When Tracy R. Sandmann, RT(T) BA, learned she needed radiation therapy to treat infiltrating ductal carcinoma — a type of breast cancer — she knew exactly what to expect. That’s because Sandmann, 57, has worked as a radiation therapist at the Dartmouth Cancer Center (DCC) in Lebanon, N.H., for more than two decades.

“I was treated on the very machine I work on,” Sandmann says. 

Her diagnosis came after a routine mammogram in 2013 identified an abnormality that turned out to be breast cancer. Fortunately, it was early in the cancer’s development. Malignant cells had not spread to her lymph nodes. 

In October 2013, Sandmann had a partial mastectomy with reconstruction. That December, she began a treatment course of 33 sessions, or fractions, of radiation therapy. 

“I had radiation therapy five days a week for just over six weeks,” Sandmann says. While at work, she’d stop to get her treatment, and then continue on with her day of treating other people.

Sandmann’s experience on both sides of the linear accelerator — the machine that delivers radiation — means she understands how vulnerable patients may feel. As a professional who treats people with cancer, she also knows how critical it is to deliver a precise dose of radiation to destroy cancer cells and preserve healthy tissue. 

But verifying that radiation reached exactly the right spot in a patient’s treatment plan had never been possible — because nobody could see radiation. Until now.

Specialized technology called BeamSite Cherenkov imaging cameras, developed by a team of researchers and physicians at Dartmouth, has made radiation visible. The cameras capture a blue glow known as the Cherenkov effect, allowing therapists like Sandmann to see the treatment field and deliver targeted radiation therapy with confidence. 

Verifying radiation’s location 

The blue glow emitted by radiation, named for Russian physicist Pavel Cherenkov, occurs when radiation-charged particles travel through a medium — such as the human body — faster than the speed of light in that specific medium. BeamSite cameras capture images of this blue glow, which appears when radiation interacts with human tissue.

With Cherenkov imaging cameras, Sandmann and her colleagues can now watch as radiation targets cancer cells in real time. The technology helps ensure that radiation gets where it needs to go and nowhere else.

Radiation oncologists develop therapy plans specific to each patient’s needs. Therapists then treat each patient using their personalized plan, which includes detailed notes about how to position the patient. Care teams rely on checklists and pretreatment checks of the patient’s position to make sure radiation is delivered to the right location. 

But patients must stay completely still during treatment and sometimes, they don’t. Even the slightest movement may change radiation’s path. 

“Patients may get uncomfortable or wiggly,” says Dr. Lesley Jarvis, MD, PhD, a radiation oncologist and associate professor in the Department of Radiation Oncology and Applied Sciences in the Geisel School of Medicine at Dartmouth. “A chin may drop into the field, or an arm will move.” 

Making the invisible visible

With radiation’s application now visible thanks to Cherenkov imaging, radiation therapists can respond quickly if misalignment occurs. “In the past, we’d make sure the patient was in the right position and that the machine was programmed correctly, but once we left the room and pressed a button, we were completely blind to the treatment,” Jarvis says. “Now, we can immediately stop the beam, reposition the patient, and start again.”

Cherenkov imaging also helps minimize contralateral breast radiation during treatment for breast cancer, Sandmann says. Radiation can sometimes reach the opposite breast, which isn’t supposed to be treated, due to patient positioning or other reasons.

BeamSite camera technology helps reassure patients, according to Sandmann. “Cherenkov imaging allows us to tell patients that we can see the radiation field on their body, in real time, as they’re being treated,” she says. “Radiation can be scary … and Cherenkov imaging ups the level of quality and safety which is comforting for patients.”

Each radiation therapy room at Dartmouth Cancer Center’s Lebanon and Keene, N.H., locations now has Cherenkov imaging cameras mounted to the ceiling, according to Jarvis. Dartmouth Cancer Center’s locations in Manchester, N.H., and St. Johnsbury, Vt., will also soon have the cameras.

Collaboration fuels innovation

A chance encounter at a conference led to the development of the BeamSite Cherenkov imaging camera, says Brian Pogue, PhD, endowed as the John A. Pritzker Professor of Biomedical Engineering at Dartmouth, former co-director of the Translational Engineering in Cancer Program at DCC, and cofounder and president of DoseOptics, LLC.  He heard a colleague present on Cherenkov radiation and imaging isotopes (radioactive elements) in mice. 

Pogue knew immediately that Cherenkov radiation could be useful in imaging radiation therapy. He and his research team began photographing different objects being irradiated by the radiation therapy beam. They created a technique to capture the Cherenkov light, customizing their cameras to work in time with the linear accelerator.

Pogue soon brought his invention to Jarvis. “He stopped by and said, ‘I think I might be able to see X-rays,’” Jarvis says. 

The colleagues soon studied radiation treatments at Dartmouth to prove Cherenkov imaging’s value as a verification tool for treatment delivery. Today, the BeamSite system has been adopted by about a dozen medical centers throughout the world, and another two dozen are being installed this year, Pogue says.

BeamSite cameras are the latest entry in Dartmouth’s history of radiation innovation — in 1896, researchers at Dartmouth performed one of the first clinical X-rays in the US. Advancements like these are part of the collaborative culture at Dartmouth, according to Pogue. 

“DoseOptics was created through partnering with a team of dedicated experts at and affiliated with Dartmouth,” he says. “This never would have happened if I wasn’t at a comprehensive cancer center that welcomed research into their radiation therapy department.”

Dartmouth’s size and collaborative culture make interdepartmental innovation feel seamless, according to Jarvis. 

“There’s such an open-door policy here,” she says. “Our colleagues are neighbors that we run into in the grocery store.”

Jarvis said she and Pogue are now working to develop the next innovation in radiation therapy, focusing on technology that measures radiation dose. Different types of tissue, such as fatty tissue and glandular tissue, affect the amount of radiation a patient absorbs. “We’re developing technology that will help zero out those differences,” Jarvis says.

Sandmann says she loves being part of a team that continues to drive the future of cancer care. “It’s exciting to have this new technology at Dartmouth and to know that we’re bringing forward technologies that many other centers want to use.”