1. Department of Radiotherapy Erasmus MC Cancer Institute, University Medical Center Rotterdam The Netherlands
2. Holland Proton Therapy Center Delft The Netherlands
3. Departement of Radiation Oncology Medical University of Vienna Vienna Austria
4. Departement of Radiation Oncology Centre Antoine Lacassagne Nice France
5. Helmholtz‐Zentrum Berlin für Materialien und Energie Berlin Germany
6. Department of Ophthalmology Charité ‐ Universitätsmedizin Berlin Berlin Germany
7. Paul Scherrer Institute Center for Proton Therapy Villigen Switzerland
8. Institute of Nuclear Physics Polish Academy of Sciences Kraków Poland
9. Department of Radiation Oncology University of Florida Gainesville Florida USA
10. Department of Radiation Oncology Emory Proton Therapy Center Atlanta Georgia USA
11. Department of Radiation Oncology Dalhousie University Halifax Canada