Dual-energy X-ray absorptiometry, also known by the acronym DEXA SCAN, is a diagnostic technique based on the direct examination of bone tissue using gamma rays emitted by a radioactive source; it allows to measure the degree of bone mineralization, expressing it as the quantity of calcium in grams per unit of volume of bone tissue. Aborptiometry is used in the study of phosphorus and calcium metabolism and, in particular, in the diagnosis of conditions characterized by loss of bone minerals such as osteoporosis and osteomalacia.

The test can also be performed with ultrasound equipment, the result with this technique is however less reliable.