ESTRO 2021 Abstract Book

S94

ESTRO 2021

mechanical ventilator S. Parveen 1 , M. Parkes 2 , E. Wingate 3 , B. Shingler 4 , S. Green 5 , Q. Ghafoor 6

1 University Hospitals Birmingham , Radiotherapy Physics , Birmingham, United Kingdom; 2 AMC Amsterdam, Department of Radiation Oncology, Amsterdam, Netherlands Antilles; 3 University Hospitals Birmingham , Radiotherapy , Birmingham , United Kingdom; 4 University Hospitals Birmingham , Radiotherapy, Birmingham , United Kingdom; 5 University Hospitals Birmingham , Medical Physics , Birmingham , United Kingdom; 6 University Hospitals Birmingham , Oncology, Birmingham , United Kingdom

Abstract Text Introduction:

Radiotherapy techniques have developed hugely over the past few decades to enable a more conformal dose to be delivered to the tumour whilst minimising dose to surrounding healthy tissues. Despite these advancements, breathing motion can cause an unwanted deviation between what has been planned and what is actually delivered. What Can We Do To Mitigate This Motion? Motion mitigating practices are well established in radiotherapy but these techniques rely on high levels of compliance and considerable effort from the patient which could make delivery vulnerable to inconsistencies. We looked into a different approach to mitigate breathing motion via the use of a mechanical ventilator. What Can Mechanical Ventilation Do For Your Clinical Practice? Mechanical ventilation addresses the issues surrounding other motion mitigating techniques as it enables us to completely take over the breathing of a conscious un-medicated patient with a non-invasive mechanical ventilator. Parkes et al 2016 demonstrated that it is possible to ventilate cancer patients for up to an hour without any adverse events. This opens up many possibilities for an improved radiotherapy delivery with either: • Regularised breathing motion using ‘slow deep’ or ‘rapid shallow’ forms have been investigated by West et al 2018 and Van Ooteghem et al 2019 . Both conclude these are easy to implement and mechanical ventilation imposes a more stable, reproducible, and predictable breathing pattern. • Mechanical ventilation using 60% O2 for a >5-minute prolonged breath-hold - Parkes et al 2016 demonstrated that cancer patients can be trained to safely hold their breath on average up to 10 times longer than what is currently used in radiotherapy. The next step was to establish the principles of RTT training, these key skills include: 1. Regularised breathing motion during treatment. From our experience, this should take no longer than 1 hour to train RTT’s to perform the task and no longer than 1 minute for individual patients to be trained to undertake the task. 2. Prolonged breath holds >5 minutes during treatment. More in-depth knowledge of the ventilator is required, consequently RTT’s will initially need 1-2 days of familiarisation/training. As there is more information to be absorbed, patients also require longer to be trained ~1-4 hours ( Parkes et al 2016, 2019 ). 3. RTT’s to deliver mechanically regularised ventilation as well as prolonged (>5 minute) breath-holds with mechanical hyperventilation and 60% O2 for routine radiotherapy of chest/abdominal tumours. We followed a ‘simulated’ approach to training, the same as undergraduate RTT’s receive. We did this by working in pairs with one of us leading in ventilating whilst the other was being ventilated. This method of training allowed us to experience ventilation from the patient’s perspective but to also learn the vital skills we needed to gain patient confidence Next, we went on to create a comprehensive step-by-step guide that detailed the whole procedure (from QA to ventilating new patients). The manual is designed to prompt the reader (RTT) to think about what they had just done and why. This satisfied the ‘protocalised’ way that RTT’s are driven in clinical practice. Patient Training: Patients were set up to replicate radiotherapy treatment (figure 1) What Have We Done So Far (Training) Therapy Radiographer (Rtt) Training: