Received: 17 July 2020
Accepted: 31 August 2020
First Online: 10 September 2020
Ethics approval and consent to participate
: This retrospective study was exempt from requiring ethics approval. Bavarian state law (Bayrisches Krankenhausgesetz/Bavarian Hospital Law §27 Absatz 4 Datenschutz (Dataprotection) allows the use of patient data for research, provided that any person’s related data are kept anonymous. German radiation protection laws request a regular analysis of outcomes in the sense of quality control and assurance, thus in the case of purely retrospective studies no additional ethical approval is needed under German law.
: Not applicable.
: CB and SC received speaker honoraria and research grants from ELEKTA AB (Stockholm, Sweden) and C-Rad AB (Upsala, Sweden). The other authors declare that they have no competing interests.