The Influence of Effective Energy on Computed Tomography Number Depends on Tissue Characteristics in Monoenergetic Cardiac Imaging

Figure 3

Phantom images; each panel illustrates (counterclockwise from the top) phantoms filled with water, oil, and the contrast agent. All images are displayed with a window width of 600 HU and window level of 100 HU. Top row: typical polyenergetic images. The left panel is a representative 100 kVp image; oil appears slightly darker, and the contrast agent slightly brighter compared to the composite 120 kVp (middle panel) and Sn 140 kVp images (right panel). Water is similar among the 3 images. Bottom rows: typical monoenergetic images with increasing effective energies are shown left to right. As effective energy increased, oil became brighter, while the contrast agent darkened. Water remained unchanged throughout all effective energy levels.