1. Department of Radiation Oncology, Proton Therapy Centre, Curie Institute, Orsay, France
2. Department of Radiation oncology, Curie Institute, Paris, France
3. Department of Statistics, Curie Institute, Saint-Cloud, France
4. Department of Radiation Oncology, Pitié-Salpêtrière Hospital, Paris, France
5. Department of Radiation Oncology, Gustave Roussy Institute, Villejuif, France
6. Department of Neurosurgery, Lariboisière Hospital, Paris, France