Abstract
Nowadays X-ray tubes in conjunction with digital pixelated imagers are standardly utilized for high resolution radiography with several micrometre or even sub-micrometre resolution. Achievement of the same resolution in X-ray computed tomography is a more demanding task due to the time-dependent tube electron beam drift as well as thermal deformations of the tube. In our work, the beam drift caused by the long-term stabilization of the tube electron optics was measured by observation of radiographs of 75 μm big tin ball rigidly mounted onto the tube head. The tube spot movement comprising both the beam drift and the movement caused by thermal deformations of the tube and its fixture was evaluated measuring the virtual movement of the inspected object. For this purpose, radiographs were recorded periodically at the same object position. Both the beam drift as well as spot movement were evaluated with subpixel resolution using digital image correlation tools. It was proven that the quality of a tomographic reconstruction can be significantly improved by the correction of the spot movement.