Body composition analysis by dual energy x-ray absorptiometry using
dynamically changing samarium filtration.
Gotfredsen, Anders, Lene Bksgaard, Jannik Hilsted.
Department of Internal Medicine and Endocrinology, Copenhagen
University Hospital, Hvidovre, Denmark
APStracts 3:0540A, 1996.
Dual energy x-ray absorptiometry (DXA) 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 (app. 0.5 - 4 kg) and larger
(app. 5 - 20 kg) piles of tissue (ox muscle and lard). Scans on six
healthy volunteers covered with combinations of beef and lard (app. 5
- 15 kg) showed a good agreement (r = 0.99) between reference and DXA
values of added soft tissue mass and fat percentage. We conclude that
the DXA 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.
Received 15 May 1995; accepted in final form 13 November 1996.
APS Manuscript Number A508-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996