The planning target volume (PTV) for the boost will be delineated according to the MAASTRO protocol, by three independent observers (PTV-1A-C), using the planning CT only. Delineation of the boost will be repeated after 3D registration of the pre-operative CT scan with the planning CT-scan (PTV-2A-C). Thereafter, consensus will be obtained for the PTV-1A-C and the PTV-2A-C, resulting in one PTV-1 and one PTV-2 for each patient. Radiation treatment plans (RT-plans) will subsequently be designed for PTV-1 and PTV-2. Coverage of the treatment plans by the 85% isodose for both PTV-1- and PTV-2, and the irradiated volumes (percentage of the volume receiving 95% or more (V95)) will be calculated. Patients will be treated with the treatment plan for PTV-2.