Abstract / Summary
Objective This study aims to compare the detectability index (d′) between the human observer (HO) and advanced model observer (AMO) using the Non-Prewhitening Observer (NPW) and Non-Prewhitening Observer with Eye Filter (NPWE) for various tube currents and low-contrast objects. Methods Image data were obtained using the ACR 464 phantom at three different tube current levels (i.e., 80 mA, 140 mA, and 200 mA). The task object had contrast levels ranging from 3 HU to 15 HU, with a diameter of 3 mm. The task objects used a Gaussian profile model. The d′ values were measured using the AMO with NPW and NPWE models, while HO values were computed using the 2-AFC method. Each configuration consisted of 100 signal-present and 100 signal-absent images. Results The results demonstrated that the d′ values obtained from AMO displayed a trend similar to those derived from HO. Increases in the tube current and contrast resulted in higher d′ values across all observers. Correlation analysis revealed that NPW and NPWE showed a strong relationship with HO ( r = 0.979; p < 0.001) and ( r = 0.976; p < 0.001), respectively. Conclusion This study confirms that the AMO can effectively replicate object detection with accuracy comparable to that of HO. This behaviour was consistently observed across variations in tube current and low-contrast objects.