双能X射线骨密度仪测定技术研究

THE RESEARCH ON MEASURING PROCEDURE OF DUAL ENERGY X-RAY ABSORPTIOMETRY IN DETERMINING THE BONE MINERAL DENSITY

以Ｌｕｎａｒ公司ＤＰＸ－Ｌ型双能Ｘ射线骨密度仪为例，研究引起测量误差的主要因素并提出质控措施。用自检模块、腰椎体模评定仪器的体外测量精度好于１％。对１０位志愿者重复２次测量，体内精度对腰椎，ＭＰＤ（平均百分差）为０．４６，ＣＶ变异系数）为０．７５；对股骨颈，ＭＰＤ为１．２６、ＣＶ为０．４７；Ｗａｒｄ’ｓ三角区ＭＰＤ为２．０１、ＣＶ为１．１４；大转子ＭＰＤ为１．６６、ＣＶ为０．７２。扫描图像由２位技术人员分析比由同１人分析时的误差大。测量对象体位重复和分析技术的规范化，是减小测量误差的２个重要的技术保障。为满足数据比对的需要，建议建立我国自己的体模标准。

The influence of measuring procedure on precision in determing the bone mineral density (BMD) using dual energy X-ray absorptionmetry (DXA) is studied. The research results show that the position of measured subjects and the analysis of acqured images are two main influence facfors. The precision of BMD values obtained from images analysed by two technicians is lower than that by one technician. For DXA of Lunar DPX-L, the vitro precision is better than 1 %. The vivo precision expressed by coefficient of variation (CV) are 0. 75% at lumbar, 0. 47 % at neck, 1. 14 % at Ward's triangle and 0. 72 % at trochanter, respectively. A suggestion for establishment of standard phantom of our country is proposed in the paper.