Hi Bob & Laurie,
Scans are only a part of the "watchful waiting" process of post Tx surveillance. Typically Bob will get examined at regular intervals, usually in line with the oncology practice guidelines of the NCCN (Guidelines for Oropharnyx) http://www.nccn.org/professionals/physician_gls/PDF/head-and-neck.pdf
Basically they call for an annual chest x-ray and a visual/palpation exam every 1-3 months for the first year. Some health care providers also recommend annual MRI's or PET or PET/CT or CT scans as well. Your fear will diminish slightly with each subsequent exam. Statistically, if a recurrence is going to happen, there is an 80% chance of that happening in the first year. The second year it drops to 15% and the exam frequency is every 2-4 months. By the end of the second year the exam frequency is typically 4-6 months. The two year mark is significant because after that recurrence risk in the primary site drops to 5%. Bob should have gotten a baseline TSH (thyroid function) and should receive a followup TSH every 6 months and well as other bloodtests. You will a notice lot of stuff you took for granted pretreatment, so don't freak out. The doctors fully understand your nervousness so ask about any issue no matter how small.

Questions to ask:

1. What is the followup interval. Who will be the primary care physician? (in my case it was the head&neck surgeon)
2. What scans & how often?
3. What bloodwork & labtests?
4. How to recognize thrush and other opportunistic infections.
5. Will "salvage" or additional surgery be required? (my tumor was treated with radiation & chemo alone - Typically base of tongue cancers are treated with RT (and possibly chemo) alone depending on staging)
6. At less than a month post Tx there are probably constipation issues, coughing up blood, scar tissue, ulceration, slow healing, phasing off of pain meds, nutrition, immune system, swallowing and phasing in of solid food, etc.
7. Keep a journal.

It took quite a while before I actually started to feel like a survivor but its been almost 2 years for me now and I feel pretty good about it. I don't think too much now about the regular followup visits. It's almost like going to the dentist.

I still don't try to think past today - it keeps me a lot saner that way. We are cancer survivors one day at a time.