Body composition analysis by DEXA by using dynamically changing samarium filtration

Abstract

Gotfredsen, Anders, Lene Bæksgaard, and Jannik Hilsted.Body composition analysis by DEXA by using dynamically changing samarium filtration. J. Appl. Physiol.82(4): 1200–1209, 1997.—Dual-energy X-ray absorptiometry (DEXA) has a high accuracy for body composition analysis but is influenced by beam hardening and other error sources in the extremes of measurement. To compensate for beam hardening, the Norland XR-36 introduces a dynamically changing samarium filtration 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 and in smaller (∼0.5–4 kg) and larger (∼5–20 kg) piles of tissue (ox muscle and lard). Scans of six healthy volunteers covered with combinations of beef and lard (∼5–15 kg) showed a good agreement ( r = 0.99) between reference and DEXA values of added soft 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 gaining status as a reference method in the future and may presently be used as a supplement to the traditional methods for body composition analysis.