Hays M T
J Nucl Med. 1985 Sep;26(9):1068-74.
A physiologically based compartmental model for T4 and T3 metabolism in man was used to generate time-activity curves for residence of radioiodine in key organs. T4 and T3 labeled with 123I, 124I, 125I, and 131I were studied. Conditions modeled included radioactive iodine uptake (RAIU) values of 0%, 1%, 5%, 15% and 25%, and RAIU of 15% combined with various degrees of pharmacologic block of thyroidal RAIU. Using the MIRD "S" tables, rad doses were generated for each condition. While the shapes of the time-activity curves varied widely with alterations in physical and biological turnover and with changes in steady-state due to iodine administration, it was possible to calculate overall effective half-lives for each organ of interest from the integral of the time-activity curve projected by solution of the model. This overall effective half-life of the hormone for the body's exchangeable hormone compartments correlated well with calculated radiation dose to the thyroid in the unblocked state. With progressive degrees of iodine block, this correlation persisted, though with proportionately reduced thyroid radiation doses. Use and manipulation of a compartmental model, rather than the usual multiexponential model, for radiation dosimetry facilitates conceptualization and the projection of the effects of interventions such as iodide block.
采用基于生理学的人体 T4 和 T3 代谢房室模型来生成放射性碘在关键器官中的滞留时间 - 活度曲线。研究了用 123I、124I、125I 和 131I 标记的 T4 和 T3。模拟的条件包括放射性碘摄取（RAIU）值为 0%、1%、5%、15%和 25%，以及 15%的 RAIU 与各种程度的甲状腺 RAIU 药物阻断相结合。使用 MIRD “S”表，针对每种情况生成辐射剂量。虽然时间 - 活度曲线的形状会随着物理和生物周转的改变以及由于碘给药导致的稳态变化而有很大差异，但可以通过模型解所预测的时间 - 活度曲线的积分来计算每个感兴趣器官的总体有效半衰期。激素在人体可交换激素房室中的这种总体有效半衰期与未阻断状态下甲状腺的计算辐射剂量密切相关。随着碘阻断程度的增加，这种相关性仍然存在，尽管甲状腺辐射剂量相应降低。使用和操作房室模型而非通常的多指数模型进行辐射剂量测定有助于概念化以及预测诸如碘化物阻断等干预措施的效果。
