Dual-energy X-ray absorptiometry

The dual X-ray absorptiometry (dual energy X - ray absorptiometry DXA, formerly DEXA also, German Doppelröntgenabsorptiometrie ) is an X-ray diagnostic procedure for the determination of body composition. It is used by some authors as a reference method ( gold standard ) called in this area.

Principle

It can be made two shots with different X-ray energy. The proportion of the soft tissue at the X-ray absorption can be subtracted.

The measurement of bone density is by default made ​​in two areas: the hip and lumbar spine and takes about 15 to 30 minutes.

In the context of whole-body DXA measurements can be in addition to bone density and mass and the composition of the entire body determine. Here, a model of the human body with three compartments ( defined parts ) is used: fat mass, bone mass and other mass. On this basis, a calculation of skeletal muscle mass is possible.

Applications

DXA allows a bone density test and thus the detection of osteoporosis. It is a widely used method to detect osteoporosis as early as possible.

In addition, whole-body DXA is associated with nutritional studies, particularly in obesity, used.

In Germany, no measurements of children and adolescents may be performed with this method because of the radiation exposure. Differs from the method also in pregnant women. The radiation dose with a full body measurement that takes between 5 and 20 minutes, is about 5-7 mSv.

Costs

Measurements are only in certain cases by the health insurance paid ( cost: about 40-50 € ), namely:

• Bone fractures
• Osteoporosis disease
• Specific gastrointestinal diseases ( Crohn's disease, ulcerative colitis, malabsorption )
• Corticosteroids for a long time
• A parathyroid disease