Bone Densitometry uses low-dose X-ray (and sometimes ultrasound) to accurately measure the density of bone.  The devices are used primarily to detect osteopenia or osteoporosis, diseases where the bone's mineral density are low and the risk of fractures is increased. Bone Densitometers can also be used for Fracture Risk Assessment (IVA), and to very accurately measure Body Fat Composition (Lean Mass vs. Body Fat).