Radiology (IMH), Linköping University, Linköping, Sweden.
Br J Radiol. 2013 Jan;86(1021):20110784. doi: 10.1259/bjr.20110784.
Objectives To propose a method to study the effect of exposure settings on image quality and to estimate the potential for dose reduction when introducing dose-reducing measures. Methods Using the framework of visual grading regression (VGR), a log(mAs) term is included in the ordinal logistic regression equation, so that the effect of reducing the dose can be quantitatively related to the effect of adding post-processing. In the ordinal logistic regression, patient and observer identity are treated as random effects using generalised linear latent and mixed models. The potential dose reduction is then estimated from the regression coefficients. The method was applied in a single-image study of coronary CT angiography (CTA) to evaluate two-dimensional (2D) adaptive filters, and in an image-pair study of abdominal CT to evaluate 2D and three-dimensional (3D) adaptive filters. Results For five image quality criteria in coronary CTA, dose reductions of 16-26% were predicted when adding 2D filtering. Using five image quality criteria for abdominal CT, it was estimated that 2D filtering permits doses were reduced by 32-41%, and 3D filtering by 42-51%. Conclusions VGR including a log(mAs) term can be used for predictions of potential dose reduction that may be useful for guiding researchers in designing subsequent studies evaluating diagnostic value. With appropriate statistical analysis, it is possible to obtain direct numerical estimates of the dose-reducing potential of novel acquisition, reconstruction or post-processing techniques.
目的 提出一种研究曝光设置对图像质量影响的方法，并估计引入降低剂量措施时的潜在剂量降低。 方法 使用视觉分级回归（VGR）框架，在有序逻辑回归方程中包含对数（mAs）项，以便可以定量地将降低剂量的效果与添加后处理的效果相关联。在有序逻辑回归中，使用广义线性潜在和混合模型将患者和观察者身份视为随机效应。然后，从回归系数估计潜在的剂量降低。该方法应用于冠状动脉 CT 血管造影（CTA）的单图像研究中，以评估二维（2D）自适应滤波器，并应用于腹部 CT 的图像对研究中，以评估二维和三维（3D）自适应滤波器。 结果 对于冠状动脉 CTA 的五个图像质量标准，添加 2D 滤波预计会降低 16-26%的剂量。对于腹部 CT 的五个图像质量标准，估计 2D 滤波允许降低 32-41%的剂量，3D 滤波允许降低 42-51%的剂量。 结论 包含对数（mAs）项的 VGR 可用于预测潜在的剂量降低，这可能有助于指导研究人员设计后续研究评估诊断价值。通过适当的统计分析，可以直接获得新采集、重建或后处理技术的剂量降低潜力的数值估计。
