DXA provides precise measurement of bone density, lean tissue mass, and total regional body fat. It is currently the gold standard in body composition assessment. This test is non-invasive, painless, and completed in approximately 15 minutes. The DXA in the HNRU is a General Electric LUNAR Prodigy High Speed Digital Fan Beam X-Ray-Based Bone Densitometer. The DXA uses very low dose x-rays or two different levels to distinguish between bone and soft tissue. The amount of radiation an individual is exposed to during a DXA scan is equivalent to that of a cross country flight.