What is a DXA Scan?
DXA stands for Dual Energy X-Ray Absorptiometry .
The X-ray beam contains two distinct energy peaks. One is absorbed by soft tissues and the other by the bone. By subtracting one reading from the other a figure is produced which represents the bone mineral density. There are two scores produced:-
- The T-Score compares your reading with that of healthy bones in people aged approximately 30 (peak density) . If the reading is above -1 then no action is usually taken. A reading of between -1 and -2.5 is classed as Osteopenia. This indicates a bone density between normal and Osteoporosis. You may be recommended treatment. A reading of -2.5 or greater means you are classified as having Osteoporosis.
- The Z-Score compares your reading with healthy bones in your age group.
A repeat scan can be recommended in 2-3 years. This will tell your doctor the rate of loss of bone or, if you are on treatment, it will give some indication of whether the treatment is being effective.
What do I have to do?
You will have to lie on the X-Ray couch for about 5 - 10 minutes. Normally the lumbar spine and one hip are scanned each taking about 2 minutes.You have to keep still while a small arm moves above you.
What should I wear?
Please wear comfortable clothing with no metal round the waist and hip areas. Trousers or skirts with elasticated waistbands are fine but please avoid wearing jeans. Dresses are fine as long as they do not have a zip down the back. You can wear a bra but not underwired. Try and avoid shirts or blouses with buttons and jeans or trousers with studs on them. Belly button bars will have to be removed. If you follow the above advice you will not need to get undressed for the examination.
What is the radiation dose?
It is an extremely low dose examination.
Each area is about one tenth of a standard chest X-Ray. Usually 2 sites are scanned.
How long will it take?
The whole examination should take about 10-15 minutes.
Who gets the results?
The information will be interpreted by the computer and the printout commented on by a specialist. You will be told the results at the end of the scan plus a report will be sent to the medical practitioner who referred you and/or your GP.
Is there anything I should do before I come?
No, but if you have recently had:-
a) a Barium study or CT scan with contrast
b) been injected with a contrast agent for an X-Ray or
c) had a radioisotope scan
then please let us know as you may have to wait up to 14 days before you have your scan.
If there is any chance that you might be pregnant you must inform the Radiographer prior to your scan.