How radiotherapy is performed

Radiotherapy can be administered in a number of ways. The treatment recommended for you will depend on your individual circumstances.

If radiotherapy is recommended, you'll be referred to a specialist radiotherapydepartment for treatment.

Your treatment team will discusspossible side effectsof radiotherapy with you and you 'll be asked to sign a Consent to treatment form to confirmyou agree to the treatment and understand any risks involved.

Planning your treatment

Your treatment will be carefully planned to ensure the highest possible dose is delivered to the tumour (to maximise the effectiveness of the treatment) while minimising the dose to surrounding healthy tissues.

Your treatment plan depends on:

  • where the cancer is in your body
  • the type and size of the cancer
  • your general state of health

In planning your treatment, your doctor (a radiotherapy specialist or clinical oncologist) will use all the information gathered during your diagnosis. They may also carry out some additional tests to findmore about the size and site of the cancer andget a clearer understanding of the area of your body to be treated.

Once your oncologist has all the relevant information, they'll calculate the total dose of radiotherapy you need and the number of individual doses required.


If you're having external radiotherapy (see below), a simulator machine may be used as part of your treatment planning. The simulator moves in the same way as the machine used for your treatment. It uses X-rays to take pictures soyour treatment teamknows how to position your body when you have treatment.

Most patients have a CT scan to help the oncologist target the tumour accurately. After the scan, the radiographer may put small but permanent ink marks on your skin to ensure the treatment area is targeted accurately each time.

If you're having external radiotherapy to your head or neck, or if it's difficult for you to keep the part of your body having treatment still, a plastic mould will be made for you to wear during treatment. In this case, the ink markings will be made on the mould rather than on your skin.

You can read more about planning external radiotherapy on the Cancer Research UK website.

Courses of treatment

Radiotherapy is usually given as a number of individual treatments delivering a small dose of radiation daily over several weeks.

Most people have five treatments a week (one treatment a day from Monday to Friday), with a break at the weekend. However, in some cases treatment may be given more than once a day or over the weekend.

The course of treatment usually lasts between one and seven weeks.

Theindividual radiotherapy doses are often called "fractions". However, the term "attendances" may be used to indicate how many hospitals visits will be needed during treatment. This term is sometimes preferred because it's possible to have several treatment fractions during one hospital visit.

The number of fractions or attendances required depends on the type of cancer being treated and the aim of treatment. If radiotherapy is used to relieve symptoms, rather than cure the cancer, fewer sessions are usually needed.

External beam radiotherapy

External beam radiotherapy can be delivered using a variety of techniques.

Conventional external beam radiotherapy

Most people receiving radiotherapy have external radiotherapy delivered by a source of radiation outside the body.

External radiotherapy is usually carried out as an outpatient procedure, so you won't have to stay in hospital overnight. However, you may need to stay in hospital if you're having chemotherapy in combination with radiotherapy (chemoradiotherapy), or if you're unwell.

During the procedure, you'll be positioned on a treatment table and a radiotherapy machine (usually a machine called a linear accelerator) directs high-energy radiation at the area being treated.

You'll need to keep as still as possible throughout the treatment, although you can breathe normally. The procedure only takes a few minutes each day and is completely painless.

While you're having treatment, you'll be left alone in the treatment room. A radiographer operates the machine from outside the room and watches you through a window or on closed circuit television. If necessary, you'll be able to talk to the radiographer during the procedure using an intercom.

Intensity-modulated radiation therapy (IMRT)

Intensity-modulated radiation therapy (IMRT) is an advanced type of radiation therapy used to treat cancer and noncancerous tumours. IMRT uses computer technology to manipulate multiple small radiation beams of varying intensities to precisely conform to the shape of a tumour. The radiation intensity of each beam is controlled, and the beam shape changes throughout each treatment.

The goal of IMRT is to distribute the radiation dose to maximize the dose delivered to the tumour while avoiding or minimising exposure of healthy tissue to limit the side effects of treatment.

Image-guided radiation therapy (IGRT)

Image-guided radiation therapy (IGRT) uses a variety of advanced imaging techniques throughout the course of radiotherapy to accurately identify, pinpoint and monitor your tumour for changes. IGRT allows your oncologist to modify the treatment beams during treatment,which increases the chances of the treatment being effective.

Stereotactic radiosurgery (SRS)

Stereotactic radiosurgery (SRS), sometimes known as Gamma Knife radiosurgery, is a highly precise radiation therapy used to treat tumours and other abnormalities in the brain.

Specialised equipment focuses up to 200 tiny beams of radiation to deliver a high dose to the treatment area, usually in one treatment in a single day. During the procedure, your head is placed in a frame to keep it still. The accuracy of SRS results in minimal damage to healthy tissues.

Stereotactic body radiation therapy (SBRT)

Stereotactic body radiation therapy (SBRT) can be delivered on some modern linear accelerators or with a CyberKnife machine.

CyberKnife treatment involves using a small linear accelerator mounted on a mobile arm. This allows multiple radiation beams to be directed at any part of the body from any direction to deliver a high radiation dose to the tumour and, at the same time, limit damage to healthy tissue.

Internal radiotherapy

Sometimes a source of radiation inside the body is used to deliver internal radiotherapy.

Internal radiotherapy can involve a radioactive implant, drink or injection. Depending on the type of treatment being used, you may need to stay in hospital for a short period of time. Radiation emitted by internal radiotherapy is painless, though the procedure to insert the source can sometimes cause mild discomfort.

Radioactive implants

The use of radioactive implants (known as brachytherapy) usually involves the insertion of metal wires, seeds or tubes near the cancerous cells.

These implants are often used to treat areas of the body where an implant can be placed inside the body without surgery. For example, a radioactive implant can be placed in the vagina to treat cervical cancer . In some cases, surgery is used to place an implant near the cancerous cells.

The length of time the radioactive implant is left inside your body depends on the type and nature of your cancer. It could be a few minutes or a few days. In some cases, tiny radioactive implants may be left inside the body permanently.

If you're having a radioactive implant, you may need to stay in hospital for a few days until the radioactive source is removed. After the implant has been removed, you're not a risk to others.

Permanent implants don't present a risk to others because they produce a very small amount of radiation that gradually decreases over time.

Liquid radiotherapy

Liquid radiotherapy involves the use of radioactive liquids, usually to treat thyroid cancer . These can be given either as a drink, an injection into a vein, or an injection directly into the area affected by cancer.

After having liquid radiotherapy, you may be radioactive for a few days. This won't cause any long-term harm to your body, but you'll probably have to stay in hospital as a precautionary measure until the radioactivity decreases.

The radiation dose will be carefully monitored and you'll be able to leave hospital after the radiation has fallen to a safe level. Your treatment team may give you some safety advice to follow for a few days when you get home.

If there's anything about your treatment you don't understand, or if there's anything you're unsure about, you should ask a member of your treatment team to explain it to you in more detail.

You can read more about internal radiotherapy safety on the Cancer Research UK website.

Follow-up appointments

After your course of radiotherapy has finished, you'll have an appointment with your oncologist to check on your progress. The first appointment is often between four and six weeks after treatment finishes.

You may need follow-up appointments for several years, but they'll usually become less frequent as time passes.

Your GP will be sent a report about your treatment. You'll also be able to contact a member of your treatment team if you have any questions after your course of radiotherapy has finished.

Content supplied by the NHS Website

Medically Reviewed by a doctor on 4 Jan 2017