Received: 9 August 2019
Accepted: 6 January 2020
First Online: 13 January 2020
Ethics approval and consent to participate
: The institutional ethics committee granted an exemption from requiring ethics approval in this study (W19_194 # 19.233; Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands).
: Figures depicting individual person’s data are unidentifiable and there are no details on individuals reported within the manuscript. Therefore, separate consent for publication is not deemed necessary for the figures shown this manuscript.
: A.B. does consultancy work for Elekta and is project leader of several Elekta-sponsored projects outside of this work. This company had no involvement in study design, data collection and analysis, or writing of the manuscript. The other authors have no relevant conflicts of interest to disclose.