Follow-up plans vary based on the type and extent of OC you had.

I think you would be classified under the NCCN Guidelines Follow-up Recommendations "Foll-A".

"Foll-A" recommends:
- post-treatment imaging of primary and neck within six months of RT treatment and futher reimaging as indicated based on signs/symptoms; NOT routinely recommended for asymptomatic patients.
- chest imaging as clinically indicated.

"Foll-A" is what the NCCN classifies as a "Catagory 2B" recommendation in that the CCC's on the board do not have a uniform consensus, but have no major disagreements.

Nevertheless, if a scan (CT, PET/CT or other) will help reduce your worry, then I think you should push for one.