1. Radiation Oncology Department, Hospital del Mar Barcelona, 08003 Barcelona, Spain
2. Facultat de Medicina, Campus del Mar, Universitat Pompeu Fabra, 08002 Barcelona, Spain
3. Radiation Oncology Department, Institut Català d’Oncologia, Hospital Trueta, 17007 Girona, Spain
4. Facultat de Medicina, Campus Centre, Universitat de Girona, 17004 Girona, Spain
5. Radiation Oncology Department, Hospital Universitario Miguel Servet, 50009 Zaragoza, Spain
6. College of Liberal Arts, Texas A&M University, College Station, TX 77843, USA