1. Department of Radiotherapy; Oncorad Garonne, 330 Avenue Marcel UNAL 82000 Montauban France
2. Department of Medical Physics; Institut de Cancérologie de l'Ouest Centre René Gauducheau; 44805 Saint-Herblain France
3. Department of Medical Physics; Centre Eugène Marquis; 35000 Rennes France
4. INSERM UMR 1232; IRS UN; 8 quai Moncousu 44007 Nantes France