ESTRO 2023 - Abstract Book

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ESTRO 2023

reduce patient treatment time (171 in 2020 versus 141 in 2019, with percentage variation + 21.3%), this trend was confirmed in 2021 for all pathologies, in particular palliative treatment with one fraction reached +54% (267, Figure 2).

Conclusion In the last 3 years, the activity of our radiotherapy department has never stopped. Compared to 2019, our activity has decreased, especially in the first months of 2020. This decrease was mainly related to clinical visits of patients because people were afraid of spreading COVID -19. During 2021, all activities gradually increased, favouring the use of hypofractionated regimens for all pathologies.

PO-1082 Early experience of setting up a Cardiac SABR service and treatment of Ventricular Tachycardia

M. Khan 1 , J. Whitaker 2 , A. Rinaldi 2 , M. O'Neil 2 , S. Ahmad 1

1 Guys and St Thomas' NHS Foundation Trust, Radiotherapy & Oncology, London, United Kingdom; 2 Guys and St Thomas' NHS Foundation Trust, Cardiology, London, United Kingdom Purpose or Objective Cardiac SABR (cSABR) is a new treatment for intractable ventricular tachycardia (VT). Myocardial fibrosis or scarring caused by ischaemic damage gives rise to electrical re-entry and subsequent arrhythmia. Indication for radiotherapy for this benign condition is after conventional treatments have been exhausted. Reported data show up to 90% success rate in termination of VT. The precise mechanism of action is unclear and further pathophysiological studies are underway. Materials and Methods 4 centres in UK are currently offering this treatment. We discuss our experience of setting up the service at our centre and early results. The treatment is available on a compassionate basis and is not a commissioned NHS service. We obtained departmental governance (Cardiology & Oncology) and senior hospital level approval. We developed a partnership with Cardiology colleagues at our Institution to identify suitable patients. Patients are discussed at a virtual UK cSABR MDM that takes place monthly to review each case. We devised a clinical protocol to include clinical indications and patient selection. The protocol specified the planning process and treatment in detail. The finalised process included advice from other centres offering this service and from our personal experiences as a well established SABR site. Patients are immobilised as per standard upper body. A 4DCT scan is acquired with abdominal compression when needed, and IV & oral contrast given. Volumes are contoured on the average dataset derived from all respiratory phases of the 4DCT planning scan. GTV, ITV and PTV are outlined jointly by oncologist and cardiologist as well as OARs including ICD and pacing leads. Using a combination of cardiac CT, 12-lead ECG and electrophysiological mapping data a target for treatment in the ventricle is identified. Patients are planned with a VMAT technique using FFF photons; particular attention is needed to maintain oesophagus and stomach doses remain within tolerance. RPM was used to gate the treatment and AlignRT was used to track the patient’s position.