ESTRO 2021 Abstract Book

S431

ESTRO 2021

Conclusion We defined the national guideline for selection of patients with CIED close to target for proton therapy at DCPT. Individual evaluations will be necessary for patients identified as ‘may be possible to treat’. Changing the dose-fractionation scheme from 2.67 to 2 Gy RBE per fraction may be considered for selected breast cancer patients to reduce the amount of SNE since the SNE is proportional to dose per fraction. PH-0547 Quality assurance of Treatment Planning Systems: upgrading the NCS report 15 Y. Jourani 1 , A. Delor 2 , W. Crijns 3 , G. Bol 4 , R.G.J. Kierkels 5 , C.L. Ong 6 , J. Penninkhof 7 , E. van der Bijl 8 , T.A. van de Water 9 , W. Verbakel 10 , D. Schuring 5 , R. Westendorp 11 , J. van de Kamer 12 1 Institut Jules Bordet - Université Libre de Bruxelles, Medical Physics department, Brussels, Belgium; 2 Institut Roi Albert II, Cliniques universitaires Saint-Luc, Radiation Oncology department, Brussels, Belgium; 3 KU Leuven, Radiation Oncology, UZ Leuven, Department of Oncology, Leuven, Belgium; 4 University Medical Center Utrecht, Department of Radiotherapy, Utrecht, The Netherlands; 5 Radiotherapiegroep, Radiation Oncology department, Arnhem/Deventer, The Netherlands; 6 Haga Hospital, Radiation Oncology department, The Hague, The Netherlands; 7 Erasmus MC Cancer Institute, University Medical Center Rotterdam, Radiation Oncology department, Rotterdam, The Netherlands; 8 Radboud University Medical Center, Department of Radiation Oncology, Nijmegen, The Netherlands; 9 Radiotherapy Institute Friesland, Radiation Oncology department, Leeuwarden, The Netherlands; 10 Amstedam University Medical Centers, location VUmc, Department of Radiation Oncology, Amsterdam, The Netherlands; 11 Isala, Department of Radiation Oncology, Zwolle, The Netherlands; 12 The Netherlands Cancer Institute, Radiation Oncology department, Amsterdam, The Netherlands Purpose or Objective Treatment planning (TP) has considerably evolved over the last decades, for example by a growing use of IMRT, VMAT and automated TP. The Netherlands Commission on Radiation Dosimetry (NCS) initiated a subcommittee that focuses on the QA of commercially available TPS with a special focus on new developments. Materials and Methods The NCS subcommittee QA of TPS focused on photon beams and dynamic delivery techniques, with and without flattening filter. The report will consist of the following chapters: • General remarks