Ok I'll bite. My CCC required annual MRI's for several years post Tx. My RO, there, wrote the book on H&N IMRT treatment - UCSFCCC. This was their protocol. They were read by the reading radiologist where the scan was done then again at the CCC by their reading radiologist. My first MRI's were not happy ones either so they caused me more angst than I needed at the time. it was an entire year before the MRI's were truly clean.

Some get PET (or PET/CT) scans but it is not on the list of NCCN protocols for cancer follow-up. Some doctors order them anyway. They are also the most expensive scan so insurance companies are reluctant to pay for them unless the doctor presents a compelling reason ($3K - $7K).

Scans are just a part of the total diagnostic package and by no means absolutely conclusive or definitive. MRI's can only resolve tumors down to 2mm and they are the most accurate. Scan reports are often filled with frightening conclusions from the reading radiologist as they must list every anomaly they spot (probably more to CTA), so it must be subject to further interpretation by the ENT or H&N Surgeon and possibly direct visualization may be ordered as a follow up to it. So never freak out if you get your hands on a raw, uninterpreted scan report.

Don,
This will tell you everything you want to know about the risks and benefits of scans and x-rays:

http://www.radiologyinfo.org/en/safety/index.cfm?pg=sfty_xray