Bone mineral density test

A technique for measuring bone density through evaluating the mineral content of bones, above all calcium. Bone density increases up until the age of 40 and then diminishes. A low density (osteoporosis) is an indicator of a risk of incurring fractures. To measure it, a photon source is directed at the bone, which absorbs a part of it and then the outgoing flow is measured. The denser the bone the more it absorbs the photons.