DEXA scan

Also called dual energy X-ray absorptiometry scan

A DEXA (dual energy X-ray absorptiometry) scan is used to check the strength of your bones, by using X-ray equipment and a computer to measure bone density.

Generally, the more dense the bone, with less air spaces, the stronger it is, and the less likely it is to break or fracture. 

When is a DEXA scan performed?

Your doctor may request a DEXA scan if you are at increased risk of thinning of the bone or osteoporosis. The results of the scan help to estimate your risk of fractures in different bones, for example hip, wrist or bones of the spine and the scan can also show how well treatment for osteoporosis is working. 

How is a DEXA scan performed?

The DEXA scan is performed using X-ray equipment and a computer. The scanner sends a thin, invisible beam of low-dose x-ray that passes over the body and the computer calculates the density of density of bone. 

  • The scan usually takes between 10 and 20 minutes, depending on which part of your body is being examined.
  • You must hold very still and may be asked to keep from breathing for a few seconds while the x-ray picture is taken to reduce the possibility of a blurred image.
  • The technologist will walk behind a wall or into the next room to activate the x-ray machine.
  • Having the scan is a quick, painless procedure and you'll be able to go home after you've had it done.

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How to prepare for a DEXA scan?

  • On the day of the exam you can eat normally. You should not take calcium supplements for at least 24 hours before your exam.
  • Wear loose, comfortable clothing, avoiding garments that have zippers, belts or buttons made of metal. 
  • You may be asked to remove some or all of your clothes and to wear a gown during the exam. Objects such as keys or wallets that would be in the area being scanned should be removed. You may also be asked to remove jewellery, removable dental appliances, eye glasses and any metal objects or clothing that might interfere with the x-ray images. 

Recent scans or pregnancy?

  • Tell your doctor if you recently had a barium examination or have been injected with a contrast material for a computed tomography (CT) scan or any other type of scan. You may have to wait 10 to 14 days before undergoing a DEXA scan.
  • Women should always let your doctor know if there is any possibility that they are pregnant. Many imaging tests are not performed during pregnancy so as not to expose the foetus to radiation. If an x-ray is necessary, precautions will be taken to minimise radiation exposure to the baby. 

Learn more

DEXA scan Patient Info, UK

References

DEXA (DXA) scan - how it is performed NHS Choices
Prevention of osteoporosis BPAC 2008