Dual energy x-ray absorptiometry is a diagnostic imaging test that is performed to look for signs of bone loss. Doctors usually order the test when patients have symptoms of osteopenia or osteoporosis. Imaging results are interpreted by radiologists to determine highly accurate bone density calculations. Dual energy x-ray absorptiometry is normally performed by a trained radiology technician in a hospital or outpatient clinic, and it can usually be completed in less than half an hour.
The large machine used to conduct dual energy x-ray absorptiometry works by emitting two beams of x-ray radiation. One beam is considered high energy, meaning that it can easily penetrate hard, healthy bone tissue. The other beam is lower energy, and it can only make it through soft tissue such as cartilage and weakened bone. In order to calculate bone density, a radiologist subtracts the total reading of the low energy beam from that of the high energy beam. The resulting number can then be compared to normal densities to determine if osteoporosis exists.
Most of the time, x-ray absorptiometry tests are performed on the hip or a section of the spine since those bones are generally the most susceptible to density loss. A doctor can generalize bone loss in other parts of the body from hip and spine readings. If a patient is experiencing widespread pain in his or her wrists, knees, and ankles, a full-body scan may be performed. In addition, smaller, less precise versions of absorptiometry machines are installed in many health clinics and pharmacies so patients can take their own readings on their wrists.
When a patient is scheduled for dual energy x-ray absorptiometry, he or she is typically instructed to put on a hospital robe and remove metal jewelry. Since the amount of radiation exposure is minimal, protective vests for the patient and the technician are usually unnecessary. The procedure is painless and normally takes about 15 minutes. If a radiologist is on-hand, results can be interpreted right away. In most cases, however, patients and their doctors find out about test results a few days after the procedure.
Dual energy x-ray absorptiometry is not just used to diagnose bone density loss. It is also a very helpful tool in assessing the effectiveness of ongoing treatment. Patients with osteoporosis are usually prescribed medications and supplements to boost bone density. Periodic dual energy tests help doctors determine if treatments are helping to strengthen bone tissue.