Trajtenberg M
Med Phys. 1984 Jul-Aug;11(4):456-64. doi: 10.1118/1.595537.
Previous studies of the imaging performance of computed tomography (CT) scanners, and other imaging modalities, have failed to apply appropriate statistical methods to data analysis, thus impairing the accuracy and significance of results. Given that imaging performance involves a number of interrelated variables and an element of randomness, its empirical assessment requires multivariate regression analysis. This method is used here to analyze anew a set of contrast-detail data from a previous study on CT scanners. The main issues considered are the specification of the proper functional form linking perceptibility, dose and contrast, the estimation of the contrast and dose coefficients, and of scanner-specific constants to be used in computing indices of imaging quality. One of the main empirical findings is that the dose coefficient of the CT scanners studied is significantly less than that predicted by the theoretical model: 1/5 instead of 1/3. This result suggests that actual dose used in routine clinical studies could be reduced substantially without impairing much the quality of the images. On the other hand, the coefficient of contrast does correspond to its predicted value, i.e., 2/3. The methodology used here is not limited to the contrast-detail framework, but is applicable to, and indeed essential in, empirical studies of the performance of any imaging modality.
以往对计算机断层扫描（CT）扫描仪及其他成像方式成像性能的研究，未能将适当的统计方法应用于数据分析，从而削弱了结果的准确性和显著性。鉴于成像性能涉及多个相互关联的变量以及一定程度的随机性，其经验性评估需要多元回归分析。本文采用这种方法重新分析了之前一项关于CT扫描仪的对比细节数据集。所考虑的主要问题包括连接可感知性、剂量和对比度的适当函数形式的设定、对比度和剂量系数的估计，以及用于计算成像质量指标的特定扫描仪常数的估计。主要的经验发现之一是，所研究的CT扫描仪的剂量系数显著低于理论模型预测的值：为1/5而非1/3。这一结果表明，在不严重损害图像质量的情况下，常规临床研究中使用的实际剂量可以大幅降低。另一方面，对比度系数确实与其预测值相符，即2/3。本文所采用的方法不仅限于对比细节框架，而是适用于任何成像方式性能的经验性研究，并且实际上是此类研究必不可少的。
