2 Department of Radiation Oncology, Oncology Institute of Southern Switzerland, Bellinzona 6500, Switzerland; Università della Svizzera Italiana, Lugano, Switzerland.
3 Department of Radiation Oncology, Oncology Institute of Southern Switzerland, Bellinzona 6500, Switzerland; Università della Svizzera Italiana, Lugano, Switzerland; Faculty of Medicine, Geneva, Switzerland. Electronic address: thomas.zilli@eoc.ch.