Bone density or DEXA scans

This information sheet from Great Ormond Street Hospital (GOSH) tells you about bone density or DEXA scans and why you might need one.A DEXA scan is used to measure how dense or strong your bones are. DEXA stands for Dual Emission or Energy X-ray Absorptiometry. It works by aiming two x-ray beams at your bone, which are either absorbed or pass through. The stronger your bone, the fewer x-rays can pass through it. A computer records the x-rays and then works out how strong your bone is.

Someone might need a DEXA scan if they are taking medicine that weakens their bones, have a medical condition that affects their bone strength or they have broken a bone easily in the past. Your doctor will explain why a DEXA scan might be a good idea for you.

What happens?

The scanning staff will measure how tall you are and how much you weigh before the scan. They’ll ask you some questions and if you’re a girl aged 12 years or older, they’ll ask you about your periods and whether there is any chance you could be pregnant. This is important as the x-rays used in the scan could harm an unborn baby.

After all the questions, you’ll lie flat on the scanning bed. You don’t need to get undressed but it helps not to wear clothes with too much metal, such as zips or buttons – a pair of tracksuit bottoms and a t-shirt will be fine.

When you’re lying still, the scanner arm will move over your body but it won’t touch you. This only lasts a minute of two. You’ll need to lie very still but you won’t have to hold your breath. Afterwards, you can get up off the scanning bed and go home if you don’t have any other appointments. The radiologist will write a report of the scan – if you have a clinic appointment after the scan, they may give you a copy to take with you. Otherwise, they’ll send the report to your doctor.

Will it hurt?

No – the scanner arm won’t touch you at all during the scan and you’ll only need to keep still for a few minutes.

Last reviewed: February 2016

Compiled by:
the Radiology department in collaboration with the Child and Family Information Group