1 Department of Radiation Oncology, Hospital Universitario HM Sanchinarro, Madrid, Spain.
2 Department of Radiation Oncology, Complejo Hospitalario Universitario de Albacete, Albacete, Spain.
3 Department of Radiotherapy and Oncology, Universitätsklinikum Frankfurt am Main, Frankfurt am Main, Germany.
4 Department of Radiation Oncology, Universitätsklinikum Erlangen, Erlangen, Germany.
5 Department of Radiation Oncology, Strahlenzentrum Hamburg, Hamburg, Germany.
6 Department of Radiation Oncology, Hospital Universitari Sant Joan de Reus, University of Rovira i Virgili, Tarragona, Spain meritxell.arenas@gmail.com.