Tsujiguchi Takakiyo, Obara Hideki, Ono Shuichi, Saito Yoko, Kashiwakura Ikuo
Department of Radiation Sciences, Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki, Aomori, Japan.
Department of Radiology, Division of Medical Technology, Hirosaki University School of Medicine Hospital, 53 Hon-cho Hirosaki, Aomori, Japan.
J Radiat Res. 2018 Jul 1;59(4):430-435. doi: 10.1093/jrr/rry022.
Computed tomography (CT) has recently been utilized in various medical settings, and technological advances have resulted in its widespread use. However, medical radiation exposure associated with CT scans accounts for the largest share of examinations using radiation; thus, it is important to understand the organ dose and effective dose in detail. The CT dose index and dose-length product are used to evaluate the organ dose. However, evaluations using these indicators fail to consider the age and body type of patients. In this study, we evaluated the effective dose based on the CT examination data of 753 patients examined at our hospital using the size-specific dose estimate (SSDE) method, which can calculate the exposure dose with consideration of the physique of a patient. The results showed a large correlation between the SSDE conversion factor and physique, with a larger exposure dose in patients with a small physique when a single scan is considered. Especially for children, the SSDE conversion factor was found to be 2 or more. In addition, the patient exposed to the largest dose in this study was a 10-year-old, who received 40.4 mSv (five series/examination). In the future, for estimating exposure using the SSDE method and in cohort studies, the diagnostic reference level of SSDE should be determined and a low-exposure imaging protocol should be developed to predict the risk of CT exposure and to maintain the quality of diagnosis with better radiation protection of patients.
计算机断层扫描（CT）最近已被应用于各种医疗场景，并且技术进步使其得到广泛使用。然而，与CT扫描相关的医疗辐射暴露在使用辐射的检查中占比最大；因此，详细了解器官剂量和有效剂量非常重要。CT剂量指数和剂量长度乘积用于评估器官剂量。然而，使用这些指标进行的评估没有考虑患者的年龄和体型。在本研究中，我们使用特定体型剂量估计（SSDE）方法，根据我院753例接受检查的患者的CT检查数据评估有效剂量，该方法可以在考虑患者体格的情况下计算暴露剂量。结果显示，SSDE转换因子与体格之间存在很大相关性，在单次扫描时，体型较小的患者暴露剂量更大。特别是对于儿童，发现SSDE转换因子为2或更高。此外，本研究中接受最大剂量照射的患者是一名10岁儿童，其接受了40.4毫希沃特（五组/次检查）。未来，为了使用SSDE方法估计暴露剂量以及在队列研究中，应确定SSDE的诊断参考水平，并制定低暴露成像方案，以预测CT暴露风险，并在更好地保护患者辐射的情况下维持诊断质量。
