Treatment of Head and Neck Cancers with MR-Linac

Head and neck cancers constitute a heterogeneous group of tumors with varying behaviors. Treatment of these tumors is complex and often involves high doses of radiotherapy delivered to an anatomically constrained area with many nearby organs at risk. Consequently, treatments are often quite toxic. MR-Linac (MRL) radiotherapy offers the potential to improve toxicity outcomes by allowing precise delivery of radiation to the target volumes while minimizing radiation exposure to nearby structures. This technique offers the possibility of treatment adaptation with volume and/or dose escalation or de-escalation as lesions change in size. MR-guided radiotherapy also provides anatomical and functional information, which could help monitor treatment response and develop image-based predictive outcome models. However, MRL radiotherapy has its limitations such as the inability to support volumetric arc therapy. Data on the use of MRL for head and neck cancers is also limited and validation studies are under way. This chapter highlights the current literature, potential benefits, technical considerations, limitations, and future directions of MRL radiotherapy for head and neck cancers.