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Conformal radiotherapy

Landing page about cancer imageThis page has information about a type of radiotherapy called conformal radiotherapy. There is information about


What conformal radiotherapy is

Conformal radiotherapy is also called 3D conformal radiotherapy or 3DCRT. It is a very commonly used type of radiotherapy.

Conformal radiotherapy uses a specialised planning CT scanner and sometimes other scans, such as MRI scans. This allows the treatment team to plan the radiotherapy treatment area very precisely in 3 dimensions – width, height and depth.


Planning conformal radiotherapy

Planning conformal radiotherapy treatment involves several steps.

You start with a session in the radiotherapy department. You have a CT scan. The 360° photo is of a CT scanner. Use the arrows to look around the room.

You may also have MRI scans or PET scans of the area of the body to be treated. The information from these scans feeds directly into the radiotherapy planning computer.

The computer programme then designs radiation beams that follow the shape of the tumour very closely. They make sure that all of the tumour is inside the radiotherapy field and healthy tissue is avoided as far as possible. This reduces the risk of side effects.

Skin markings

The radiographers may make marks on your skin to make sure the same area is treated at each session.

Moulds and masks

If you are having conformal radiotherapy to your head or neck, you may need to wear a plastic mould during your treatment. You may hear this called a shell or mask. Some types of mask are see through, others aren't. You can have a mould for other parts of the body, such as the breast, limbs and sometimes the whole body.

The mould or mask keeps the treatment area completely still. So your treatment will be as accurate as possible. This also means that you can have any markings you need made on the mask, instead of on your skin.


After the planning session

After the planning session you usually have to wait a few days or up to 2 weeks for the physicist and your radiotherapy doctor to create your treatment plan. You then get an appointment for your first dose of radiotherapy.


Having your treatment

To have the treatment you lie on a radiotherapy couch. The radiographers will help you to get into the right position and put on any moulds that you may need. 

A photo of a linear accelerator, which gives radiotherapy

Once you are in the right position the staff leave you alone in the room. This is so they are not exposed to the radiation. You will be alone for between 15 and 30 minutes. 

The radiographers watch you carefully on a closed circuit television screen. They may ask you to hold your breath or take shallow breaths during the treatment.

You can't feel radiotherapy when you actually have the treatment. It doesn’t hurt but the couch is hard and you may feel uncomfortable. The machine may make a beeping noise from time to time.


Possible side effects

With conformal radiotherapy techniques there is less normal tissue in the field of the radiotherapy than in the past. So the risk of side effects is lower. 

Unfortunately you can still have side effects. As with any external beam radiotherapy, the side effects only affect the part of the body that the radiotherapy treatment is aimed at.


More information about radiotherapy

Look at our general information about radiotherapy.

We have detailed information about

Radiotherapy skin markings

Radiotherapy moulds and masks

Radiotherapy side effects

For general information and support 

Contact the Cancer Research UK nurses on freephone 0808 800 4040 (Open 9am to 5pm, Monday to Friday)

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Updated: 29 February 2016