CROSS CALIBRATION OF BONE MINERAL DENSITIY (BMD) VALUES BETWEEN VARIOUS DUAL-ENERGY X-RAY ABSORPTIOMETRY (DXA) SYSTEMS : SPECIAL REFERENCE TO THE BMD VALUES IN DISTAL RADIUS

Abstract

The values of bone mineral density (BMD) obtained by different dual-energy X-ray absorptiometry systems are known to be not identical. In this study, the BMD values in the distal radius measured by various DXA instruments were cross-calibrated by in vivo study. The instruments studied were the QDR-1000 (Hologic), DPX-L (Lunar), and DCS-600 (Aloka). Cross calibration was performed by calculating the linear regression formulae of BMD values between different systems. The correlation coefficients (r) were 0.987-0.992. Therefore, highly reliable conversions of BMD values between different systems could be obtained in the distal radius. However, it was shown that the conversion formulae of BMD values in the distal radius were essentially different to those in the lumbar vertebrae or proximal femur.