"speed of sound (SOS): measures velocity in the bone"
"gamma rays (gamma decay): replaced by radiographic methods"
Expected headings
"Bone mineral density measurement"
"single-energy photon absorptiometry (SPA) was superseded by the introduction of single x-ray absorptiometry; both methods measure density at peripheral sites in the skeleton (e.g. distal radius, calcaneus), but the disadvantage is that it cannot measure trabecular and cortical bone separately"