Yamaguchi Yuki, Fukunaga Masaaki, Mitsui Hideki, Nagaki Akio, Ito Osamu, Yamamoto Hiroyuki, Kawakami Yuji, Watanabe Daiki
Department of Radiological Technology, Kurashiki Central Hospital.
Nihon Hoshasen Gijutsu Gakkai Zasshi. 2022 Oct 20;78(10):1149-1157. doi: 10.6009/jjrt.2022-1131. Epub 2022 Aug 26.
There are problems with dose management in X-ray computed tomography (CT) because the protocol used for any examination is not always in the same scan range. The purpose of this study was to investigate the usefulness of setting the CT protocol based on the scan range.
We evaluated the examination data of patients who underwent plain CT based on a scan range of chest to pelvis and abdomen to pelvis. The previous protocol [Chest-Abdomen Routine] was changed to the current protocols [Chest_Abdomen] and [Chest_Pelvis], and the previous protocol of [Abdomen Routine] was changed to the current protocols [Abdomen] and [Abdomen_Pelvis]. Examination data of height, scan length, volume CT dose index (CTDI), and dose length product (DLP) were obtained from digital imaging and communications in medicine, and radiation dose structured report using Radimetrics. The relationship between patient height and scan range, and CTDI and DLP was indicated in a scatter plot. Standard deviation (SD) of scan length and DLP were compared between current and previous protocols. Outliers were defined as the data exceeding average ±2SD.
The SD of scan length decreased by 77.1% on abdomen to pelvis, and the SD of DLP decreased by 65.2% on abdomen to pelvis. The causes of the outliers were CT scan range, scan parameter, arm position, metal implants, and body thickness of patients.
Setting CT protocols based on the scan range reduced SD of scan length and DLP. It was helpful for reducing the number of scan range outliers and analyzing the cause of outliers.
在X射线计算机断层扫描（CT）中，剂量管理存在问题，因为用于任何检查的协议并不总是在相同的扫描范围内。本研究的目的是探讨基于扫描范围设置CT协议的有用性。
我们评估了接受胸部至骨盆和腹部至骨盆扫描范围的普通CT检查的患者的检查数据。先前的协议[胸部-腹部常规]改为当前的协议[胸部_腹部]和[胸部_骨盆]，先前的[腹部常规]协议改为当前的协议[腹部]和[腹部_骨盆]。从医学数字成像和通信以及使用Radimetrics的辐射剂量结构化报告中获取身高、扫描长度、容积CT剂量指数（CTDI）和剂量长度乘积（DLP）的检查数据。在散点图中显示患者身高与扫描范围以及CTDI与DLP之间 的关系。比较当前协议和先前协议之间扫描长度和DLP的标准差（SD）。将超过平均值±2SD的数据定义为异常值。
腹部至骨盆扫描长度的SD下降了77.1%，腹部至骨盆DLP的SD下降了65.2%。异常值的原因是CT扫描范围、扫描参数、手臂位置、金属植入物和患者的身体厚度。
基于扫描范围设置CT协议可降低扫描长度和DLP的SD。这有助于减少扫描范围异常值的数量并分析异常值的原因。
