administered. The biological and radiological kinetics of radioiodine for protracted uptakes were derived from the Medical Internal Radiation Dose Committee (MIRD) model (MIRD75). Resulting calculations yielded estimates of dose commitment rates to the thyroid as a function of thyroidal uptake. The extrapolated value of the 1-hr inhalation curve for 131I with 30% uptake compares well with the established MPCa value and intercepts the origin. The calculated KI-blocking efficiency as a function of time after radioiodine uptake agrees well with previously reported experimental data. The prevention or "blocking" of 25 rad to the thyroid was the criterion used to define critical values of radioiodine in the thyroid. Critical values are functions of isotope, the duration of uptake and the elapsed time between inhalation and assay of thyroid content. The presence of radioiodine in the thyroid in amounts greater than the critical value indicates that more than 25 rad to the thyroid can be averted, and KI should be administered in the absence of contraindications. Critical average concentrations are implicitly defined by the method of calculation used in the derivation. Critical average concentrations are presented as criteria for KI administration when assays of the radioiodine content of the thyroid are unavailable. Illustrative applications of critical values and critical average concentrations are presented in the Appendix.
对科学数据进行审查，以评估放射性碘摄取的风险，并将这些风险与低毫克剂量稳定碘化钾（KI）的益处和风险进行比较。将放射性碘摄取导致甲状腺吸收25拉德的限值作为“盈亏平衡点”，高于此值应给予130毫克KI剂量。长期摄取放射性碘的生物和放射动力学源自医学内照射剂量委员会（MIRD）模型（MIRD75）。由此产生的计算得出了甲状腺剂量承诺率与甲状腺摄取量的函数关系。摄取率为30%的131I 1小时吸入曲线的外推值与既定的MPCa值吻合良好，并与原点相交。计算得出的放射性碘摄取后KI阻断效率与时间的函数关系与先前报道的实验数据吻合良好。预防或“阻断”甲状腺吸收25拉德是用于定义甲状腺中放射性碘临界值的标准。临界值是同位素、摄取持续时间以及吸入与甲状腺含量检测之间经过时间的函数。甲状腺中放射性碘含量超过临界值表明可避免甲状腺吸收超过25拉德，在无禁忌症的情况下应给予KI。临界平均浓度由推导中使用的计算方法隐含定义。当无法检测甲状腺放射性碘含量时，给出临界平均浓度作为KI给药的标准。附录中给出了临界值和临界平均浓度的示例应用。
