Dual X-ray absorptiometry

Whole body DEXA scan (left bone, right soft tissue)

The dual X-ray absorptiometry ( dual energy X-ray absorptiometry DXA , formerly DEXA , German double X-ray absorptiometry ) is an X-ray diagnostic method for determining body composition . Some authors refer to it as a reference method ( gold standard ) in this area.

principle

Two images are made with different X-ray energies. The portion of the soft tissue in the X-ray absorption can thus be subtracted.

The standard measurement of bone density is carried out in two areas: hip joint and lumbar spine and takes about 15 to 30 minutes.

Whole-body DXA measurements can be used to determine not only bone density and mass, but also the composition of the entire body. A model of the human body with three compartments (delimited parts) is used: fat mass, bone mass and other mass. The skeletal muscle mass can also be calculated on this basis .

Areas of application

DXA enables bone density measurement and thus the detection of osteoporosis . It is a widely used method to identify osteoporosis as early as possible.

Whole-body DXA is also used in connection with nutritional examinations, especially in the case of obesity .

In Germany, measurements on children and adolescents using this method are not allowed due to the radiation exposure. The method is also ruled out for pregnant women. The radiation exposure for a whole-body measurement, which takes between 5 and 20 minutes, is around 5–7 µSv .

costs

Measurements are only paid for by the health insurances in certain cases (cost factor: approx. 40-60 €), namely for:

Broken bones

a disease of osteoporosis

special gastrointestinal diseases ( Crohn's disease , ulcerative colitis , malabsorption )

Long-term use of cortisone
a parathyroid disease

Individual evidence

^ ^A ^b Manfred J. Müller: Nutritional Medicine Practice: Methods - Prevention - Treatment. Springer, Heidelberg 2007, ISBN 3-540-38230-5 , pp. 40-42.
↑ ^a ^b Christine Becker: Formulation of population-specific algorithms for determining the body fat mass of children, adolescents and adults, based on field methods with air displacement plethysmography as a reference . Diss., Kiel 2002 (pdf 1.9 MB)

[Müller_2007-1] A ^b Manfred J. Müller: Nutritional Medicine Practice: Methods - Prevention - Treatment. Springer, Heidelberg 2007, ISBN 3-540-38230-5 , pp. 40-42.

[Becker-2] Christine Becker: Formulation of population-specific algorithms for determining the body fat mass of children, adolescents and adults, based on field methods with air displacement plethysmography as a reference . Diss., Kiel 2002 (pdf 1.9 MB)