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The early and reliable detection of breast cancer is often difficult with conventional mammography, especially within dense breast parenchyma. An alternative approach using x-rays are phase-sensitive imaging techniques, which are able to visualize the borders of tissues with different refraction indices with very high contrast. These phase contrast imaging techniques can generate projection images with much less glandular dose than conventional mammography. Even the acquisition of phase contrast CT data sets with an acceptable exposure dose is possible. As brilliant x-ray beams are required for phase contrast imaging, which up to now were only available at synchrotron facilities, these methods were restricted to only a few laboratories. However, with the advent of newly developed high intensity lasers which are also able to produce such radiation, a widespread and affordable use of this technique seems realistic. The further development of phase contrast imaging is funded by the excellence cluster MAP of the Munich universities.

This article is an introduction to dual X-ray absorptiometry (DXA), the most widely used method today for diagnosis of osteoporosis. DXA can be used to assess projective bone mineral density at the lumbar spine, the proximal hip, and the whole body as well as the skeletal periphery at the forearm, the hand, and the heel. The prominent area of application of DXA is the diagnosis and monitoring of osteoporosis and its treatment. Because of its high accuracy, precision, and ability to predict osteoporotic fracture as well as its relatively low cost, DXA has prevailed over alternative methods. This article discusses the underlying X-ray physics and technological aspects, acquisition protocols, quality characteristics, and sources of error and their relevance. It also describes the various skeletal regions accessible to measurement, details on precision, nominal results, usability to predict fracture risk, and results of influential clinical trials.