A dual energy X-ray absorptimetry (DEXA) scan measures how dense your bones are and what your risk is of broken bones due to osteoporosis. A DEXA scan is the most accurate test of bone density available. It's most often used to measure the density of the bones at your hip or spine, where fractures are most likely from osteoporosis.

A bone density scan is painless, uses low levels of radiation and only takes about 10 minutes.

Before the bone density scan, remove jewelry or any clothing that has metal on it such as zippers or buckles. If you have recently had any nuclear medicine tests that involved having an injection of radioactive tracers, be sure to tell your doctor and the technician. Radioactive tracers may interfere with your bone density test.

If you are or think you might be pregnant, tell your doctor. Because the bone density test uses radiation - though at low levels - it could possibly cause pregnancy complications.

During the DEXA scan, you will lie on a padded table while an imager - a mechanical arm-like device - passes over your body. The imager emits radiation, although you only receive about one-tenth of the amount that you would during a chest X-ray.

The results of a bone density test are reported as:

• A T-score, which is your bone density compared to what is normally expected in a healthy young adult of your gender. A healthy young adult generally has the best possible bone density.
• A Z-score, which compares your bone density to what's normally expected for someone of your age, gender, weight and ethnic or racial origin. This helps pinpoint whether factors other than aging are causing your bone loss.