During treatment I recall my MO saying after the neck nodes it usually metastasized to lungs. I wasn't aware of the risk prevalence to the liver and kidneys.

Any info on the value of an annual MRI or simple chest X-ray instead of a PET/CT to cut the radiation exposure?

I mentioned this to one of my RO's, but got the feeling he didn't think the exposure level from the newer CT's was significant enough to statistically cause a problem within my remaining life-time.