Eterovic Davor, Antunovic Zeljko, Markovic Vinko, Grosev Darko
Department of Nuclear Medicine, University Hospital Split, University of Split Medical Faculty, Split, Croatia.
J Nucl Med. 2008 Dec;49(12):2026-30. doi: 10.2967/jnumed.108.053934. Epub 2008 Nov 7.
We evaluated the effects on the absorbed dose to thyroid follicular cells of self-absorption of (131)I radiation (specifically, beta-rays) in the follicular colloid.
Thyroid follicles were modeled as colloid-filled spheres, containing a uniform concentration of (131)I and surrounded by a concentric monolayer of cells. Assuming close packing of identical follicles, we used Monte Carlo simulation to assess the absorbed dose to follicular cells.
Because of beta-ray self-absorption in colloidal spheres with radii larger than 50 mum, the absorbed dose to follicular cells is less than the average thyroid absorbed dose.
For the same thyroid mass, radioiodine thyroid uptake, and effective half-life, patients with follicles with colloidal sphere radii of 100, 200, 300, and 400 microm should be administered 9%, 15%, 21%, and 30% more (131)I, respectively, than patients with colloidal sphere radii of less than 50 microm, to yield the same absorbed dose to follicular cells.
我们评估了滤泡胶体中¹³¹I辐射（具体为β射线）的自吸收对甲状腺滤泡细胞吸收剂量的影响。
将甲状腺滤泡模拟为充满胶体的球体，球体中¹³¹I浓度均匀，周围有一层同心的单层细胞。假设相同滤泡紧密排列，我们使用蒙特卡罗模拟来评估滤泡细胞的吸收剂量。
由于半径大于50μm的胶体球体内β射线的自吸收，滤泡细胞的吸收剂量低于甲状腺平均吸收剂量。
对于相同的甲状腺质量、放射性碘甲状腺摄取量和有效半衰期，与胶体球半径小于50μm的患者相比，胶体球半径为100、200、300和400μm的滤泡患者，为使滤泡细胞获得相同的吸收剂量，应分别多给予9%、15%、21%和30%的¹³¹I。
