- Title
- Comprehensive linear accelerator quality assurance testing for Volumetric Modulated Arc Therapy (VMAT)
- Creator
- Barnes, Michael Paul
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2022
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Prior to the IMRT/VMAT treatment techniques the Quality Assurance (QA) paradigm was one of routine linac QA supplemented by plan specific independent Monitor Unit checks and simple checks of data transfer. With the introduction of IMRT/VMAT treatment techniques the paradigm changed to include a patient specific measurement to ensure acceptable plan deliverability. Whether QA procedures can be improved so that a return to the historical paradigm can be achieved safely such that the need for potentially resource intensive patient specific QA is no longer considered to be a requirement is a contemporary question in Radiation Oncology Medical Physics. A key sub-question is whether routine linac QA can be developed to a high standard such that patient specific QA may no longer be required for this aspect. This thesis aims to answer this sub-question. To do this the linac components relevant to VMAT treatment delivery were identified along with the dynamic systems used to control them. The study was broken into two parts with the first evaluating the Machine Performance Check (MPC) application as a general routine QA program to assure the functionality and performance of each of the identified individual VMAT relevant linac components. MPC was selected for evaluation as it appeared to provide appropriate testing, while for the first time having the associated advantages of being integrated into the linac. Deficiencies of MPC for this study were identified and solutions developed and evaluated such that if implemented then MPC would be considered a suitable tool for VMAT general linac QA. In Part 2 of the study, methodology was developed and evaluated for testing the dynamic control systems used to temporally control the individual components during VMAT delivery. The tests were all time or gantry resolved so that a proper assessment of the time or gantry resolved control systems under assessment could be performed. Such methodologies were first developed for commercial 2D array type devices, before being translated onto the EPID, which would allow the methodologies to also be incorporated into MPC, which would then provide a comprehensive VMAT deliverability QA program within a single application. Deficiencies of the EPID based methodologies were identified and solutions developed and evaluated. It is proposed that MPC with inclusion of the developed time/gantry resolved control system testing and the other developed improvements would provide a routine linac QA program that could be used to assure VMAT linac deliverability performance such that this aspect of patient specific QA is no longer required. Discussion is also presented regarding the other aspects of patient specific QA namely TPS simulation accuracy and data transfer validity so that a complete pathway is described to remove the need for patient specific QA measurements.
- Subject
- linear accelerator; quality Assurance; VMAT; EPID; MPC; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1512062
- Identifier
- uon:56583
- Rights
- Copyright 2022 Michael Paul Barnes
- Language
- eng
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 9 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 268 KB | Adobe Acrobat PDF | View Details Download |