Alshammari, Hamed Abdulrzaq T
(2022)
Proof of Concept Study of a
Semiconductor Compton Camera to Be
Used for Prompt Gamma Ray Imaging
During Proton Therapy.
PhD thesis, University of Liverpool.
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201271121_Jun2022.pdf - Author Accepted Manuscript Download (20MB) | Preview |
Abstract
Protons are used in radiation therapy of cancerous tissue as they have the potential benefit of sparing dose to healthy tissue. Given the accuracy of the proton beam range and treatment plan uncertainties, a large safety margin has been used in planning and delivery. Using the prompt gamma (PG) for range verification and the monitoring of dose delivery in real-time is proposed to provide better control of beam direction and reduce currently used safety margins. A gamma-ray imaging system (Gri+) that includes a three-tier semiconductor Compton camera system has been evaluated to assess its potential to image prompt rays emitted during proton therapy. This work has been able to show the imaging capabilities of the Gri+ system for high-energy ray and propose sets of operational recommendations for future measurements in the proton radiotherapy facility. The Gri+ system can successfully image a high-energy -ray of 1.8 MeV for single and multiple interaction events in the system. This significantly increases the Gri+ system imaging efficiency from 27 % to 70 % but degrades the imaging resolution. Using an offline algorithm can mitigate the image resolution degradation. The image resolution was 7.2 ± 0.6 mm and 10.5 ± 0.8 mm for single and multiple interaction events in the system, respectively. The Gri+ system shows a limited count rate capability that can be linked to digitiser cards within the digital data acquisition system. The maximum Compton imaging rate that the Gri+ system could process is 1400 CPS. There is a critical situation where the system loses the ability to process the Compton imaging events at a true count rate of 49k CPS. A collaboration with the manufacturer is recommended to rectify the count rate loss issue and a minor modification to data processing hardware to maximise the operational energy range. A preliminary analysis of the operational environment in a proton therapy delivery room has also been undertaken using data that was available from Clatterbridge Cancer Centre. Results of the work have been used to inform the proposal of a systematic set of data for full evaluation in future work.
| Item Type: | Thesis (PhD) |
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| Divisions: | Faculty of Science and Engineering > School of Physical Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 15 Dec 2022 12:55 |
| Last Modified: | 01 Jan 2024 02:31 |
| DOI: | 10.17638/03166216 |
| Supervisors: |
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| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3166216 |
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