Magnetic resonance guided radiotherapy for the treatment of bladder and pancreatic cancer

Abstract

Magnetic resonance guided radiotherapy (MRgRT) has many postulated benefits over conventional radiotherapy treatment techniques. Its superior soft tissue definition, lack of imaging related ionising radiation and the integration of daily adaptive re-planning offers the potential for improved radiotherapy related outcomes for patients with pancreatic and muscle invasive bladder cancers. However, as with any new technology, robust pre-clinical and early stage workflow studies must be undertaken in order for this potential to be reached. This thesis focuses on pre-clinical research into the use of magnetic resonance imaging (MRI) within the radiotherapy pathway and the development of clinically deliverable MRgRT workflows for use by my institution for the treatment of pancreatic and muscle invasive bladder cancers. The thesis investigates inter-observer MRI based contouring variability within the baldder cancer radiotherapy community and shows how this can be improved through education/guideline creation. Intra-fraction target motion is modelled and suitable treatment margins for use in an online adaptive hypofractionated bladder cancer radiotherapy workflow are recommended. A pilot study shows that MRgRT to the bladder is feasible and well tolerated. the thesis describes the development and evaluation of MRI sequences for use within a pancreatic cancer MRgRT pathway. The feasibility of abdominal compression to reduce intra-fraction pancreatic target motion during an MRgRT fraction is evaluated and found to be both effective and tolerated by volunteers. A hypofractionated, 15 fraction MRgRT protocol for locally advanced pancreatic cancer is proposed utilising mid-ventilation planning techniques to enable personalisation of treatment margins. This work serves as a foundation for MRgRT for bladder and pancreatic cancer patients at the Royal Marsden. It also provides the basis for further work on the development of dose escalated treatments for these two cancer types which will hopefully lead to improved patient outcomes in the future.