Cancers are often treated with external beam radiotherapy. Current radiotherapy treatments are performed using computed tomography (also known as CT) scans which may not always clearly identify the cancer. In some instances, magnetic resonance imaging (MRI) may be able to better identify cancers. Therefore, efforts are currently underway to use the MRI scans to improve radiotherapy treatments or eventually even use radiotherapy equipment that only uses MRI scans to guide treatments. This new technology that will only use MRI scans to guide treatments is called the Linac-MR (linear accelerator with an MRI). The purpose of this pilot phase of the study is to test whether the Alberta linac-MR P3 system at the Cross Cancer Institute can acquire high quality MR images safely. It will allow the researchers to develop the best collection of MR images possible with this new machine, in order to allow them to visualize tumors for future patients that are treated on this machine.

This prospective, pilot phase, clinical trial is an imaging study to optimize the necessary MR sequences on the Alberta linac-MR P3 system to allow for MR-guided radiotherapy in adult patients with cancer that are treated with high dose external beam radiotherapy. Each participant will undergo a single MR imaging session (30 - 40 minutes) on the Alberta linac-MR P3 system. Towards the end of the study, patients will be approached to participate in an optional sub-study, where they will undergo a total of five MR imaging sessions (performed every two to five days) to allow for an assessment of inter-fraction motion.

Inclusion Criteria:

• Adults ≥ 18 years of age
• Patients deemed fit to undergo high dose external beam radiation therapy by their attending radiation oncologist

Exclusion Criteria:

• Patients with contraindications for MRI
• Patients who are unable to lie flat and still for the duration of the expected scan acquisition
• Patients who are unable to provide informed consent