DEXA Scanning or bone densitometry is a simple, painless procedure used
to measure bone mineral density and accurately diagnose osteoporosis,
the bone-thinning disease that mainly affects post-menopausal women. The
test is performed by a radiologist or technologist and requires no
injections, sedation, special diet or any other advance preparation. In
most cases, it can be completed in 30 minutes or less.
DEXA stands for Dual-Energy X-ray Absorptiometry. During this
quick procedure, the patient lies fully clothed on a padded table while
the DEXA scanner beams low dose X-rays from two different sources
towards the bone being examined (usually the lower spine or hip). Two
energy peaks are captured—one absorbed mainly by soft tissue and the
other by bone. The difference between the soft tissue amount and total
is the bone mineral density. A computer is then used to analyze the
resulting images and calculate bone density based on the amount of
radiation absorbed by the bone (the denser the bone, the more radiation
In addition to diagnosing osteoporosis, DEXA scanning can be used to
measure and monitor a patient's response to treatment.
DEXA scanning has become the most popular osteoporosis screener for
several reasons, including:
Accuracy: DEXA scanning uses two different
X-ray energy sources, which helps make it the most sensitive,
precise, and accurate method available to measure subtle changes
in bone density over time or in response to drug therapy.
Low Radiation Exposure: DEXA scanning uses less
radiation than other tests, such as CT scans or radiographic
absorptiometry. In fact, DEXA scanning exposes patients to less
radiation than a chest X-ray or a coast-to-coast airline flight.
Versatility: Unlike other osteoporosis
screeners, DEXA scanning can be used to test bone density in the
entire body, including the spine and extremities.
Cost: DEXA scanning is less expensive than
other bone mineral density tests and thus more widely available
Who Shouldn't Use DEXA Scanning?
Although DEXA scanning is the best method for measuring bone density,
certain conditions may interfere with the accuracy of test. Those
Spinal deformities or previous spinal surgery
Vertebral compression fractures or degenerative diseases such as
Calcium in the blood vessels that overlie the area being scanned
(this condition, sometimes found in patients with heart disease,
may falsely increase bone density)
In addition, pregnant women should not undergo X-ray tests
because exposure to ionizing radiation may harm the fetus.
What Happens Next?
An experienced Main Line Health radiologist will analyze your DEXA scans
and send a report to your referring physician, who will inform you on
your test results. Results cannot be given directly to the patient or
For more information, call 1.866.CALL.MLH.