Tonkopi Elena, Duffy Susan, Abdolell Mohamed, Manos Daria
1 Department of Diagnostic Radiology, Dalhousie University, 1276 South Park St, PO Box 9000, Halifax, NS B3H 2Y9, Canada.
2 Department of Diagnostic Imaging, Nova Scotia Health Authority, Halifax, NS, Canada.
AJR Am J Roentgenol. 2017 May;208(5):1073-1081. doi: 10.2214/AJR.16.16361. Epub 2017 Feb 28.
The purpose of this study is to establish provincial diagnostic reference levels (DRLs) and to determine whether this process may help reduce the patient radiation dose from the most frequently performed CT examinations.
We investigated the following CT examinations: head, chest, low-dose chest, abdomen and pelvis, and chest, abdomen, and pelvis examinations. The sample for each protocol included 15 patients of average body weight (mean [± SD], 70 ± 20 kg). The differences in dose between scanners were evaluated using one-way ANOVA. Correlations between dose, scanner age, and the number of detector rows were assessed using the Pearson correlation coefficient. A sample of abdominal and chest examinations were randomized and blinded for review by experienced radiologists who graded diagnostic image quality. Provincial DRLs were calculated as the 75th percentile of patient dose distributions. For hospitals with doses exceeding the DRLs, dose reduction was recommended, followed by another survey.
The initial survey included data of 1185 patients, and an additional 180 patients were surveyed after protocol optimization. The differences between the mean values of the dose distributions from each scanner were statistically significant (p < 0.05) for all examinations. The variation was greatest for low-dose chest CT, with a greater than fivefold difference in the mean dose values noted between scanners. A very weak correlation was found between dose and scanner age or the number of detector rows. Analysis of image quality revealed no statistically significant differences in any scoring categories, with the exception of the noise category in abdominal imaging. Implementation of the DRLs allowed a reduction in patient dose of up to 41% as a result of a protocol change.
Establishing provincial DRLs allows an effective reduction in patient dose without resulting in degradation of image quality.
本研究旨在建立省级诊断参考水平（DRLs），并确定这一过程是否有助于降低最常见的CT检查中患者所接受的辐射剂量。
我们调查了以下CT检查项目：头部、胸部、低剂量胸部、腹部和骨盆，以及胸部、腹部和骨盆联合检查。每个检查方案的样本包括15名平均体重的患者（均值[±标准差]，70±20kg）。使用单因素方差分析评估不同扫描仪之间的剂量差异。使用Pearson相关系数评估剂量、扫描仪使用年限和探测器排数之间的相关性。对腹部和胸部检查的样本进行随机分组并遮蔽信息，由经验丰富的放射科医生进行审查，对诊断图像质量进行评分。省级DRLs计算为患者剂量分布的第75百分位数。对于剂量超过DRLs的医院，建议降低剂量，随后进行另一项调查。
初始调查纳入了1185名患者的数据，在方案优化后又调查了180名患者。所有检查中，各扫描仪剂量分布均值之间的差异具有统计学意义（p<0.05）。低剂量胸部CT的差异最大，不同扫描仪之间的平均剂量值相差超过五倍。在剂量与扫描仪使用年限或探测器排数之间发现了非常弱的相关性。图像质量分析显示除腹部成像的噪声类别外，在任何评分类别中均无统计学显著差异。实施DRLs后，由于方案改变，患者剂量最多可降低41%。
建立省级DRLs可有效降低患者剂量，且不会导致图像质量下降。
