ASTRONOMERS ARE WORKING with medical physicists and radiation oncologists to develop a potential new radiation treatment—one that is intended to be tougher on tumours, but gentler on healthy tissue.
In studying how chemical elements emit and absorb radiation inside stars and around black holes, the astronomers discovered that heavy metals such as iron emit low-energy electrons when exposed to X-rays at specific energies.
Their discovery raises the possibility that implants made from certain heavy elements could enable doctors to obliterate tumours with low-energy electrons, while exposing healthy tissue to much less radiation than is possible today. Similar implants could enhance medical diagnostic imaging.
Last month, at the International Symposium on Molecular Spectroscopy, Ohio State University senior research scientist Sultana Nahar announced the team’s computer simulations of the elements gold and platinum, and the design of a prototype device that generates X-rays at key frequencies.
Their simulations suggest that hitting a single gold or platinum atom with a small dose of X-rays at a narrow range of frequencies—equal to roughly one tenth of the broad spectrum of X-ray radiation frequencies—produces a flood of more than 20 low-energy electrons.
“As astronomers, we apply basic physics and chemistry to understand what’s happening in stars. We’re very excited to apply the same knowledge to potentially treat cancer,” Nahar said.
“We believe that nanoparticles embedded in tumours can absorb X-rays efficiently at particular frequencies, resulting in electron ejections that can kill malignant cells,” she continued. “From X-ray spectroscopy, we can predict those energies and which atoms or molecules are likely to be most effective.”
Reducing patient’s radiation exposure
“From a basic physics point of view, the use of radiation in medicine is highly indiscriminate,” Pradhan added. “Really, there has been no fundamental advance in X-ray production since the 1890s, when Roentgen invented the X-ray tube, which produces X-rays over a very wide range.”
No fundamental advance, that is, until now.
Nahar and Anil Pradhan, professor of astronomy at Ohio State, discovered that particular frequencies of X-rays cause the electrons in heavy metal atoms to vibrate and break free from their orbits around the nucleus, creating what amounts to an electrically charged gas, or plasma, around the atoms at the nanometer scale.
“Together with long-time collaborator and medical physicist Yan Yu from Thomas Jefferson University Medical College, we’ve developed the … methodology, which we hope will have far-reaching consequences for X-ray imaging and radiation therapy,” Pradhan said.
While typical therapeutic X-ray machines such as CT scanners generate full-spectrum X-rays, hospitals could employ the new technique to greatly reduce a patient’s radiation exposure.
That’s the function of the proof-of-principle device that the team has constructed. Though the working tabletop prototype needs to be further developed, these first experiments show that the effect can be used to deliver specific frequencies of X-ray radiation to heavy metal nanoparticles embedded in diseased tissue for imaging or therapy.
“This work could eventually lead to a combination of radiation therapy with chemotherapy using platinum as the active agent,” Pradhan said.
Adapted from information issued by Ohio State University.
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