Diessel E, Fuerst T, Njeh C F, Tylavsky F, Cauley J, Dockrell M, Genant H K
University of California San Francisco, 94143-1349, USA.
J Appl Physiol (1985). 2000 Aug;89(2):599-605. doi: 10.1152/jappl.2000.89.2.599.
This study evaluated a new body composition phantom and its use for quality control and cross-calibration of dual-energy X-ray absorptiometry (DXA) instruments for measurements of body composition. We imaged the variable composition phantom (Lunar, Madison, WI) on eight different DXA devices. Deviations of up to 7% fat were observed when we compared the percent fat values measured by the different devices with the nominal values provided by the manufacturer. Absolute precision error of percent fat measurements for the phantom ranged from 0.6 to 0.8%. The phantom's percent fat values were also compared with whole body composition measurements from 130 female and male volunteers. The phantom detected differences in percent fat values that were similar to those found by comparing in vivo measurements with values from different DXA scanner models from the same manufacturer. When comparing different models of scanners from different manufacturers, such as the Hologic QDR-4500 and the Lunar DPX-IQ, the phantom showed a different relationship than was seen for patients. Therefore, corrections or comparisons based on the phantom data alone would be incorrect. In conclusion, the Lunar variable composition phantom is capable of accurately measuring the fat calibration of DXA devices and may be suitable for cross-sectional cross-calibration between scanners from the same manufacturer; however, for comparison of DXA scanners from different manufacturers, in vivo cross-calibration is still the only accurate method. The phantom may be used in longitudinal quality control to verify an instrument's temporal stability.
本研究评估了一种新型身体成分体模及其在双能X线吸收法（DXA）仪器身体成分测量的质量控制和交叉校准中的应用。我们在八台不同的DXA设备上对可变成分体模（Lunar，麦迪逊，威斯康星州）进行了成像。当我们将不同设备测量的脂肪百分比值与制造商提供的标称值进行比较时，观察到脂肪偏差高达7%。体模脂肪百分比测量的绝对精度误差范围为0.6%至0.8%。还将体模的脂肪百分比值与130名女性和男性志愿者的全身成分测量值进行了比较。该体模检测到的脂肪百分比值差异与通过将体内测量值与同一制造商不同DXA扫描仪型号的值进行比较所发现的差异相似。当比较不同制造商的不同型号扫描仪时，如Hologic QDR - 4500和Lunar DPX - IQ，体模显示出与患者不同的关系。因此，仅基于体模数据进行校正或比较是不正确的。总之，Lunar可变成分体模能够准确测量DXA设备的脂肪校准，可能适用于同一制造商扫描仪之间的横断面交叉校准；然而，对于不同制造商的DXA扫描仪比较，体内交叉校准仍然是唯一准确的方法。该体模可用于纵向质量控制，以验证仪器的时间稳定性。
