How does DEXA work?
DEXA passes X-rays of 2 different energies through the tissues of the body. These energies are blocked or attenuated, relative to the density of the tissues they are penetrating. The characteristic densities of bone, fat, and lean tissue are then used to calculate the relative masses of each in any given region.
How long does a scan take?
The actual scan takes about 3 minutes to complete. While lying on the padded bed surface, the scanner arm makes a series of 3 passes over your body. There is no discomfort at all.
What should I wear?
All metal objects such as keys and wallets from the pockets as well as belt buckles and shoes need to be removed. Metal bra clips do not need to be removed. Ideally, wear clothing without metal zips or studs.
Is it safe?
Yes. Even though there is a very small amount of radiation present, DEXA scans are one of the lowest radiation dose tests. One whole body scan gives a radiation dose of 0.2 uSv to the person being scanned. The average daily background radiation exposure dose is 6.3 uSv per day (in Australia). So, a DEXA whole body scan equates to an extra 2.5 hours of natural background radiation exposure. In comparison, a chest XR dose is 20 uSv, a lumbar spine XR dose is 700 uSv, and a CT chest is 8000 uSv.
How often should I be scanned?
It depends. For those actively trying to lose fat, a minimum timeframe of 4 weeks is recommended. 4-12 weekly is ideal. For those who are happy with their results, it may be a case of having a scan only 1-2 times per year to make sure fat and lean tissue levels are being maintained.
Can I be scanned if I am pregnant?
No. Please make sure this is not a realistic possibility at the time of the scan. Although there is no evidence that a scan will harm the baby, it is not recommended to proceed if there is any possibility of being pregnant. A home pregnancy test is recommended if there is any doubt.
Can children be scanned?
Generally the answer is no to those under 16 years. However, individual cases may be considered after discussion with the doctor.