What effect does an off-level grid error have on the image?

When an off-level grid error occurs in radiographic imaging, it typically results in decreased exposure at the edges of the image. This phenomenon occurs because the grid is designed to absorb scatter radiation and allow only the primary X-ray beam to reach the detector. When the grid is not level, the angles at which the X-rays interact with the grid change, leading to a misalignment that causes part of the X-ray beam to be attenuated more than it should be.

In the case of a tilted grid, the primary X-rays that are meant to produce an image may be distorted or absorbed unevenly. As a result, the center of the image might receive adequate exposure, while the edges, especially those further away from the point of optimal alignment, receive significantly less exposure. This causes the edge areas to appear darker or more underexposed, resulting in a non-uniform image with compromised quality. Understanding this principle is essential for radiologic technologists to ensure accurate imaging and effective troubleshooting of common errors.