Cancer Research

Behind the research: Sunnybrook’s first human image taken on MR-Linac

radiation therapist adjust patient on MR-Linac

Sunnybrook’s radiation and clinical trials teams took a huge leap forward today when they took the first human images on the Odette Cancer Centre’s new MR-Linac – the Elekta Unity.

This new technology is the first machine in the world to combine radiation and high-resolution magnetic resonance imaging (MRI), and will let doctors at the Odette Cancer Centre target tumours and monitor their response to radiation with unprecedented precision — even as a tumour moves inside the body — thanks to the machine’s real-time MRI guidance.

As the first Canadian centre to install an MR-Linac, Sunnybrook’s team is leading the way and helping to set up and conduct clinical trials that will establish the best treatment protocols for this new machine.

The first step is an imaging study that started this week with the first patients. These study participants will have their imaging and treatment as usual, and then will undergo an extra MRI on this new machine.

Radiation oncologist Dr. Arjun Sahgal, medical physicist Dr. Claire McCann, and Mikki Campbell, radiation therapist and strategic initiatives manager in the Radiation Therapy Program, answered some questions about this exciting new study and revolutionary equipment.

What’s this phase – the imaging study – all about?

This volunteer imaging study aims to establish the MR (magnetic resonance) scan protocols that will be used to treat patients on the MR-Linac. We will use the images in our study to help us develop procedures that will allow us to adapt a patient’s radiation treatment to changes in the tumour that may occur over time.

Right now, a patient has a CT image taken before radiation. We use that image to plan a patient’s treatment, like where to aim the radiation beam. For some patients, we also get a single MR image, which helps us with this radiation planning. With our new MR-Linac, we will be able to get MR images before every radiation treatment. Those MR images will be used to help us ensure the most accurate treatment based on the tumours specific location each and every day. These images will also allow us to monitor how the tumour responds and determine the best way to adapt the treatment to those changes in real time.

This volunteer imaging study is the first step in getting us there, as the images taken during the study will help us to develop the clinical workflows – procedures and processes for how we manage any tumour changes, to ensure the most effective way to adapt the patient’s treatment.

We will also be testing research MRI sequences, which are specialized images of the tumour that can tell us: are the cells are dying? Is the blood flow changing in the tumour? And is the tumour overall resisting the effects of radiation? A team of scientists at the Sunnybrook Research Institute has been working on these sequences so we can ultimately image with the MR-Linac and personalize radiation delivery based on tumour response.

Why is this an important step?

Many people think that when we get a new piece of equipment, we just plug it in and start using it, but it takes a lot of planning and preparation to ensure patients are safe and the new technology is effective.

For the MR-Linac, exquisite image quality combined with an optimized workflow for real time MR-guided adaptive radiotherapy (meaning, taking images in real-time and changing the radiation beam target accordingly) will help us to improve the accuracy in targeting the radiation to the disease. This means we can potentially reduce the radiation to the surrounding normal tissues, and/or increase the radiation dose to the tumour for better outcomes. This first step of our imaging study helps us set up those workflows and image sequences.

This radiation oncology technology reflects a key step towards the personalized cancer medicine.

What comes next after this?

Once we receive full Health Canada approval of the combined MR-Linac system, we will be able to start clinical trials where we treat patients with this technology using the imaging parameters and workflow developed as part of this imaging study for MR-guided adaptive radiotherapy.

Anatomical imaging lets us see the tumour’s anatomy. Functional imaging lets us looks at biological changes, for example changes in tumour blood flow as a result of radiation treatment. As our experience with this technology develops, we will add functional imaging to supplement the anatomical imaging, which will allow us to adapt radiation treatment not only to changes in tumour size, shape and location but based on biological response to the radiation as well.

How does it feel for you to get to this point?

We are exhilarated to finally see this game-changing technology go from the bench-top to clinical use in such a short time with the knowledge that it has the potential to impact clinical outcomes and ultimately redefining the patient’s cancer journey.


Learn more about this and other new cancer ablation therapy techniques at

About the author

Alexis Dobranowski

Alexis Dobranowski is a Communications Advisor at Sunnybrook.