Basta, D; (2017) Increasing robustness, compactness and cost-effectiveness of edge-illumination X-ray phase contrast imaging as a key step towards translation into real-world applications. Doctoral thesis , UCL (University College London).

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Abstract

Novel laboratory implementations of the Edge Illumination X-Ray Phase Contrast imaging (EI-XPCi) method were presented in this thesis, with the aim of facilitating its commercial translation. A portable system, based on compact piezoelectric motors, was developed to enable the easy transportation of the setup. Tests on the system positioning accuracy were presented, and images of standard samples were benchmarked against those obtained with the existing prototype based on stepper motors. An alternative EI implementation, which simultaneously allows the use of cheaper X-ray sources and the realisation of more compact setups, was also presented. An additional ``source mask'' introduced in a standard EI setup allows to section the large focal spot of a conventional tube into multiple sub-sources, creating a corresponding number of spatially shifted images, which need to be disentangled through dedicated algorithms. A proof-of-principle experiment provided results in agreement with simulated predictions, demonstrating the feasibility of the approach. A quantitative study on the dependence of the angular sensitivity on the source-to-detector distance (at constant system magnification, tube settings and total exposure time) was also presented. Results of a simulation based on the assumption of Poisson-distributed noise in the images (valid for photon counting detectors) were compared with experimental ones obtained by using an integrating detector. The observed discrepancies were successfully related to the additional noise sources present in an integrating detector, thus indirectly validating the simulation model. The adaptation of EI with a laser-plasma source was investigated through a proof-of-concept experiment, with the aim of realizing a system providing a synchrotron-like performance with a more compact and accessible setup. Non-ideal experimental conditions affecting the system performance were discussed, while the results of the source characterization were used to establish some basic requirements that must be satisfied to successfully implement EI with these ``new generation'' X-ray sources.

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