1. Children′s University Hospital University Hospital (UH) of Tuebingen Tuebingen Germany
2. Department of Radiation Oncology UH of Tuebingen Tuebingen Germany
3. Children′s University Hospital UH of Jena Jena Germany
4. Dr. von Hauner'sches Kinderspital Ludwig‐Maximilians‐Universität Munich Munich Germany
5. Children's University Hospital UH of Essen Essen Germany
6. Clinic for Paediatric Haematology and Oncology University Medical Centre Hamburg‐Eppendorf Hamburg Germany
7. Department of Bone Marrow Transplantation UH of Essen Essen Germany