Magnetic Resonance Imaging (MRI) guided radiotherapy for the treatment of locally advanced non-small cell lung cancer
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Embargo End Date
2026-07-28
ICR Authors
Authors
Shiarli, A
Document Type
Thesis or Dissertation
Date
2025-07-28
Date Accepted
Abstract
The use of Magnetic Resonance Imaging (MRI) in radiotherapy (RT) offers significant advantages over Computed Tomography (CT), including superior soft tissue contrast and the opportunity of daily treatment adaptation. For the radical RT or chemoradiotherapy (CRT) treatment of locally advanced non-small cell lung cancer (NSCLC), MR-guided RT (MRgRT) has the potential to enhance the accuracy of RT delivery, reduce treatment-related toxicity and enable treatment intensification. However, the MRgRT workflow in locally advanced NSCLC on MR-guided systems, such as the Unity MR-Linac, is still not fully implemented. MR-guided RT in the thoracic region presents unique challenges including limited clinician experience with target delineation on MRI, suboptimal MR image quality in the thorax, and complexities in dosimetric calculations due to the inherent physiological characteristics of the thorax.
This thesis explores key stages of the MRgRT online workflow for locally advanced NSCLC using the Unity MR-Linac.
In the first section I focus on clinician training on Gross Tumour Volume (GTV) delineation on thoracic MRI. I present the first contouring study to assess interobserver variability (IOV) in GTV delineation, which led to the development of the first international consensus guideline document for GTV contouring in locally advanced NSCLC on MRI. The impact of this guideline document was evaluated through a second contouring study after its circulation.
In the second section I investigate the selection of an optimal thoracic MRI sequence, acquired on the MR Linac, for integration into the MRgRT workflow. I then compare this MRI sequence to Cone Beam CT (CBCT), the imaging standard for Image Guided Radiotherapy (IGRT) on the CT-Linac, in terms of image quality and image registration to the CT planning scan.
Finally, I assess the dosimetric accuracy of using the method of bulk electron density (ED) assignment to generate synthetic CT scans for creating clinically acceptable RT plans for locally advanced NSCLC, on the Unity MR-Linac.
This research work provides critical insights towards implementing the clinical workflow for MRgRT for locally advanced NSCLC, addressing key challenges and paving the way for improved RT treatment strategies.
Citation
2025
DOI
Source Title
Publisher
Institute of Cancer Research (University Of London)
ISSN
eISSN
Collections
Research Team
Radiother Phys Modelling