Which of the following grid errors would result in an image that shows normal exposure in the middle but decreased exposure on the sides and may follow removal and replacement of the grid?

• A. Upside down
• B. Off-level
• C. Lateral decentering
• D. Grid-focus decentering

Answer: (A)

Grid orientation and how it interacts with the divergent X-ray beam is what this item is testing. A focused grid is designed so the lead strips align with the beam’s path, minimizing grid cutoff across the image. When the grid is placed upside down, that alignment is lost: the central rays still pass through the gaps fairly well, but rays toward the edges encounter more lead, producing reduced exposure at the sides. This peripheral attenuation pattern can occur after removing and reloading the grid if it’s reinserted in the wrong orientation. So you end up with normal exposure in the middle and decreased exposure toward the sides, which matches the described effect.