Quantitative analysis: hypoxic fraction determined retrospectively (secondary endpoints and ancillary study). The Gross Target Volume (GTV) will be delineated on FDG PET/CT images using an adaptive method (Vauclin, PMB 2009). The contour of the GTV will be copied onto F-miso PET images after registration. Voxels with a signal to noise ratio greater than 1.2 will be considered as the hypoxic volume.