When you treat postop head and neck cancer, do you typically add a CTV margin to the delineated postoperative bed, or just treat postop bed plus PTV margin?  

We don't ever have a CTV margin. It is postop bed which accounts for all pre-surgery GTV and all postoperative changes on imaging, also review the op note and path. We then add a 3-5mm margin to account for set-up.

I think the practice would vary and there is also some uncertainty in the delineation of surgical bed. That being said, if post-op RT is for close or positive margin or PNI, then we make sure we add CTV margin to surgical bed and then PTV margin.