CAMRT Radiography Practice Exam

What error causes an overall decreased density when using a grid?

1. Grid misalignment

2. Off level or off centered grid

3. Incorrect exposure time

4. Inadequate filtration

The correct answer is: Off level or off centered grid

An overall decreased density when using a grid is caused by an off level or off centered grid. When a grid is misaligned, the primary radiation that would normally reach the film or digital receptor is partially absorbed by the grid's lead strips, which are designed to attenuate scatter radiation. If the grid is not positioned correctly—either angled incorrectly (off level) or not aligned with the central ray of the primary beam (off centered)—more of the primary radiation can be absorbed than intended, resulting in a reduction of the total amount of radiation that reaches the detector. This misalignment leads to a decrease in image density, producing a lighter image. Grid misalignment, while it can contribute to density changes, specifically refers to the grid being incorrectly positioned rather than being off level or centered in relation to the x-ray tube. Incorrect exposure time primarily affects the amount of radiation reaching the receptor and is less about the grid's alignment. Inadequate filtration does not directly relate to grid usage but instead pertains to the proper filtration of the x-ray beam to reduce patient exposure and improve image quality.