Dual Energy X-ray Absorptiometry (DEXA) is the preferred scanning technique for measuring bone mineral density (BMD), which is a key measurement in the diagnosis of osteoporosis. A DEXA scanner emits one low-energy and one high-energy X-ray beam. The thickness of the bone can be measured by calculating the difference in the amount of X-rays that pass through the bone for each beam.
How Is a DEXA Scan Performed?
A DEXA scan is relatively easy to perform. The amount of radiation exposure is low. A bone density scan or DEXA scan takes approximately 20 minutes. The typical exam will capture images in your hip and spine—it is a completely painless and noninvasive procedure.
It is important to obtain the scan images in the same positon for all follow-up exams to accurately compare your results. The typical DEXA scan involves the following:
- You will be asked to change into a hospital gown.
- You will then recline on the exam table.
- A cushioned box will be placed under your knees prior to scanning the spine. The cushioned box allows the small of your back or lower spine to lie flat on the table.
- A small X-ray will be positioned to scan your lumbar spine.
- To scan the hip, a plastic brace is placed between your feet to standardize the position for future comparison.
- After the scan, you can return to your normal activities.
Preparing for Your DEXA Scan
Minimal preparation is required for this procedure. If you have any questions or concerns, please discuss them with us. We strive to make the diagnostic imaging procedure as comfortable as possible. Here are some helpful things to remember:
- Medications can be taken as usual.
- Fasting is not required.
- Loose-fitting clothes without metal buttons or zippers are recommended.
- The small amount of radiation used is unsuitable for pregnant women.
- Inform your radiologist of metallic implants as this area might not be eligible for evaluation.
- Wait 1 week after undergoing a radiological imaging procedure using a contrast agent or nuclear medicine test. The contrast agent may interfere with the accuracy of the DEXA scan.