Generally 10-12 weeks is about usual for the first PET/CT scan (the fused PET/CT is considered quite a bit more accurate than PE alone). Even so there may well be "hot" areas which show up, due to healing, inflammation, infection, etc. and not to cancer. A radiologist who sees a lot of head/neck scans can usually separate these out but sometimes there are false positives. The PET/CT is usually repeated at about 6 months to check on progress. In between there will be lots of other exams which are equally important in detremining status, including physical exams, chest xrays, endoscopes etc.

Gail