双能X射线骨密度仪检定结果分析及临床应用

Analysis of Verification Results of Dual Energy X-Ray Absorptiometry and Its Clinical Application

目的:探讨双能X射线骨密度仪(DXA)检定结果在临床的应用。方法:按照JJG1050-2009《X、γ射线骨密度仪》规程方法检定DXA的重复性、测量误差,采用最小二乘法线性回归分析校正测量结果。结果:检定某型DXA的重复性<1%,临床上在比较患者治疗前后的骨密度变化,在0.05显著性水平,对超过2.8%骨密度的变化判断有效;在观察药物疗效的样本量计算时,要发现骨密度增高0.5%,需42例。该型DXA的测量误差范围在1.5%~13.6%,不满足规程要求,经线性校正后为-3.9%~3.9%,骨密度测量结果可信。某4台DXA的测量误差范围在校正前最大为-10.2%~15.0%,校正后最大为-2.0%~6.4%,4台DXA的测量误差变小且互相趋于一致,测量结果具有可比性。结论:骨密度仪重复性可以确定骨密度变化的最小显著变化值及计算观察药物疗效的样本量,对超差骨密度仪线性校正测量值,可使测量误差变小。不同型号DXA的测量标准模体,并对测量值进行线性校正,其测量结果具有可比性,可以互相校正。

Objective:To explore the clinical application of the verification results of dual energy X-ray absorptiometry(DXA).Methods:The repeatability and measurement error of DXA were verified according to JJG1050-2009“X,gamma-ray Densitometry for Bone Mineral Density”,and the measurement results were corrected by ordinary least squares linear regression analysis.Results:The repeatability of a certain type of DXA was less than 1%.Clinically,when comparing the changes of bone mineral density(BMD)of patients before and after treatment,it is effective to judge the BMD changes of more than 2.8%at 0.05 significant level,In the calculation of the sample size for the observation of drug efficacy,to find a 0.5%increase in BMD at 0.05 significant level,42 samples are required.The measurement error of the DXA was 1.5%-13.6%,which did not meet the requirements of the regulations.After linear correction,it was-3.9%-3.9%,and the measurement results of BMD were credible.The maximum measurement error range of four DXA was-10.2%-15.0%before correction and-2.0%-6.4%after correction.The measurement errors of four DXA became smaller and tended to be consistent with each other,and the measurement results were comparable.Conclusion:The repeatability of DXA can determine the least significant change of BMD and calculate the sample size for observing the efficacy of drugs,and the linear correction of the measurement value of out-of-tolerance DXA can reduce the measurement error.Different types of DXA measure the standard phantom and carry out linear correction on the measured values,their measurement results are comparable and can be corrected with each other.