University of Patras, Department of Medical Physics, Patras, Greece.
BioEmission Technology Solutions, R&D Department, Athens, Greece.
Phys Med. 2019 Sep;65:181-190. doi: 10.1016/j.ejmp.2019.08.020. Epub 2019 Sep 5.
The purpose of this study is to create an organ dose database for pediatric individuals undergoing chest, abdomen/pelvis, and head computed tomography (CT) examinations, and to report the differences in absorbed organ doses, when anatomical differences exist for pediatric patients.
The GATE Monte Carlo (MC) toolkit was used to model the GE BrightSpeed Elite CT model. The simulated scanner model was validated with the standard Computed Tomography Dose Index (CTDI) head phantom. Twelve computational models (2.1-14 years old) were used. First, contributions to effective dose and absorbed doses per CTDI and per 100 mAs were estimated for all organs. Then, doses per CTDI were correlated with patient model weight for the organs inside the scan range for chest and abdomen/pelvis protocols. Finally, effective doses per dose-length product (DLP) were estimated and compared with the conventional conversion k-factors.
The system was validated against experimental CTDI measurements. The doses per CTDI and per 100 mAs for selected organs were estimated. The magnitude of the dependency between the dose and the anatomical characteristics was calculated with the coefficient of determination at 0.5-0.7 for the internal scan organs for chest and abdomen/pelvis protocols. Finally, effective doses per DLP were compared with already published data, showing discrepancies between 13 and 29% and were correlated strongly with the total weight (R > 0.8) for the chest and abdomen protocols.
Big differences in absorbed doses are reported even for patients of similar age or same gender, when anatomical differences exist on internal organs of the body.
本研究旨在为接受胸部、腹部/骨盆和头部 CT 检查的儿科个体创建器官剂量数据库，并报告当儿科患者存在解剖差异时，吸收器官剂量的差异。
使用 GATE 蒙特卡罗（MC）工具包对 GE BrightSpeed Elite CT 模型进行建模。使用标准的计算机断层扫描剂量指数（CTDI）头部体模验证模拟的扫描仪模型。使用 12 个计算模型（2.1-14 岁）。首先，估计了所有器官的有效剂量和每 CTDI、每 100mAs 的吸收剂量的贡献。然后，将胸部和腹部/骨盆协议中扫描范围内器官的每 CTDI 剂量与患者模型体重相关联。最后，估计了每剂量长度乘积（DLP）的有效剂量，并与传统的转换 k 因子进行了比较。
该系统针对实验性 CTDI 测量进行了验证。估计了选定器官的每 CTDI 和每 100mAs 的剂量。对于胸部和腹部/骨盆协议中的内部扫描器官，用决定系数计算了剂量与解剖特征之间的依赖关系的大小，其值在 0.5-0.7 之间。最后，将每 DLP 的有效剂量与已经发表的数据进行了比较，显示差异在 13%到 29%之间，与胸部和腹部协议的总重量（R>0.8）高度相关。
即使对于年龄相似或性别相同的患者，当体内内部器官存在解剖差异时，吸收剂量也会有很大差异。
