Estimation of optical density of bone tissue radiograms with laser densitometry

Bone tissue samples excised from the femoral heads of human were X-rayed together with the aluminum reference standard of density. The radiograms were scanned with the laser densitometer UltroScan XL (Pharmacia). Form the optical density profiles of bone samples the mean optical densities were determined. The optical densities were recalculated into equivalent thickness of the aluminium standard [mm Al]. Inter-measurement reproducibility of optical density determination was found to be very good (SD less than 3% of the mean). Relatively high variability (SD about 13% of the mean) was found for the optical density determination of a single bone sample X-rayed repeatedly. The inter-individual variability, which reflects the variability of bone tissue density between human subjects, was estimated as about 25% (SD as percent of the mean). We concluded that the laser densitometry performed according to our protocol provides the precise estimation of bone tissue density. Therefore, laser densitometry of bone tissue radiograms is potentially useful method for studies of bone in medical research and diagnosis.