Delete loaded image file

I am working on the admin side of a photographers flash site (as3). A major aspect of this is file organization and I am trying to set it up so that a user can click on a thumbnail image, hit a delete button and, using PHP, delete the full size and its thumbnail counterpart from the server. Deleting the full size is no problem, however the thumbnail sticks around because it is still open by the FlashPlayer.

I know that removing the thumbnail from the display list isnt enough but my knowledge of garbage collection isnt vast. Any ideas?