What issue arises when the grid and laser are not properly aligned during imaging?

When the grid and laser are not properly aligned during imaging, the issue that arises is the formation of moiré patterns. Moiré patterns occur when there is an interference between the grid lines and the lattice structure of the digital imaging receptor. These patterns may appear as wavy lines or bands across the image, which can obscure diagnostic information and lead to misinterpretation of the radiographs.

Proper alignment of the grid and the laser is crucial because the grid's purpose is to absorb scatter radiation and enhance image quality by allowing only the primary radiation to reach the image receptor. If there is a misalignment, the expected uniform distribution of exposure is disrupted, resulting in the superimposition of the grid lines and creating these undesirable patterns.

While other issues like phantom images, extraneous line patterns, and scratches or tears can occur due to different factors in the imaging process, moiré patterns specifically relate directly to alignment issues between the grid and laser system.