A single-center retrospective study was carried out on 50 patients with suspected coronary artery disease undergoing dual-energy coronary CT angiography (DE-CCTA), to determine the optimal window settings for coronary artery assessment on virtual monoenergetic images (VMI). Image quality was objectively assessed based on contrast-to-noise ratio on both conventional imaging and VMI. Two independent radiologists determined the best window for VMI at 40 keV and 70 keV. Based on the best results obtained in this study, the recommended window settings are 1155/270 HU for VMI 70 and 3230/880 HU for VMI 40.