New tools to increase precision and safety of radiation treatment in cancer patients

A scientific breakthrough may give the field of radiation oncology new tools to increase the precision and safety of radiation treatment in cancer patients by helping doctors "see" the powerful beams of a linear accelerator as they enter or exit the body.

Dartmouth began to investigate a scientific phenomenon called the Cherenkov effect in 2011. Our scientists and engineers theorized that by using Cherenkov emissions the beam of radiation could be "visible" to the treatment team. The ability to capture a beam of radiation would show:
• how the radiation signals travel through the body
• the dose of radiation to the skin
• any errors in dosage.

For the first time in humans, researchers have used the technology with patients. The first case was a female breast cancer patient undergoing radiation.

"Breast cancer is suited for this because the imaging visualizes the superficial dose of radiation to the skin," said Lesley A. Jarvis, MD, radiation oncologist, Norris Cotton Cancer Center. Skin reactions, similar to sunburn, are a common and bothersome side effect during breast radiation. "By imaging and quantitating the surface dose in a way that has never been done before," said Jarvis, "we hope to learn more about the physical factors contributing to this skin reaction."

By seeing the effect of radiation on the body, Norris Cotton Cancer Center radiation oncologists and physicists can make adjustments to avoid side effects to the skin. Most radiation patients undergo somewhere between 8-20 sessions. The Cherenkov images of the breast cancer patient showed a hot spot in her underarm, which physicians and physicists could work to prevent in future sessions.

"The actual images show that we are treating the exact correct location, with the appropriate beam modifications and with the precise dose of radiation," said Jarvis.

This trial showed that the Cherenkov effect is feasible for use real-time during radiation. "We have learned the imaging is easy to incorporate into the patient's treatment, adding only minimal time to the treatments," said Jarvis.

"The time needed to acquire this information is negligible, even with our experimental, non-integrated system," said Gladstone. By integrating Cherenkov imaging into routine clinical care, Gladstone says the technology could be used to verify that the proper dose is being delivered to patients, helping to avoid misadministration of radiation therapy, a rare, but dangerous occurrence.

Twelve patients are participating in a pilot study, which is almost complete. The research team plans to publish the results in a peer reviewed journal. The Cherenkov effect project team includes Lesley Jarvis, MD, assistant professor of Medicine, Geisel School of Medicine; Brian Pogue, PhD, professor of Engineering, Thayer School, professor of Physics & Astronomy, Dartmouth College, professor of Surgery, Geisel School of Medicine; David J. Gladstone, ScD, DABMP associate professor of Medicine, Geisel School of Medicine; Adam Glaser, engineering student; Rongxiao Zhang, physics student; Whitney Hitchcock, medical school student.