In external radiotherapy, a machine called a linear accelerator directs radiation at the cancer and surrounding tissue. Different types of machines may be used – some are better for treating cancers near the skin; others are better for cancers deeper in the body.
Your radiation oncologist may use metal blocks to shape the direction of the radiation beams so they overlap the tumour. This is called conformal radiotherapy.
There are some specialised types of external radiotherapy, such as intensity modulated radiotherapy and gamma knife treatment, that are available at only a few hospitals in NSW. Talk to your doctor about more information or call the Helpline on 13 11 20.
Where will I have treatment?
External radiotherapy is usually given in hospital or at a treatment clinic.
If you have to travel to treatment, you may be able to get some practical support, such as accommodation or financial assistance. Speak to the hospital social worker for more information.
How is treatment planned?
Your first appointment at the radiotherapy department will be a planning session. Your treatment must be planned in detail to ensure that enough radiation reaches the cancer but does as little damage as possible to the surrounding tissues.
- Examination: Your radiation oncologist will examine you and may ask for further scans and tests, such as x-rays, CT (computerised tomography) scans or MRI (magnetic resonance imaging) scans, to find out more about your tumour. The radiation oncologist will then decide which part of your body to treat and how much radiation to use – that is, the dose of radiation you will have.
- Simulator: An x-ray machine called a simulator is often used to pinpoint the area of the body to be treated. This is like having ordinary x-rays, but it may take a little longer. You may also have a CT scan, which transfers images of your body to a computer so your doctors can plan your treatment.
- Skin markings:
- The doctor or radiation therapist may mark your skin with permanent tattoos about the size of a pinhead to make sure the radiation is directed at the same place on your body each time. The radiation therapist or doctor will explain the marks and ask your permission before the procedure is carried out.
- Some people have temporary ink marks. This ink will gradually wear off, and it may need to be redrawn periodically during the course of your treatment.
- Moulds and casts: Depending on the type of treatment you receive, you may need support devices to help you stay still during treatment so the radiation is directed at the same place each time. For example, you may lie on a table, sit in a chair, or wear a lightweight cast or mould (sometimes called a bolus) over the treatment area.
What happens during treatment?
- You may be asked to change into a hospital gown before going to the treatment room.
- You will probably be in this room for 10-30 minutes. You will only have radiation for 1-5 minutes, depending on the dose prescribed. The rest of the time is spent positioning you and the treatment machine.
- The radiation therapist will settle you on the treatment table or in a chair, then spend some time getting the machines in the right place and checking the required steps. The therapist may adjust the treatment machine to shield the healthy parts of your body. You may also wear lead shields over parts of your body. Radiation can’t pass through lead.
- Once everything is in place, the radiation therapist will go to a nearby room to turn on the machine. You will be alone in the room, but you can still talk with the radiation therapist through an intercom, and they will watch you all the time on a television screen or through a window.
- The radiation therapist may move you or the machine before repeating the procedure. You will have to stay still, but if you need to re-settle yourself or take a break, the therapist can switch off the machine and resume treatment when you’re ready.
- The linear accelerator machine used for treatment is very large. It may make noises like a vacuum cleaner as it moves around to aim at the cancer from different angles. You can breathe normally during treatment but it is important that you stay very still while the machine is working.
Will I be radioactive?
External radiotherapy does not make you radioactive. It is safe to be with other people during the course of your treatment and afterwards.
Your doctor may recommend that you use a condom or female condom during treatment and for a period of time after treatment finishes. This may be to prevent conception if you are having radiotherapy near your reproductive organs, or it may be to prevent infection.
How long will it last?
Each person needs a specific dose of radiotherapy treatment. While some people need only one or a few treatments, most people need radiotherapy five days a week for 5-8 weeks.
Having many small doses of daily radiation rather than a few large doses helps protect normal body tissues in the treatment area. Weekend breaks allow normal cells to recover. The process of delivering the radiation in a series of small doses over many days is called fractionation. This allows higher doses to be delivered than would be possible if all the radiation was delivered at once.
