Xraydensitometrie

X-ray densitometry, or X-ray densitometry, is a radiologic technique that measures the density of tissues or materials by assessing how X-rays are attenuated as they pass through them. In clinical practice it is most commonly used to quantify bone mineral density, providing information that helps diagnose osteoporosis, assess fracture risk, and monitor changes over time.

The most widely used modality is dual-energy X-ray absorptiometry (DXA). DXA uses two X-ray energies to separate bone from soft tissue and yields a bone mineral density value in grams per square centimeter (g/cm2). Central DXA targets the spine and hip, while peripheral devices measure sites such as the forearm. Quantitative computed tomography (QCT) provides volumetric density measurements in mg/cm3 and can offer separate analysis of trabecular and cortical bone, albeit with higher radiation exposure. Other forms, such as radiographic densitometry on conventional radiographs, can provide semi-quantitative density estimates but are less precise than DXA or QCT.

Results are interpreted using reference standards, typically reporting a T-score (comparison with young healthy adults) and a Z-score (age-matched comparison). A T-score between −1.0 and −2.5 indicates osteopenia, while ≤−2.5 suggests osteoporosis. Limitations include sensitivity to degenerative changes in the spine, body size, and calibration differences between devices. X-ray densitometry remains a standard tool for assessing skeletal density, contributing to fracture risk evaluation and management decisions.