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%0 Thesis
%A Grozmani, Natalia
%T Measuring parameters determination for multispectral computed tomography
%I Rheinisch-Westfälische Technische Hochschule Aachen
%V Dissertation
%C Aachen
%M RWTH-2025-07888
%P 1 Online-Ressource : Illustrationen
%D 2025
%Z Veröffentlicht auf dem Publikationsserver der RWTH Aachen University
%Z Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2025
%X New or advanced manufacturing processes are characterised by the smaller volumes and greater complexity of individual products. There is, therefore, a need for effective, non-destructive approaches to quality assurance, with computed tomography (CT) acting as one of the key technologies in the context of Industry 4.0. The measurement data obtained with the CT goes beyond individual measurement points, as a resulting CT volume is recorded based on the absorption properties of the particular materials in the assembly. To realise the full potential of CT, process-related challenges must be addressed. These include the reduction of radiation artefacts and the determination of material boundaries, considering the unique properties of multi-material workpieces. The artefacts are the unwanted and unexpected structures on the reconstructed volume that do not correspond to any existing geometrical elements of the acquired part. Even algorithmically predicted CT measurement parameters cannot completely eliminate the influence of artefacts on measurement uncertainty, as these are inherent in the measurement process, e.g. due to the polychromatic nature of an X-ray spectrum. A solution to minimise the influence of the multi-material nature of the measured workpiece is offered by multi-spectral CT (MSP-CT) measurements. The MSP-CT is a repeated CT measurement process of a part with different CT setting parameters, such as voltage, prefilter, or current. The central aspect of the CT parameter variation is the modification of the polychromatic X-ray spectra. The final MSP-CT measurement is typically the result of a subsequent fusion of the individual CT projection pictures. Determining the most advantageous pair of X-ray generator voltages and setting parameters for each of the individual repetitions fused to the MSP-CT volume is the focus of the presented research work. Another focused CT measuring parameter is the orientation of the workpiece in the CT system and its variation during the MSP-CT measurement. Through the development of a novel approach for the determination of the advantageous MSP-CT measurement parameters, a Monte Carlo simulation of the CT system is developed, which can be controlled from a user-friendly web interface. Moreover, a simplified industry-related variation of the validation method is developed as part of the validation process. The validation is performed on two pre-calibrated components, POM-Al-Cube and POM-Steel-Worm. The latter one is an actual industrial component provided through one of the project partners of the institute. The developed simulation is built to incorporate X-ray source or detector simulations as connected modules. Furthermore, adding the reconstruction module will enable the creation of a comprehensive digital twin of the actual CT system. The results of the present research work can be adapted and extended for the successful study of ore rocks or other geological objects. The possible future work is an investigation of the MSP-CT application and a parameterisation without a pre-defined STL model.
%F PUB:(DE-HGF)11
%9 Dissertation / PhD Thesis
%R 10.18154/RWTH-2025-07888
%U https://publications.rwth-aachen.de/record/1018600