In CT, reducing the slice thickness from 5 mm to 2.5 mm while keeping mAs constant will result in:

• A Improved z-axis resolution and reduced image noise
• B Improved z-axis resolution and increased image noise ✓
• C Worsened z-axis resolution and reduced image noise
• D Worsened z-axis resolution and unchanged image noise

Explanation

Thinner collimation improves z-axis (longitudinal) spatial resolution and reduces partial volume averaging. However, with the same mAs, fewer photons reach the detector, so quantum noise increases roughly in proportion to the reduction in slice thickness.

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.