ESTRO 2021 Abstract Book

S1446

ESTRO 2021

Results Initial viability: A qualitative comparison of automated and manually analysed results showed good agreement and demonstrated a time saving benefit. Sensitivity testing: Picket fence leaf offset measured with SunCEHCK Machine 0.58mm (0.5mm expected). VMAT QA – DR+GS first section measured 10.6% lower (9.01% expected), LS measured 2.1% lower (expected 2.01%). Flatness (variance definition) 2.5% (0cm solid water), 2.8% (1cm), 3.0%(2cm), 3.3% (3cm). The measured mean change in symmetry (normalised point difference definition) 0.88% (expected 1%). Field size, mean difference from expected 0.03mm. WL mean measured offset in X, Y, Z 0.81mm (1mm expected). Commissioning: The process described was successful, although bugs were identified and reported. QA templates cannot easily be secured once set up. Although templates can be copied, they lose association, meaning future changes need to be made to all templates. Long Term use: For 12 months the platform has successfully completed all QA across 9 linacs, >95% without intervention. Troubleshooting guides were produced for routine issues e.g. smooth profiles, adjust image registration, etc. SunCHECK Machine has enabled quantitative analysis of imaging tests where previous qualitative analysis was used. Time Saved: SunCHECK machine has saved 22hours and 43mins, per linac, per year. (Details in table) Conclusion The platform provided significant efficiency and quality benefits to the department. The simplifications allow technicians to acquire and manage the QA, rather than physicists. PO-1721 Use of a bolus for skin cancer interventional radiotherapy in absence of model-based algorithms. E. Placidi 1 , A. Napolitano 2 , B. Fionda 1 , F. Greco 1 , P. Cornacchione 1 , D. Cusumano 3 , C. Casà 1 , G. Stimato 1 , V. Lancellotta 1 , S. Teodoli 1 , M. Ferioli 4 , S. Cilla 5 , G. Macchia 5 , G. Kovacs 6 , M.A. Gambacorta 1 , L. Tagliaferri 1 , L. Indovina 1 1 Fondazione Policlinico Gemelli "A. Gemelli" IRCCS, Diagnostica per Immagini, Radioterapia, Oncologia ed Ematologia, Rome, Italy; 2 Bambino Gesù Children's Hospital, Medical Physics, Rome, Italy; 3 Mater Olbia Hospital, Radiation Oncology, Rome, Italy; 4 IRCCS Azienda Ospedaliero-Universitaria di Bologna, Radiation Oncology, Bologna, Italy; 5 Gemelli Molise Hospital - Università Cattolica del Sacro Cuore, Radiation Oncology Unit, Campobasso, Italy; 6 Università Cattolica del Sacro Cuore, INTERACTS, Rome, Italy

Purpose or Objective The aim of this work is to evaluate the introduction of a bolus when treating non-melanoma skin cancer