The Integration of Stereotactic Body Radiotherapy for the Treatment of Localised Prostate Cancer of a 1.5 Tesla Magnetic Resonance Linear Accelerator
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Embargo End Date
2025-07-24
ICR Authors
Authors
Westley, R
Document Type
Thesis or Dissertation
Date
2025-01-24
Date Accepted
Abstract
The MR-linear accelerator (MRL) delivers adaptive radiotherapy under MRI guidance thereby offering the potential to mitigate the errors introduced on other platforms and provide a promising modality for the delivery of prostate radiotherapy in the era of prostate Stereotactic Body Radiotherapy (SBRT). However, as with any new technology ongoing studies examining the clinical and technical data are required to ensure its full potential is reached.
The MOMENTUM repository is an extensive source of real-world data of patients imaged and treated on 1.5T MRL. Interrogation of this data supports the delivery of SBRT to localised prostate cancer on the MRL with low levels of clinician reported toxicities and good patient reported outcomes (PRO). Furthermore, when examining whether overall treatment time (OTT) can be adapted to further decrease toxicity, there is no evidence to support such a concept.
Reducing planning target volumes (PTVs) is an important concept when aiming to decrease the dose to the associated organs at risk (OARs) and potentiate dose escalation to the primary tumour. Cine images taken during the delivery of five fraction SBRT show that PTV margins can be reduced to 3 mm when treating on a 1.5T MRL using the workflow adopted in my centre.
The interim analysis of HERMES, examining the delivery of 2-fraction and 5-fraction SBRT to localise prostate cancer shows that such regimes can successfully be delivered by utilising the MRL. This thesis finds that acute genitourinary toxicity was no worse than that measured in PACE, allowing for recruitment to continue. Analysis of the dose deliver to the targets and OARS in both the 2-fraction and 5-fraction cohort is reassuring suggesting that both schedules are effectively and safely delivered on the MRL.
Finally, the role of MRI guided adapted radiotherapy in the setting of locally relapsed prostate cancer is explored. The literature to data and a detailed case report suggests that re-irradiation with SBRT on the MRL is safe treatment. The resulting guidelines should help to guide future practice.
Citation
2025
DOI
Source Title
Publisher
Institute of Cancer Research (University Of London)
ISSN
eISSN
Collections
Research Team
Uro-oncology Trials