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You may be referred to the radiotherapy department if you have cancer and need treatment for this disease. Radiotherapy can also be used for non-cancerous diseases.

About radiotherapy treatment

Having radiotherapy treatment can be daunting if you have never experienced this before, but there is no need to be alarmed as there are lots of people on hand to support you. Don't be afraid to ask questions about any part of the procedure, the staff are there to answer your queries and support you during your treatment.

What is radiotherapy?

Radiotherapy (sometimes called radiation therapy), is when radiation is used to damage and kill cancerous or unwanted cells in the body. The treatment is carefully planned and delivered so that the radiation targets the unwanted cells and avoids the healthy cells as much as possible.

Radiotherapy is sometimes used as the sole treatment, but more commonly it is used alongside other therapies such as chemotherapy and surgery.

What is radiation?

Radiation is simply the transfer of energy from one place to another. Radiation is all around us, for instance, light, radio waves and microwaves are all forms of radiation. We give the different types of radiation different names depending on how much energy the radiation is transferring. Some radiation is harmful to humans and some is not. Radiotherapy uses a type of radiation that transfers enough energy to damage harmful cells in the human body.

The radiation used in radiotherapy can be produced in different ways, for example:

-          In a machine called a ‘linear accelerator’, particles called ‘electrons’ are accelerated to high speed towards a metal target. When they hit the target they have to slow down very quickly and this forces them to release energy in the form of radiation. Magnets and shielding blocks are used to direct the radiation to the right place.

-          The radiation can come from a ‘radioactive material’ this is a material which has excess energy. The material naturally loses this energy over time by releasing radiation.

Why is radiotherapy used?

Radiotherapy treatment may be used for two mainpurposes:

  • to cure the cancer by destroying all of the malignant or harmful cells
  • to relieve the symptoms caused by the cancer and to improve the quality of life.

The choice of radiotherapy treatment depends on a number of factors which the radiotherapy team will consider when planning your treatment:

  • type of tumour
  • extent of disease
  • position of tumour
  • position of other parts of the body in relation to the tumour (especially sensitive structures e.g. spinal cord, kidneys, lens of the eye)


How is radiotherapy delivered?

There are two main ways of delivering the radiotherapy treatment, either directing the radiation from outside the body into the area of the tumour (external beam radiotherapy) or by placing a small source of radiation inside the body close to or within the area where the cancer is located (internal radiotherapy or brachytherapy).

External beam radiotherapy:

External beam radiotherapy is most commonly delivered using a machine called a ‘linear accelerator’ which is sometimes called a ‘linac’ or ‘LA’. A picture of a typical linear accelerator is shown below.

Linear Accelarator

Sometimes, if the treatment area is close to the skin, then a superficial treatment unit will be used. This delivers lower energy radiation that penetrates less deep in the body. 


Brachytherapy can be delivered in a couple of different ways. Sometimes a machine called an ‘after-loader’ is used. A number of tubes will be placed in the treatment area. The after-loader is attached to the tubes and the radioactive source will travel down the tubes into the treatment area in a very precisely controlled manner. Another way in which Brachytherapy can be delivered is when small radioactive ‘seeds’ are implanted in the treatment area.

Which delivery method will I have?

The decision as to which delivery method to use depends on the tumour type and location. The radiotherapy team will make a recommendation as to which treatment they think is most likely to be effective for the particular type of disease. This recommendation will take into account the side-effects of the different treatments. The radiotherapy team will always take into account your personal circumstances and wishes.

What happens during typical radiotherapy treatment?

This is the typical ‘patient pathway’ through a radiotherapy treatment using external beam radiotherapy:

Step 1: Decision to give radiotherapy

Your doctor will decide that radiotherapy is a good treatment option for you. They will discuss this with you and check that you agree. You will be referred to the nearest radiotherapy department that offers the treatment you need. You will normally have an appointment with a ‘radiation oncologist’ who is a specialist doctor trained in prescribing and overseeing radiotherapy treatments. At the appointment you will have the chance to ask any questions you have and to discuss any worries.

Step 2: Imaging

You will get an appointment at the radiotherapy department to have some x-ray images taken on a CT scanner or on a machine called a ‘simulator’. This step in the process is sometimes called ‘simulation’. The staff at the CT scanner or simulator will position you in exactly the same position as you will receive your radiotherapy in. This may involve use of some ‘immobilization devices’ such as cushions and knee rests. These devices are designed to help you lie still and to make sure you lie in the same position for the images as you will for your treatment. Sometimes, if it is important that your arms are in a particular position, you will be asked to hold onto a bar, or you may be asked to put your arms in scoop shaped holders. If you are having treatment to your head or neck you may be fitted with a special plastic mask that will hold your head in the right position. Once you have been positioned correctly, the staff will ask you to lie still and then they will go out of the room while they take some x-ray images. Occasionally, they will give you an injection before they take the images. The injection helps them to see what they want in the images. Usually it only takes the staff a few minutes to take the images. The staff will come back into the room and will take some measurements of you in the treatment position. Sometimes they will make some pen marks on your skin and they will usually make some tiny tattoo marks on your skin. These tattoo marks will be no larger than a freckle. The staff will use the tattoos later on as reference marks to help set you up in the treatment position. They may switch the lights out and use lasers to help them put the tattoos in the right place.

Occasionally you will have special instructions for your CT or ‘simulation’ session. For instance, if you are having treatment to your prostate you may be asked to drink a certain amount of water prior to the session or you may be asked to do something or take something to ensure your bowels are in a particular state. These sorts of instructions can apply to other treatment sites too.

Step 3: Treatment Planning

The images taken in your CT or ‘simulation’ session will be sent to the treatment planning department. The staff there will look carefully at the images and plan how to deliver the radiation. This step can take a few weeks or can be a quick as a few hours depending on the type of treatment you are having.

Normally, one of the first steps in this process is when the radiation oncologist looks at the images and marks on the area he/she wants to treat. They may also mark other areas that they to avoid treating. When they have done this some other specially trained staff will use a computer to plan the radiation delivery. Each patient’s treatment is individually planned and optimised to ensure they are getting the best treatment for their individual shape, size, and disease. Once the treatment plan has been produced, there is a comprehensive checking process where a lot of other staff look at the treatment plan and check that it is suitable.

Step 4: Treatment

Once the treatment plan has been produced and thoroughly checked, the details of the plan are given to the staff who will deliver the treatment. The details of the treatment delivery are different depending on what type of treatment you are having. If you are having ‘external beam radiotherapy’ the treatment will normally be delivered in lots of small parts on different days. These separate parts of the treatment are called ‘fractions’. Depending on what treatment you are having, you could have a treatment with as many as 35 fractions. Normally one fraction will be given each day, so a 35 fraction treatment will last 7 weeks (treatment is often on week days only).

When you go for your treatment, you will be taken into the treatment room and asked to lie in the treatment position. This is usually the same position as you lay in for the imaging session. The radiographers who deliver the treatment may spend a bit of time making sure you are in the right position. Usually they will switch the lights off and check the position of your tattoo marks against some lasers. When they are happy with your position, they will leave the room. No body else will be allowed in the room with you when the treatment is being delivered, but the radiographers will be watching you on TV cameras from outside and there is often an intercom system. They will tell you how to alert them if there is any problem. You should lie still while the treatment is being delivered. Often they will take some x-ray images of you before the treatment is delivered. These images help them check that they have got you in the right position. Sometimes they will have to adjust your position after taking the images. When the radiation is being delivered, the equipment can be a little noisy and there may also be some warning sounds that go off. These alarms are normal and are to warn other people not to enter the room while the treatment is being delivered. The radiographers will tell you what you can expect to hear. Usually the treatment only lasts a few minutes (5-10), so you do not have to be on your own for long. The treatment machine may move around you during the treatment delivery.

Having radiotherapy can be very daunting, and the equipment can look very large to people who have never seen it before. The best thing to do is to try and remain as relaxed as possible and don’t be afraid to ask any questions you may have.

Once you have been for a few treatments, the whole process will begin to feel a lot less daunting. Normally, by the end of treatment most patients will have become good friends with the staff and with the other patients who are treated before or after them!

The delivery of radiotherapy itself does not hurt. Sometimes people find lying in the treatment position a little uncomfortable. Over the course of your treatment you may experience some side effects due to the radiation damaging some of the healthy tissues close to the treatment area. This is unavoidable and staff will have done everything they can to minimise this by producing a good treatment plan, and setting you up carefully every day. The radiographers who deliver the treatment will explain to you what side effects you should expect and will check on a regular basis how you are managing with these. Make sure you tell them if the side effects are causing you a problem or are worrying you. They may be able to give you some medications or creams that can help.

During your treatment you will normally see a radiographer  and/or your clinical oncologist on a weekly basis so that they can also check how the treatment is going.

Step 5: End of treatment

After your course of treatment is finished you will normally have a number of follow-up appointments with your radiation oncologist who will review how the treatment went. They will normally take x-ray images and review the results with you.


Here are some phrases or words that you may hear related to your radiotherapy treatment:

Radiation: Radiation transfers energy from one place to another. There are lots of different types of radiation with different names depending on how much energy is transferred and how it is transferred.

Radioactive Substance: A radioactive substance is a material which has too much energy and looses the energy naturally over time by releasing radiation.

Radiotherapy/Radiation Therapy: Radiotherapy is where we direct radiation towards harmful cells in the body with the intention of killing those cells. The harmful cells are often cancer cells, by radiation therapy can also be used to treat other non-cancerous diseases.

IGRT: This stands for ‘Image Guided Radiation Therapy’. This means that the staff will take x-ray (or other similar) images of you immediately before they treat you. The images help them make sure they have you in the right position and the radiation will target exactly the right spot. They may ask you to move if they don’t think they have you in the right position.

IMRT: This stands for ‘Intensity Modulated Radiation Therapy’. This is a special type of Radiation Therapy where the radiation beams are shaped so that the radiation dose is delivered very precisely to the tumour. IMRT used to be considered to be quite complicated, but in recent years the technology has improved and it is being used for more and more treatments.

VMAT: This stands for ‘Volumetric Modulated Arc Therapy’. This is a type of IMRT where the treatment machine moves continuously round you during the treatment delivery. It has the same ability as IMRT to deliver radiation in highly complex shapes, but VMAT deliveries are usually a bit quicker than IMRT, so they are being used more and more.

Simulation: This is when you are set up in the treatment position and imaged using x-ray imagers or a CT scanner. The images acquired are used to generate your treatment plan. Simulation can sometimes be a few weeks before treatment commences, or can be as little as a few hours before treatment commences depending on the complexity of the treatment.

CT Scan/CAT Scan: This is a ‘computed tomography’ scan or ‘computer assisted tomography’ scan. This is a special type of x-ray scanner which gives the medical staff 3D images of the inside of your body.

PET Scan: This is a ‘ Positron Emission Tomography’ scan. This is when a radioactive substance is injected into you. The substance is attached to special chemicals that will navigate their way to particular places within your body. The medical staff then use a special scanner to take images of the radiation being emitted from your body. The places that the radiation is being emitted from will tell them a lot about what is going on inside your body.

MRI Scan: This is a ‘Magnetic Resonance Imager’. This applies a number of magnetic fields that have an effect on the cells in your body. The scanner can then look at signals your body cells give off and get a very clear picture of the structure of the inside of your body. MRI scanners can be very noisy due to the magnets being switched on and off.

Ultrasound: This is where sound waves are sent into your body and a machine used to capture the reflection of these sounds off of different structures inside your body. The imaging machine can build up a picture of the structures inside your body.

Brachytherapy: This is a type of radiation therapy where radioactive sources are placed inside your body. Sometimes these radioactive sources are implanted permanently (although they are only radioactive for a certain amount of time after they are implanted). Sometimes the radioactive sources are put into your body temporarily and then removed again later.

Afterloader: This is a machine that delivers Brachytherapy. A number of tubes will be put in (or on) your body. The radioactive sources will travel down the tubes in a precisely controlled way. They go back into the machine when the treatment is finished.

Linear Accelerator (linac, LA): This is a machine that delivers ‘external beam radiotherapy’. It accelerates particles called ‘electrons’ down a linear (long straight) guide. The electrons hit a metal target and produce radiation. It is this radiation that is used to deliver radiation therapy.

Treatment Planning: This is when medical staff decide the exact details of how the radiation will be delivered for you radiation therapy. Each patient’s treatment is individually planned so that the radiation is targeted at the harmful cells and avoids as much healthy tissue as possible.

External Beam Radiotherapy: This is when the radiation is generated outside your body and is directed in at the harmful cells.






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