London, January 21 : Swiss researchers have devised a novel technique to produce dark-field x-ray images at wavelengths used in typical medical and industrial imaging equipment.
Dark-field images, which provide more detail than ordinary x-ray radiographs, could be used to diagnose the onset of osteoporosis, breast cancer or Alzheimer's disease. They might also help identify explosives in hand luggage, or pinpoint hairline cracks or corrosion in functional structures.
Researchers at the Paul Scherrer Institute (PSI) and the EPFL said that their technique could facilitate the production of dark-field images from ordinary x-ray equipment, already in place in hospitals and airports around the world.
This development attains significance as dark-field x-ray imaging, so far, required sophisticated optics and could only be produced at facilities like the PSI's 300m-diameter, 200 million dollars synchrotron.
As compared to traditional x-ray images that show a simple absorption contrast, dark-field images capture the scattering of radiation within the material itself, and, thereby, expose subtle inner changes in bone, soft tissue, or alloys.
The researchers said that the improved sensitivity in measuring bone density and hairline fractures might be helpful in diagnosing the onset of osteoporosis.
The dark-field x-ray imaging might also make for an early diagnosis of breast cancer and the plaques associated with Alzheimer's disease by equipping medical practitioners the ability to explore soft tissue.
Installing security screening equipment equipped with dark-field image capability might improve the detection of explosives, whose micro-crystalline structures strongly scatter x-ray radiation, said the researchers.
Since x-rays do not damage a material while penetrating it, dark-field images might expose scattering-producing micro-cracks and corrosion in structures like airplane wings and the hulls of boats, they added.
"Researchers have been working on dark-field x-ray images for many years. Up until now these images have only been possible using sophisticated crystal optical elements," Nature Materials quoted Franz Pfeiffer, a professor at EPFL and researcher at the PSI, as saying.
However, crystal optics only work for a single x-ray wavelength, and, thus, are highly inefficient.
"Our new technique uses novel x-ray optical components, in the form of nanostructured gratings, that permit the use of a broad energy spectrum, including the standard range of energies in traditional x-ray equipment used in hospitals or airports," said Christian David, Pfeiffer's colleague at PSI.
"This opens up the possibility for adapting current imaging equipment to include dark-field imaging," David added.
Pfeiffer is now looking forward to working with the Center for
Biomedical Imaging (CIBM), a joint centre with the Universities of
Lausanne and Geneva, to develop an adaptation for existing medical
equipment. When combined with the phase contrast imaging technique
that we developed in 2006, we now have the possibility of providing
the same range of imaging techniques in broad-spectrum x-ray
imaging that we do with visible light," Pfeiffer said.