Medical collaboration: NIST researchers collaborate with medical physicists at the radiation oncology facilities of the University of Colorado Anschutz Medical Campus and, in the evening, run experiments in the same radiation suites that treat patients by day with accelerator-generated high-energy X-ray and electron beams.
Russek and his team hope their research will help medical physicists with the key goal of their job: preparing treatment plans based on patient-specific calculations that maximize the dose to a tumor and minimize dose to surrounding tissue to optimize patients’ prognosis for a long, healthy life following treatment.
An anthropomorphic dosimeter: To gather data and develop standards that could improve patient outcomes, NIST has developed a “human-head-shaped container filled with radiation-sensitive material” and “special polymers that change their chemistry when exposed to radiation,” Russek said.
“The phantom can be thought of as a three-dimensional, radiation-sensitive photographic film. When radiation hits parts of the phantom, we can record changes in the film. We do this using a special type of MRI that provides data and measurements, not just pictures, known as quantitative MRI. It is our expertise in quantitative MRI that brings this new opportunity to radiation dosimetry,” Russek said.
NIST builds expertise: Back in 2005, Russek explained, “medical societies, pharmaceutical companies, and other stakeholders asked NIST to lead a program on standards for quantitative medical imaging.” Then, in 2020, NIST began working on radiation dosimetry using quantitative MRI techniques to generate 3D images of the changes in phantoms, made of materials that mimic human tissue during radiation.
“NIST began collaborations with international groups working on MRI-readable radiation dosimetry, and we’ve been working to advance this science since then,” Russek said. “Using the quantitative MRI rather than a traditional MRI, we can better measure where and how much radiation is deposited and use this information to verify the accuracy of dose plans. We’re planning to use these gels to study different types of radiation, such as X-ray, electron, proton, ultrasound, and microwaves. We hope to better understand how and where they are absorbed in the body.”
Future focus: The long-term goal is to produce a cost-effective phantom and tabletop MRI system that can be used in radiation oncology to help patients get precise and customized treatment.
“One of the most exciting aspects of this research is that once it's perfected, we can expand it to other measurements beyond dosing,” Russek said. For example, Russek and his team are studying DNA damage due to radiation, such as that used for cancer treatment, and DNA repair processes in the human body. “We’re working to sensitize our gels to measure DNA strand breakage, so we can study this damage,” he said.
NIST is also collaborating with NASA on measuring the effects of cosmic radiation exposure in space, including exposure of both humans and materials and sensitive electronics. “If humans are going to spend any amount of time in space, we need to know how to do so in a healthy way,” Russek said.
