In CT imaging, a technologist adjusts the 'window width' from 400 HU to 100 HU while keeping the window level constant at 40 HU. What is the PRIMARY effect on the displayed image?
- A Contrast between tissues differing by a few HU increases ✓
- B Spatial resolution improves significantly
- C The image becomes brighter overall
- D The radiation dose to the patient is reduced
Correct answer: A. Contrast between tissues differing by a few HU increases
Explanation
Window width controls the range of HU mapped to the gray scale. C narrow window (e.g., 100 HU) displays a small HU range across all available gray shades, so small differences in attenuation become visually distinct, increasing contrast. Brightness is governed by window level, not width. Spatial resolution is determined by detector size and reconstruction kernel, and dose is unaffected by post-processing window settings.
Reference: Bushberg, The Essential Physics of Medical Imaging, 3rd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.