3D COMPUTED X-RAY TOMOGRAPHY OF HUMAN CANCELLOUS BONE AT 8 MU-M SPATIAL AND 10(-4) ENERGY RESOLUTION

Human cancellous bone was imaged and its absorptive density accurately measured in three dimensions (3D), nondestructively and at high spatial resolution by means of computerized microtomography (mu CT). Essential for achieving the resolution and accuracy was the use of monoenergetic synchrotron radiation (SR) which avoided beam hardening effects, secured excellent contrast conditions including the option of energy-modulated contrast, and yet provided high intensity. To verify the resolution, we selected objects of similar to 8 mu m size that could be observed on tomograms and correlated them in a unique manner to their counter images seen in histological sections prepared from the same specimen volume. Thus we have shown that the resolution expected from the voxel size of 8 mu m used in the mu CT process is in effect also attained in our results. In achieving the present results no X-ray-optical magnification was used. From mu CT studies of composites (Bonse et al., X-ray tomographic microscopy (XTM) applied to carbon-fibre composites. In: Materlik G, ed. HASYLAB Jahresbericht 1990. Hamburg: DESY, 1990;567-568) we know that by including X-ray magnification a resolution below 2 mu m is obtained. Therefore, with foreseeable development of our mu CT method, the 3D and nondestructive investigation of structures in mineralized bone on the 2 mu m level is feasible. For example, it should be possible to study tomographically the 3D distribution and amount of osteoclastic resorption in the surrounding bone structure.