- Title
- EPID-based dosimetry for remote auditing of radiotherapy clinical trials
- Creator
- Miri, Narges
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2019
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- The objective of this research is to implement a novel approach for remote dosimetric auditing of clinical trials. The audit should ensure an accurate dose delivery at different radiotherapy centres with minimum cost. High variation and complexity of planning and delivery systems may result in discrepancy of dose delivery for the trials. The deliveries are assessed to reduce variability and improve reliability of the trials. The assessment is conducted through rigorous quality assurance (QA) and/or external dosimetric audits. Conventionally, an independent centre performs external audits by site visits or mailing phantoms and dosimeters. This research presents an innovative approach to remotely audit dose deliveries for clinical trials performed at centres in Australia and New Zealand. Participants are provided with CT data sets of two trial patients and two virtual phantoms. They plan the trials for intensity modulated radiotherapy (IMRT) and/or volumetric modulated arc therapy (VMAT) deliveries using local treatment planning systems (TPSs). Then, they send in-air acquired images from their electronic portal imaging devices (EPIDs) to the auditing site. The EPIDs provide relatively consistent data acquisition system for analysis significantly reducing the audit cost. A model was developed using images from aS1200 EPIDs for verification of IMRT dose distribution from deliveries of TrueBeam linacs. The model was based on published methods and a clinically established IMRT QA procedure for Varian C-series linacs. Similarly, an Elekta specific model was developed for deliveries of Elekta systems and the results were compared to those from Varian specific model. Minor improvement was observed for the vendor specific models. The QA method was extended for remote auditing of IMRT/VMAT deliveries. The audit instruction provided benchmark planning exercise of two head and neck (HN) and post-prostatectomy (PP) patients and two flat and cylindrical phantoms for participants. The feasibility of the approach including implementation details was demonstrated over six facilities in a pilot study. Then, the audit results from 30 facilities were used to develop a linear model on explanatory variables. It demonstrated significant influence of TPS-linac, calculation grid resolution and IMRT/VMAT type on the audit outcome. The audit outcome demonstrated high gamma pass rates for the trials and provided results comparable to the established more resource-intensive audit methods.
- Subject
- medical physics; radiotherapy; auditing; clinical trials; VMAT/IMRT; linear accelerator; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1398001
- Identifier
- uon:34381
- Rights
- Copyright 2019 Narges Miri
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 6 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 346 KB | Adobe Acrobat PDF | View Details Download |