Types of external beam radiotherapy

The way you have your radiotherapy will depend on what type of cancer you have and where it is in the body. There are different types of external radiotherapy:

  • Conformal radiotherapy – shapes the radiotherapy beams to fit the treatment ar-ea.
  • Intensity modulated radiation therapy (IMRT) – shapes the radiotherapy beams and gives different doses to different parts of the treatment area. 
  • Volumetric-modulated arc radiotherapy (VMAT) – the machine moves around the person having treatment.
  • Image guided radiotherapy (IGRT) – uses images taken before your treatment starts, to show the size, shape and location of the tumour.
  • 4D radiotherapy (four-dimensional radiotherapy) – takes images during treatment.
  • Stereotactic radiotherapy – uses lots of small beams to target the tumour.
  • Total body irradiation (TBI) – a single dose of radiation is given to the whole body.
  • Proton therapy – uses proton radiation rather than x-rays.
  • Intraoperative radiotherapy – a single dose of radiation is given when you are having surgery.

Your medical team will decide which type of radiotherapy is most suitable for you.

External radiotherapy

There are different ways of having external radiotherapy. The way you have your treatment will depend on the type of cancer you have, and which part of the body needs treating.


Conformal radiotherapy

This uses a device inside the radiotherapy machine to shape the radiotherapy beams to fit the treatment area.

Conformal radiotherapy is used to treat many types of cancer.


Intensity-modulated radiotherapy (IMRT)

IMRT shapes the radiotherapy beams and allows different doses of radiotherapy to be given to different parts of the treatment area. This means lower doses of radiotherapy are given to the healthy tissue surrounding the tumour, reducing the risk of immediate and long-term side effects. It may also allow higher doses of radiotherapy to be given to the tumour.

Because IMRT can reduce damage to healthy tissue and side effects, it’s often used to treat tumours that are close to important organs or structures. For example, when IMRT is used to treat pelvic tumours, it can reduce the risk of long-term bowel problems.

When it’s used for head and neck tumours, IMRT can reduce damage to the salivary glands and the risk of permanent mouth dryness.

Many, but not all, treatment centres in the UK provide IMRT for people that need it. It’s mainly used to treat breast, head and neck, anal, prostate, bladder, gynaecological and lung cancers. We have more specific treatment information about these types of cancer.

You can find out more about IMRT and whether it’s a suitable treatment for you from your clinical oncologist. They can arrange for you to have IMRT at another treatment centre if it’s not possible for you to have it at your local centre.


Volumetric-modulated arc radiotherapy (VMAT)

VMAT is a newer way of giving IMRT. It is sometimes called RapidArc®. The radiotherapy machine moves around the person while the treatment is being given. This shortens the treatment time, and uses a lower dose of radiation.


Image guided radiotherapy (IGRT)

Before, and sometimes during, a course of radiotherapy, images are taken to make sure the treatment accurately targets the treatment area.

With IGRT, images are taken just before each treatment. This may involve taking x-ray images or moving the machine around you to get an image similar to a CT scan. The images are compared to those taken during the planning scan. They are used to make adjustments to the treatment area, making it very precise.

IGRT is helpful because some tumours can shrink in size, or change shape or position, during or between treatment sessions. For example, the position of a tumour in the prostate gland or cervix can change if you have a full bladder or bowel on the day of your treatment. With IGRT, adjustments are made before each treatment to allow for these changes.


4D radiotherapy (four-dimensional radiotherapy)

This treatment uses a radiotherapy machine that takes pictures or images during your treatment. The pictures show any movement of the tumour. The information from the pictures is used to adjust the radiotherapy treatment area during your treatment. This means that as the tumour moves, it’s possible to make sure it’s fully treated.

4D radiotherapy is particularly helpful for tumours that are in an area of the body that moves during the time you’re having treatment. For example, tumours in the lung that move as you breathe. This treatment is not available in all radiotherapy centres.


Stereotactic radiotherapy

This treatment uses many small beams of radiation to target the tumour. This makes it very precise and able to deliver high doses of radiotherapy to very small areas of the body. This reduces the risk of side effects.

Stereotactic radiotherapy is used to treat a variety of tumours. You may be offered this treatment as part of a clinical trial. This treatment is not available in all radiotherapy centres.

If the treatment is suitable for you, your team will discuss it with you. We have more information about stereotactic radiotherapy.


Total body irradiation (TBI)

This type of radiotherapy is used much less often than other types of radiotherapy. It may be given to people who are having a stem cell transplant as part of their treatment.

TBI involves giving a large single dose, or 6–8 smaller doses, of radiation to the whole body to destroy the cells of the bone marrow. The bone marrow is the spongy part inside some bones and is where blood cells are made.


Proton therapy

Proton therapy is used to treat some cancers. It’s given using a machine that uses proton radiation to kill the cancer cells, rather than x-rays. The proton beam is aimed directly at the cancer, causing little damage to surrounding healthy tissues.

Proton therapy is currently only available to treat tumours of the eye in one UK NHS trust, the Clatterbridge Cancer Centre in Liverpool.

There are plans to have two new proton treatment centres, one in London and one in Manchester, in 2018. Until the treatment is available in these centres, the Department of Health can arrange for people who need this type of radiation to have it in the USA or Europe, paid for by the NHS. Your specialist team will give you more information if proton therapy is suitable for your type of cancer.


Intraoperative radiotherapy

This uses a special machine to give a single dose of radiation in the operating theatre at the time a cancer is removed.

Research is being carried out to see if this type of treatment could be an alternative for women with early breast cancer, who would normally have radiotherapy after surgery.

Back to External beam radiotherapy explained

What is external beam radiotherapy?

External beam radiotherapy is the most common type of radiotherapy. A big machine directs external radiotherapy beams at the affected area.