Final answer:
An image plate in a cassette should be erased if it has not been used for 8 hours to prevent residual data from affecting future images.
Step-by-step explanation:
The image plate on a cassette should be deleted after 8 hours of non-use. In digital radiography, image plates are used to store the image captured during an X-ray exposure. Latent images can form as a result of background radiation or other noise sources if the image plate is not used for an extended length of time. This can lower the quality of subsequent images. To ensure that the next image is unaffected by residual data from previous exposures, erase the image plate before using it. The plate is typically subjected to intense light during this process, which bleeds off the stored energy and gets the plate ready for a fresh exposure.