Bone Density Scan

  • Medical Author:
    Catherine Burt Driver, MD

    Catherine Burt Driver, MD, is board certified in internal medicine and rheumatology by the American Board of Internal Medicine. Dr. Driver is a member of the American College of Rheumatology. She currently is in active practice in the field of rheumatology in Mission Viejo, Calif., where she is a partner in Mission Internal Medical Group.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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Who invented the bone density scan?

The bone density scan was invented by the late John R. Cameron (1922-2005), professor emeritus at the University of Wisconsin at Madison. He earned a PhD in physics. He invented bone densitometry in the late 1960s. Bone densitometry, which uses precise, very small radiation measurements to determine the mineral content of bone, was one of his many important contributions to medical physics.

Who performs bone density scans?

Bone density scans, or DXA scans, are performed by a trained technician using a DXA machine. The results are then interpreted by a physician. Many different specialist interpret bone density scans, including radiologists, endocrinologists, rheumatologists, gynecologists, and internists.

Where is a bone density test done?

Bone density tests can be done in a physician's office or in a radiology center in or out of the hospital where other tests such as mammograms, CT scans, and X-rays are performed.

What information is on a DXA report?

There is some variation in DXA reports depending on the facility performing the test. All reports should include the following:

  • The date of the test, location, and medical equipment used for the test (manufacturer and model of the densitometer)
  • The reason the test was performed
  • The overall diagnosis (normal bone density, osteopenia, or osteoporosis) based on the results of the scan
  • It should mention the results of the test at each site tested. The hip and lumbar spine are always tested. Many medical facilities also measure bone density at the forearm. The bone density is usually reported with three different numbers. First, the actual bone density is reported. This is measured in grams per centimeter squared (g/cm2). Because the exact bone density varies based on the manufacturer and model of the densitometer, the bone density is also reported as a T-score and a Z-score. The T-score is a measure of how dense a patient's bone is compared to a normal, healthy 30-year-old adult. The Z-score is a measure of how dense a patient's bone is compared to the average person of the same age and gender.
  • Comparison of the bone density to any prior tests performed at the same medical facility
  • Many reports include a calculation estimate of the patient's risk of bone fracture based on the results of the bone density scan. This is reported as the risk over the following 10 years of breaking a bone.
  • Some reports also include a vertebral fracture assessment, which uses the DXA to see if there are any bones in the spine that have already fractured.
  • A notation suggesting how long before a follow-up test is needed
Medically Reviewed by a Doctor on 2/22/2017

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