What technique is used to evaluate bone density at central skeletal sites like the hip and spine?

• A. Quantitative ultrasound
• B. X-ray radiography
• C. CT scan
• D. Dual-energy X-ray absorptiometry (DXA)

Answer: (D)

The technique used to evaluate bone density at central skeletal sites like the hip and spine is dual-energy X-ray absorptiometry (DXA). DXA is considered the gold standard for bone densitometry because it provides precise measurements of bone mineral density (BMD) by differentiating between bone and soft tissue. The technique utilizes two different energy X-ray beams to assess the density of bone at specific anatomical sites, which are critical for diagnosing conditions such as osteoporosis.

DXA is particularly effective for central skeletal sites because it can offer accurate and reproducible BMD measurements, which are essential for evaluating fracture risk. The technology is also quick, involves relatively low radiation exposure, and allows for the assessment of changes in bone density over time, making it invaluable for monitoring patients who may be at risk for osteoporosis.

In contrast, other techniques such as quantitative ultrasound, X-ray radiography, and CT scans have limitations in this specific application. For example, while quantitative ultrasound can assess bone quality and density, it is typically used for peripheral sites rather than central skeletal locations. X-ray radiography does not provide quantitative measures of BMD, and although CT scans can assess bone density, they are more invasive and expose the patient to higher doses of radiation compared to DXA