Final answer:
A loss of density at the lateral edges of a radiograph using a 12:1 grid ratio is typically due to issues with the grid alignment or focal distance, not simply because the SID was too great.
Step-by-step explanation:
When a radiograph exposure using a 12:1 grid ratio exhibits a loss of density at its lateral edges, it's often not due to the SID being too great. This condition is typically related to the grid itself, where the grid lines are visible as a result of improper alignment or because the focal distance of the grid does not match the SID used during the exposure. The purpose of a grid is to improve image contrast by absorbing scattered radiation before it reaches the film or detector. A 12:1 grid ratio indicates that the grid is designed to have a more significant improvement in image quality, especially useful for thicker body parts where scatter could be a larger issue. However, if the radiographic grid is misaligned or if the SID does not match the prescribed focal distance for the grid, the edges of the radiograph may show a decrease in density known as grid cut-off