ESTRO 2025 - Abstract Book

S2586

Physics - Detectors, dose measurement and phantoms

ESTRO 2025

1496

Digital Poster EPIbeam Portal Dosimetry: Commissioning, Validation, and Clinical Implementation of Photon Beam Energy Mohandass Palanisamy, Ashik Muhammed, Monika Shanmugam, Narayanan Radhakrishnan, Mathew Abraham, Narendra Kumar Bhalla, Manishi Bansal, Abhishek Puri Department of Radiation Oncology, Fortis Hospital, Mohali, India Purpose/Objective: EPIbeam (DOSIsoft, USA) is a portal dosimetry software that facilitates patient specific quality assurance (PSQA) using Electronic Portal Imaging Device (EPID) in Elekta™ Versa HD linear accelerator. Objective of this study is commissioning, validation and clinical implementation of EPIbeam. Material/Methods: The measurement was performed using calibrated EPID panel (iViewGT, Elekta, Sweden) at fixed source to detector distance of 160cm. EPIbeam software used for comparing predicted portal image from Monaco™ V6.1.4 TPS with actual EPID image. The commissioning steps such as Calibration, Ghosting, Sagging, dose prediction and verification test were performed on both TPS and EPID system for all photon beams (6,10 & 15MV, 6FFF,10FFF). EPIbeam library model was prepared and validated using different verification fields based on gamma index (GI) 2%,2mm and 3%,2mm as per Dosisoft procedure. The GI was evaluated for 10 Volumetric modulated arc therapy plans using PTW Octavius 1500 2D array and comped with EPIbeam for 3%,2mm and 3%,3mm. Results: The results of commissioning and validation performed for all the photon beams. Similarly, the results of GI (2%,2mm & 3%,2mm) of verification fields for all the photon beams were 99.9%, 100%; 100%, 100%; 100%, 100%; 99.6%, 100%; and 99.4%, 100% for 6MV, 10MV, 15MV, 6FFF &10FFF. The average GI (3%, 2mm & 3%, 3mm) of VMAT plan using PTW 1500 array and EPIbeam were 96.3±0.2, 97.2±0.3; 98.5±0.5, 99.7± 0.6. Conclusion: EPIbeam is an alternative and efficient PSQA tool in terms of high spatial resolution, without phantom, reduced volume averaging effect and less setup time. Moreover, the average GI was higher in EPIbeam as compared to PTW1500 array. 1. Dogan N, Mijnheer BJ, Padgett K, Nalichowski A, Wu C, Nyflot MJ, Olch AJ, Papanikolaou N, Shi J, Holmes SM, Moran J. AAPM Task Group Report 307: use of EPIDs for patient ‐ specific IMRT and VMAT QA. Medical Physics. 2023 Aug;50(8):e865-903. 2. Baek SH, Choi SH, Han MJ, Cho GS, Jang W, Kim JS, Kim KB. Clinical Efficacy of an Electronic Portal Imaging Device versus a Physical Phantom Tool for Patient-Specific Quality Assurance. Life. 2022 Nov 18;12(11):1923. 3. Grein EE, Lee R, Luchka K. An investigation of a new amorphous silicon electronic portal imaging device for transit dosimetry. Medical physics. 2002 Oct;29(10):2262-8. Keywords: EPIbeam, Portal Dosimetry, Commissioning References: