Final answer:
A radiography exposed using a 12:1 ratio grid may exhibit a loss of density at its lateral edges due to the grid absorbing scattered x-rays. The lead strips in the grid absorb the scattered x-rays, resulting in a darker image at the edges.
Step-by-step explanation:
A radiography exposed using a 12:1 ratio grid may exhibit a loss of density at its lateral edges because the grid absorbs some of the x-rays that are scattered away from the intended area. The grid consists of alternating strips of lead and radiolucent material. The lead strips absorb the scattered x-rays, while the radiolucent strips allow the primary x-rays to pass through. This results in a loss of density at the lateral edges of the radiography.