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On-belt Tomosynthesis: 3D Imaging of Baggage for Security Inspection

Kolokytha, S; (2016) On-belt Tomosynthesis: 3D Imaging of Baggage for Security Inspection. Doctoral thesis , UCL (University College London). Green open access

Selina Kolokytha PhD Thesis_redacted.pdf

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This thesis describes the design, testing and evaluation of `On-belt Tomosynthesis' (ObT): a cost-e ective baggage screening system based on limited angle digital x-ray tomosynthesis and close-range photogrammetry. It is designed to be retro tted to existing airport conveyor-belt systems and to overcome the limitations of current systems creating a pseudo-3D imaging system by combining x-ray and optical imaging to form digital tomograms. The ObT design and set-up consists of a con guration of two x-ray sources illuminating 12 strip detectors around a conveyor belt curve forming an 180 arc. Investigating the acquired ObT x-ray images' noise sources and distortions, improvements were demonstrated using developed image correction methods. An increase of 45% in image uniformity was shown as a result, in the postcorrection images. Simulation image reconstruction of objects with lower attenuation coe cients showed the potential of ObT to clearly distinguish between them. Reconstruction of real data showed that objects of bigger attenuation di erences (copper versus perspex, rather than air versus perspex) could be observed better. The main conclusion from the reconstruction results was that the current imaging method needed further re nements, regarding the geometry registration and the image reconstruction. The simulation results con rmed that advancing the experimental method could produce better results than the ones which can currently be achieved. For the current state of ObT, a standard deviation of 2 mm in (a) the source coordinates, and 2 in (b) the detector angles does not a ect the image reconstruction results. Therefore, a low-cost single camera coordination and tracking solution was developed to replace the previously used manual measurements. Results obtained by the developed solution showed that the necessary prerequisites for the ObT image reconstruction could be addressed. The resulting standard deviation was of an average of 0.4 mm and 1 degree for (a) and (b) respectively.

Type: Thesis (Doctoral)
Title: On-belt Tomosynthesis: 3D Imaging of Baggage for Security Inspection
Event: UCL (University College London)
Open access status: An open access version is available from UCL Discovery
Language: English
UCL classification: UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
URI: http://discovery.ucl.ac.uk/id/eprint/1476732
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