Cherenkov Effect Breakthrough Allows Clinicians to Visualize Radiotherapy in Body

A scientific breakthrough may provide radiation oncologists with new tools to increase the accuracy and safety of radiation treatment in cancer patients by helping them visualize the powerful beams of a linear accelerator as they enter or exit the body.

Dartmouth University (Hanover, NH, USA) began to study a scientific phenomenon called the Cherenkov Effect in 2011. The scientists and engineers hypothesized that by using Cherenkov emissions the beam of radiation could be “visible” to the treatment team. The capability to seize a beam of radiation would show: how the radiation signals move through the body, the dose of radiation to the skin, and any errors in dosage.

Scientists, for the first time in humans, have used the technology, and 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. Similar to sunburn, skin reactions are a typical and annoying side effect during breast radiation. “By imaging and quantitating the surface dose in a way that has never been done before,” said Dr. Jarvis, “we hope to learn more about the physical factors contributing to this skin reaction.”

By seeing the effect of radiation on the body, Dartmouth’s 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,” stated Dr. Jarvis.

This trial revealed 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 Dr. Jarvis.

This was the first time Cherenkov studies came out of the laboratory and into a treatment setting. The scientists coined the approach Cherenkoscopy. As they anticipated, during the session they were able to see comprehensive data about the treatment field and the dose. The findings were published in the November 2013 issue of the Journal of Biomedical Optics. “This first observation in the dog proved that we could image a radiation beam during treatment in real time,” said David Gladstone, ScD, chief of clinical physics at Norris Cotton Cancer Center. “The images verified the shape of the beam as well as intended motion of the treatment machine. The time needed to acquire this information is negligible, even with our experimental, nonintegrated system.”

By incorporating Cherenkov imaging technology into routine clinical care, Dr. Gladstone reported that the technology could be used to prove that the correct dose is being delivered to patients, helping to avoid misadministration of radiation therapy, a rare, but dangerous occurrence. “The time needed to acquire this information is negligible, even with our experimental, nonintegrated system,” said Dr. Gladstone. “Cherenkov images were found to contain much richer information than anticipated, specifically, we did not expect to visualize internal blood vessels.”

Twelve patients are participating in a pilot study, which is almost complete. The researchers now plan to publish their findings.

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