This study will evaluate the feasibility and safety of using MR-guided adaptive Head and Neck stereotactic radiotherapy (SBRT) at each fraction on the 1.5T MR-Linac.

At the Sunnybrook Odette Cancer Centre (OCC), stereotactic body radiation therapy (SBRT) (35- 50 Gy in 5 fractions delivered 2x/week) has been employed in a subgroup of palliative Head and Neck cancer (HNC) patients, as part of an institutional protocol, when greater tumor response is desirable when compared to more palliative regimens. The MR-Linac has been approved by Health Canada for radiation treatment. With superior soft tissue contrast and the possibility for daily plan adaptation, it allows for higher treatment precision delivery, improved target coverage and greater normal tissue sparing. As a first step, this study will evaluate the feasibility and safety of using the 1.5T MR-Linac on patients with HNC who are treated with SBRT.