Bone density scan
A bone density scan is an imaging test that uses x-rays to measure how strong your bones are. It is also called a bone densitometry or dual energy x-ray absorptiometry (DXA) scan.
Why a bone density scan is done
A bone density scan may be done to:
- measure the amount of minerals, such as calcium, in bone
- assess your risk of breaking a bone
- check for bone loss
- diagnose osteoporosis
How a bone density scan is done
A bone density scan is usually done as an outpatient procedure in the x-ray (radiology) department of a hospital or clinic. This means that you don’t stay overnight. The test can take 5 to 20 minutes, depending on the number of areas being scanned, but it may take longer.
Before you have a bone density scan, it is important to tell the x-ray technologist or radiologist if you are breastfeeding or pregnant or think you may be pregnant.
It is also important to tell the x-ray technologist or radiologist if you recently had a barium examination or have been injected with a contrast medium for another test. You may have to wait 10 to 14 days before having the bone density scan.
You can eat normally but should not take calcium supplements for 24 hours before the test.
You may be told to not wear clothes with metal zippers, belts or buttons on the day of the scan. Or you may change into a gown for the test. If you are wearing glasses, jewellery or other objects that could interfere with the test, you will be asked to take them off.
You will lie on a table and be placed in position. When the scan is being done, you must stay very still and you may be asked to hold your breath.
The scanner moves over the area to be scanned and uses low-dose x-rays to produce images on a computer screen. X-rays are taken of the bones of the lower spine and hip. Sometimes x-rays are also taken of the forearms. In some cases, the whole body is scanned.
Bone density scans use low levels of ionizing radiation. Ionizing radiation is strong enough to damage cells in our bodies and increase the chance of developing cancer. But the risk associated with any one scan is very small. Scans and other x-rays are strictly monitored and controlled to make sure they use the least possible amount of radiation. The benefits of having a bone density scan outweigh the risk of exposure to the small amount of radiation received during the scan.
What the results mean
A bone density scan tells your doctor how strong your bones are by using a numbered score. Your doctor will use this score to discuss whether you have normal bone mass, low bone mass or osteoporosis.
A bone density scan can also predict how likely you are to break a bone over the next 10 years by using a percentage. Your doctor will use this percentage to discuss if you have a low, moderate or high risk.
What happens if the results are abnormal
Your doctor will decide whether further tests, procedures, follow-up care or additional treatment are needed.
Special considerations for children
Preparing children before a test or procedure can help lower their anxiety, increase their cooperation and develop their coping skills. This includes explaining to children what will happen during the test, such as what they will see, feel and hear.
Preparing a child for a bone density scan depends on the age and experience of the child. Find out more about helping your child cope with tests and treatments.
A substance used in some diagnostic procedures to help parts of the body show up better on x-rays or other imaging tests.
In most cases, contrast medium is injected into or around the structure to be examined.
Also called contrast dye or contrast agent.
A type of high-energy radiation that can remove particles from an atom or molecule resulting in charged ions. These charged ions can cause changes to cells’ DNA that can damage or kill the cells. This can increase the risk of cancer.
Ionizing radiation is present in the atmosphere. It can also come from medical tests or treatments, such as x-rays or radiation therapy.
Great progress has been made
Some cancers, such as thyroid and testicular, have survival rates of over 90%. Other cancers, such as pancreatic, brain and esophageal, continue to have very low survival rates.