All diagnostic imaging during treatment and treatment planning will be performed according to national guidelines (as per cancer diagnosis). For the radiotherapy planning, a planning CT scan will be performed in DIBH as well as in free-breathing for each patient. On both scans the gross tumor volume (GTV), the clinical target volume (CTV) which comprises the GTV adjusted for normal tissue, and the planning target volume (PTV) which is the CTV including a planning margin, will be defined. All relevant, healthy organs at risk from radiation exposure will be contoured (e.g. heart, female breasts, lungs, esophagus, thyroid, salivary glands, spinal cord, bone marrow, stomach, spleen, kidneys, liver). A DIBH and a free-breathing radiotherapy plan will be calculated, both with similar planning objectives for the tumor and organs at risk. All DIBH treatment plans will be designed to keep the number of breath-holds per fraction as low as reasonably achievable (including image guidance) for patient comfort.