In the context of reducing the patient dose coming from CT scanner examinations without penalizing the diagnosis, the assessment of both patient dose and image quality (IQ) with relevant metrics is crucial. The present study represents the first stage in a larger work, aiming to compare and optimize CT protocols using dose and IQ new metrics. We proposed here to evaluate the capacity of the Non-PreWhitening matched filter with an eye (NPWE) model observer to be a robust and accurate estimation of IQ. We focused our work on two types of clinical tasks: a low contrast detection task and a discrimination task. We designed a torso-shaped phantom, including Plastic Water slabs with cylindrical inserts of different diameters, sections and compositions. We led a human observer study with 13 human observers on images acquired in multiple irradiation and reconstruction scanning conditions (voltage, pitch, slice thickness, noise level of the reconstruction algorithm, energy level in dual-energy mode and dose), to evaluate the behavior of the model observer compared to the human responses faced to changing conditions. The model observer presented the same trends as the human observers with generally better results. We rescaled the NPWE model on the human responses by scanning conditions (kVp, pitch, slice thickness) to obtain the best agreement between both observer types, estimated using the Bland-Altman method. The impact of some scanning parameters was estimated using the correct answer rate given by the rescaled NPWE model, for both tasks and each insert size. In particular, the comparison between the dual-energy mode at 74 keV and the single-energy mode at 120 kVp showed that, if the 120 kVp voltage provided better results for the smallest insert at the lower doses for both tasks, their responses were equivalent in many cases.

在减少来自 CT 扫描仪检查的患者剂量而不影响诊断的情况下，使用相关指标评估患者剂量和图像质量 (IQ) 至关重要。本研究代表了更大工作的第一阶段，旨在使用剂量和 IQ 新指标来比较和优化 CT 协议。我们在此建议评估具有眼睛 (NPWE) 模型观察器的非预白化匹配滤波器的能力，以便对 IQ 进行稳健且准确的估计。我们将工作重点放在两种类型的临床任务上：低对比度检测任务和辨别任务。我们设计了一个躯干形状的幻影，包括塑料水具有不同直径、截面和成分的圆柱形嵌件的板坯。我们领导了一项人类观察者研究，由 13 名人类观察者对在多种照射和重建扫描条件（电压、间距、切片厚度、重建算法的噪声水平、双能量模式下的能量水平和剂量）下获得的图像进行评估，以评估行为模型观察者与人类面对不断变化的条件的反应相比。模型观察者呈现出与人类观察者相同的趋势，结果通常更好。我们通过扫描条件（kVp、间距、切片厚度）重新调整了人类反应的 NPWE 模型，以获得使用 Bland-Altman 方法估计的两种观察者类型之间的最佳一致性。使用重新缩放的 NPWE 模型给出的正确回答率来估计一些扫描参数的影响，对于任务和每个插入尺寸。特别是，74 keV 的双能模式和 120 kVp 的单能模式之间的比较表明，如果 120 kVp 电压为两个任务的较低剂量的最小插入提供更好的结果，则它们的响应是等效的在许多情况下。