Bone density scan (DEXA, DXA)

DEXA scan stands for dual energy x-ray absorptiometry. It’s also called a bone densitometry scan.

It uses low dose x-rays to take measurements to work out the strength (density) of your bones.

You have a DEXA scan in the x-ray (radiology) or nuclear medicine department of the hospital. A ​radiographer​ or a specially trained technician usually does the scan. It takes about 10 to 20 minutes.

For this test you’re not enclosed in a small place as the machine has an arm that hangs over the scanning couch.

Why might you have a DEXA scan?

You might have this scan if you’re having or have had cancer treatment that can cause your bones to get thinner and weaker. This makes them more at risk of breaking (fracturing). This is known as osteoporosis.

For example, women diagnosed with breast cancer may start a hormonal treatment called an ​aromatase inhibitor​ . The side effects of this type of drug includes an increased risk of developing osteoporosis later on.  

Your doctor might use an assessment tool to work out your risk of osteoporosis. The tool looks at a number of different factors including, your age, history of fractures and bone density. It also looks at other conditions you may have, such as ​rheumatoid arthritis​ or type 1 diabetes.

Your bone density scan results will help your doctors decide whether you need bone strengthening treatment. 

To find out more about bone loss, click on the links below.

Bone loss in women

• Bone loss in men

Preparing for your DEXA scan

There is no special preparation for a DEXA scan. You can eat and drink normally beforehand and take any medicines as normal.

You might need to fill out a questionnaire beforehand. You're either sent it to fill in at home or they might ask you to fill it in when you arrive in the department for your scan. Some of the questions include:

• Are you still having periods?

• Are you on treatment to strengthen your bones?

• Are you on medication that might thin your bones such as steroids?

• Do you smoke?

• Do you drink alcohol?

If you are pregnant or think you may be pregnant you should tell the department before your appointment. X-rays from a DEXA scan could affect your developing baby.

What happens during a DEXA scan?

Before the test

When you arrive the radiographer will measure your height and weight. This is put into the computer to accurately calculate your bone density. 

The radiographer might ask you to change into a hospital gown, but you can usually have this scan in your own clothes. They’ll also ask you to remove any metal objects on your clothes like zips, belts, clasps, bras and piercings.

During the test

You usually lie on the scanning couch on your back. The radiographer will help you get onto the couch and into the right position.

The radiographer then lines the machine up to make sure it's in the right place. You must keep very still while you are having the scan. Let them know if this will be a problem.

The radiographer is usually in the room for this scan, so you won’t be alone. 

The DEXA scan takes x-rays. These are painless so you won’t feel anything.

When everything is ready, and you are comfortable, the radiographer starts the scan. It usually passes over your hips and the lower part of your spine. They may also scan your forearm. 

After the test

After the DEXA scan you can get dressed and go home or back to work.

Possible risks

The amount of radiation you receive from a DEXA scan is small and the risk of this radiation causing any problems in the future is very low. Your doctor will make sure the benefits of having the scan outweigh any risk there may be from radiation.

Talk to your doctor if you're worried about the possible effects of having a DEXA scan.

Getting your results after a DEXA scan

You should get your DEXA scan results within 1 or 2 weeks.

Ask your doctor, radiographer or nurse how long it will take to get them. Contact the doctor who arranged the test if you haven’t heard anything after a couple of weeks.

Waiting for test results can be a worrying time. You might have contact details for a specialist nurse. You can get in touch with them for information and support if you need to. It may help to talk to a close friend or relative about how you feel.