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Topic Name: Researchers have Developed a Novel Method for Producing Dark-Field X-Ray Images for Typical Medical and Industrial Imaging Equipment

Category: Optical imaging

Research persons: Franz Pfeiffer

Location: Ecole Polytechnique Fédérale de Lausanne, Switzerland

Details

Researchers at the Paul Scherrer Institute (PSI) and the Ecole Polytechnique Fédérale de Lausanne 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.

“Researchers have been working on dark-field x-ray images for many years,” explains Franz Pfeiffer, a professor at EPFL and researcher at the PSI. “Up until now these images have only been possible using sophisticated crystal optical elements.” Crystal optics, however, 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,” adds Christian David, Pfeiffer’s colleague at PSI. “This opens up the possibility for adapting current imaging equipment to include dark-field imaging.”

Pfeiffer plans to collaborate with the Center for Biomedical Imaging (CIBM), a joint center with the University of Lausanne and University of Geneva and their associated hospitals, 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.”

Note for Osteoporosis
Osteoporosis is a disease of bone leading to an increased risk of fracture. In osteoporosis the bone mineral density (BMD) is reduced, bone microarchitecture is disrupted, and the amount and variety of non-collagenous proteins in bone is altered. Osteoporosis is defined by the World Health Organization (WHO) in women as a bone mineral density 2.5 standard deviations below peak bone mass (20-year-old sex-matched healthy person average) as measured by DXA; the term "established osteoporosis" includes the presence of a fragility fracture. Osteoporosis is most common in women after the menopause, when it is called postmenopausal osteoporosis, but may develop in men and premenopausal women in the presence of particular hormonal disorders and other chronic diseases or as a result of smoking and medications, specifically glucocorticoids, when the disease is called steroid- or glucocorticoid-induced osteoporosis (SIOP or GIOP).
Osteoporosis can be prevented with lifestyle advice and medication, and preventing falls in people with known or suspected osteoporosis is an established way to prevent fractures. Osteoporosis can be treated with bisphosphonates and various other medical treatments.

Note for Alzheimer's disease
Alzheimer's disease (AD), also called Alzheimer disease, and simply known as Alzheimer's, is a neurodegenerative disease that, in its most common form, is found in people over the age of 65. Approximately 24 million people worldwide have dementia of which the majority (~60%) is due to Alzheimer's.
Clinical signs of Alzheimer's disease are characterized by progressive cognitive deterioration, together with declining activities of daily living and by neuropsychiatric symptoms or behavioral changes. Plaques which contain misfolded peptides called amyloid beta (Aβ) are formed in the brain many years before the clinical signs of Alzheimer's are observed. Together, these plaques and neurofibrillary tangles form the pathological hallmarks of the disease. These features can only be discovered at autopsy and help to confirm the clinical diagnosis. Medications can help reduce the symptoms of the disease, but they cannot change the course of the underlying pathology.
The ultimate cause of Alzheimer's is unknown. Genetic factors are clearly indicated as dominant mutations in three different genes that account for the small number of cases of familial, early-onset AD have been identified. For the more common form of late onset AD, ApoE is the only clearly established susceptibility gene. All four genes can contain mutations or variants that confer increased risk for AD, but account for only 30% of the genetic picture of AD. These four genes have in common the fact that mutations in each lead to the excessive accumulation in the brain of Aβ, the main component of the senile plaques that litter the brains of AD patients.

In figure 1, Traditional absorption image of chicken wing

In figure 2, Dark-field image of chicken wing