MagnetTx’s New Aurora-RT Linear Accelerator

For this installment of our interview series with leaders in the field of radiation oncology, we spoke with Dr. Gino Fallone. The inventor of MagnetTx’s new Aurora-RT linear accelerator, he serves as Professor and Director of the Division of Medical Physics in the University of Alberta’s Department of Oncology.

Dr. Fallone is one of the most prolific researchers in radiation oncology, with 344 peer-reviewed publications and book chapters. Linac-MR technology is a special area of interest for him—75 of his publications concern this topic. He has been invited to present at over 190 conferences, and he received the 2021 Gold Medal Award from the Canadian Organization of Medical Physicists—the highest award given by the organization. In addition to the Inaugural Alberta Lifetime Contribution to Cancer Research Award, he was knighted in the Italian government’s Order of Merit for his outstanding contributions to his field.

Outside academia, he is the Founder, Chairman, and scientific leader of MagnetTx (pronounced “magnetics”), which was recently awarded an FDA 510(k) for its Aurora-RT Linac-MR system. We at ROS think this is one of the most interesting new technologies on the market, and it’s the focus of our conversation with Dr. Fallone.

What makes the MagnetTx Aurora-RT so special?

The Aurora-RT is simply the latest linac-MR technology that has entered the market. We have taken the concept of linac-MR and made it better.

Linac-MRs are already a breakthrough in fighting cancer. Seeing a tumor in real time, with the clarity and definition that only MR imaging provides, is absolutely marvelous. For the first time ever, this technology enables clinicians to know exactly where the tumor is located before targeting it with radiation.

We made this existing technology even better for the patient by shortening treatment times. Patients don’t have to sit on the couch for long periods of time, and it’s more flexible and simpler for the clinical staff, as well.

How is it different from other linac-MR technology?

One of the things that makes our system unique is that we found a way to eliminate the electron return effect, which means that the radiation that is delivered from the linear accelerator does not change.

Our system is also unique in that it has a very large bore. At 110 cm x 60 cm, it’s so large that it allows us to put any tumor in the isocenter position. We can go ± 25  cm to the left, right, up, or down. Our competitors cannot do that. The option of positioning tumors at  isocenter (linac’s center of rotation) facilitates achieving the optimal  treatment plan for the patient. This results in better delivery of the radiation dose to the tumor, while avoiding damaging healthy tissue.

Couches of conventional linacs have significant lateral and vertical motion to move any tumor, irrespective where it is, to the positioned planned with the treatment planning system (TPS).

Our competitors’ couches, however, can only move laterally or just minimally vertically or not at all. So there’s a limitation on how they can position each patient. This is because typical radiology MRIs and the competitors’ MRI linacs, which are all based on cylindrical MRIs,  simply do not have sufficient  bore space for significant  vertical  or lateral  shifts. If the tumor cannot be placed in the planned position as is done with conventional linacs, these systems require a re-plan while the patient is lying motionless on the treatment couch for over an hour. There is no such limitation with the Aurora RT as the tumor is placed to the planned position.

When you can place the tumor in the isocenter, the physician has more options for treatment planning, and they can use the same techniques that they have always used.

Another great aspect of the Aurora-RT is that it can use any TPS. You would be able to use current commercial TPS (such as  Eclipse, Monaco, or RayStation. etc), in the same way linacs from different vendors can be used.  Our competitors require a very specific TPS that is designed only for their system. Why? Because the magnetic field in the other systems changes the dose distribution. With ours, it doesn’t.

So really, with the Aurora-RT, you can continue to do things the same way. You can plan the same way, using the same TPS. You can position the patient optimally, with the tumor at isocenter. And you don’t have the issue of the electron return effect or the magnetic field distorting the radiation.

So, is it safe to say that the Aurora-RT, with its ability to position patients with far more flexibility, can treat most tumors?

Yes, it can treat any solid tumor, whether it’s in the center or periphery of the body. We can treat cancers in the prostate, lung, pancreas, liver, breast, and other areas.

What inspired you to design and develop this machine?

Image guidance for radiotherapy was always part of my research. A major problem in radiotherapy is knowing where the tumor is, to accurately hit it with radiation.

The linac-MR was a natural evolution: First, in radiotherapy, images of the tumor were taken using film. Then, it evolved to portal imaging and portal dosimetry, and later to CT and cone-beam CT Use of MRI was the next phase, but it was much harder since linacs and MRIs don’t work well together. So, we had to find specific solutions to hard problems.

In the early years, we used a tomotherapy machine, which was the first machine to combine a linac with a CT scanner. We moved the patient on a couch between it and our 3 Tesla MRI system, a few yards away, to exquisite MR images. But of course, the tumour can also move because of breathing or other processes during this time.

Although we were early developers of this technology, it took us longer because we had to resolve some of the critical issues, e.g., avoid the electron return effect and provide significant couch shifts to move any tumour on the position that was planned. We knew we could not just “snap” the MRI and linac together.

In the world of MRIs, people always use Tesla (T) strength as a measure of a machine’s capability and image quality. How does the Aurora-RT stack up to its competitors?

With MRIs, people generally talk about the signal-to-noise ratio (SNR), or the ratio of a desired signal’s level to the level of background noise. The SNR increases with increased Tesla strength. But there is another characteristic that is critical for radiation therapy. This is contrast-to-noise ratio (CNR). This is the difference from one tissue to the next, like a tumor to its surrounding healthy tissue. We found for fast MRI that the greatest CNR occurs at mid-level magnetic fields.

In 2015, we published a peer-reviewed paper showing that, for fast-imaging required for linac-MR’s, the maximum difference between the tumor and non-tumor occurs at 0.5 T.

A few years later, in 2019, an NIH study published in Radiology determined that 0.5 T was preferred to 1.5 T for image-guided therapies The images might look a bit noisier, but the intensity of a tissue against another tissue is much greater. We had designed our machine for the sweet spot, at 0.5 T.

Your competitors are 0.35T for the View Ray and 1.5T for the Elekta Unity. So you are right in between and able to provide the better contrast ratio. Now, the machine is FDA-approved. Looking back, what was the biggest hurdle you faced?

Early on, in research mode, it was all about getting funding. It’s hard to get funding when people did not believe we could do it this way, and it took us a while, and many papers, to convince them.

We did all this development with competitive grant funding which always takes longer and requires us to publish papers, and of course, these are in the public domain.  We did all this within an academic setting.

We had some technical hurdles as well. We had to develop the first MRI that rotates on its axis. Ours is not a cylindrical magnet—it’s a rotating, bi-planar, linac-MR. That, too, was a big challenge.

What advice would you give other physicists and engineers looking to develop new products and technologies?

It’s simple. Believe in yourself, even when others tell you you’re wrong. Keep fighting and pushing to make your dream come alive. “It costs too much… it won’t work… you need a cylindrical magnet…” I heard all these comments, but I just kept pushing.

On a personal note, what inspired you to become a physicist?

I just have always loved physics. I’ve always been curious and wanted to know how and why things occur, and physics answers that for me.

How do you relax in your free time?

I like to listen to music to unwind. I also exercise every morning that I can, to start the day with some energy.

And I like to ski. I used to play a lot of soccer until my knees started hurting. I’m Italian, so I have to love soccer, right? I’m also a big Edmonton Oilers fan, although we haven’t seen a Stanley Cup in a while!

For those interested in learning more about the Aurora-RX, Dr. Fallone will be at ASTRO in San Antonio on October 23 to 26, 2022, at booth #1742. Radiology Oncology Systems will also be there at booth #954, with specialists prepared to answer questions about the Aurora-RX and other high-quality radiation oncology products.