Compared to IMRT, PBRT is thought to give less radiation exposure to the surrounding healthy tissues. It is possible that side effect rates with PBRT will be lower or the same compared to IMRT, but this has not been well studied to date. Although both of these radiation therapies have been used in the past to treat head and neck cancer, this research study will compare the effects of these two different radiation treatment modalities with each other to see whether PBRT is better, the same or worse than IMRT.