BODY-COMPOSITION ANALYSIS BY DEXA BY USING DYNAMICALLY CHANGING SAMARIUM FILTRATION

Dual-energy X-ray absorptiometry (DEXA) has a high accuracy for body c omposition analysis but is influenced by beam hardening and other erro r sources in the extremes of measurement. To compensate for beam harde ning, the Norland XR-36 introduces a dynamically changing samarium fil tration system, which depends on the current-absorber thickness. With this system we found a good agreement (r = 0.99) between reference and measured amounts of tissue or fat percentages in a plastic phantom an d in smaller (similar to 0.5-4 kg) and larger (similar to 5-20 kg) pil es of tissue (OX muscle and lard). Scans of six healthy volunteers cov ered with combinations of beef and lard (similar to 5-15 kg) showed a good agreement (r = 0.99) between reference and DEXA values of added s oft tissue mass and fat percentage. We conclude that the DEXA method ( and, in particular, the Norland XR-36 using dynamic filtration) has a high accuracy for body composition analysis. It has a potential for ga ining status as a reference method in the future and may presently be used as a supplement to the traditional methods for body composition a nalysis.