 Patients will receive a normal 3D FDG PET-CT scan. By participating in this trial, one extra 4D CT scan will be made. For both the PET and the 4D CT acquisition, the patient gets an abdominal belt around the waist to register breathing motion. No extra FDG PET scan is required for this study. The 4D CT scan is the only intervention which increases the radiation dose exposure compared to the standard PET-CT scan. However, in comparison to the expected radiation dose delivered, if a patient will be treated with curative chemoradiotherapy, this increase in radiation dose is negligible and secondary risks due to this intervention are therefore not increased. For patients who are not eligible for curative treatment the extra dose is also not relevant, given the life expectancy of this group. 