Judith van Loon1, Anne-Marie C Dingemans2. 1. MAASTRO Clinic, Department of Radiation Oncology, GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands. Electronic address: judith.vanloon@maastro.nl. 2. Department of Pulmonary Diseases, GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands.