University of Iceland, Faculty of Medicine, Radiography, Stapa við Hringbraut 31, 101 Reykjavík, Iceland; Icelandic Radiation Safety Authority, Rauðarárstígur 10, 105 Reykjavík, Iceland.
Landspítali - the National University Hospital of Iceland, 101 Reykjavík, Iceland.
Radiography (Lond). 2021 Aug;27(3):903-907. doi: 10.1016/j.radi.2021.02.012. Epub 2021 Mar 9.
Exposure index (EI) is important to evaluate correct exposure in radiography and thus important for image quality. The purpose of this study was to evaluate whether the target exposure index (EI) and deviation index (DI) were used efficiently.
Radiography departments in Iceland, using <10 years old equipment, were invited to participate. For each x-ray unit, admin users were asked about the use of EI and data was gathered on EI for five body parts (BP); lumbar spine, chest, hip, knee and hand. For each of the five BP, 100 examinations from the past year were selected randomly (or all, if < 100). The EI from one predefined view was recorded and the corresponding DI calculated.
A total of ten x-ray units, from four manufacturers and located at eight departments, were included in the study. The departments involved are comprised of a university hospital, smaller hospitals, and miscellaneous private departments. Two departments (25%) had not set EI, five (62.5%) used default values and only one had revised EI values. In four departments (50%) radiographers favored "acceptable EI range" over DI. The mean EI was significantly different (p < 0.05) from the EI in the majority of the five BP, in four out of the six departments that had defined EI. In total 30% of images from all departments combined had DI outside the range of -3.0 < DI < +3.0. The standard deviation of DI was from 1.4 to 2.7.
The study shows that the EI and DI are not used efficiently, regardless of equipment vendor or department characteristics.
Current recommendations on targeting the mean DI of 0 need to be reinforced. Theoretical knowledge and training need to be improved.
曝光指数（EI）对于评估放射摄影中的正确曝光非常重要，因此对于图像质量也很重要。本研究的目的是评估目标曝光指数（EI）和偏差指数（DI）是否得到有效利用。
邀请冰岛使用使用年限不超过 10 年设备的放射科参加研究。为每台 X 射线设备，管理用户被询问 EI 的使用情况，并收集了过去一年中五个身体部位（BP）的 EI 数据：腰椎、胸部、臀部、膝盖和手部。对于每个 BP，随机选择了 100 次检查（如果<100 次，则选择所有检查）。记录了一个预定义视图的 EI，并计算了相应的 DI。
共纳入十台 X 射线设备，来自四个制造商，位于八个部门。涉及的部门包括一所大学医院、较小的医院和各种私营部门。有两个部门（25%）未设置 EI，五个部门（62.5%）使用默认值，只有一个部门修改了 EI 值。在四个部门（50%）中，放射技师更倾向于“可接受的 EI 范围”而不是 DI。在四个有定义 EI 的部门中的六个部门中的四个中，平均 EI 与大多数五个 BP 的 EI 显著不同（p<0.05）。在所有部门组合的图像中，有 30%的 DI 值超出了-3.0<DI<+3.0 的范围。DI 的标准偏差从 1.4 到 2.7 不等。
该研究表明，无论设备供应商或部门特征如何，EI 和 DI 的使用都不是有效的。
目前针对平均 DI 为 0 的目标的建议需要加强。需要改进理论知识和培训。
