1. Department of Radiation Oncology, RWTH Aachen University, Aachen, Germany;
2. Department of Radiation Oncology, MediClin Robert Janker Klinik, Bonn, Germany;
3. Department of Urology, RWTH Aachen University, Aachen, Germany;
4. Department of Urology/Neuro-Urology, Friedrich-Wilhelms-University Bonn, Bonn, Germany