目的 验证基于临床CT的数字体相关(digital volume correlation,DVC)方法在测量股骨内部变形场时的准确性,并通过DVC进一步测量股骨在跌倒情况下的内部变形,验证基于临床CT的有限元分析方法(finite element analysis,FEA)在计算股骨内部变形场的准确性.方法 使用猪股骨,模拟侧向跌倒姿态,进行分步力学加载实验,同步进行多次CT成像.通过重复扫描和虚拟位移验证DVC方法的准确性.DVC以子体积作为配准两组图像的研究对象,分别设置8、12、16 和20 mm的子体积进行测试.量化误差指标包括位移系统误差-平均值(mean)、位移随机误差-标准差(standard deviation,SD)、应变准确度-平均绝对误差(mean absolute error,MAER)和应变精确度-标准差误差(standard deviation of the error,SDER).基于CT图像建立股骨有限元模型,模拟实验条件,计算股骨内部位移,与DVC测量的内部变形场对比验证.结果 基于临床CT的DVC方法重复扫描位移偏差小于 0.013 mm,MAER和SDER均小于200 με;虚拟位移偏差小于0.098 mm,MAER为1093～1687 με,SDER为604～1267 με,远小于骨组织屈服应变.FEA计算的位移和DVC测量的位移之间具有较强的相关性(R2≥0.76,P＜0.05).结论 基于临床CT的DVC方法可以准确测量股骨内部变形场,并且基于临床CT的有限元模型可以准确计算股骨内部变形场.
Internal deformation field of femur based on clinical CT digital volume correlation and finite element analysis
Objective To verify the accuracy of digital volume correlation(DVC)method based on clinical computed tomography(CT)in measuring the internal deformation field of femur,and to measure the internal deformation of femur in the falling position through the verified DVC method,so as to verify the accuracy of finite element analysis(FEA)based on CT in calculating the internal deformation field of femur.Methods The pig femur was place in a lateral fall position,then multiple CT imaging was performed simultaneously with step-by-step mechanical loading.The accuracy of DVC method was verified by repeated scanning and virtual displacement.The sub volume was used as the research object for registering two sets of images in the DVC method,and sub volumes of 8,12,16,and 20 mm 16 and 20 mm were set for testing,respectively.Quantitative error indicators included displacement system error mean,displacement random error standard deviation(SD),strain accuracy mean absolute error(MAER),and strain accuracy standard deviation of the error(SDER).The FE model of femur was established based on CT images and experimental conditions,and the internal displacement of femur calculated by the model was compared with the measurement results of DVC.Results The displacement deviation of repeated scanning of DVC method was less than 0.013 mm,the strain accuracy MAER and strain accuracy SDER were less than 200 με.The virtual displacement deviation was less than 0.098 mm.The MAER(1 093～1 687 με)and SDER(604～1 267 με)of virtual displacement were much less than the yield strain of bone tissue.There was a strong correlation between the displacement calculated by FEA and that measured by DVC(R2≥0.76,P＜0.05),indicating that FE model could accurately calculate the internal deformation field of femur.Conclusions Both the DVC method based on clinical CT and the FEA based on clinical CT can accurately calculate the internal deformation field of femur.
CT imagingfinite element analysisdigital volume correlationosteoporosisfemoral fracture
万方数据
维普
