Sunnybrook radiation therapist Mikki Campbell with the Elekta Unity MR-Linac. (Photography by Kevin Van Paassen)
Sunnybrook researchers are leading the way in cancer treatment with the Elekta Unity MR-Linac. The revolutionary new machine combines high-resolution MRI and radiation, delivering greater precision and new hope for patients.
Sunnybrook took a step toward the future in August 2019 when the first patient in Canada received treatment on the Elekta Unity MR-Linac, the first machine in the world to combine radiation and high-resolution magnetic resonance imaging (MRI). The team directed a beam of radiation precisely at a glioblastoma, the most common and aggressive type of brain tumour, and watched it strike the tumour in real time. It was a feat that would have been impossible in the past, because doctors could only plan treatment based on images taken before radiation treatment began.
With the Elekta Unity MR-Linac, the team at the Odette Cancer Centre can target a tumour and monitor its response to radiation with unprecedented accuracy – even as that tumour moves inside the body.
The moment that first patient was treated on the Elekta Unity MR-Linac was one of personal and professional pride for Mikki Campbell, a radiation therapist and manager of strategic initiatives at Sunnybrook, who has been involved in the Elekta Unity MR-Linac project since it started in 2013. It was also bittersweet.
“I really wanted to call my dad and tell him, ‘Dad, we did it,’” Mikki says.
From tragedy to inspiration
Mikki was just seven years old when her 32-year-old father Ronnie was diagnosed with glioblastoma on Canada Day weekend.
With no MRI at their hospital in Sudbury, Ont., Mikki’s parents flew back and forth to Ottawa for imaging tests.
“I’m not sure how they did it. My little sister was three. We didn’t really understand what was going on,” Mikki says.
During this time, Mikki’s parents explained that her father would need radiation treatments to treat his brain tumour.
“When my dad realized he was coming close to the end, it was really hard for him to go in for radiation,” Mikki recalls. “But he had an outstanding radiation therapist who he’d tell me about.”
Mikki’s dad died just a few months after his diagnosis, in November 1992. Though she was still a child, Mikki decided then she’d become a radiation therapist, a job she thought “would be neat to help patients and families get through a really challenging time.”
As Mikki embarked on her career, she met Dr. Arjun Sahgal, a radiation oncologist specializing in brain and spinal tumours and head of Sunnybrook’s Cancer Ablation Therapy Program, who was joining a global group to develop new radiation technology. Sunnybrook was one of seven health sciences centres in an international consortium with Elekta to develop the Elekta Unity MR-Linac and bring it into clinical use.
“As Dr. Sahgal explained the [Elekta Unity MR-Linac] to me, I got excited by the opportunity. It really fit with what I thought of as my purpose – to improve the care for these patients and their families,” Mikki says. “It was easy for me to jump on board.”
Since then, Dr. Sahgal, Mikki and a talented team at Sunnybrook have been involved in the Elekta Unity MR-Linac’s development every step of the way.
A major feat of engineering
The Elekta Unity MR-Linac is an MRI machine capable of running diagnostic imaging sequences to look at how tumours behave and metabolize. It’s combined with a linear accelerator, which delivers radiation by accelerating electrons to a very high speed. The resulting beams of radiation destroy cancer cells, while leaving the surrounding tissue untouched.
“If you asked me 10 years ago if we’d ever have a radiation machine with an MRI built into it, I would have said, ‘You’re crazy. That’s not possible,’” says Sunnybrook radiation oncologist and specialist in prostate and breast cancer Dr. Danny Vesprini. “You can’t have a machine that produces electrons, which are negatively charged, in a magnet. But here we are.”
Normally, a magnetic field would cause the electrons in the linear accelerator to reverse course and start bending backward, Dr. Sahgal explains. But the Elekta Unity MR-Linac is able to mitigate that issue through software and advanced computing, allowing radiation to be delivered in a highfield- strength MRI. “That’s a major engineering feat,” he says.
The one-two punch of imaging and radiation allows doctors to precisely monitor how a tumour is responding to treatment day by day and make the tiniest of adjustments in where to aim the radiation.
“If you asked me 10 years ago if we’d ever have a radiation machine with an MRI built into it, I would have said, ‘You’re crazy. That’s not possible.’”
– Dr. Danny Vesprini, Sunnybrook radiation oncologist
In November 2019, Sunnybrook treated its first patient with prostate cancer on the Elekta Unity MR-Linac. Dr. Vesprini said it was like his eyes had been opened.
“We are already very precise with prostate radiation on a regular linear accelerator,” he said. “But now, this imaging allows us to really see what we are doing; we are planning the treatment based on what we see each day, and by doing that, we can decrease the radiation to the surrounding tissue.”
In Canada, the Elekta Unity MR-Linac is Health Canada approved but still under evaluation, meaning that all patients treated on it at Sunnybrook are part of clinical trials. The first trials involve patients with brain tumours, to be followed by patients with prostate and pancreatic cancers, Dr. Sahgal says.
“The challenge will be to prove that treating with [this] technology is better than our current standard of care,” says Dr. Sahgal.
The team is working closely with researchers, who will use the daily MRIs to look at the metabolism – the cell death or growth – of each tumour and determine how the tumour responds to the radiation.
“By studying this data, in the future we will be able to predict which tumour will respond to treatment, and which will not, so that we can truly personalize treatment,” Dr. Sahgal says.
This is particularly important for patients with brain tumours, he says, because there has been little advancement in treatment options for these cancers in many years.
“This is giving us all some hope,” he says.
Mikki says she’s excited for the Elekta Unity MR-Linac’s precision therapy to one day become available to more patients and families. She’ll never forget the day she witnessed the first patient receive treatment.
“From seeing my parents fly hours away to get an MRI, to having one built right into the radiation-treatment device – it was overwhelming,” she says. “I was speechless. I had to step out for a moment and call my mom. We shed some tears together.”
When Mikki went home that night, she sat down with her sons, who are aged nine and 11 years.
“I told them what their mom did that day at work, and what that means for people in Canada and around the world,” Mikki says. “My eldest said, ‘Mom, you did this for Grandpa Ronnie.’ And I did. We did.”