What is external beam radiotherapy?

External beam radiotherapy is given from a radiotherapy machine outside the body.

This treatment is normally given as a number of short, daily treatments in a radiotherapy department. These are called treatment sessions or fractions. It is given using a machine that looks like a large x-ray machine or CT scanner. There are different types of radiotherapy machine. The most commonly used machine is called a linear accelerator (LINAC).

External beam radiotherapy

You usually have external beam radiotherapy as an outpatient. The number of treatment sessions you have will depend on the type of cancer you have and the aim of the treatment. Your doctor, radiographer or nurse will explain the treatment plan to you. This includes how many treatment sessions you will have, and when you will have them.

Types of external beam radiotherapy

There are different ways of having external radiotherapy. How you are given your treatment will depend on:

  • the type of cancer you have
  • the part of the body that needs treating.

Your clinical oncologist or radiographer can tell you more about these treatments and whether they are suitable for you. If a type of radiotherapy is not available at your local hospital, they may arrange for you to have it at another treatment centre.

  • Conformal radiotherapy

    Many types of external beam radiotherapy are conformal. This means the beams are specially shaped to fit the treatment area. Conformal radiotherapy can be used to treat many different 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. 

    This can help reduce the risk of side effects and late effects. It may also allow higher doses of radiotherapy to be given to the tumour. IMRT is often used to treat tumours that are close to important organs or structures. This is because it may reduce damage to healthy tissue and side effects. 

    Many treatment centres in the UK provide IMRT. It is mainly used to treat breast, head and neck, anal, prostate, bladder, gynaecological and lung cancers.

  • Volumetric-modulated arc radiotherapy (VMAT)

    VMAT is a newer way of giving IMRT. It is sometimes called RapidArc®. The radiotherapy machine moves around you and reshapes the beam during treatment. This makes it more accurate and shortens the treatment time.

  • Image guided radiotherapy (IGRT)

    IGRT uses the pictures from scans taken before, and sometimes during, each treatment. The pictures are compared to those taken during the planning scan to check your position and the treatment area. 

    IGRT is helpful for treating tumours in areas of the body that change shape or position during or between treatment sessions. IGRT means the radiographers can adjust the treatment area before each treatment. This makes the radiotherapy very precise.

  • 4D radiotherapy (four-dimensional radiotherapy)

    4D radiotherapy uses a radiotherapy machine that takes pictures during your treatment. The pictures show any movement of the tumour. The radiotherapy team use the information from the pictures to adjust the radiotherapy treatment area during your treatment. 

    4D radiotherapy is helpful for treating tumours in areas of the body that move during treatment. This treatment is not yet available in all radiotherapy centres. 

    There are other ways to help reduce movement in the treatment area. Your radiographer may show you some breathing techniques. Or they may use gentle compression on your tummy area, depending on where you are having treatment. They will do this during planning and treatment. It helps to reduce movement in the area being treated. This allows them to treat the area more accurately.

  • Stereotactic radiotherapy

    Stereotactic radiotherapy uses many small beams of radiation to target the tumour. This makes it very precise. It means high doses of radiotherapy can be given to very small areas of the body. This can reduce the risk of side effects. 

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

  • Total body irradiation (TBI)

    TBI treatment is when a large single dose of radiation, or 6 to 8 smaller doses, is given to the whole body. This type of radiotherapy is not used very often. It is sometimes given to people who are having a stem cell transplant.

  • Proton beam therapy

    Proton beam therapy uses proton radiation rather than x-rays to destroy cancer cells. Proton beams can be made to stop when they reach the area being treated. This is different to standard radiotherapy beams, which pass through the area and some healthy tissue around it. Using proton beam radiotherapy may help to reduce side effects and the risk of long-term effects.

    Proton beam therapy is only suitable for a small number of people.

  • Intraoperative radiotherapy

    Intraoperative radiotherapy is when a single dose of radiation is given during surgery to remove a cancer. It is given in the operating theatre. 

    This treatment is still being researched and may only be available as part of a research trial. It may be an option in some situations. For example, it may be used for women with early breast cancer who would normally have radiotherapy after surgery.

Why am I having external beam radiotherapy

You may have external beam radiotherapy for different reasons:

Radiotherapy to cure the cancer (curative or radical radiotherapy)

The term radical radiotherapy is used when doctors are hoping to cure the cancer. It usually involves having several treatment sessions. This is called a course of treatment.

You usually have one session of radiotherapy a day, often with a rest at the weekends. Some radiotherapy departments give treatment at the weekend. This means you would have rest days during the week instead. For certain types of cancer, treatment is given up to 3 times a day.

The treatment may last between 1 and 8 weeks.

Giving the treatment in several sessions means that normal healthy cells have time to recover between treatments. You may have curative radiotherapy:

Radiotherapy to treat symptoms (palliative radiotherapy)

Palliative radiotherapy may be used to help shrink the cancer and to control symptoms. For example, you may have it to help:

  • control pain caused by cancer that has spread to the bones
  • reduce coughing caused by cancer in the lungs
  • control bleeding caused by certain types of tumour.

If you are having palliative radiotherapy, you may have 1 to 2 sessions of treatment. Sometimes you may have a course of up to 10 to 15 sessions. For some types of brain tumour, it can be up to 30 sessions. How many treatment sessions you have depends on your situation and the type of cancer you have.

How is external beam radiotherapy given?

Treatment sessions

Usually, each radiotherapy appointment takes about 10 to 30 minutes, although you may be in the department for longer. The treatment itself usually only takes a few minutes. Most of the appointment is spent getting you into the correct position and checking your details.

Before your first treatment, the radiographers explain what you will see and hear. It is normal to feel a bit nervous about having your treatment. But, as you get to know the staff and understand what to expect, it usually gets easier. You can talk to the staff about any worries you have.

Positioning you for treatment

Before your treatment, the radiographer may ask you to change into a hospital gown. This is so they can easily reach the marks on your skin that show the treatment area.

The radiographers help you onto the treatment couch and position you carefully. They also adjust the height and position of the couch. They will talk you through what they are doing.

The radiographers look at the marks on your skin (or on your mask or mould, if you have one). This is to help get you in the same position you were in for your planning scan. They help you arrange your clothes or gown so that the area of your body being treated is bare. They are careful to protect your privacy so that nobody else can see you.

It is important that you are comfortable, as you have to lie as still as possible during the treatment. Let the radiographers know if you are not comfortable. The room may be quite dark to help the radiographers while they are getting you into the correct position.

Your radiographers will tell you how long your treatment will take. When you are in the correct position, they leave the room and you are given your treatment. There is a camera, so they can see you from outside the room. There is usually an intercom, so you can talk to them if you need to during your treatment.

During treatment

The radiotherapy machine does not usually touch you. But if you are having radiotherapy for some types of cancer, it may gently press against your skin.

The treatment itself is painless. You may hear a slight buzzing noise from the radiotherapy machine while you are having the treatment.

Some treatment rooms have music players, so you can listen to music to help you relax. If you would like to listen to your own music, ask your radiographers if this is possible.

Most curative (radical) radiotherapy involves having treatment from several different directions. To do this, the radiotherapy machine may move around you into different positions during your radiotherapy. This may happen several times and you will need to stay lying still. Sometimes, the radiographers will come into the treatment room during your treatment to change the position of the machine.

The radiotherapy machine may take pictures (x-rays or CT scans) of the treatment area during your treatment. They may be taken on the first day and again on other days. These pictures are used to help make sure the treatment is given accurately. They are not used to show how well treatment is working, as treatment takes time to work.

After the treatment session

Once your treatment session has finished, the radiographers will come and help you off the treatment couch. It is important to wait until they tell you it is okay to move. Then you can get ready to go home, or back to the ward if you are having treatment as an inpatient.

External beam radiotherapy does not make you radioactive. It is safe for you to be with other people, including children, throughout your treatment. It is also safe to have sex. 

We have more information about relationships and sex.

Getting support

Macmillan is here to support you. If you would like to talk, you can do the following: