DEXA bone density scan: what to expect, prep and results

Who is offered a scan

The USPSTF recommends screening with a DXA scan, with or without a fracture risk assessment, for women 65 and older. For postmenopausal women younger than 65, it suggests first checking for risk factors and then using a risk tool; those at increased risk are screened (both grade B). For men, it found the evidence insufficient (I statement). (USPSTF, 2025) One of the risk tools is FRAX, which estimates the 10-year chance of a hip or other major fracture; the USPSTF notes it is more accurate when the bone density result is included. (USPSTF, 2025) Full details: osteoporosis screening.

How to prepare

Eat normally on the day of the exam. (RadiologyInfo, 2024)
Calcium supplements: RadiologyInfo says not to take them for at least 24 hours before; MedlinePlus says you may be told to stop them 24 to 48 hours before. Follow your imaging center's instructions. (RadiologyInfo, 2024) (MedlinePlus, 2024)
Wear loose, comfortable clothes without metal zippers, belts or buttons, and leave jewelry at home. You may be asked to change into a gown and to take off glasses, removable dental appliances and other metal objects. (RadiologyInfo, 2024) (MedlinePlus, 2024)
Tell your doctor if you recently had a barium exam or a contrast injection for a CT or radioisotope scan: you may have to wait 10 to 14 days before the DXA test. (RadiologyInfo, 2024)
Tell the staff if you could be pregnant. (RadiologyInfo, 2024) (MedlinePlus, 2024)

What happens during the scan

For the usual (central) scan of the hip and spine, you lie on a padded table with an x-ray source below and a detector arm above. For the spine, your legs rest on a padded box to flatten your lower back; for the hip, your foot is placed in a brace that turns the hip inward. The arm passes slowly over the area. You need to hold very still and may be asked to hold your breath for a few seconds, while the technologist steps behind a wall to run the machine. (RadiologyInfo, 2024) You will probably fill out a questionnaire about conditions and medicines that affect fracture risk. (RadiologyInfo, 2024)

How long: usually 10 to 30 minutes, depending on the equipment and the parts of the body scanned. (RadiologyInfo, 2024) (MedlinePlus, 2024)
Spine fracture check (VFA): many centers can add a low-dose x-ray of the spine on the same machine to look for spine fractures, mainly for older patients; it adds only a few minutes. (RadiologyInfo, 2024)
Wrist, heel or finger scanners: smaller peripheral devices, sometimes found in drugstores or health vans, give a reading within a few minutes. RadiologyInfo says that if one suggests treatment may be needed, a central DXA scan should be done as a baseline. (RadiologyInfo, 2024)

DXA is of limited use in people with a spinal deformity or past spine surgery, and spine compression fractures or osteoarthritis can affect accuracy; a CT scan may then be more useful. (RadiologyInfo, 2024)

Radiation, in plain terms

RadiologyInfo says the dose is extremely small: less than one-tenth of a standard chest x-ray, and less than a day's exposure to natural background radiation. No radiation stays in your body afterward. (RadiologyInfo, 2024) MedlinePlus says the test is safe for most people but is not recommended during pregnancy. (MedlinePlus, 2024)

Results: T-score and Z-score

A radiologist or another trained doctor reads the scan and sends a report to your doctor, who goes over it with you; MedlinePlus says your provider usually gets the results within a few days. (RadiologyInfo, 2024) (MedlinePlus, 2024)

T-score: your bone density compared with a healthy young adult of the same sex. Around -1 or higher is normal, -2.5 or lower is osteoporosis, and in between is low bone mass (osteopenia). (RadiologyInfo, 2024) (MedlinePlus, 2024)
Z-score: your bone density compared with people of your age, sex and size. An unusually high or low score may mean more tests are needed. (RadiologyInfo, 2024)

How to read each part of the report, including FRAX: bone density test results.

Small changes between scans are normal because of differences in positioning, and usually do not matter. (RadiologyInfo, 2024) When to have the next scan differs by source; see bone density test: how often.

Cost and coverage

Medicare Part B covers a bone mass measurement once every 24 months, or more often if medically necessary, if you meet one of its conditions: for example, a woman whose doctor finds she is estrogen-deficient and at risk, x-rays showing possible osteoporosis or spine fractures, taking or starting steroid-type drugs such as prednisone, primary hyperparathyroidism, or monitoring osteoporosis treatment. You pay nothing if your provider accepts assignment. (Medicare.gov) For private plans, see preventive screenings covered by insurance.

Questions people ask

How long does a DEXA scan take?

Usually 10 to 30 minutes, depending on the machine and which parts of the body are scanned. A spine fracture check (VFA) on the same machine adds only a few minutes. (RadiologyInfo, 2024) (MedlinePlus, 2024)

Does a bone density scan hurt?

No. It is quick and painless, and no anesthesia or needle is needed. You lie still on a padded table while the scanner arm passes over you. (RadiologyInfo, 2024)

Can I eat before a DEXA scan?

Yes. You may eat normally on the day of the exam. RadiologyInfo says not to take calcium supplements for at least 24 hours before; MedlinePlus says you may be told to stop them 24 to 48 hours before. Follow what your imaging center tells you. (RadiologyInfo, 2024) (MedlinePlus, 2024)

How much radiation is in a DEXA scan?

Very little: RadiologyInfo puts it at less than one-tenth of a standard chest x-ray and less than a day of natural background radiation. It is still an x-ray, so tell the staff if you could be pregnant. (RadiologyInfo, 2024) (MedlinePlus, 2024)

At what age should I get a bone density scan?

The USPSTF recommends a DXA scan for all women 65 and older, and for postmenopausal women under 65 whose risk assessment shows increased risk (grade B). For men, it found the evidence insufficient to recommend for or against. (USPSTF, 2025)