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What is a Bone Density Scan (DXA)?

Bone density scanning, also called dual-energy x-ray absorptiometry (DXA) or bone densitometry, is an enhanced form of x-ray technology that is used to measure bone mineral content. DXA is today's established standard for measuring bone mineral density (BMD).

DXA is most often performed on the lower spine and hips. DXA is used to diagnose osteoporosis, a condition that often affects women after menopause but may also be found in men. Osteoporosis involves a gradual loss of calcium, as well as structural changes, causing the bones to become thinner, more fragile and more likely to break.  DXA is also effective in tracking the effects of treatment for osteoporosis and other conditions that cause bone loss.

How should I prepare?

This examination is done on an outpatient basis, and an appointment is necessary. Please arrive 15 minutes prior to your appointment to register. If you are late for your appointment you will be rebooked.

You must bring a valid health card and requisition.

You should not take calcium supplements for at least 24 hours before your exam. Please call ahead if you recently had a barium examination or have been injected with a contrast material for a computed tomography (CT) scan or radioisotope scan. You may have to wait 10 to 14 days before undergoing the DXA test.

You should wear loose, comfortable clothing, avoiding garments that have zippers, belts or buttons made of metal. Objects such as keys or wallets that would be in the area being scanned should be removed.  You may be asked to remove some or all of your clothes and to wear a gown during the exam. You may also be asked to remove jewelry, eye glasses and any metal objects or clothing that might interfere with the x-ray images.

Women should always inform the x-ray technologist if there is any possibility that they are pregnant. Many imaging tests are avoided during pregnancy so as not to expose the fetus to radiation. If an x-ray is necessary, precautions will be taken to minimize radiation exposure to the baby.

How is the procedure performed?

The technologist, an individual specially trained to perform radiology examinations, will bring the patient into the room, verify the information, obtain a brief history, and perform the examination.  The patient will be asked to lie on a padded table. To assess the spine, the patient's legs are supported on a padded box to flatten the pelvis and lower (lumbar) spine. To assess the hip, the patient's foot is placed in a brace that rotates the hip inward. In both cases, the detector is slowly passed over the area, generating images on a computer monitor. On occasion, images are obtained of the forearm.

You must hold very still while the picture is taken to reduce the possibility of a blurred image. The DXA bone density test is usually completed within 10 to 30 minutes.

A radiologist, a physician specifically trained to supervise and interpret radiology examinations, will analyze the images and send a signed report to your referring physician, who will discuss the results with you.  The DXA test will provide an individual’s10 year risk for developing fractures. The risk of fracture is affected not only by the bone density, but by other factors such as age, body weight, history of prior fracture, and steroid use.