Heartlands, Good Hope, and Solihull Hospitals, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom.
Br J Radiol. 2020 Jun;93(1110):20190771. doi: 10.1259/bjr.20190771. Epub 2020 Mar 25.
Computed tomography scans of the kidney, ureters, and bladder (CT-KUB) are crucial in investigating urinary calculi but impart a substantial radiation doses. Radiation can be limited by minimising the scanning field to the necessary area ( from the kidneys to urethra). Before auditing, the superior limit of CT-KUB scans had not been formally clarified at our trust. Consistently ensuring the upper limit of scans is at or below T10 has been shown to be a viable method of performing CT-KUB scans. This study aimed to assess the overscan length of CT-KUB investigations and modify practice accordingly to minimise it. There were two standards that were set for CT-KUB scanning. First, the mean percentage overscan length ( percentage of the scan above the kidneys) should be <15%. Second, all scans should include the superior borders of both kidneys.
90 consecutive CT-KUB scans for ureteric calculus were retrospectively investigated using IMPAX software in the first phase of data collection. After these data were analysed, a newly devised protocol using T11 as the superior scan limit was delivered to radiographers in the department. and 105 in the second phase (re-audit). The analysis parameters were: percentage overscan length, distance between diaphragm and upper border of kidneys, vertebral level at which the scan commenced, and whether both kidneys were fully included.
In the first phase, overscan of >15% was present in 94.4% of scans. The mean percentage overscan length was 28.2%. The superior vertebral limit of 59% of scans was at T10 or below and a lower superior vertebral limit correlated with decreasing overscan. 99% of scans fully included both kidneys. In the second phase (3 months later), the mean overscan percentage reduced to 10.6% (standard deviation = 4.4%). Excessive overscan affected 35.2% of scans. The superior vertebral limit of 8% of scans was at T10 or below. 100% of scans fully included both kidneys.
Excessive overscanning was due to inconsistent technique in capturing CT-KUB scans. Before this audit, the superior limit of CT-KUB scans had not been formally clarified at our trust. By successfully standardising the process with a reproducible method, the overscan target was comfortably met. Therefore, patient dose was minimised without compromising scan quality.
This audit has successfully shown a feasible standardised protocol for CT-KUB investigations which can be used to minimise overscanning of patients.
肾脏、输尿管和膀胱的计算机断层扫描（CT-KUB）在尿路结石的检查中至关重要，但会带来大量的辐射剂量。通过将扫描范围缩小到必要的区域（从肾脏到尿道），可以限制辐射。在审核之前，我们的信托机构尚未正式明确 CT-KUB 扫描的上限。一致确保扫描的上限在 T10 或以下已被证明是执行 CT-KUB 扫描的一种可行方法。本研究旨在评估 CT-KUB 检查的过度扫描长度，并相应地修改实践以最小化过度扫描。设定了两个 CT-KUB 扫描标准。首先，平均过度扫描长度百分比（扫描超过肾脏的部分）应<15%。其次，所有扫描都应包括肾脏的上缘。
在数据收集的第一阶段，使用 IMPAX 软件回顾性地研究了 90 例连续的输尿管结石 CT-KUB 扫描。分析这些数据后，为该部门的放射技师提供了一种新的使用 T11 作为上限的扫描方案，然后在第二阶段（重新审核）进行了 105 次扫描。分析参数包括：过度扫描长度百分比、膈肌与肾脏上缘之间的距离、开始扫描的椎体水平以及是否完全包括两个肾脏。
在第一阶段，超过 15%的扫描中有 94.4%存在过度扫描。平均过度扫描长度百分比为 28.2%。59%的扫描的上界椎体在 T10 或以下，较低的上界椎体与减少过度扫描相关。99%的扫描完全包括了两个肾脏。在第二阶段（3 个月后），平均过度扫描百分比降至 10.6%（标准差=4.4%）。过度扫描影响了 35.2%的扫描。8%的扫描的上界椎体在 T10 或以下。100%的扫描完全包括了两个肾脏。
过度扫描是由于在捕获 CT-KUB 扫描时技术不一致所致。在这次审核之前，我们的信托机构尚未正式明确 CT-KUB 扫描的上限。通过成功地使用可重复的方法标准化该过程，轻松实现了过度扫描目标。因此，在不影响扫描质量的情况下，最大限度地减少了患者的剂量。
本审核成功展示了一种可行的 CT-KUB 检查标准化方案，可用于最大限度地减少对患者的过度扫描。
