Bone Densitometry - DEXA Scan
A DEXA scan is a special type of X-ray that measures bone density. DEXA stands for dual energy X-ray absorptiometry. 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. A DEXA scan is a quick and painless bone scan and is more effective than a normal X-ray in identifying low bone density. It also uses a much lower level of radiations than a standard X-ray.
What are the benefits of bone densitometry (DEXA) scanning?
Scanning for osteoporosis is the only way to find out if you have osteoporosis or if you are likely to develop it. Steps can then be taken to help prevent its development. Osteoporosis usually has no symptoms – the first sign is often a break or fracture. You should be scanned if you are at risk of osteoporosis.
You have a greater risk of developing osteoporosis if you:
- Have already suffered a break or fracture resulting from a minor bump, strain or fall
- Are over 50
- Have gone through early menopause (before the age of 45)
- Have had your ovaries removed (before the age of 45)
- Have a history of missed periods
- Are on long-term corticosteroid medication
- Have a family history of osteoporosis or fractures
- Have low levels of calcium and vitamin
- Have digestive disorders that affect nutrient absorption
Who should not have the test?
You should not have the test if you are pregnant or think you are pregnant. Also if you have had another x-ray with contrast media in the last 7 days (some examples: barium enema, upper GI , some CAT scans] or if you have had a nuclear scan (including bone scan and thyroid study) in the last 7 days, you should not have this test.
How to prepare for the test
This is a non-invasive test and requires very little preparation. If you are taking calcium supplements, stop taking them for 48 hours before your test. If you are taking any medications for osteopenia or osteoporosis, do not take them the day of your test. You can eat and drink normally on the day of the test.
The DEXA machine is used to scan the bones in your lower back and hip, and sometimes your forearm. These are the bones most prone to fracture if you have osteoporosis. The scan will measure the density of bone and tissue separately.
You will be asked to lie flat on a couch and stay still while the different parts of your body are scanned. The procedure is painless and takes around 20 minutes.
The information from the scanner is sent to a computer to be processed and you will be given a T-Score, which compares your bone density to that of healthy bones.
The following can help build healthy bones:
- Eating calcium-rich foods including dairy products and green, leafy vegetables
- Getting enough vitamin D in your diet, which is essential for absorbing calcium. Vitamin D is found in foods such as milk, eggs and oily fish
- Bone-building exercise such as jogging, aerobics, tennis, dancing, brisk walking and weight lifting, and low-impact exercise such as swimming, gardening, walking or playing golf
- Avoiding smoking as this can reduce your bone density
- Avoiding drinking alcohol as this damages our skeleton and increases the risk of fracture
- Avoiding drinking too much caffeine as this may affect the balance of calcium in the body
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