Creeden A, Curtis M
Radiology Department, University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry, CV2 2DX, UK.
Radiology Department, University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry, CV2 2DX, UK.
Radiography (Lond). 2020 Nov;26(4):308-313. doi: 10.1016/j.radi.2020.02.009. Epub 2020 Mar 18.
Radiographers have a duty to ensure that radiation doses to patients are as low as reasonably achievable. With digital technologies, exposure factors which achieve the optimum balance between image noise and patient dose must be sought. In digital radiography, Deviation Index (DI) values provide the radiographer with feedback on the appropriateness of individual exposures but can also be tracked as part of a departmental quality assurance programme.
In November 2017, exposure logs were extracted from six digital radiography (DR) x-ray systems, collated and analysed. Five examinations were identified which frequently produced DI values outside the manufacturer's recommended Optimal Range (-3 to +2). Incremental improvements were made to the default exposure settings for these examinations via a cyclical process of modification and re-evaluation. A full data collection exercise was then repeated in April 2019.
At baseline, 10,658 out of 29,637 (36.0%) exposures had DI values outside the manufacturer's recommended Optimal Range, but for some individual examinations the proportion was as high as 547 out of 725 (74.5%). Following multiple optimisation cycles, the overall proportion of examinations outside the Optimal Range had fallen to 7611 out of 26,759 (28.4%). Default milliampere-seconds (mAs) values for these examinations were reduced by between 22% and 50%.
A marked reduction in patient doses can be achieved through a departmental programme of DI value monitoring and targeted optimisation of default exposure settings.
DI values should be routinely monitored as part of routine quality assurance programmes. Radiographers have a responsibility to ensure that they possess a clear understanding of DI values and that appropriate exposure settings are selected for each individual patient.
放射技师有责任确保给予患者的辐射剂量尽可能低且合理可达。借助数字技术，必须找到能在图像噪声和患者剂量之间实现最佳平衡的曝光参数。在数字放射摄影中，偏差指数（DI）值为放射技师提供有关个别曝光适宜性的反馈，也可作为部门质量保证计划的一部分进行跟踪。
2017年11月，从六个数字放射摄影（DR）X射线系统中提取曝光日志，进行整理和分析。确定了五项经常产生超出制造商推荐最佳范围（-3至+2）的DI值的检查。通过修改和重新评估的循环过程，对这些检查的默认曝光设置进行了逐步改进。然后在2019年4月重复进行了一次全面的数据收集工作。
基线时，29637次曝光中有10658次（36.0%）的DI值超出制造商推荐的最佳范围，但对于某些个别检查，这一比例高达725次中的547次（74.5%）。经过多次优化循环后，超出最佳范围的检查总体比例降至26759次中的7611次（28.4%）。这些检查的默认毫安秒（mAs）值降低了22%至50%。
通过部门性的DI值监测计划和对默认曝光设置进行有针对性的优化，可以显著降低患者剂量。
DI值应作为常规质量保证计划的一部分进行常规监测。放射技师有责任确保他们清楚了解DI值，并为每位患者选择合适的曝光设置。
