DEXA scan 


DEXA scans measure bone density and can be used to detect bone-related conditions such as osteoporosis 

A DEXA scan is a special type of X-ray that measures bone density. DEXA stands for dual energy X-ray absorptiometry.

DEXA scans, also known as bone density scans or bone densitometry scans, are often used to diagnose osteoporosis (where the bones become weak and fragile and more likely to break).

They can also be used to assess the risk of osteoporosis developing in women above 50 years of age and in men who are 60-65 years age.

A DEXA scan can also help detect other bone-related conditions, such as osteomalacia (softening of the bones caused by a vitamin D deficiency). In children, osteomalacia is known as rickets.

As well as being quick and painless, a DEXA scan is more effective than normal X-rays in identifying low bone density.


If you're over 50 years of age, you may need to have a DEXA scan if you're at risk of developing osteoporosis. People below the age of 50 may need a DEXA scan if there are other risk factors.

Osteoporosis can affect people of both sexes and all ages, although older, post-menopausal women are particularly at risk. This is because after the menopause the level of the hormone oestrogen decreases, resulting in a decrease in bone density.

The denser your bones, the stronger and less likely they are to fracture (break). Osteoporosis doesn't cause any symptoms until a bone is broken. In the past it was difficult to measure bone density and identify those at risk of developing osteoporosis until a fracture occurred.

However, by using bone densitometry techniques, such as DEXA scans, it's now possible to measure bone density before fractures occur.

Read more about when DEXA scans are used.

Measuring bone density

During a DEXA scan, X-rays will be passed through your body. Some radiation will be absorbed by the bone and soft tissue and some will travel through your body.

Special detectors in the DEXA scanner measure how much radiation passes through your bones and this information is sent to a computer.

The measurements will be compared to the normal range for bone density in a healthy adult and someone of the same gender and ethnicity, equal to or above 30 years of age.

Read more about how DEXA scans are carried out.


DEXA scans use a much lower level of radiation than standard X-rays, which means that the radiographer (the specialist carrying out the scan) will be able to stay in the scanning room with you during the scan. 

The amount of radiation used during a DEXA scan is equivalent to less than two days' exposure to natural background radiation. By comparison, a chest X-ray uses the equivalent of about five days' exposure to natural background radiation.

Despite being very safe procedures, DEXA scans and X-rays aren't recommended for pregnant women because X-rays can cause damage to an unborn child.

Read more about your health during pregnancy.

Page last reviewed: 19/03/2014

Next review due: 19/03/2016


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Bone is a hard, dense tissue that shows up clearly on X-rays, making them very useful for diagnosing bone-related problems