Department of Engineering Physics, Tsinghua University, Beijing, People's Republic of China.
Institute of Radiation Medicine, Helmholtz Zentrum München-German Research Center for Environmental Health (GmbH), Neuherberg, Germany.
Phys Med Biol. 2021 Sep 20;66(19). doi: 10.1088/1361-6560/ac1ef1.
Pediatric patients are in a growing stage with more dividing cells than adults. Therefore, they are more sensitive to the radiation dose when undergoing computed tomography (CT) scanning. It is necessary and essential to assess the organ absorbed dose and effective dose to children. Monte Carlo simulation with computational phantoms is one of the most used methods for dose calculation in medical imaging and radiotherapy. Because of the vast change of the pediatric body with age increasing, many research groups developed series pediatric phantoms for various ages. However, most of the existing pediatric reference phantoms were developed based on Caucasian populations, which is not conformable to Chinese pediatric patients. The use of different phantoms can contribute to a difference in the dose calculation. To assess the CT dose of Chinese pediatric patients more accurately, we developed the Chinese pediatric reference phantoms series, including the 3-month (CRC3m), 1-year-old (CRC01), 5-year-old (CRC05), 10-year-old (CRC10), 15-year-old male (CRCM15), and a 15-year-old female (CRCF15) phantoms. Furthermore, we applied them to dose assessment of patients undergoing CT scanning. The GE LightSpeed 16 CT scanner was simulated and the paper presents the detailed process of phantoms development and the establishment of the CT dose database (with x-ray tube voltages of 120, 100 and 80 kVp, with collimators of 20, 10, and 5 mm width, with filters for head and body), compares for the 1-year-old results with other results based on different phantoms and analyzes the CT dose calculation results. It was found that the difference in phantoms' characteristics, organ masses and positions had a significant impact on the CT dose calculation outcomes. For the 1-year-old phantom, the dose results of organs fully covered by the x-ray beam were within 10% difference from the results of other studies. For organs partially covered and not covered by the scan range, the maximum differences came up to 84% (stomach dose, chest examinations) and 463% (gonads dose, chest examinations) respectively. The findings are helpful for the dose optimization of Chinese pediatric patients undergoing CT scanning. The developed phantoms could be applied in dose estimation of other medical modalities.
儿科患者正处于生长阶段，其体内的细胞分裂比成人更为活跃。因此，他们在接受计算机断层扫描（CT）时对辐射剂量更为敏感。对儿童的器官吸收剂量和有效剂量进行评估是必要且至关重要的。蒙特卡罗模拟结合计算体模是医学影像学和放射治疗中最常用的剂量计算方法之一。由于儿科患者的身体会随着年龄的增长而发生巨大变化，许多研究小组针对不同年龄段开发了一系列儿科体模。然而，大多数现有的儿科参考体模都是基于白种人群开发的，并不符合中国儿科患者的情况。使用不同的体模可能会导致剂量计算结果存在差异。为了更准确地评估中国儿科患者的 CT 剂量，我们开发了中国儿科参考体模系列，包括 3 个月（CRC3m）、1 岁（CRC01）、5 岁（CRC05）、10 岁（CRC10）、15 岁男性（CRCM15）和 15 岁女性（CRCF15）体模。此外，我们还将其应用于接受 CT 扫描的患者的剂量评估。我们模拟了 GE LightSpeed 16 CT 扫描仪，并介绍了体模开发和 CT 剂量数据库建立的详细过程（管电压为 120、100 和 80 kVp，准直器宽度为 20、10 和 5 mm，头部和体部滤波器），比较了 1 岁儿童的结果与基于不同体模的其他结果，并分析了 CT 剂量计算结果。结果发现，体模的特征、器官质量和位置的差异对 CT 剂量计算结果有显著影响。对于 1 岁儿童体模，完全被射线束覆盖的器官的剂量结果与其他研究的结果相差不超过 10%。对于部分被扫描范围覆盖和未被覆盖的器官，最大差异可达 84%（胃部剂量，胸部检查）和 463%（性腺剂量，胸部检查）。这些发现有助于优化中国儿科患者接受 CT 扫描的剂量。所开发的体模可应用于其他医学模态的剂量估算。
