评估Dpx-MD型双能X射线吸收仪测定骨体模的精确度和准确性

Precision and accuracy of Dpx-MD type Dual-energy X-ray absorptiomerty in measuring the vertebral phantom

通过用Dpx-MD型X射线吸收仪对骨园筒（骨体模）的测定，了解该仪器的精确度与准确度，并确定该仪器的准确度校正回归方程。实验于2002-09/2007-12在川北医学院附属医院内分泌骨密度室进行。用美国LUNAR公司生产的Dpx-MD型X射线吸收仪测量四川大学华西第四医院骨质疏松中心研制的骨园筒3个，扫描测量10次，测量出投影面积、骨矿含量，并计算骨密度。将被测量后的骨园筒烧灰并用准确度为10^-4g的电子天平称灰重为骨矿含量，通过计算得烧灰骨矿密度值。由上述值算出的Dpx-MD型X射线吸收仪检测骨体模1-3号的精确度分别为2.8%，1.6%，1.9%；准确度误差分别为-1.2%，-8.5%，-3.5%，准确度校正回归方程（测量值与灰值）Y=0.066＋0.924X。提示不同的骨密度其精确度和准确度不同，但其准确度可用回归方程校正以增强测量结果的可靠性。

In this study, we tested the precision and accuracy of vertebral phantom by Dual-energy X-ray absorptiomerty （DXA） of Dpx-MD type and determine the correct regression equation of accuracy of DXA. The experiment was performed at the Bone Density Laboratory rarefaction of the West China Hospital of Sichuan University from September 2002 to December 2007. Three vertebral phantoms, which were produced by the Osteoporosis Centre of the West China Hospital of Sichuan University, were measured by Dpx-MD type DXA, screened for 10 times. The bone mineral density was calculated according to the projected area and bone mineral content. After measurement, the vertebral phantoms were burned, and weighed by an electronic balance （accuracy, 10^-4 g） and the bone mineral density of the ash was calculated. The precision of No. 1-3 vertebral phantom was 2.8%, 1.6%, and 1.9%, and the accuracy was -1.2%, -8.5% and -3.5%. The correct regression equation of accuracy of DXA was Y=0.066＋0.924X. The results indicate that the precision and accuracy are different in different bone mineral density. However, the regression equation can be used to correct and increase the reliability of the measurement.