DXA Bone Density
Know Your Bone Health.
A bone density screening, also known as bone mineral density testing (or a DXA scan), is a simple test that measures bone mass, usually in the hips and lumbar spine. It determines if a patient has or is at risk for osteoporosis, a disease that causes bone to become more fragile over time. A bone density screening test can determine if bones are starting to thin, and more importantly, it allows you to treat bone loss before a fracture occurs. After age 35, both men and women lose bone at a greater rate than it forms, causing bone loss. Women start to lose bone at a much more rapid rate after menopause.
At Washington Radiology, we follow the recommendations of the International Society for Clinical Densitometry (ISCD) and suggest that healthy women begin routine bone density screenings at age 65. Physicians may request bone density screenings for women younger than age 65 based on certain risk factors and medical conditions, shown below.
Pre-menopausal women with the following conditions:
- Fragility fracture
- Disease or condition associated with low bone mass or bone loss
- Medication use associated with low bone mass or bone loss
Women during menopausal transition with clinical risk factors for fracture, such as:
- Low body weight
- Prior fracture
- High-risk medication use
Post-menopausal women with a risk factor for low bone mass, such as:
- Low body weight
- Prior fracture
- High-risk medication use
- Disease or condition associated with bone loss
We offer the following bone density studies:
Dual-Energy X-ray Absorptiometry (DXA) scan and Vertebral Fracture Assessment (VFA)
Vertebral Fracture Assessment (VFA)
A VFA examination is an imaging procedure used to assess and detect possible vertebral fractures. A vertebral fracture that is not known to be due to prior trauma is diagnostic of osteoporosis, even if your DXA results are normal. Your doctor might order both a DXA and a VFA examination depending on your clinical picture.
Bone is living tissue that is constantly being broken down and reformed. As a person grows, bone forms faster than it break down until it reaches a peak bone mass between the ages of 25 and 35. After age 35, both men and women lose bone at a greater rate than it forms, causing bone loss. After menopause, women start to lose bone at a much more rapid rate than men of the same age. This rapid bone loss is usually due to a decrease in the production of the hormone, estrogen. As a greater amount of bone is lost, the bones become porous and brittle and much more susceptible to fracture. Early detection is the best way to prevent osteoporosis.
Your physician will use the bone density information to decide if treatment for osteoporosis is needed. Whether or not treatment is prescribed, you may need a follow-up study later to evaluate for possible progression of bone loss.
A certified DXA technologist will conduct the exam. You will lie still on the exam table, breathing normally. A scanner (using a dual energy beam of very low dose X-rays) will pass over the lower spine and hip area. You won't feel anything during the screening. DXA technology works by measuring the number of X-rays that are absorbed by the bones in your body. The two (dual) X-ray energies allow the machine to differentiate between bone and soft tissue, giving a very accurate estimation of bone density. The radiologist will produce a report for your referring physician based on the bone density measurements and your medical history.
DXA scanning has been proven to be the most accurate method of measuring bone density; it uses the least amount of radiation and is lower in cost than other imaging methods.
No. Although the two are often confused because they sound alike, they are completely different. A bone scan is a nuclear medicine study used to determine other elements of bone health such as hairline fractures and cancerous deposits. It does not determine bone density.
This examination lasts approximately 15 minutes.
The amount of radiation for a DXA scan is only a fraction of that received from a standard chest X-ray. It is comparable to the amount received on a transcontinental airline flight. The DXA method produces less radiation than other methods. Although DXA emits a very low amount of radiation, always inform the technologist if there is a chance that you are pregnant.
A VFA or Vertebral Fracture Assessment is a 10-second X-ray of the spine, taken in combination with DXA. With VFA, doctors can see existing vertebral (spine) fractures, which may indicate the need for more aggressive treatment, even if the DXA bone density results are in the “normal” range. Not all patients need a VFA. However, using VFA—when clinically indicated—can be beneficial in assessing bone health. This assessment is performed upon physician request.
FRAX is a tool used to calculate a postmenopausal woman's 10 year risk of hip fracture and overall osteoporotic fracture risk based on several clinical factors like family history, age, height and weight, smoking and drinking history, use of steroids and history of rheumatoid arthritis as well as the hip DXA measurement.
DXA is covered under most insurance plans. Medicare covers bi-annual screening DXA exams, and more frequently if medically indicated. Always check with your insurance carrier to determine your specific coverage.
A DXA machine is used to obtain side (lateral) view of your thoracic and lumbar spine in one view. Their image is then analyzed quantitatively by a computer and visually by a radiologist.
Preparing for Your Visit
During scheduling, a Washington Radiology team member will review with you the preparation instructions specific to your DXA exam. These instructions are repeated here for easy reference.
In addition to the written order from your doctor, please remember to bring any prior images or reports from outside Washington Radiology with you to your appointment if related to the reason for your visit with us.
- Unless instructed otherwise, eat normally on the day of the exam.
- No calcium supplements for 24 hours prior to your appointment.
- Wear loose, comfortable clothing. Sweat suits and other casual attire without zippers, buttons, grommets or any metal are preferred.
- You should not have had a barium study, radioisotope injection, oral contrast material from a CT scan or MRI, or any X-ray contrast study within 7 days prior to your DXA exam.
If you have any follow-up questions about these important preparations, please contact the Washington Radiology office where your exam is scheduled and ask to speak with the Technologist.
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Chevy Chase, MD
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