X-rays are one of the most commonly used medical imaging tools. And while no-one is likely to reach the 10,000 X-ray lifetime limit (100 mSv) recommended by the American College of Radiology, few would argue against technology that can lower the radiation dose of X-ray imaging. And that's just what a team of researchers has developed, in the form of novel nanocrystals that allow the radiation dose from a diagnostic X-ray to be much lower, while also enabling higher resolution images at a lower cost.
Currently, most conventional X-ray machines rely on inorganic crystals for their scintillators, which convert X-ray energy into visible light. However, these inorganic crystals are expensive because they need to be produced at high temperatures and are difficult to fabricate in large films that are uniformly thin. An international team of researchers has developed an alternative scintillator material in the form of lead halide perovskite nanocrystals, which are much simpler and cheaper to produce and can be made at much lower temperatures.
And unlike the inorganic crystals that have a low light emission conversion efficiency –meaning they require higher doses of X-rays to produce an effective image – the newly developed nanocrystals are able to convert even small doses of X-ray photons into visible light. Additionally, the nanocrystals can also be tuned to illuminate in different colors, which, coupled with the increased efficiency, allowed the researchers to develop a new type of detector that they claim can sense X-rays at a radiation dose around 400 times lower than the standard dose in current machines.
The team replaced the scintillators of commercial flat-panel X-ray imagers with their new nanocrystal-based detector to test their performance, and reported impressive results.
"Our experiments showed that using this approach, X-ray images can be directly recorded using low-cost, widely available digital cameras, or even using cameras of mobile phones," says Dr Chen Qiushui, a Research Fellow with the National University of Singapore (NUS) Department of Chemistry and the first author of the study. "This was not achievable using conventional bulky scintillators. In addition, we have also demonstrated that the nanocrystal scintillators can be used to examine the internal structures of electronic circuit boards. This offers a cheaper and highly sensitive alternative to current technology."
In addition to medical imaging, X-rays are also used in security, advanced manufacturing, nuclear technology, and environmental monitoring, so the team believes the new nanocrystals hold promise for a variety of applications. A patent for the technology has been filed and the team is looking for partners to help commercialize it, but in the meantime further testing will be undertaken on the performance of the nanocrystals over longer time periods, and at different temperature and humidity levels.
The study from the international team, made up of researchers from Australia, China, Hong Kong, Italy, Saudi Arabia, Singapore and the United States, was published in the online edition of Nature.
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