Evaluation of the European Spine Phantom in a multi-centre clinical trial.
The European Spine Phantom (ESP) has recently been developed as a universal standard for instruments measuring bone density. The ESP is composed of three semi-anthropomorphic hydroxyapatite vertebrae of varying densities surrounded by soft tissue equivalent plastic designed to resemble human bone and soft tissue when scanned on bone densitometers. In multi-centre studies it is particularly important to verify that each participating bone densitometer is performing in a stable and linear fashion. The aim of this study was to evaluate the ESP within the context of a multi-centre clinical trial. Eighteen centres in the UK and Canada with dual-energy X-ray absorptiometry (DXA) instruments (Lunar DPX, DPX-alpha and DPX-L) participated in the study. The ESP was scanned 10 times on each instrument without repositioning using standardized protocols. The precision of the bone mineral density (BMD) measurements (LI-3) expressed as a coefficient of variation ranged from 0.4% to 1.1% (mean 0.7%). The mean BMD of each instrument was expressed as a percentage difference from the overall mean and ranged from -1.33% to 1.33%. Linear regression analysis showed that all instruments behaved in a linear fashion across the range of densities with correlation coefficients all > or = 0.999 and standard errors of the estimate < 1.5% of the mean BMD ESP value. The data from this study demonstrate that the ESP is a useful phantom for assessing the linearity, stability and differences between DXA instruments from one manufacturer.
Lees
B
B
Wynn Division of Metabolic Medicine, Imperial College School of Medicine, National Heart and Lung Institute, London, UK.
Garland
S W
SW
Walton
C
C
Stevenson
J C
JC
D015502:Absorptiometry, Photon / Q000295:instrumentation; D015519:Bone Density; D019047:Phantoms, Imaging / Q000592:standards*; D012044:Regression Analysis