This chapter looks at the equipment used to ensure patients are treated in the planned position. Immobilisation is a key aspect of radiotherapy treatment delivery. The position of the patient for treatment must be achievable and reproducible for all subsequent treatment fractions. This equipment ensures the immobilisation devices, and therefore the patient, are at a similar point on the treatment couch for every radiotherapy treatment delivered. The main aim of this is to reduce the occurrence of random set-up errors and improve reproducibility of treatment position throughout the course of radiotherapy. Image quality is a main consideration when deciding modality for radiotherapy planning. Many issues affect imaging quality that need to be considered when deciding on imaging equipment for both pretreatment/planning imaging and on-treatment/verification imaging. The use of a computed tomography scanner in radiotherapy planning is vital for imaging and visualisation of target areas, including surrounding healthy tissue, and also provides dose information required for the planning process.