I am using the code below I found somewhere in this issues queue months back, but I want to modify it to add "?qr" or something similar to the url so I can track visitors visiting my site from the qr codes provided on my site.

<?php
print theme('qr_codes', 'http://www.yoursite.com/' . $node->path, 150, 150);
?>

Is this the best way to track something like this, and if so how do I append that to the code above? PHP is not my strength. Thanks!