Bone Density Scan (DEXA or Bone Densitometry)
Bone density scanning, also referred to as dual-energy x-ray absorptiometry (DEXA) or bone densitometry, uses x-rays to measure bone mass. Bone density scans are the standard measure of bone mineral density (BMD).
A bone density scan sends a low-dose X-ray beam with two energy peaks through the bones being examined. One peak is absorbed by soft tissue, the other by bone. Bone mineral density is determined by subtracting the amount absorbed by soft tissue from the total measurement.
The scan is a fast and convenient way to measure the bone/calcium density of the spine and hips. It is most often used to screen for osteoporosis, a condition causing a gradual loss of calcium causing bones to become thinner and more likely to break.
What to expect during a bone density scan:
The scan will last from 10 to 30 minutes. An Advanced Radiology technician will ask you to lie on a padded platform while a mechanical arm passes over your body.
The amount of radiation exposure is considered very low, less than the amount used during a chest X-ray.
How should I prepare for a bone density scan?
You may eat normally on the day of your exam. Do not take calcium supplements for at least 24 hours before the scan.
You should wear loose, comfortable clothing free of zippers, belts or metal buttons, such as sweat pants, during the scan. An Advanced Radiology technician may ask you to change out of your clothes and to put on a gown to ensure an accurate scan.
Women should inform their doctor or technician if they are pregnant.