What is radiotherapy (or x-ray treatment/radiation treatment)?

Radiation uses high energy x-rays to kills cancer cells in the area of treatment, but it can also affect normal tissue. Normal tissue recovers better than cancer cells. Radiotherapy is used as part of treatment in about half of patients with cancer.

Why is radiotherapy used?

To cure the cancer

Radiotherapy can be used to cure cancer. It may be used alone, or in combination with surgery, chemotherapy and/or hormonal treatment. It may be used before surgery (to make the tumour smaller) or after surgery to kill any leftover cancer cells.

Sometimes chemotherapy may be given at the same time as the radiotherapy

To relieve cancer symptoms

In patients with cancer that is not curable, radiotherapy may be used to treat pain, improve the patient’s quality of life or extend the patient’s life. This is called palliative treatment.


Planning your treatment


Each patient has an individual treatment plan designed by the team comprised of a radiation oncologist, medical physicist and radiotherapist.

You will need a planning scan before treatment can be planned. This helps your oncologist decide how much radiotherapy you will need. You may need to have contrast (given by mouth or in an injection) to help get a clearer picture from the scan.


You must lie still during radiotherapy to stay in the correct position. If you are having treatment in the head and neck area, a mould may be used to help keep you in the correct position.

Marks on the skin

A small tattoo may also be made on your skin which helps the radiation therapists to position you correctly every day.

There will be a few days to a week between the planning scan and treatment start date. During the planning process the doctor and physicist ensure everything is correct. Any normal tissue receiving radiotherapy is kept to the minimum, and within internationally accepted standards to reduce the risk of side effects.

Types of radiotherapy

External beam

This is the most common type of radiation treatment for cancer. Radiation is produced outside the body by a linear accelerator (linac). These high-energy x-rays, protons or electrons deliver their energy to the area of tumour, killing the cancer cells. Newer technology allows the focused delivery of external beam radiation therapy. This ensures less damage to normal tissues, so doctors can use higher doses of radiation.

External radiation is usually done during outpatient visits to our treatment center. Most people get external radiation therapy in multiple sessions over 5-6 weeks. Sometimes the treatment time is shorter.

When radiation is given for symptom control, sometimes only 1 treatment or a few treatments are given.

Methods of giving radiotherapy

Three-dimensional conformal radiation therapy (3D-CRT) delivers radiation beams from different directions designed to match the shape of the tumor. This helps to reduce radiation damage to normal tissues and better kill the cancer by focusing the radiation dose on the tumor.

Image guided radiation therapy (IGRT) is a form of 3D-CRT where imaging scans (like a CT scan) are done before each treatment. This allows the radiation oncologist to adjust the position of the patient for more accurate delivery of the radiation. IGRT is also useful to adapt the treatment plan where there are anatomical changes, thereby ensuring precise treatment of the tumour and reducing side effects.

Intensity modulated radiation therapy (IMRT) is an advanced form of radiotherapy, where beams are made up of smaller “sub-beams” of different strengths. This gets stronger doses to certain parts of the tumor and helps lessen damage to nearby normal body tissues.

Rapid Arc. With rapid arc the treatment is delivered with a single 360-degree rotation around the patient. This significantly shortens the treatment time, compared to normal treatment time, which improves patient comfort as the time they spend on the treatment couch is much shorter. During a 360◦ rotation a precise sculpted 3-D distribution is delivered. This is made possible by a treatment planning algorithm that simultaneously changes three parameters during treatment, namely the rotation speed of the gantry, the shape of the treatment aperture by using multi-leaf collimator, and the dose delivery.

Gated radiotherapy

This method is sometimes used in areas (like lungs, liver and stomach) where breathing may change the position of the tumour thereby making the delivery of radiation less precise. The treatment scan is done and pictures taken at a specific time during the breathing cycle. During treatment, the beam is only switched on during that same phase of the breathing cycle and so radiation dose to healthy tissue is limited.

Stereotactic radiosurgery isn’t surgery, but a very precise type of radiation treatment that gives a large dose of radiation to a small tumor area, usually in one session. It’s used for brain tumors and other tumors inside the head. A head cast or shell may be used to help keep the patient’s head still. Once the exact location of the tumor is known from brain scans, radiation is sent to the area from many different angles. The radiation is very precisely aimed to affect nearby tissues as little as possible.

Treatment outside the brain is called stereotactic body radiation therapy (SBRT). SBRT may be used for certain lung, spine, and liver tumors.

Although most patients will be given the full radiation dose in one session with stereotactic radiosurgery, it may be repeated if needed. Sometimes doctors give the radiation in several smaller treatments to deliver the same or slightly higher dose. This may be called fractionated radiosurgery or fractionated stereotactic radiotherapy.

How long does external radiation treatment take?

In most cases the total dose of radiation needed to kill a tumor can’t be given all at once. This is because a large dose given one time can cause more damage to nearby normal tissues. This can cause more side effects than giving the same dose over spread out into many treatments.

The total dose of external radiation therapy is usually divided into smaller doses called fractions. Most patients get radiation treatments daily, 5 days a week (Monday through Friday) for 5 to 6 weeks. Weekend rest breaks allow time for normal cells to recover.

Palliative treatment schedules are usually shorter as the dose of radiation is lower. The aim is to relieve symptoms rather than cure the cancer.

What happens during each treatment visit?

The treatment itself is painless and takes only a few minutes. Treatments take 15 to 30 minutes because of the time it takes to set you up in the right position.

External radiation therapy is usually given with a linear accelerator (or linac) which delivers a beam (or multiple beams) of radiation. The machine has a wide arm that extends over the treatment table. The machine can move around the table to change the angle of the radiation, if needed, but it won’t touch you.

Wear comfortable clothes, as you may need to undress and put on a gown for your treatment. You will lie very still on the treatment couch and it may take a little while to set you up in the correct position.

Once you’re in the right position, the radiation therapist will go into a nearby room to operate the machine and watch you on a TV screen. The room is shielded from the radiation so that the therapist isn’t exposed to it. You can talk with the therapist over an intercom. You’ll be asked to lie still during the treatment, but you won’t have to hold your breath.

Will I be radioactive during or after external radiation treatment?

External radiation therapy affects cells in your body only for a moment. Because there’s no radiation source in your body, you are not radioactive at any time during or after treatment.

What are the side-effects of radiotherapy?

Like other cancer treatments, radiation may cause unpleasant side effects, such as overall fatigue, skin irritation, and other local side effects depending on the part of the body being treated.

Every person reacts differently to treatment. Any side effects you might have depend on the type of cancer, location, dose of radiation, and your general health. Some people have no side effects at all, while others have quite a few. There’s no way to know who might have side effects. Before treatment, ask your cancer care team what you might expect.

Radiation therapy can cause early and late side effects.

  • Early side effects happen during or shortly after treatment. These side effects tend to be short-term, mild, and treatable. They’re usually gone within a few weeks after treatment ends.
    • The most common early side effects are fatigue (feeling tired) and skin changes.
    • Other early side effects usually are related to the area being treated, such as hair loss and mouth problems when radiation treatment is given to this area.
    • If your radiotherapy is in the region of your abdomen, you may feel nauseous. This can be managed with medication.
  • Late side effects can take months or even years to develop. They can occur in any normal tissue in the body that has received radiation. The risk of late side effects depends on the area treated as well as the radiation dose that was used.

You will see your doctor weekly during your treatment, so do mention anything that is worrying you.

Here are some general tips:

  • Rest- You may feel more tired than usual. Try to get good, restful sleep at night. Severe fatigue, may last for many weeks after treatment ends. Gentle exercise may help your energy levels.
  • Eat a balanced, healthy diet- Depending on the part of your body getting radiation, your cancer care team may suggest changes in your diet. Patients tolerate treatment better if they can maintain their weight and eat well.
  • Tell your cancer care team about all medicines and supplements you’re taking. Give your team a full list of everything you take and how often you take it, even things like aspirin, vitamins, or herbs.
  • Take care of the skin in the treatment area. If you get external radiation therapy, the skin in the treatment area may become more sensitive or look and feel sunburned.  Keep the skin dry and don’t use perfumed products.

How long do side effects last?

Radiation side effects often start during the second or third week of treatment depending on the prescribed dose and schedule. Most side effects go away within a few months of ending treatment. Some side effects may continue after treatment ends because it takes time for the healthy cells to recover from radiation. If you have bad side effects, the doctor may stop your treatments for a while, change the schedule, or change the type of treatment you’re getting. Tell your cancer care team about any side effects you notice so they can help you with them.