A chest radiograph shows low contrast. Which post-processing adjustment might be used to increase the contrast?

• A. Decreased kilovoltage peak (kVp)
• B. Decreased window width
• C. Decrease exposure time
• D. Decreased SID

Answer: (B)

Understanding how window width affects displayed contrast is key. The window width in post-processing sets how many gray values are shown as distinct shades. A wide window covers a broad range of densities, which flattens differences and lowers contrast. Narrowing the window width reduces the range of gray values displayed, so differences between tissues—like air in the lungs, soft tissues, and heart/muscle—become more pronounced, increasing perceived contrast.

So, when a chest radiograph looks low in contrast, decreasing the window width is the appropriate post-processing adjustment to enhance visibility of structures.

Acquisition factors, such as lowering kVp, exposure time, or changing SID, affect image brightness, noise, or magnification during capture, not the post-processing display contrast in the same direct way.