Calvert, N;
(2016)
Time-of-flight Compton scatter imaging for cargo security.
Doctoral thesis , UCL (University College London).
Abstract
By measuring the time of flight of scattered x-ray photons, the point of interaction, assuming a single scatter, can be determined, providing a three dimensional image of cargo containers. The present work introduces the technique, and provides experimental and theoretical results to show the feasibility of such a technique. Monte Carlo simulations were performed to investigate the proportion of multiple scatter detected using a proposed experimental setup, and it was found that it accounted for almost 50% of the recorded signal. Monte Carlo simulations of a scintillation detector were provided and used to design the detectors used. Experimental measurements at a picosecond length x-ray source resulted in the reconstruction of scatter position of photons interacting in a 5 cm thick test object to an accuracy of 12 cm full width at half maximum. Preliminary experiments were also performed using a conventional commercially available linear accelerator with a pulse length of 170 ns. Deconvolution techniques were applied to the recorded data to estimate the position of scatter. An analytic single scatter forward model was derived from the radiative transfer equation, discretised and the inverse problem was solved using a number of different methods. The alternating direction method of multipliers was adapted for nonlinear problems and provided image quality that was comparable to the gold standard linear method.
| Type: | Thesis (Doctoral) |
|---|---|
| Title: | Time-of-flight Compton scatter imaging for cargo security |
| Event: | University College London |
| Language: | English |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1503664 |
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