DXA: 30years and counting: Introduction to the 30th anniversary issue.

Dual-energy X-ray absorptiometry (DXA) has a colorful history of development and evolution over the past 30years, from early predecessors that were cumbersome and limited in their clinical applications to current elegant instruments with a wide range of uses. DXA is used to diagnose osteoporosis, assess fracture risk, and monitor changes in bone mineral density (BMD). Non-BMD applications include vertebral fracture assessment, measurement of hip geometry, measurement of whole body tissue mass (i.e., bone, fat, and lean mass), abdominal aortic calcification detection and trabecular bone score measurement. This is an introduction to a special issue of this journal devoted to the celebration of the innovators in this field, the progress that has been made, and the challenges that remain.