As we observe Breast Cancer Awareness Month, we’re reminded that treating breast cancer isn’t just about targeting tumors—it’s also about protecting healthy tissue.
Across Dartmouth Cancer Center (DCC), about 300 breast cancer patients are treated each year with radiation therapy. One area of growing concern is contralateral breast dose—the small amount of radiation that sometimes reaches the breast opposite the one being treated.
In ongoing research, DCC radiation oncology resident Allison Matous, MD, is using an innovative technology called Cherenkov imaging to better understand and reduce this risk.
“Cherenkov imaging allows us to visualize radiotherapy beams in real-time as they interact with the patient,” explains Matous. “We can see invisible beams.”
The technique is based on the Cherenkov effect—a faint blue glow created when charged particles move faster than light through tissue. Special cameras capture this glow, letting therapists see radiation delivery directly on the patient’s skin.
Why contralateral dose matters
While contralateral dose may be small, research shows it’s not insignificant. Previous studies found that radiation exposures above a certain amount in younger patients are linked to an increased risk of developing cancer in the opposite breast.
“Seeing dose spill into the contralateral breast in our imaging really sparked the question: What is the actual dose going over there, and should we be worried about it?” asks Matous.
This question is especially timely. According to data, between 2012 and 2021, the increase in breast cancer incidence among women under 50 outpaced the increase in women 50 and older. “The breast is a radiosensitive organ, especially in younger patients. Since we’re treating younger and younger women who have excellent prognoses and many decades ahead of them, minimizing contralateral breast dose is essential,” says Matous.
Insights from the EDUCATE Trial
To find the answer, Matous and her team launched the EDUCATE trial in October 2024. So far, the study has analyzed Cherenkov images from more than 200 patients.
The results show that more than 40% of patients had some level of contralateral exposure, about 10% of which were unplanned and unexpected. “That’s a surprisingly high number,” Matous observes. “And importantly, with the aid of Cherenkov imaging, it’s something we can act on during the course of a patient’s radiation treatment.”
What it means for patients and providers
For radiation therapists, Cherenkov imaging delivers more than just data.
“For therapists, Cherenkov imaging provides immediate feedback. You’re not just assuming what the contralateral dose might be—you can actually see it during treatment,” Matous explains.
Though the research is still in early stages, the potential is clear.
“Ultimately, this technology helps us make radiation treatments safer and more precise,” says Matous. Technology that can improve both the quality of care and the peace of mind for patients.