What is external beam radiotherapy?

External beam radiotherapy is a treatment that uses high energy beams to destroy cancer cells. The beams are given using equipment similar to a large x-ray machine. A radiographer operates the machine.

This type of radiotherapy may be used to:

  • Treat and cure the cancer (curative radiotherapy)
  • Control symptoms caused by the cancer (palliative radiotherapy).

Before you have your radiotherapy, you may be asked to take off some of your clothes and wear a gown. The radiographers will put you into the correct position using any marks on your skin (or mask) that have been made. They will make sure you are comfortable.

The radiographers will then leave the room. They will be able to see you and may be able to speak to you through an intercom. The treatment itself takes a few minutes and is not painful.

It’s normal to feel worried about having external radiotherapy. But don’t be afraid to talk to the radiotherapy staff about your worries – they’re there to help.

External radiotherapy

External radiotherapy is the most common way of giving radiotherapy. It is normally given as a series of short, daily outpatient treatments in the radiotherapy department using equipment similar to a large x-ray machine. Several different types of radiotherapy machines are used to give radiotherapy but they all work in a similar way. One commonly used machine is called a linear accelerator (LINAC).

How many treatments you have will depend on whether the aim is to cure the cancer (curative) or to control its symptoms (palliative).

Curative radiotherapy

Curative radiotherapy usually involves having a course of treatments given once a day, often with a rest at the weekends. The treatment may last between 2–7 weeks. Each treatment is called a fraction. Giving the treatment in fractions makes sure that less damage is done to normal cells than to cancer cells. The damage to normal cells is mainly temporary, but this is what causes the side effects of radiotherapy.

Some people may have more than one treatment each day or treatment every day for two weeks, including the weekends. Sometimes treatment may only be given on three days each week – for example, Mondays, Wednesdays and Fridays.

Palliative radiotherapy

Palliative radiotherapy (for symptom control) may be used in a number of different situations. For example, radiotherapy may be given:

  • to one or more bones to help control pain caused by cancer spreading to the bones
  • to the lungs to reduce coughing caused by cancer in the lungs
  • to help control bleeding caused by lung, bladder or skin tumours.

Palliative radiotherapy may involve only one or two sessions of treatment, but it can involve up to 10 sessions. When treatment is given in one or two sessions, it may cause slightly more short-term side effects, such as flu-like symptoms.

Having external radiotherapy treatment

Usually, each radiotherapy appointment takes about 10–30 minutes. The treatment itself only lasts a few minutes and most of the appointment is spent getting you in position and doing checks.

Before your first treatment, the radiographers will explain to you what you’ll see and hear. It’s normal to feel anxious about having your treatment, but as you get to know the staff and understand what’s going on, it should become easier. The sight of large radiotherapy machines can be frightening, especially for children. Don’t be afraid to talk to the staff about any fears or worries you have – they are there to help you, and the more you understand your treatment, the more relaxed you’ll be.

Before your treatment, you may be asked to take off some of your clothes (from the area of your body that needs treating) and to put on a gown. This is so that the radiographers can easily access the marks on your skin that show the treatment area. When the radiographers are ready for you, they’ll position you carefully on the treatment couch and adjust its height and position. This is often called ‘setting up’ and may take a little while. Your radiographers will tell you how long it will take. The radiographers will use the marks (tattoos) on your skin (and your mask, if you have one) to help position you. They will get you in the same position you were in for your planning scan. It’s important that you’re comfortable as you have to lie as still as possible during the treatment. Let the radiographers know if you aren’t comfortable.

The room may be in semi-darkness while the radiographers are setting up. Once you’re in the correct position, the radiographers will leave the room and you’ll be given your treatment. Your radiographers will tell you how long your treatment will take before you start. There will be a camera or a window so they can see you. Many treatment rooms also have an intercom so the radiographers can talk to you while you have your treatment. During each treatment they will watch you from the next room. If you have any problems, you can speak to them through the intercom and they will come in to help you. If there isn’t an intercom in the room, the radiographers will let you know how you can attract their attention if you have a problem. They will also take care to protect your privacy so that nobody else can see you.

Positioning the radiotherapy machine
Positioning the radiotherapy machine

View a large version

Read a description of this image

Some treatment rooms have CD or MP3 players so you can listen to music to help you relax during your treatment. If you’d like to listen to your own music, ask your radiographers if this is possible.

The treatment itself is painless. You may hear a slight buzzing noise from the radiotherapy machine while your treatment is being given. Most curative (radical) radiotherapy involves having treatment from several different directions. This means that during your treatment the radiotherapy machine will automatically stop and move into the new position before your treatment continues. This may happen several times and you’ll need to stay lying still. Occasionally, the radiographers will come into the treatment room to change the position of the machine.

During your treatment, the radiotherapy machine may take images (x-rays or CT scans) of the treatment area as part of the normal treatment process. These are taken to make sure the treatment is given accurately. They may be taken on the first day and again on other days. The radiographers will explain more about this to you.

The radiotherapy machine doesn’t normally touch you, although for some types of skin cancer it may press against your skin. Once your treatment session has finished, the radiographers will come back into the room and will help you off the treatment couch. You will then be able to get ready to go home or back to the ward.

External radiotherapy doesn’t make you radioactive. It’s perfectly safe for you to be with other people, including children, throughout your treatment. It’s also safe to have sex.

Back to External beam radiotherapy explained

Making a radiotherapy mask

During radiotherapy to the head and neck a mask is used to help you keep still so that exactly the right area is treated.

Stereotactic ablative radiotherapy (SABR)

Stereotactic ablative radiotherapy (SABR) is a treatment that uses scans and specialist equipment to precisely target certain cancers. It is usually only suitable for smaller cancers.