Department of Radiology, School of Medicine, Makerere University, Kampala, Uganda.
Clinical Epidemiology Unit, School of Medicine, Makerere University, Kampala, Uganda.
BMC Med Imaging. 2022 Jun 11;22(1):112. doi: 10.1186/s12880-022-00838-x.
Diagnostic Reference Levels (DRLs), typically set at the 75th percentile of the dose distribution from surveys conducted across a broad user base using a specified dose-measurement protocol, are recommended for radiological examinations. There is a need to develop and implement DRLs as a standardisation and optimisation tool for the radiological protection of patients at Computed Tomography (CT) facilities.
This was a retrospective cross-sectional study conducted in seven (7) different CT scan facilities in which participants were recruited by systematic random sampling. The study variables were dose length product (DLP) and volume-weighted CTDI (CTDIvol) for the radiation doses for head, chest, abdomen and lumbar spine CT examinations. The DRLs for CTDIvol and DLP were obtained by calculating the 3rd quartiles of the radiation doses per study site by anatomical region. The national diagnostic reference levels were determined by computation of DRLs using the 75th centile of the median values.
A total of 574 patients were examined with an average age of 47.1 years. For CTDIvol estimates; there was a strong positive significant relationship between the CTDIvol and examination mAs (r = 0.9017, p-value < 0.001), and reference mAs (r = 0.0.7708, p-value < 0.001). For DLP estimates; there was a moderate positive significant relationships between DLP and total mAs (r = 0.6812, p-value < 0.001), reference mAs (r = 0.5493, p-value < 0.001). The DRLs were as follows; for head CT scan - the average median CTDIvol was 56.02 mGy and the DLP was 1260.3 mGy.cm; for Chest CT, the CTDI volume was 7.82 mGy and the DLP was 377.0 mGy.cm; for the abdomen CT, the CTDI volume 12.54 mGy and DLP 1418.3 mGy.cm and for the lumbar spine 19.48 mGy and the DLP was 843 mGy.cm, respectively.
This study confirmed the need to optimize the CT scan parameters in order to lower the national DRLs. This can be achieved by extensive training of all the CT scan radiographers on optimizing the CT scan acquisition parameters. Continuous dose audits are also advised with new equipment or after every three years to ensure that values out of range are either justified or further investigated.
诊断参考水平（DRL）通常设定为在使用特定剂量测量协议对广泛用户群进行的调查中剂量分布的第 75 百分位，建议将其用于放射学检查。需要制定和实施 DRL，作为 CT 设施中患者放射防护的标准化和优化工具。
这是一项在七个不同 CT 扫描设施中进行的回顾性横断面研究，通过系统随机抽样招募参与者。研究变量为头部、胸部、腹部和腰椎 CT 检查的剂量长度乘积（DLP）和体积加权 CTDI（CTDIvol）。通过按解剖区域计算每个研究部位的辐射剂量的第 3 四分位数来获得 CTDIvol 和 DLP 的 DRL。通过计算中位数的 75 百分位来确定国家诊断参考水平。
共有 574 名患者接受了检查，平均年龄为 47.1 岁。对于 CTDIvol 估计值；CTDIvol 与检查 mAs（r=0.9017，p 值<0.001）和参考 mAs（r=0.0.7708，p 值<0.001）之间存在很强的正显著关系。对于 DLP 估计值；DLP 与总 mAs（r=0.6812，p 值<0.001）和参考 mAs（r=0.5493，p 值<0.001）之间存在中度正显著关系。DRLs 如下：头部 CT 扫描的平均中位数 CTDIvol 为 56.02mGy，DLP 为 1260.3mGy.cm；胸部 CT 的 CTDI 体积为 7.82mGy，DLP 为 377.0mGy.cm；腹部 CT 的 CTDI 体积为 12.54mGy，DLP 为 1418.3mGy.cm，腰椎为 19.48mGy，DLP 为 843mGy.cm。
本研究证实需要优化 CT 扫描参数以降低国家 DRL。这可以通过对所有 CT 扫描放射技师进行广泛的培训来实现，以优化 CT 扫描采集参数。还建议进行连续剂量审核，包括新设备或每三年一次，以确保超出范围的值是合理的，或者需要进一步调查。
