@inproceedings{64129,
  abstract     = {{<jats:p>Selecting scan angles such that surface segments are aligned with straight X-ray paths (i.e., rays are tangential to the surface and therefore perpendicular to the local surface normal) is known to produce sharper transitions of those surface segments in the reconstructed volume. This enhances dimensional accuracy in sparse-view computed tomography (CT). However, existing approaches offer no direct means to exploit this criterion for automatic scan-angle optimization. We propose a method that uses a virtual representation of the CT setup, including an STL surface model of the inspected part, to automatically identify taskspecific scan angles. Using elementary vector calculus, the algorithm determines projection directions that generate tangential X-rays for targeted surface segments. To support different levels of geometric complexity, we introduce two variants of the angle-selection procedure. The methods were experimentally validated on two objects with distinct absorption and geometric characteristics. For a steel gauge block, employing the minimum number of task-specific projections required for surface-data completeness substantially outperformed a conventional high-projection scan. For a geometrically more complex test object, surface-related errors were still reduced within the region of interest. The proposed approach – particularly suited for flat surface structures and not accounting for image-degrading factors other than cone-beam artifacts – shows promise for high-throughput dimensional metrology of mono-material parts.</jats:p>}},
  author       = {{Butzhammer, Lorenz and Braun, Matthias Robert Oskar and Herath, Colin and Hausotte, Tino}},
  booktitle    = {{e-Journal of Nondestructive Testing}},
  issn         = {{1435-4934}},
  location     = {{Linz}},
  number       = {{3}},
  publisher    = {{NDT.net GmbH & Co. KG}},
  title        = {{{Higher accuracy with fewer projections? Automated scan angle selection for dimensional Computed Tomography based on a simple data completeness measure for the part surface}}},
  doi          = {{10.58286/32560}},
  volume       = {{31}},
  year         = {{2026}},
}

@article{64861,
  abstract     = {{<jats:p>In-situ computed tomography (CT) experiments on materials with time-dependent mechanical behaviour are affected by relaxationinduced motion, which can lead to image blur and motion-related artefacts if scans are initiated before relaxation-induced motion has subsided. Scan start times are therefore commonly defined based on force relaxation or force-gradient criteria, although these signals do not directly quantify image-relevant specimen motion. In this work, a radiography-based approach is presented to estimate relaxation-induced motion via pixel shifts from projection images acquired prior to CT scans. These projection-based pixel shift estimates of relaxation-induced motion are related to scan-specific image blur observed in the reconstructed volumes. Thereby, a direct link between specimen motion during the scan and CT image quality is established. The method is demonstrated for thermo-mechanically loaded specimens with pronounced temperature-dependent material behaviour, where relaxation-induced motion persists over extended time scales. The results show that projection-based pixel shift estimation provides a physically meaningful and experimentally accessible basis for defining scan start criteria. CT acquisition can be initiated based on an allowable level of relaxation-induced motion, rather than waiting for mechanical equilibrium to be reached. The proposed approach therefore offers a direct, image-related framework for scan timing in in-situ CT experiments on time-dependent materials.</jats:p>}},
  author       = {{Dargel, Alrik and Troschitz, Juliane and Gude, Maik and Kupfer, Robert}},
  issn         = {{1435-4934}},
  journal      = {{e-Journal of Nondestructive Testing}},
  number       = {{3}},
  publisher    = {{NDT.net GmbH & Co. KG}},
  title        = {{{In-situ CT of Viscoelastic Plastic Materials: A Radiography-Based Lead Time Determination for Composite–Metal Joints at Elevated Temperature}}},
  doi          = {{10.58286/32601}},
  volume       = {{31}},
  year         = {{2026}},
}

@article{51192,
  abstract     = {{<jats:p>
Destructive micrograph analysis (MA) is the standard method for the assessment of clinched joints. However, during the joint preparation for the MA, geometric features of the joint can change due to elastic effects and closing cracks. X-ray computed tomography (CT) is a promising alternative to investigate the joint non-estructively. However, if the material properties of similar joining partners are the same, the CT is not able to correctly resolve surfaces in the joint that are close to or pressing onto each other. These surfaces are relevant for the determination of characteristic dimensions such as neck thickness and undercut. By placing a thin, highly radiopaque tin layer between the joining partners, the interfacial area in the reconstructed volume can be highlighted. In this work, a method for the localisation of the tin layer inside the joint as well as threshold value procedures for the outer joint contour in cross section images are investigated. The measured characteristic dimensions are compared with measured values from MA of the same samples and of samples without tin layer. In addition, possible effects of the tin layer on the joining point characteristics as well as problems of the MA are discussed.
</jats:p>}},
  author       = {{Busch, Matthias and Köhler, Daniel and Hausotte, Tino and Kupfer, Robert and Troschitz, Juliane and Gude, Maik}},
  issn         = {{1435-4934}},
  journal      = {{e-Journal of Nondestructive Testing}},
  number       = {{12}},
  publisher    = {{NDT.net}},
  title        = {{{Approach to Determine the Characteristic Dimensions of Clinched Joints by Industrial X-ray Computed Tomography}}},
  doi          = {{10.58286/27519}},
  volume       = {{27}},
  year         = {{2022}},
}