Question

Two radiographic images were taken under the same conditions except that the first image was taken at 72" SID and the second image was taken at 40" SID. Which image would be darker?

Answer 1

The first image taken at 72" SID would be brighter compared to the second image taken at 40" SID. The reason is that when the source-to-image distance (SID) decreases, the image appears darker because the X-rays have a shorter distance to travel and result in less overall exposure on the image receptor.