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Central DXA can also provide whole-body imaging for total and regional BMD a, body composition (lean muscle and fat mass) and VFA. Osteoporosis can be diagnosed if the value of BMD a is 2.5 or more standard deviations (SD) below the mean value of a young reference population (T score at or below −2.5). Interpretation of BMD a measurements is based on the World Health Organisation (WHO) recommendations. In clinical practice, ‘areal’ bone mineral density (BMD a g/cm 2) assessment of lumbar spine (L1–L4), proximal femur (femoral neck and total hip) and forearm (distal) is made by central DXA. Dual-energy X-ray absorptiometry (DXA)ĭXA technology has evolved from pencil beam to fan beam, allowing short acquisition time and improved image quality. Although the sensitivity of VFA was found to be less than that of radiography, in certain circumstances results support the use of VFA for the detection of prevalent vertebral fracture. A recent study evaluated the utility of VFA to detect vertebral fractures. Vertebral fracture assessment (VFA) developed by DXA manufacturers provides information on the vertebral body heights and their ratios and the patient’s fracture status is given. The method for identification of vertebral fractures using computational techniques has also been applied to spine images acquired by dual-energy X-ray absorptiometry (DXA). The assessment of vertebral fractures is possible using visual, morphometric and semiquantitative methods. Vertebral fractures on radiographs are not always reported and remain under-diagnosed radiologically with false negative rates up to 45%. Spinal radiography is the most widely used imaging method for identification of vertebral fractures. The objective of this article was to briefly review the current X-ray methods used for the assessment of the skeleton, provide data that document the magnitude of radiation exposure and discuss radiation safety issues.
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Although the ionising radiation doses incurred during X-ray-based imaging techniques used in osteoporosis are relatively low, the use of radiological methods for the assessment of bone status has increased rapidly, and therefore merits attention with regard to radiation protection. Ī wide variety of methods for the non-invasive assessment of skeletal status have been developed, most of which are based on the use of ionising radiation. The total number of hip fractures in the European Union is estimated to increase from 414,000 in 2000 to 972,000 in 2050. Studies show that the number of osteoporotic fractures is increasing worldwide mainly due to the extension of the average lifespan. The most common low-energy fractures are those of the vertebrae, wrist and hip. Osteoporotic fractures usually occur in skeletal sites that are rich in trabecular bone. The importance of osteoporosis lies in the fact that osteoporotic bones are more fragile and susceptible to fracture than normal bones. Although the condition affects a higher percentage of women, it is now known that substantial bone loss occurs with advancing age in men. Osteoporosis is a systemic disorder of the skeleton that is characterised by a reduction in bone mass and deterioration of bone micro-architecture. Low-dose protocols are needed to reduce radiation exposure from these methods and minimise associated health risks. New 3D volumetric hip and spine quantitative computed tomography (QCT) techniques and high-resolution MDCT for evaluation of bone structure deliver doses to patients from 1 to 3 mSv. Methods based on multi-detector CT (MDCT) are associated with higher radiation doses. Dose optimisation is more important for paediatric examinations because children are more vulnerable to radiation than adults. When an examination is justified, the emphasis must be on dose optimisation of imaging protocols. However, as with any X-ray imaging technique, each particular examination must always be clinically justified. Radiation doses associated with dual-energy X-ray absorptiometry are very low. This article provides (a) a brief review of the current X-ray methods used for quantitative assessment of the skeleton, (b) data on the levels of radiation exposure associated with these methods and (c) information about radiation safety issues. Recent advances in medical X-ray imaging have enabled the development of new techniques capable of assessing not only bone quantity but also structure.