All patients receiving radiotherapy need to have a treatment plan. Firstly, the patient is scanned in a computed tomography (CT) scanner. This produces a three-dimensional view of the patient. Some patients will also have special devices made to keep them in the exact same position throughout their treatment. The doctor will draw the location of the tumour on the CT scans, and a team of radiographers and physics staff will produce a treatment plan that maximises the radiation dose to the tumour, and at the same time minimises the dose to healthy parts of the body. The patient may have other types of scan, such as Magnetic Resonance Imaging (MRI) or Positron Emission Tomography (PET) to help the doctor locate the tumour.