Blocking a single referring page

How do I block a certain referring page? I'm using a random image script on one of my sites and the easiest way to keep the images from loading on a certain page would be to be able to block the referring page from accessing the php file that contains the rotaters script. Can anyone tell me how I could go about blocking a certain referring page from accessing the script? such as www.mysite.com/terms.php

 

edited out

 

hmm i still havent figured this one out :-(

 

in your php file:
if ($_SERVER['HTTP_REFERER'] == "blocked_site") {
echo "you are blocked";
exit()
}