php cron to check and remove files

Hi, I need to be able to do the following procedure; retrieve all items from a mysql db table, then check to see if the files from that table exist on the server (images), if not, to "clean up" and remove the physical file - so that only the files from the db exist. This will run via cron Has anyone done something similar before, willing to assist me with a basic scope of actions to work on? Thanks in advance Steven