Explain Dual Energy X-ray Absorptiometry (DEXA)?

Dual energy X-ray absorptiometry (DEXA) is a relatively new technology that is being identified as a reference method for body composition analysis. This method is based on three-compartment model that divides the body into total-body mineral, mineral-free lean and fat tissue masses.

A device emits X-rays at two different energy levels and a detector measures the reduction of energy through the body. From this, bone density and soft tissue can be calculated. The values of body fat mass and lean tissue can be estimated. DEXA provides segmental and regional measures of body composition. This method can also be used for showing distribution of fat on the body.

This is a very accurate and reproducible method, has good relationship correlation with other methods. DEXA is an alternative to hydro densitometry (W) as a reference method because it is rapid (a total body scan takes 20 minutes), safe, requires minimal subject cooperation and takes into account inter individual variability in bone mineral content.