Palakkappilly Alikunju, Rimcy;
(2024)
Innovative, CMOS-based sensor solutions for X-ray detection and dual-energy imaging.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Dual-energy single shot X-ray imaging is a cutting-edge technique that combines the benefits of both dual-energy imaging and single-shot acquisition in medical and industrial radiography. This approach allows for the simultaneous acquisition of two X-ray images at different energy levels in a single exposure, providing valuable information about material composition and density. The ability to perform dual energy in a single shot reduces motion artifacts and improves patient comfort, making it particularly advantageous in dynamic imaging scenarios. This thesis investigates the development of an optimal sandwich detector configuration for dual-energy single shot X-ray imaging that can be effectively used in various applications, including material discrimination (MD) and contrast cancellation (CC). The sandwich detector was designed and built by stacking two complementary metal oxide semiconductor (CMOS) active pixel sensors (APS) on top of each other, separated by an intermediate copper (Cu) filter to obtain the low energy (LE) and high energy images (HE) of the imaged object while utilising RQA5 (70 kV) beam quality as defined by the IEC 62220-1 standards. The sensors, top and bottom, are coupled with scintillators of appropriate thicknesses. The individual layers of the sandwich detector were subjected to detailed x-ray characterisation studies conducted while varying specific detector parameters. The optimal thicknesses of top scintillator and intermediate filter were determined by using a custom-developed dual energy algorithm model for material discrimination based on Azevedo’s SIRZ method, which allowed predicting dual-energy performance for a range of scintillator and Cu filter thicknesses. Finally, the validity of the model was tested experimentally with the developed sandwich detector with 0-, 0.25-, and 0.5-mm Cu filter thicknesses for both the MD and CC applications. This both provided promising results and showed good agreement between the model and experimental results.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Innovative, CMOS-based sensor solutions for X-ray detection and dual-energy imaging |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2024. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL 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 Med Phys and Biomedical Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10194265 |
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