ABSTRACT
QCT can be used to determine the three dimensional image of bone at any site and to compute a true volumetric density rather than an area-based density. Standard CT instruments can be used for this purpose with the application of appropriate software. However, the high radiation exposure (50 times greater than DXA), high cost, and absence of normal ranges, have led to the technique remaining a research tool. Precision errors are higher than for DXA, at 2-4%, with accuracy quoted at between 5% and 10% when used to assess the spine. Recently, special purpose QCT scanners have been developed to measure the peripheral skeleton. The most frequently assessed site is the distal radius. Accuracy and precision are broadly similar to those for DXA.
