Researchers at the Paul Scherrer Institute (PSI) and the EPFL in Switzerland have developed a novel method for producing dark-field x-ray images at wavelengths used in typical medical and industrial imaging equipment.
Dark-field images provide more detail than ordinary x-ray radiographs and could be used to diagnose the onset of osteoporosis, breast cancer or Alzheimer's disease, to identify explosives in hand luggage, or to pinpoint hairline cracks or corrosion in functional structures.
Up until this point, dark-field x-ray imaging required sophisticated optics and could only be produced at facilities like the PSI's 300m-diameter, $200 million synchrotron. With the new nanostructured gratings described in this research, published online January 20 in Nature Materials, dark-field images could soon be produced using ordinary x-ray equipment already in place in hospitals and airports around the world.
Unlike traditional x-ray images, which show a simple absorption contrast, dark-field images capture the scattering of the radiation within the material itself, exposing subtle inner changes in bone, soft tissue, or alloys. The overall clarity of the images is striking. The improved sensitivity in measuring bone density and hairline fractures could help diagnose the onset of osteoporosis. Because cancer or plaque cells scatter radiation slightly differently than normal cells, dark-field x-ray images can also be used to explore soft tissue, providing safer early diagnosis of breast cancer or the plaques associated with Alzheimer's disease.
Security screening equipment equipped with dark-field image capability could better identify explosives, whose micro-crystalline structures strongly scatter x-ray radiation. And because x-rays penetrate a material without damaging it, dark-field images could help reveal scattering-producing micro-cracks and corrosion in structures such as airplane wings or the hulls of boats.