Three months out is a normal time according to our doctors at Hopkins -- this allows time for maximum healing and reduces the risk of "false positives." The radiologist there (who primarily does HNC and brain cancer scans) also said that another PET/CT would be done at 6 months and possibly again at a year out. My husband had the first two but not the third as neither initial scan nor any of his succeeding physical exams including several endoscopic exams revealed anything suspicious.

You may also have a chest xray at some point to ensure no distant mets, although a PET/CT will look at the whole body, or at least, down to the pelvis.

Gail