Planning your external radiotherapy
This page tells you about planning for external radiotherapy. There is information about
Before you begin your treatment, the radiotherapy team carefully plan your external beam radiotherapy. This means working out how much radiation you need to treat the cancer and exactly where you need it. As cancer cells may sometimes spread into the tissues close to the tumour, your radiotherapy specialist will decide on the exact area to be treated around the cancer. They will also make allowances for possible movement of the tumour during treatment due to breathing or normal movement of body organs.
The radiotherapy planning makes sure that the cancer gets the prescribed dose of radiation while normal body tissues get as little as possible. The area of your body exposed to radiation is called the radiotherapy field. Some normal tissue immediately around the tumour will be exposed to the same dose but your doctors aim to keep this as low as possible to reduce the risk of side effects.
The steps involved in radiotherapy planning vary with the type of cancer and its position in the body.
Your doctor will take into account
- Your type of cancer
- The position of the cancer in the body
- The size of the cancer
- Whether it is close to structures that are sensitive to radiation
- How far the radiation needs to travel into the body
- Your general health and medical history
Sometimes you'll need more than one planning session. It depends on the size and position of the tumour. It's important to feel that you are involved in your treatment. Ask as many questions as you like. Often patients feel that staff are too busy to answer their questions. It's true that they are busy but they are always happy to help. The more you understand your treatment, the easier it is for you to cope.
Your planning appointment may take from 15 minutes up to a couple of hours. You will have a planning CT scan to plan your radiotherapy. The scan shows the cancer and the structures around it.
The 360° photo is of a CT scanner. Use the arrows to look around the room.
You lie on the scanner couch with the treatment area exposed. The radiographers will put some markers on your skin. The markers show up on the scan as bright white dots. Your radiographers use them to position you for your radiotherapy. You have to lie very still so that the measurements are accurate and the radiographers can record your exact position. This record means the radiographer can make sure you are lying in the correct position every time you have treatment. They may need to use some equipment to support you in the right position, such as a chest board, neck rest or arm pole.
Once you are in position the radiographers will move the couch up and through the scanner. The scanner is a doughnut shape. The radiographers will leave the room and the scan starts. It takes about 5 minutes. You won't feel anything. The radiographers watch from the next door room and you can talk to them on an intercom if you need to.
Before the planning appointment you may also have an MRI scan, PET scan or X-rays. This is so that your radiotherapy doctor (clinical oncologist) has as much information as possible about your treatment needs. They can feed the other scans into the planning scanner as part of the planning process.
The radiographer will measure your body size and shape in the treatment area. Sometimes they need to do extra things to get a clear picture of your body structures. For example
- Before the scan you may need to drink a jug of liquid containing a dye that shows up your bladder
- You may have an injection of dye to show up your kidneys
- You may have wires put on scars or around lumps
- If you are having treatment to your chest area, you may have barium liquid to drink to show up your food pipe (oesophagus) and stomach
While planning your radiotherapy, the radiographers may make pin point sized tattoo marks on your skin to make sure they treat exactly the same area every day. They may also highlight the tattoo with pen marks that make it look like a cross. We have information about radiotherapy skin markings.
Moulds or masks
If you are having treatment to your head or neck, you may need to have a mould (shell) made to keep you perfectly still while you have treatment. You may also have a mould if you have to keep an arm or leg perfectly still. The moulds are made in the mould room. We have information about making radiotherapy moulds.
The video below shows you what happens at radiotherapy planning:
View a transcript of the video showing what happens at radiotherapy planning (opens in a new window).
You may have to wait a few days or up to 2 weeks before you start treatment. During this time the physicists and your radiotherapy doctor decide the final details of your plan. Your doctor will plan the areas that need treatment and outline areas to limit the dose to or avoid completely. They call this contouring. Then the physicists and staff called dosimetrists plan the treatment very precisely using advanced computers.
There is also detailed information about the side effects of radiotherapy.
You can phone the Cancer Research UK nurses on freephone 0808 800 4040. The lines are open from 9am to 5pm, Monday to Friday. They will be happy to answer any questions that you have.
Our general organisations page gives details of people who can also provide information about radiotherapy. Some organisations can put you in touch with a cancer support group. Our cancer and treatments reading list has information about books, leaflets and other resources about radiotherapy treatment.
If you want to find people to share experiences with online, you could use Cancer Chat, our online forum.
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