Introduction: Magnetic resonance-guided adaptive radiotherapy (MRgART) has the potential to improve treatment processes and outcomes for a variety of tumour sites; however, it requires significant clinical resources. Magnetic resonance linear accelerator (MRlinac) treatments require a daily multidisciplinary presence for delivery. To facilitate sustainable MRgART models, agreed protocols facilitating therapeutic radiographer (RTT)-led delivery must be developed to establish a service similar to conventional imageguided radiotherapy (IGRT). This work provides a clinical perspective on the implementation of a protocol-driven 'clinician-lite' MRgART workflow at one institution. Methods: To identify knowledge, skills, and competence required at each step in the MRgART workflow, an interdisciplinary informal survey and needs assessment were undertaken to identify additional or enhanced skills required for MRgART, over and above those required for conventional cone-beam computed tomography-based IGRT. The MRgART pathway was critically evaluated by relevant professionals to encourage multidisciplinary input and discussion, allowing an iterative development of the RTT-led workflow. Starting with the simplest online adaptation strategy, consisting of a virtual couch shift and online replanning, clear guidelines were established for the delivery of radical prostate radiotherapy with a reduction in staff numbers present. Results: The MRgART-specific skills identified included MRI safety and screening, MR image acquisition, MRI-based anatomy, multimodality image interpretation and registration, and treatment plan evaluation. These skills were developed in RTTs via tutorials, workshops, focussed self-directed reading, teaching of colleagues, and endto-end workflow testing. After initial treatments and discussions, roles and responsibilities of the three professional groups (clinicians, RTTs, and physicists) have evolved to achieve a 'clinician-lite' workflow for simple radical prostate treatments. Discussion: Through applying a definitive framework and establishing agreed threshold and action levels for action within anticipated treatment scenarios similar to those in cone-beam computed tomography-based IGRT, we have implemented a 'clinician-lite' workflow for simple adaptive treatments on the MR-linac. The responsibility for online plan evaluation and approval now rests with physicists and RTTs to streamline MRgART. Early evaluation of the framework after treatment of 10 patients has required minimal online clinician input (1.5% of 200 fractions delivered). Conclusion: A 'clinician-lite' prostate treatment workflow has been successfully introduced on the MR-linac at our institution and will serve as a model for other tumour sites, using more complex adaptive

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Introduction: To audit the dynamic interrelationship between rectal distension at diagnosis magnetic resonance (MRI) scan with the computed tomography (CT) radiotherapy planning scan; to determine the effect of rectal movement on the position of the prostatic gland. This review will examine the efficacy of rectal preparation. At present rectal distension at RT CT planning scan is assessed on control slices using GSTT protocol prior to having a full CT scan. If this is outside tolerance a repeat CT scan appointment whereby the patient is given an enema. If rectal size can be predicted prior to the CT planning scan, bowl preparation can be preempted to ensure efficiencies in the patient pathway. Method: A retrospective audit looking at the MRI diagnostic scans and radiotherapy CT planning scans of 141 patients with adenocarcinoma of the prostate between May to August 2019. To find out if rectal size at MRI serves as an indicator of rectal size at planning RT CT. Dependent on the outcome of the retrospective study, a prospective study will then be undertaken to assess if an intervention prior to RT CT scan such as a prescription of Docusate Sodium enema help resolve the issue of rectal size at planning. Results: Results pending. Conclusions & Discussion: The outcome should inform clinical practice, benefit patients and clinicians and provision of service. The audit may result in reduction of rebooking patients for repeat CT scan and cease the delay of treatment processes.

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