Which action will reduce pixel size without changing the field of view?

• A. Increase FOV
• B. Increase Matrix Size
• C. Increase Exposure Time
• D. Increase KVP

Answer: (B)

Pixel size (pixel pitch) depends on how much area is imaged and how many pixels cover that area. If you keep the field of view the same and increase the matrix size, more pixels fit into the same area, so each pixel becomes smaller. Smaller pixels translate to higher spatial resolution without changing what part of the patient is imaged. Increasing the field of view would enlarge the area and typically increase pixel size if the matrix isn’t changed. Exposure time and kVp affect exposure and contrast, not the pixel dimensions, so they don’t change pixel size. So, increasing matrix size reduces pixel size while keeping the field of view constant.