DEXA Scanner: What to Expect

A DEXA scanner uses very low-dose X-rays to estimate bone mineral density at selected parts of the body.

During the scan, the machine compares how two X-ray energy levels pass through bone and soft tissue. Bone density is commonly assessed at the hip and lower spine because measurements there can help a clinician evaluate bone strength. The scan is painless, and the images are interpreted with your health history and other clinical information.

You usually lie flat on a padded table while a scanning arm moves over the area being examined. Keeping still helps the machine obtain a clear measurement. Staff may ask you to remove metal items near the scan area because they can interfere with the image. Tell the team about recent imaging with contrast, implanted hardware, and any possibility of pregnancy before the scan.

Preparation instructions can differ by facility. Bring a list of medicines and supplements, and check in advance whether you should pause a calcium supplement on the day of the appointment. Wear clothing that is easy to change out of if needed.

A DEXA result estimates density; it does not directly show every aspect of bone quality or predict exactly whether an individual fracture will occur. Arthritis, previous fractures, spinal changes, and metal implants can affect some measurements. Results from different machines or body sites may not be directly comparable, so your clinician considers the report together with age, medical conditions, medicines, and fracture history.

A normal-looking result does not explain every source of back, hip, or joint pain. New severe pain after a fall, inability to bear weight, or a visible deformity needs timely medical assessment rather than waiting for a routine bone-density result.

A clinician may use plain X-rays, blood tests, or other imaging for a different question, such as investigating pain, a suspected fracture, or a medical cause of bone loss. These tests do not all measure the same thing. DEXA is selected when an estimate of bone density will help guide prevention, follow-up, or treatment decisions.

Your report may include scores that compare your bone density with a reference group. The clinician who requested the scan can explain which comparison is relevant to you and whether the result changes your plan. This may include attention to nutrition, weight-bearing activity when appropriate, fall prevention, medication review, or a future repeat scan.

DEXA uses a low dose of radiation, but staff should know if you are pregnant or think you could be pregnant before the appointment. Tell them about recent contrast imaging and any difficulty lying flat. Staff can explain positioning and whether the scan should proceed or be rescheduled in your circumstances.