Which statement best describes the effect of increasing matrix size on pixel size when the overall field of view is kept constant?

Which statement best describes the effect of increasing matrix size on pixel size when the overall field of view is kept constant?

• A. Pixel size increases
• B. Pixel size remains constant
• C. Pixel size decreases
• D. Pixel size becomes unpredictable

Answer: (C)

When the field of view is kept the same, how many samples (pixels) you use across that view determines how big each pixel appears. Pixel size is basically the field of view divided by the number of pixels along one dimension. So, increasing the matrix size adds more pixels to cover the same FOV, and each pixel ends up covering a smaller area. For example, with a 20 cm field of view, 256 samples across gives roughly 0.78 mm per pixel, while increasing to 512 samples across reduces it to about 0.39 mm per pixel. This inverse relationship is why pixel size decreases as matrix size increases. The other options would imply the pixel size stays the same, grows, or behaves unpredictably, which doesn’t match how sampling works for a fixed field of view.

When the field of view is kept the same, how many samples (pixels) you use across that view determines how big each pixel appears. Pixel size is basically the field of view divided by the number of pixels along one dimension. So, increasing the matrix size adds more pixels to cover the same FOV, and each pixel ends up covering a smaller area. For example, with a 20 cm field of view, 256 samples across gives roughly 0.78 mm per pixel, while increasing to 512 samples across reduces it to about 0.39 mm per pixel. This inverse relationship is why pixel size decreases as matrix size increases. The other options would imply the pixel size stays the same, grows, or behaves unpredictably, which doesn’t match how sampling works for a fixed field of view.