Dual Energy X-Ray Absorptiometry (DEXA) is a test that uses x-rays to measure the thickness of the bones in the hip, spine, wrist, heel, finger, and whole body. A DEXA scan is a screening test for osteoporosis. The scan of the whole body, spine, and hip takes about 30 minutes. The DEXA takes images while you lay comfortably on the scanner bed. DEXA scanning is not done if you weigh more than 297 lbs, the weight limit for the scanner bed. A DEXA scan of the spine or hip is not done if you have had reconstructive or replacement surgery.