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Michael Bellamy

Researcher uses new models to quantify risk associated with radiation exposure

Michael Bellamy

Michael Bellamy, a participant in several Oak Ridge National Laboratory educational programs, helped develop mathematical models to better quantify the interaction of radiation with tissue. His research could help answer critical questions regarding the dangers surrounding radiation. Photo credit: Lynn Freeny, DOE

Nearly 48 million mammograms are performed on women in the United States per year. Scientists like Dr. Michael Bellamy want to know: how safe are they? What about x-rays taken for patients with broken bones—are these safe? What measurable harm, if any, is being done to employees who work with radioactive materials? 

“There is a sort of mystery and paranoia around radiation,” said Bellamy, who took part in three educational research participation programs, all managed by the Oak Ridge Institute for Science and Education, while at Oak Ridge National Laboratory (ORNL). “Because of these uncertainties, we need to study it and understand how to quantify the risk associated with exposure.”

Bellamy began his first appointment as a participant in the Nuclear Engineering Science Laboratory Synthesis program, a cooperative research initiative geared toward students working in physics and nuclear engineering applications. He later moved into the ORNL Post-Master’s Research Participation Program, and upon receipt of his Ph.D. from Georgia Tech, he joined the Postdoctoral Research Associates Program.

The educational programs aim to provide research opportunities for outstanding students and enhance interactions with the wider scientific community. They also promote the influx of new ideas and skills into the laboratory and advances scientific and technical training in key areas of science and technology, like national security and neutron science.

Under the guidance of world-renowned scientists, Bellamy engaged his degrees in nuclear engineering and previous background in mathematics, physics and computer science, proposing a new model to assess radiation-induced DNA damage.

“Recently, experimentalists have found that low-energy electrons and photons are more dangerous than high-energy photons for the same absorbed dose, which is a poorly understood phenomenon,” said Bellamy. “My research focuses on the relationship between cancer risk and the energy of photons and electrons.”

Bellamy explained that the best way to determine this relationship is to conduct research with live tissue, such as tissue from a human, dog or plant, but he said this kind of study is not always feasible due to cost consideration and availability. So, the next best thing is to fuse powerful computers with physics knowledge to simulate the radiation, according to Bellamy.

“By computer-simulating the electron track interacting with a DNA molecule, we can quantify the types and locations of interactions, which can help us estimate how dangerous that particular radiation is,” he said. Bellamy and his peers developed two models to do this.
“The first model exploits the idea that the most dangerous part of the electron track is the tail where damaging ionizations tend to cluster,” explained Bellamy. Ionizations occur when an atom loses electrons. The model, Bellamy said, seeks to determine what fraction of the radiation interactions could be considered highly clustered, which would make them more dangerous.

“The second model predicts the types and frequencies of DNA damage and is focused on a type of DNA damage called a double-strand break,” Bellamy said. “In contrast to a single strand break, which is repaired easily by the body, double-strand breaks are more difficult and dangerous to repair, so they are an appropriate endpoint to study.”

Bellamy and his mentor, Dr. Keith Eckerman, who leads the ORNL dosimetry research team and recently received the prestigious Gold Medal for Radiation Protection award, spent about a year and a half developing these models. After months of computer simulations, the models suggested some surprising findings regarding radionuclides, the unstable atoms that undergo radioactive decay and emit the radiation.

“Our models have identified a short list of radionuclides that are more dangerous than originally thought, but the main finding is that risks associated with the vast majority of radionuclides are unchanged.” He added that another interesting result of the study was that the tube voltage—whether high or low—of x-rays does not seem to be a determining factor in cancer risk.

As a science enthusiast for most of his life, Bellamy emigrated from the Republic of Trinidad and Tobago with a full scholarship to gain a double major in physics and math from Morehouse College in Atlanta. Bellamy said the programs granted him the additional educational opportunities he always wanted.

Bellamy said when he was 6 years old, he asked one of his teachers, “Where does electricity go when you unplug a socket from the wall?” This teacher gave Bellamy an answer he said he knew right then was incorrect. “That is when I knew I was going to be a scientist,” he said.

Bellamy described his experience as a participant in the ORNL programs as “absolutely flawless” and strongly recommended them to anyone to consider pursuing. He said, “I am honored and very lucky to conduct research with such a renowned scientist as Dr. Eckerman.  An early career scientist enrolled in the ORNL Postdoctoral or Post-Master’s programs can expect world-class scientific guidance, career advice, professional development and financial security.”

So, are mammograms and x-rays safe? Bellamy cannot answer these questions with certainty, but he is continuing to search for these answers. “As the mechanisms behind cancer induction are better understood, we can develop more sophisticated models that capture more of the phenomenon.”

According to Bellamy, research in radiation protection is quite active in the world, but it is “frightfully inactive” in the United States.  He said the ORNL program is one of the few opportunities around to become involved deeply in the study of radiation dosimetry, or the measurement and calculation of doses of radiation in matter and tissue. “The research we do protects workers and citizens of the United States and world; what nobler purpose is there?”