Bone Mineral Density

DEXA Scan, Dual Photon Absorptiometry (Bone Mineral Denistry)

How It Is Done

A bone mineral density scan is usually done in the special radiology department or clinic by a technologist. Peripheral dual-energy X-ray absorptiometry (P-DEXA) machines are portable units that can be used in a doctor's office.

You will need to lie on your back on a padded table. You can usually leave your clothes on. You may need to lie with your legs straight or with your lower legs resting on a platform built into the table.

The machine will scan your bones and measure the amount of radiation they absorb. The DEXA technique, which scans the hip and lower spine, takes about 20 minutes to perform. Other techniques may take 30 to 45 minutes.

Portable machines (P-DEXA) can measure bone density in the wrist or forearm. Ultrasound measurements are usually taken in the heel. For these measurements, you may be able to sit in a chair during the test.

Testing at least two different bones (preferably the hip and spine) each time is the most reliable way of measuring BMD. It is best to test the same bones and to use the same measurement technique and BMD equipment each time.

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Author:	Shannon Erstad, MBA/MPH	Last Updated: September 23, 2008
Medical Review:	Anne C. Poinier, MD - Internal Medicine Carla J. Herman, MD, MPH - Geriatrics
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