IMRT planning Treatment planning CT scans will be required to define target volumes. The treatment planning CT scan should be acquired with the patient in the same position and immobilization device as for treatment. All tissues to be irradiated must be included in the CT scan. MRI or whole body PET/CT scans may be included to assist in definition of target volumes, especially when primary or retropharyngeal nodal disease extends near the base of skull. The immobilization device should include neck and shoulder immobilization. GTV, CTVs, PTVs, and normal tissues must be outlined on all CT slices in which these structures exist.