<prompt> Gold standard for diagnosis of osteoporosis-DEXASingle beam densitometryQuantitative computed tomographyBone histomorphometry  <response>: Gold standard for diagnosis of osteoporosis is DEXA scan. DEXA SCAN Commercially introduced in 1987. Principle - 2 x ray of 70Kv and 140kv are fired on site of measurement with lag time of 4ms. Detector detects accentuation of 2 beams. Data is fed into computer powered with complex algorithm and calculates BMD. SITES- Central dexa- lumbar spine, hip, whole body. Peripheral dexa- forearm , calcaneum. CONTRAINDICATIONS- PREGNANCY. RECENT ADMINISTRATION OF CONTRAST. AGENT,NUCLEAR MEDICINE SCAN. RADIOPAQUE IMPLANT IN MEASUREMENT AREA. MARKED OBESITY ref : maheswari 9th ed 