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Biological imaging for adaptive bladder radiotherapy
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Rogers, Jane Ann (2019) Biological imaging for adaptive bladder radiotherapy. PhD thesis, University of Warwick.
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WRAP_Theses_Rogers_2019.pdf - Submitted Version - Requires a PDF viewer. Download (20Mb) | Preview |
Official URL: http://webcat.warwick.ac.uk/record=b3494357~S15
Abstract
Outcomes for muscle-invasive bladder cancer (MIBC) have changed little over recent decades, with long term survival remaining around 50 % [1]. Standard radiotherapy treatment for MIBC involves resection of tumour followed by uniform radiotherapy to the whole bladder, as the residual tumour is not readily visible on conventional computed tomography (CT) imaging. This thesis investigates the use of diffusion-weighted MRI (DW-MRI) to enable a dose-escalated radiotherapy treatment, aiming to improve local control of MIBC.
Geometrical distortion in DW-MRI was investigated via bladder-mimicking phantoms, and positional differences were quantified between DW-MRI, standard T2-weighted MRI, and CT. Deformable registration within a commercial radiotherapy treatment planning system was tested to see whether it could mitigate distortion. All markers were located within a maximum discrepancy of 5 mm (mean 3 mm). Open-source software designed to correct geometric distortion in DW-MRI was tested and produced improved results with a maximum of 1.8 mm (mean 1.3 mm).
Tumours were simulated in 6 locations within the bladder on a CT dataset of a previously-treated MIBC patient. Expansions producing planning target volumes incorporated the findings from the phantom investigations, aiming to mimic the use of DW-MRI registered to CT. Escalated dose distributions were compared against the standard, using established dose-constraints for nearby sensitive organs. Maximum dose-escalations to 70 - 78 Gy were possible depending on tumour location.
Poisson-based tumour control probability (TCP) models were fitted to MIBC trials data for radiotherapy-only and radio-chemotherapy treatments, and used to calculate TCP for all dose distributions. TCP increased 9.0 - 19.2 % depending on tumour location and model used. The feasibility of delivery of the dose distributions was assessed via dose-accumulation using cone beam CT.
This work showed that the use of DW-MRI for planning and pre-treatment imaging of MIBC patients could isotoxically improve local control of MIBC.
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QC Physics R Medicine > RC Internal medicine R Medicine > RC Internal medicine > RC0254 Neoplasms. Tumors. Oncology (including Cancer) |
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Library of Congress Subject Headings (LCSH): | Bladder -- Cancer -- Magnetic resonance imaging, Bladder -- Cancer -- Radiotherapy, Diffusion magnetic resonance imaging, Radiotherapy | ||||
Official Date: | November 2019 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | Department of Physics | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Duffy, J. A. (Jon A.) ; Manolopoulos, Spyros ; Hase, Thomas P. A. | ||||
Format of File: | |||||
Extent: | xx, 171 leaves : illustrations (some colour) | ||||
Language: | eng |
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