1. West German Proton Therapy Centre Essen WPE Essen Germany
2. Faculty of Medicine University of Duisburg‐Essen Essen Germany
3. University Hospital EssenWest German Cancer Center WTZ Essen Germany
4. RaySearch Laboratories Stockholm Sweden
5. Radiation Oncology and Imaging German Cancer Consortium DKTK Heidelberg Germany
6. Technische Universität Dortmund Otto‐Hahn‐Str. 4a Dortmund44227Germany
7. Carl von Ossietzky Universität Oldenburg Oldenburg Germany
8. Department of Particle Therapy University Hospital Essen Essen Germany