DEXA Bone Density Scan
Bone densitometry, also called dual-energy x-ray absorptiometry, DEXA, or DXA, is an enhanced form of x-ray technology that is used to measure the amount of calcium inside your bones. DEXA is today's established standard for measuring bone mineral density (BMD) which is a major factor in determining bone strength and predicting fracture risk. DEXA scan results are used to:
- Diagnose osteoporosis or identify low bone mass
- Evaluate your risk for breaking bones
- Monitor response to therapy
DEXA scans are safe, using only a fraction of the dose of radiation that you would receive from a conventional X-ray.
The standard measurement sites are in the central skeleton: the lumbar spine and both hips (proximal femur bones). Large bones such as these are best for diagnosis and monitoring as they tend to show changes sooner. Any implants in the body will not be affected; however, some may limit the amount of bone that can be measured.
At UConn Health, our technologists take great care to acquire and analyze your DEXA scans using a technique called reproducibility. Your current measurements are performed identically to your previous measurements to ensure the most reliable comparison for monitoring changes in your bone over time.
Preparing For Your Exam
In addition to our general preparation instructions, please do not take calcium supplements for at least 24 hours before your exam. On the day of your exam, you may eat normally.
Wear loose, comfortable clothing, avoiding garments that have zippers or buttons made of metal. If you can avoid metal fasteners in your clothing, you may not need to remove anything for the test.
During Your Exam
During the DEXA scan, you will lie on an open table. The technologist will position your legs, and a narrow scanning arm will move over you. The test is simple and painless. The actual scanning time is typically around 15 minutes.
After Your Exam
The doctor who ordered your exam will receive the results of your DEXA scan. For each region measured, BMD and either a T-score or Z-scores (whichever is appropriate to you) will be calculated.
The T-scores are a comparison of your own BMD to the average normal adult at peak bone mass to diagnose osteoporosis or identify low bone mass. Z-scores compare BMD to an age-matched reference population.
Your BMD values will also be compared to your previous measurements to determine if your bone mass is increasing, decreasing, or stable.