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Planning treatment

Before you start radiotherapy treatment it will need to be planned. This is an important part of radiotherapy and may take several visits.

Planning helps ensure that enough radiation reaches the cancer but does as little damage as possible to the surrounding healthy tissues and organs.

Planning consists of several steps:

  • Examination—your radiation oncologist will examine you and may request further x-rays or scans to find out more about the cancer. They will then decide which part of your body to treat, how much radiation to use (the dose) and the number of treatments you will have.
  • Planning appointment—your planning appointment may take several hours, but the actual treatment will be much shorter.
  • Simulation—you will be asked to lie still on a table while the radiation therapist uses a special x-ray machine called a simulator to pinpoint the exact area on your body where the radiation beams will be aimed. This is like having an x-ray but may take a little longer. At the same time a radiation therapist will take measurements of you.
    Some simulators use CT (computerised tomography) scans instead of x-rays. A CT scan takes pictures of the cancer from different angles to build up a three-dimensional picture of the area. You will lie in exactly the same position as when you have your treatment. You may also have an MRI (magnetic resonance imaging) scan, PET (positron emission tomography) scan or an ultrasound. The measurements and the information from the scans are fed into a computer that helps the radiation oncologist plan your treatment precisely.
  • Moulds and casts—depending on the type of radiotherapy treatment you receive you may need a special device to help keep an area of your body still during treatment sessions so radiation is directed at the same place each time. For example if you need radiotherapy to the head and neck area you will wear a plastic mask called a shell or cast and markings can be made on the shell rather than your skin. You will be able to hear, speak and breathe normally while wearing the shell but it may feel strange and claustrophobic at first. Tell the staff if you feel worried or anxious as they may be able to offer you strategies to help you cope.
  • Skin markings—to ensure the radiation is aimed at exactly the same position at each treatment session, two or three very small semi-permanent ink marks or tattoos may be placed on the skin. These tattoos are less than the size of a freckle and are too small to be seen easily. If marks are made on your skin ask the radiation therapist if you can wash off the ink or if you need to keep it until your full course of treatment is finished. The ink will gradually fade but it can be redrawn periodically during the course of your radiotherapy treatment.