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Regularization approach for tomosynthesis X-ray inspection

 
: Tigkos, K.; Hassler, U.; Holub, W.; Woerlein, N.; Rehak, M.

:

Chimenti, D. ; American Society for Nondestructive Testing -ASNT-, Columbus/Ohio:
40th Annual Review of Progress in Quantitative Nondestructive Evaluation 2013. Vol.33B. Pt.2 : Incorporating the 10th International Conference on Barkhausen Noise and Micromagnetic Testing; 40th NDE, 10th ICBM; Volume 33A and 33B; Baltimore, Maryland, USA, 21-26 July 2013
Melville/NY: AIP Press, 2014 (AIP Conference Proceedings 1581)
ISBN: 978-0-7354-1213-2
ISBN: 978-0-7354-1211-8
ISBN: 978-1-63266-043-5
pp.1793-1799
Annual Review of Progress in Quantitative Nondestructive Evaluation <40, 2013, Baltimore/Md.>
International Conference on Barkhausen Noise and Micromagnetic Testing <10, 2013, Baltimore/Md.>
English
Conference Paper
Fraunhofer IIS ()

Abstract
X-ray inspection is intended to be used as an escalation technique for inspection of carbon fiber reinforced plastics (CFRP) in aerospace applications, especially in case of unclear indications from ultrasonic or other NDT modalities. Due to their large dimensions, most aerospace components cannot be scanned by conventional computed tomography. In such cases, X-ray Laminography may be applied, allowing a pseudo 3D slice-by-slice reconstruction of the sample with Tomosynthesis. However, due to the limited angle acquisition geometry, reconstruction artifacts arise, especially at surfaces parallel to the imaging plane. To regularize the Tomosynthesis approach, we propose an additional prescan of the object to detect outer sample surfaces. We recommend the use of contrasted markers which are temporarily attached to the sample surfaces. The depth position of the markers is then derived from that prescan. As long as the sample surface remains simple, few markers are required to fit the respective object surfaces. The knowledge about this surface may then be used to regularize the final Tomosynthesis reconstruction, performed with markerless projections. Eventually, it can also serve as prior information for an ART reconstruction or to register a CAD model of the sample. The presented work is carried out within the European FP7 project QUICOM. We demonstrate the proposed approach within a simulation study applying an acquisition geometry suited for CFRP part inspection. A practical verification of the approach is planned later in the project.

: http://publica.fraunhofer.de/documents/N-301191.html