5 Questions on MRI Linac

By Patrick Hwu, M.D. - July 25, 2022

Dr. Stephen Rosenberg, director of MRI guided radiation therapy at Moffitt Cancer Center, recently sat down with me to discuss the new technology. His work is part of the Future of Radiation Therapy research program aimed at personalizing radiation therapy using novel approaches to improve local control of tumors and decrease side effects for patients.

Dr. Stephen Rosenberg
Dr. Stephen Rosenberg, Radiation Oncology Program

Hwu: What’s MRI Linac?

Rosenberg: The MRI Linac is a really exciting tool we’re using to take care of our cancer patients in a brand new way. The MRI Linac is a combination of two different technologies: an MRI scan, which lets us see things in great detail, both tumor and normal anatomy way beyond what we can see with a classical CT scan, and a linear accelerator, which is a machine that produces high powered X-rays we use to treat patients and cure cancer. When you combine these two pieces of technology into one tool, we can do new and exciting things for our patients we could never do before.

Hwu: What are the advantages of MRI Linac over other imaging technologies?

Rosenberg: The MRI scan lets us see the soft tissue in very fine detail. It lets us see changes in the anatomy that we might not see with a CT scanner. Also, with MRI scan, that machine is constantly on and going. While we’re delivering treatment for radiation delivery, we can see what’s happening inside a person’s body while radiation is being delivered. So it’s a real time visualization of what’s happening inside of somebody that we just can’t get with a CAT scan right now.

Hwu: What are the advantages of this breakthrough integration?

Rosenberg: I think one of the things we’re most excited about with what we can do for our patients now is called real time adaptive radiotherapy, which is all about better personalization of treatment. So when someone comes in for their radiation treatment, they get an MRI scan every day and there can be shifts in the anatomy, there can be changes in the tumor, and we can adapt or change the radiation plan while the patient is on the table and do that all in real time. It used to take us a week to do in the background, and we can now do it in one hour while someone is literally on the treatment table. It allows us to both better personalize treatment, decrease side effects and improve tumor control. It’s a really exciting area that we’re moving forward in radiation oncology.

Hwu: How does MRI Linac account for breathing and movement during treatment?

Rosenberg: With the MRI Linac, one of the other advantages we have is called gaiting. The way we would traditionally treat a lung tumor is that we have to treat a very large area anywhere that the tumor can exist in the respiratory cycle. Your heart is beating, your lungs are moving, your diaphragm is moving. The only way we used to be able to account for that is basically treating a large area because the tumor moves while those things are happening. With this MRI scan, this software will pick up the tumor, track it in real time, and the radiation will only turn on when the tumor is in the exact right position. That allows us to decrease our treatment volumes and spare normal organs, normal tissues, and hopefully decrease side effects as well. That’s really critical for patients who have lungs that might be compromised or have other normal organs that we’re really trying to spare with treatment.

Hwu: How do you find out if you’re a candidate for MR-guided radiation therapy at Moffitt?

Rosenberg: That’s a fantastic question. This is a fantastic tool that radiation oncologists have to use to treat cancer. But it’s not our only tool. Making an appointment and coming in for an opinion with the Radiation Oncology Department to see if this sort of tool can benefit you and your cancer. We want to make sure we’re using this for the right reasons for people, so making an appointment, which can either be in person or via Zoom. We do have a lot of people who come in just for an opinion about MRI-guided technology. This is definitely very helpful for some, not helpful for everybody. We also have some clinical trials opening or will open that may benefit you that are also very specific to MRI guided and you wouldn’t necessarily know that unless you’ve had a consultation with us to learn more about those.

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