Short summary

The aim of this study is to assess the technical feasibility of delivering definitive radiotherapy for cancer in the region of pelvis (prostate, bladder, cervix and rectum) using the MR Linac. In addition acute and late GI and GU toxicity will also be assessed by clinicians and patients. In addition quality of Life (QoL) will be monitored. 

Importance of MR-guided adapted radiotherapy -feasibility study for MR Linac, OUH is a standalone project which sits within a larger collaborative effort between the centres treating on the MR Linac

Rationale

Randomised trials have demonstrated that dose escalated radiotherapy improves outcomes for patients with tumours in the pelvic region such as in the prostate. The use of increasingly conformal techniques, such as step and shoot intensity modulated radiotherapy (IMRT) or more recently volumetric modulated arc therapy (VMAT), has allowed this to be achieved while minimising associated increases in toxicity to surrounding normal structures. The accuracy of any radiotherapy delivery is, however, limited by multiple factors: organ delineation, set up error and inter-/intra-fraction organ motion, rotation, and deformation. 

To allow safe dose escalation, the uncertainties in the treatment target must be mitigated using optimal planning and image-guided radiotherapy (IGRT). In particular, the increasing usage of profoundly hypo-fractionated stereotactic therapy is predicated on the ability to confidently direct treatment precisely to the intended target for the duration of each treatment fraction. 

The use of increasingly sophisticated real time imaging has enabled monitoring of the target and organs at risk (OARs) through treatment delivery and has provided extensive data on their behaviour.  MRI, with its unrivalled soft tissue delineation, has contributed to this data but has not, as yet, emerged as a routine part of daily radiotherapy delivery. The long anticipated arrival of a fully integrated MR-Linear accelerator (MR-Linac) may change this.

The ideal scenario is to be able to adapt the radiotherapy plan to match the daily anatomy and to guide pelvic radiotherapy with MRI, imaging the patient in real time whilst delivering radiotherapy. Such improvement in dose delivery accuracy may have the potential to improve the outcome for the patient. 

Description of the cohort

Patients with cancer in the pelvis referred to Department of Oncology, OUH for definitive radiotherapy.