MR-Linac for Head and Neck SBRT

Magnetic Resonance Imaging-Guided Radiotherapy for Head & Neck SBRT on the 1.5T MR-Linac

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.

Inclusion Criteria:

• Patients aged 18 years and older
• Karnofsky performance status score of ≥70
• Biopsy-proven oligometastatic cancer to the HN
• Biopsy-proven primary HN cancer (either mucosal, nodal, skin)
• Patients deemed unsuitable by the treating radiation oncologist for radiation treatment with curative intent owing to advanced age, significant comorbidities, poor performance status, distant metastatic disease.
• ≥ 1 site amenable to HN SBRT
• Capable of providing informed consent
• Required to complete any systemic therapy ≥ 10 days prior to planned start of HN SBRT, with no plans to initiate systemic therapy ≥10 days following completion of HN SBRT.

Exclusion Criteria:

• History of radiation within the projected treatment field
• Contraindications to MR imaging per institutional policy
• Patients with connective tissue disorders
• History of severe claustrophobia
• Pregnant and or breastfeeding females
• Having an estimated glomerular filtration rate (GFR) <40 ml/min/1.73m2