← CT subtopic / Sim: HU Windowing
HU Windowing Trainer
A synthetic abdomen with fat, muscle, liver, kidney, acute blood, bone, air, and a faint lesion. Change the window width and level — see what comes in and out of visibility.
400
40
Upper = WL + WW/2, Lower = WL − WW/2 → display range computed below.
What to notice
Narrow windows (low WW) amplify contrast within a small HU range — the subdural window (WW 200, WL 80) emphasizes the difference between clotted blood and brain. Wide windows (high WW) compress a large HU range into the gray scale — lung (WW 1500) and bone (WW 2000) windows let you see from air to bone simultaneously, at the cost of low-contrast sensitivity. The data doesn't change — only the display mapping does.