1 Department of Radiology, Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115.
AJR Am J Roentgenol. 2015 Jan;204(1):W86-94. doi: 10.2214/AJR.14.12964.
The purpose of this study was to develop a departmental practice quality improvement project to systematically reduce CT doses for the evaluation of suspected pediatric appendicitis by introducing computer-generated gaussian noise.
Two hundred MDCT abdominopelvic examinations of patients younger than 20 years performed with girth-based scanning parameters for suspected appendicitis were reviewed. Two judges selected 45 examinations in which the diagnosis of appendicitis was excluded (14, appendix not visualized; 31, normal appendix visualized). Gaussian noise was introduced into axial image series, creating five additional series acquired at 25-76% of the original dose. Two readers reviewed 270 image series for appendix visualization (4-point Likert scale and arrow localization). Volume CT dose index (CTDIvol) and size-specific dose estimate (SSDE) were calculated by use of patient girth. Confidence ratings and localization accuracy were analyzed with mixed models and nonparametric bootstrap analysis at a 0.05 significance level.
The mean baseline SSDE for the 45 patients was 16 mGy (95% CI, 12-20 mGy), and the corresponding CTDIvol was 10 mGy (95% CI, 4-16 mGy). Changes in correct appendix localization frequencies were minor. There was no substantial trend with decreasing simulated dose level (p = 0.46). Confidence ratings decreased with increasing dose reduction (p = 0.007). The average decreases were -0.27 for the 25% simulated dose (p = 0.01), -0.17 for 33% (p = 0.03), and -0.03 for 43% (p = 0.65).
Pediatric abdominal MDCT can be performed with 43% of the original dose (SSDE, 7 mGy; CTDIvol, 4.3 mGy) without substantially affecting visualization of a normal appendix.
本研究旨在通过引入计算机生成的高斯噪声，开发一个部门实践质量改进项目，以系统地降低评估疑似小儿阑尾炎的 CT 剂量。
回顾了 200 例 MDCT 腹部盆腔检查，这些检查是基于周长的扫描参数进行的，用于疑似阑尾炎患者。两位评估员从排除阑尾炎诊断的 45 例检查中选择了 45 例（14 例，阑尾未显示；31 例，正常阑尾显示）。在轴向图像系列中引入高斯噪声，创建了另外五个在原始剂量的 25%-76%下采集的系列。两位读者对 270 个图像系列的阑尾显示情况进行了评估（4 分李克特量表和箭头定位）。通过使用患者周长，计算体积 CT 剂量指数（CTDIvol）和大小特异性剂量估计（SSDE）。置信度评分和定位准确性采用混合模型和非参数 bootstrap 分析进行分析，置信度水平为 0.05。
45 例患者的平均基线 SSDE 为 16 mGy（95%CI，12-20 mGy），相应的 CTDIvol 为 10 mGy（95%CI，4-16 mGy）。正确定位阑尾的频率变化很小。随着模拟剂量水平的降低，没有明显的趋势（p = 0.46）。置信度评分随着剂量减少而降低（p = 0.007）。25%模拟剂量平均降低 0.27（p = 0.01），33%降低 0.17（p = 0.03），43%降低 0.03（p = 0.65）。
儿科腹部 MDCT 可在原始剂量的 43%（SSDE，7 mGy；CTDIvol，4.3 mGy）下进行，而不会显著影响正常阑尾的显示。
