Planning your external radiotherapy
The radiotherapy team plans your external beam radiotherapy before you start treatment. This means working out the dose of radiotherapy you need and exactly where you need it. Your planning appointment takes from 15 minutes to 2 hours.
You usually have a planning CT scan in the radiotherapy department.
The scan shows the cancer and the area around it. You might have had other types of scans or x-rays before this appointment to help diagnose or stage your cancer. Your treatment team might also use these scans to plan your radiotherapy. The plan they create is just for you.
To plan the treatment your doctor thinks about:
- your type of cancer
- the position of the cancer in your body
- the size of the cancer
- whether the cancer is close to structures in your body that are sensitive to radiation
- how far the radiation needs to travel into your body
- your general health and medical history
Before your planning starts, your nurse or radiographer asks you to sign a consent form. If you're a woman they check with you that you’re not pregnant and remind you not to get pregnant during treatment. This is because radiation can damage an unborn baby. Very occasionally it can be possible to have radiotherapy if you’re pregnant. But this depends on where you’re having treatment to.
Your planning appointment
You lie on the scanner couch. Your radiographers will tell you if you need to remove any clothes. They need to see the treatment area, but will cover you up as much as possible.
You have to lie as still as you can, so that the measurements are accurate and the radiographers can record your exact position. This means they 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 your radiographers move the couch up and through the scanner. The scanner is a doughnut shape.
Your radiographers leave the room and the scan starts. It takes about 5 minutes. You won't feel anything. Your radiographers watch from the room next door and you can talk to them on an intercom if you need to.
Watch our video about radiotherapy planning, this is just under 3 minutes long.
Dan (radiographer) : Radiotherapy planning will involve you coming for an appointment for a CT scan in the radiotherapy department. The idea behind this is that the doctor needs to work out exactly where needs to be treated and where we need to avoid and so that scan starts us off on that process.
For the CT scan, most of the time no preparation is needed beforehand but if any is then you’ll receive that in a letter so for example, depending on what you having treated there might need to be a contrast agent introduced or you may need to have a full or an empty bladder depending on what is necessary for the scan.There are a number of things we do to help people keep still and make sure the cancer is treated.
It is important that you lie in the same position every time you have treatment. This is to make sure the radiotherapy is directed at the cancer and normal tissues are avoided. We may put equipment in place to fix your position. If you are having radiotherapy for a head and neck cancer you will have a mask made. The mask helps you to keep your head really still during treatment. We also line up the scanner and mark your skin with a felt pen where the light lines from the machine need to be aimed.
They’ll then leave the room and start the scanner and that scan lasts usually about 2 to 3 minutes. Because pen marks can rub easily the radiographer makes them permanent after your scan by tattooing very small marks on your skin.
After the scan the radiographers will give you any information that you need before starting treatment and answer any questions that you’ve got then you are free to go home.
Patient: When I came for the first meeting to plan the treatment. It was a case of having a scan and then lying, remaining on the scan machine and then the technicians took some measurements some dimensions and when they were satisfied that they had the right angles they tattooed me.
Dan (radiographer): The next part of planning is your doctor looking at the scan and marking out on the computer where you need treatment. Once that’s been done a physicist or a dosimetrist will start to plan your treatment. And they use very powerful computers to work out exactly what dose needs to be given and from which directions it needs to come on from.
During radiotherapy planning
Depending on your type of cancer, there are some extra things that your radiographer might do during the planning appointment. They will tell you if there's anything you have to do. For example:
- you might have an injection of dye to help show up certain parts of your body
- you may have wires put on scars or around lumps
- before the scan you may need to drink a liquid containing a dye
- if you are having treatment to your chest area, you may have a barium liquid drink to show up your food pipe (oesophagus) and stomach
- you might need a full or empty bladder
- you might need an enema so you have an empty bowel for the scan
- you might need to hold your breath at certain points during the scan
- you might need to fast for a few hours before the scan so that you have an empty stomach
While planning your radiotherapy, your radiographers may make pin point sized tattoo marks on your skin.
These marks 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.
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 still. Sometimes moulds are made for around the body to help you keep still.
The moulds are made in the mould room or in the CT scanning room.
After your planning session
You might have to wait a few days or up to 3 weeks before you start treatment. During this time the physicists and your radiotherapy doctor (clinical oncologist) decide the final details of your plan.
Then the physicists and staff called dosimetrists plan the treatment very precisely using computers.