Yeom Yeon Soo, Villoing Daphnée, Greenstein Natasha, Kitahara Cari M, Folio Les R, Kim Chan Hyeong, Lee Choonsik
Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville MD 20850, USA.
Bethesda-Chevy Chase High School, Bethesda, MD 20852, USA.
Radiat Prot Dosimetry. 2020 Jul 13;189(2):163-171. doi: 10.1093/rpd/ncaa027.
The use of iodine-131 S values based on reference computational phantoms with fixed thyroid model may lead to significant dosimetric errors in patients who may have different thyroid location from the reference phantoms. In the present study, we investigated individual thyroid location variation by examining the computed tomography image sets of 40 adult male and female patients. Subsequently, the thyroid location of the adult male and female mesh-type reference phantoms of the International Commission on Radiological Protection (ICRP) was adjusted to match each the highest, mean and the lowest locations of the thyroid observed in this dataset. The thyroid-adjusted phantoms were implemented into the Geant4 Monte Carlo code to calculate thyroid location-dependent iodine-131 S values (rT ← thyroid) for a total of 30 target regions. The maximum variation among the observed thyroid locations was 39 mm and 36 mm for male and female patients, respectively. The mean thyroid locations of both male and female patients showed a good agreement with the ICRP reference phantoms. The thyroid location-dependent Iodine-131 S values were significantly different from the reference phantoms for most target regions by up to a factor of 3. The use of thyroid location-dependent S values in dose reconstructions should help quantify the dosimetric uncertainty in epidemiologic investigations of patients receiving iodine-131 therapy for hyperthyroidism and thyroid cancer.
基于具有固定甲状腺模型的参考计算体模的碘-131 S 值的使用，可能会在甲状腺位置与参考体模不同的患者中导致显著的剂量学误差。在本研究中，我们通过检查40名成年男性和女性患者的计算机断层扫描图像集来研究个体甲状腺位置的变化。随后，调整了国际放射防护委员会（ICRP）成年男性和女性网格型参考体模的甲状腺位置，以匹配该数据集中观察到的甲状腺的最高、平均和最低位置。将甲状腺调整后的体模应用于Geant4蒙特卡罗代码，以计算总共30个靶区的甲状腺位置相关碘-131 S 值（rT ← 甲状腺）。男性和女性患者观察到的甲状腺位置之间的最大差异分别为39毫米和36毫米。男性和女性患者的平均甲状腺位置与ICRP参考体模显示出良好的一致性。对于大多数靶区，甲状腺位置相关的碘-131 S 值与参考体模显著不同，差异高达3倍。在剂量重建中使用甲状腺位置相关的S值应有助于量化接受碘-131治疗甲亢和甲状腺癌患者的流行病学调查中的剂量学不确定性。
