|
Most applications of x-ray microtomography in medicine have been to the study of bones and teeth. Of these, the majority have been devoted to investigations aimed at characterization of trabecular structure in normal and osteoporotic bone. Such studies are hindered by partial volume effects, both at the level of the trabecular boundaries, and also on a finer scale, from cells and cell processes embedded within the bone tissue. The effect of the latter on the determination of mineral concentration has been modelled by computer simulation. Primarily as a result of these partial volume effects, most studies of trabecular bone have been based on binary images produced by thresholding. If the resolution of laboratory systems were improved, changes in mineral concentration within trabeculae could also be assessed. Although most microtomography uses detector arrays, useful results can be obtained with first generation systems. These are illustrated by quantitative mineral concentration studies of bones and teeth; determination of concentrations of elements with accessible absorption edges derived from absorption spectra recorded at all points in the projections; and demonstration of diffusion of KI into cortical bone. A very exciting use of 3D microtomography is to observe changes in bone structure after specific treatments. Others have used this for in vivo studies, but here is illustrated by preliminary observation of in situ cracking of cortical bone under mechanical load.
|
