Validation of Energy Dispersive X-Ray Spectrometry as a Method to Standardize Backscattered Electron Images of Bone

The use of backscattered electron (BSE) imaging as a tool for the qualitative measurement of mineral content in bone has been well documented. The challenge still remains to develop BSE imaging as a tool for quantitative mineral content analysis in bone. The limiting factor has been the ability to standardize the BSE signal within and between laboratories. Energy dispersive x-ray spectrometry (EDX) has been proposed as a method to standardize the BSE operating environment. The goal of this study is to investigate the relationship between EDX-determined wt.% Ca measurements and BSE graylevels. A comparison with traditional ash content measurements will indicate the validity of the procedure. A comparative study was performed on a series of bones representing a broad range of mineralization. Results confirmed a high correlation between BSE graylevels and wt.% Ca measured with EDX. However, the BSE method consistently underestimated the mineral content of bone determined by traditional ash measurements. The results suggest that quantitative BSE imaging can be standardized by EDX measurements, but an empirically determined correction may be necessary if comparisons with known and accepted mineral content measurement techniques are to be performed. Further investigation into the nature of this empirical correction is warranted before the procedure can be universally applied to bone mineral content analysis