Yang Ching-Ching, Yang Bang-Hung, Tu Chun-Yuan, Wu Tung-Hsin, Liu Shu-Hsin
aDepartment of Medical Imaging and Radiological Sciences, Tzu-Chi University of Science and Technology bDepartment of Nuclear Medicine & PET Center, Buddhist Tzu-Chi General Hospital, Hualien cDepartment of Nuclear Medicine, Taipei Veterans General Hospital dDepartment of Radiology, Mackay Memorial Hospital eDepartment of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan.
Nucl Med Commun. 2017 Jun;38(6):546-555. doi: 10.1097/MNM.0000000000000679.
This study aimed to evaluate the efficacy of automatic exposure control (AEC) in order to optimize low-dose computed tomography (CT) protocols for patients of different ages undergoing cardiac PET/CT and single-photon emission computed tomography/computed tomography (SPECT/CT).
One PET/CT and one SPECT/CT were used to acquire CT images for four anthropomorphic phantoms representative of 1-year-old, 5-year-old and 10-year-old children and an adult. For the hybrid systems investigated in this study, the radiation dose and image quality of cardiac CT scans performed with AEC activated depend mainly on the selection of a predefined image quality index. Multiple linear regression methods were used to analyse image data from anthropomorphic phantom studies to investigate the effects of body size and predefined image quality index on CT radiation dose in cardiac PET/CT and SPECT/CT scans.
The regression relationships have a coefficient of determination larger than 0.9, indicating a good fit to the data. According to the regression models, low-dose protocols using the AEC technique were optimized for patients of different ages. In comparison with the standard protocol with AEC activated for adult cardiac examinations used in our clinical routine practice, the optimized paediatric protocols in PET/CT allow 32.2, 63.7 and 79.2% CT dose reductions for anthropomorphic phantoms simulating 10-year-old, 5-year-old and 1-year-old children, respectively. The corresponding results for cardiac SPECT/CT are 8.4, 51.5 and 72.7%.
AEC is a practical way to reduce CT radiation dose in cardiac PET/CT and SPECT/CT, but the AEC settings should be determined properly for optimal effect. Our results show that AEC does not eliminate the need for paediatric protocols and CT examinations using the AEC technique should be optimized for paediatric patients to reduce the radiation dose as low as reasonably achievable.
本研究旨在评估自动曝光控制（AEC）的功效，以便为接受心脏正电子发射断层显像/计算机断层扫描（PET/CT）和单光子发射计算机断层显像/计算机断层扫描（SPECT/CT）的不同年龄患者优化低剂量计算机断层扫描（CT）方案。
使用一台PET/CT和一台SPECT/CT为代表1岁、5岁和10岁儿童以及一名成年人的四个仿真人体模型采集CT图像。对于本研究中所调查的混合型系统，激活AEC进行的心脏CT扫描的辐射剂量和图像质量主要取决于预定义图像质量指标的选择。使用多元线性回归方法分析来自仿真人体模型研究的图像数据，以研究体型和预定义图像质量指标对心脏PET/CT和SPECT/CT扫描中CT辐射剂量的影响。
回归关系的决定系数大于0.9，表明数据拟合良好。根据回归模型，针对不同年龄患者优化了使用AEC技术的低剂量方案。与我们临床常规实践中用于成人心脏检查且激活AEC的标准方案相比，PET/CT中优化的儿科方案对于模拟10岁、5岁和1岁儿童的仿真人体模型分别可减少32.2%、63.7%和79.2%的CT剂量。心脏SPECT/CT的相应结果分别为8.4%、51.5%和72.7%。
AEC是降低心脏PET/CT和SPECT/CT中CT辐射剂量的一种实用方法，但应适当确定AEC设置以获得最佳效果。我们的结果表明，AEC并不能消除对儿科方案的需求，并且应针对儿科患者优化使用AEC技术的CT检查，以将辐射剂量降低至合理可及的最低水平。
