Comparison of fan-beam, cone-beam and spiral scan reconstruction in X-ray micro-CT

摘要

Laboratory instruments for high-resolution microtomography (Micro-CT) are based on the object irradiation by the X-ray sources with spot size in the micron range. The microfocus laboratory X-ray sources produce X-ray radiation by interaction of electron beam with a metal target. Spot size in this case is defined by focusing of electron beam and limited by melting point of the metal target. That means the improvement in spot size and spatial resolution can be done only against power of the X-ray sources. For most effective collection of X-ray flux from the low-power sources two-dimensional detectors should be used for images acquisition. By this reason the X-ray geometry in the high-resolution micro-CT instruments corresponding to cone-beam acquisition with relatively big divergent angle. In such geometry all conventional fan-beam CT-reconstruction algorithms may produce significant geometrical distortions. We developed and tested reconstruction software packages for different algorithms: fan-beam, cone-beam (Feldkamp) and spiral (helical) scans using two-dimensional detectors. All algorithms were applied to different simulations as well as to the real datasets from the commercial micro-CT instruments. From the results of testing a number of strong and weak points at different approaches has been found.