Connie,
Wow, his treatment time went fast, at least for me! The post treatment scans are the same as for IMRT radiation, usually after 3 months. If there is any suspicion they may do it sooner, which I believe is after 6 weeks that a certain percent that it would be accurate, so the longer one waits it would be more accurate. Of course, if suspicious, the sooner the better, but most post treatment scans are negative. Even though I had a number of recurrences (7) all my first post treatment scans were negative.
Good luck with everything!