A DEXA scan, which stands for dual energy x-ray absorptiometry, is a type of diagnostic imaging that is used to measure bone mineral density and to calculate bone loss. DEXA scans are the preferred technique for diagnosing osteoporosis, tracking the effectiveness of preventative treatment, and predicting fractures. They are typically performed on the spine and hips.   A DEXA machine uses two separate x-ray beams, each set to different energy levels, to evaluate bone density based on the amount of x-rays that pass through the bone. The procedure is painless, takes only around 10-30 minutes, and involves a minimal amount of radiation exposure.