What is a DEXA Scan (Bone Densitometry Scan or DXA)?

A bone densitometry scan, also called Dual-Energy X-ray Absorptiometry (DEXA or DXA) or simply a “bone density scan” uses an enhanced form of X-ray (radiograph) technology that applies a very small dose of ionizing radiation. DEXA is most often performed on the lower spine and hips and is the standard test for measuring bone mineral density. It is more effective in measuring bone density than a standard X-ray and is the exam used most often in diagnosing osteoporosis, a condition that thins and weaken the bones of women after menopause and can also affect men. DEXA is also used to assess a patient’s risk for developing fractures.

Portable DEXA devices, including some that use ultrasound waves rather than X-rays, measure the wrist, fingers or heel and are sometimes used for screening purposes.

DEXA scans are commonly used to assess:

  • Osteoporosis diagnosis and treatment
  • Risk of developing fractures
  • Metastasis (spreading) of cancer to bones

A DEXA scan may be appropriate if you:

  • Osteoporosis diagnosis and treatment
  • Are over 50 years of age with a risk of developing osteoporosis
  • Are a postmenopausal woman over 60 not taking estrogen
  • Have had past clinical conditions associated with bone loss
  • Have a personal history of hip fracture or smoking
  • Use medications known to result in bone loss like steroids, anti-seizure, or thyroid replacement medications
  • Have type 1 diabetes, liver or kidney disease
  • Have a thyroid condition like hyperthyroidism or hyperparathyroidism
  • Have X-ray evidence of a veterbral fracture or other osteoporosis symptoms

Routine evaluations every 2 years may be needed to notice a significant change in bone mineral density, decrease or increase. Few patients, such as patients on high dose steroid medication, may need a follow-up exam at six months.

Despite being very safe procedure, DEXA scans are not recommended for pregnant women, as X-rays can damage an unborn child.

Your HDI Technologist will have you complete an DEXA screening form and carefully screen you prior to your exam.

DEXA and radiation safety

We’re constantly exposed to background radiation in daily life, naturally occurring from radioactive materials on the earth and cosmic rays from space. X-rays used in medical imaging procedures like DEXA scans are safe when administered by qualified radiology technicians. HDI’s Technologists have been trained to use the minimum amount of radiation necessary for optimal results. The amount of radiation used in DEXA examinations is very small, less than one-tenth the dose of a standard chest X-ray and less than your exposure to natural radiation in any given day. The benefits of this diagnostic exam greatly outweigh the risk of harm.

DEXA scanning systems have tightly controlled X-ray beams with significant filtration and dose control precision to minimize secondary (scatter) radiation. This ensures those parts of a patient’s body not being imaged receive minimal radiation exposure.

Women should always inform their physician and HDI Technologist if there is any possibility that they are pregnant so that necessary precautions can be taken.

To learn more about effective X-ray radiation doses, visit radiologyinfo.org.

Medications

Continue taking your current medications as normal unless specified by your physician.

Food and drink

You may eat normally on the day of your Bone Densitometry Scan. Do not take calcium supplements for at least 24 hours before your exam as they may interfere with test results.

When to arrive

Please arrive at High Desert Imaging 15 minutes before your exam appointment.

What to wear

Wear comfortable clothing, like sweats. Be sure to avoid clothing containing metal found in eyelets, rivets, zippers or buttons. Also be conscious of metal in any undergarments worn as it can interfere with the quality of the imaging. You may be asked to remove jewelry, eyeglasses, hearing aids or any dentures and any metal objects or clothing if necessary and gowns are available if needed.

Comfort

DEXA Scans are quick and painless, having you lie on a padded table with support cushions to position your body for optimal imaging. Throughout the exam, you will be required to keep very still and asked to hold your breath for a few seconds throughout the imaging session.

Scanning

You will lie on your back on the padded DEXA table and depending on the body part to be scanned, your HDI Technologist will adjust your legs onto a cushioned box to assess your spine by flattening the pelvis and lower (lumbar) area. In assessing your hip, your foot will be placed in a brace that rotates your hip inward. In both cases, the detector will move slowly over the area being scanned, generating images on a computer monitor. You must hold very still to avoid blurring of the images. The technologist will walk behind a wall or into the next room to activate the machine.

Length of scan

DEXA exams can take anywhere between 10-30 minutes depending on which areas of the body you are having imaged.

After your DEXA exam

You may resume normal activity immediately after your bone densitometry scan.

Scan results 

Your bone density measurements are comprised of two different scores.
T-score is the difference between your bone density and that of an average healthy person. This score is used to determine your risk of breaking a bone.
Z-score is the amount of bone you have compared with the bone density of a young healthy adult or an adult of your own age, gender and ethnicity.

HDI takes pride in delivering superior studies and rapid exam results. Diagnostic exams are typically read within 24 hours with results sent to your primary care physician who will go over them with you in detail. We’ll also provide you with a DVD copy of your exam images.

If you have additional questions about our bone densitometry scans, please use our online contact form or call us at 775.621.5800.