Comparative Studies of Values of Bone Mineral Density Measured with Different Photon Absorptiometries : A Preliminary Report

In order to compare values of bone mineral density measured with various photon absorptiometries, fundamental studies, using four different types of phantoms were performed in four instruments. The QDR-1000 (dual energy X-ray absorptiometry, DEXA) and Dualomex HC-1 (dual photon absorptiometry) were employed for the determination of bone mineral of a lumbar phantom and a cylindrical phantom, and the DCS-600 (DEXA) and Bone Densitometer (single photon absorptiometry) were used for the determination of bone mineral of a rectangular phantom and a ring phantom. The results indicate that the methodology for identification of the bone edge, which is necessary to calculate bone area or bone width, and the bone mineral per unit volume, which is defined as the line bone mineral content per cross-secional area, differ with the instruments used. Furthermore, the bone mineral per unit volume depends on the bone shape of the measured objects. Therefore, it seems taht the cross calibration of bone mineral density between instruments using phantoms is limited and in vivo investigation will be required in the future