Evaluation of differences between fan-beam and pencil-beam densitometers.
We compared the bone and body composition results in vivo on two bone densitometers using fan-beam geometry (EXPERT and PRODIGY) with those using pencil-beam geometry (DPX). Measurements were made on large groups of adults ranging in weight from about 50 to 120 kg. Both spine and femur neck BMD on the fan-beam densitometers averaged within 1% of the pencil-beam results, and there was no magnitude dependence of the results by Bland-Altman analysis. Total body BMC and BMD on the PRODIGY and DPX were congruent, but on the EXPERT, BMC was about 2% lower and BMD 2% higher than corresponding values on the DPX. Soft-tissue composition was closely congruent for the PRODIGY and DPX; the comparable EXPERT-DPX differences showed greater scatter but no significant magnitude dependence. The smaller fan-angle of the PRODIGY (4 degrees ) probably contributed to its better congruence to pencil-beam results compared with the EXPERT (12 degrees ).
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Lunar Corporation, 726 Heartland Trail, Madison, Wisconsin 53717, USA.
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D015502:Absorptiometry, Photon / Q000295:instrumentation*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition / Q000502:physiology; D015519:Bone Density; D005069:Evaluation Studies as Topic; D005260:Female; D005272:Femur Neck / Q000000981:diagnostic imaging / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013131:Spine / Q000000981:diagnostic imaging / Q000502:physiology