Evaluation of Nonlinear Pixel-Wise Squaring for Enhancing Low-Contrast Resolution in CT Imaging

The non-linear squaring processing improved low-contrast visibility; however, its effectiveness was highly dependent on both the scan mode and the display window settings. Despite the documented increase in physical noise (NPS), the processing did not cause a corresponding perceived increase in noise. This study demonstrated that under specific conditions, the processing can significantly improve low-contrast visibility, both objectively (CNR_LO) and subjectively. These optimal conditions were particularly the Square-5 method for volume scans and the offset-free square method combined with a narrow window.