3D X-Ray Source Deblurring in High Cone-Angle Micro-CT

High geometric magnification X-ray micro-computed tomography (μCT) is used to study many high-resolution features in insects, cellular, bones, composite and mineral materials. The resolution of lab-based μCT in a fine-focus geometry is limited by blurring that occurs below the spatial coherence length of the illuminating radiation: resolution can be no smaller than the size of the X-ray source spot. In cases where the source spot size cannot be reduced (e.g. due to signal-to-noise, time or cost considerations) there is a need to model and correct for this blurring. In ANU CT-lab, we use a high cone angle and high geometric magnification with transmission x-ray source spot size up to three voxels, this creates blurring in the projection. This work takes a simulation approach mimicking such source spot size, and compares systems with horizontal cone-angles (often referred to as the fan angle) of 0.06, 14.36 and 60 degrees. We aim to eliminate this blurring in the reconstruction process. Furthermore, in a high cone-angle geometry, using a reconstruction method that only deconvolves each projection image leads to non-uniform resolution in the reconstruction volume. Alternatively, iterative methods that fully model the non-point source and avoid such artefacts are computationally expensive. We propose a hybrid method that corrects the effect of the non-point source by better modelling the physics rather than just deconvolving each projection image, therefore obtains results closer to the iterative full modelling method, and while being computationally much cheaper.