Understanding RadiotherapyDownload this book (pdf, 1.27 mb)
Internal radiotherapy is only used for certain types of cancer. It delivers radiation close to the tumour, giving a high dose of radiation directly to the cancer while limiting the dose to the surrounding normal tissues. This is given in several ways.
- Brachytherapy - The radioactive sources are placed in the body, close to, or inside the cancer. This is called an implant. The type of implant used depends on the type of cancer you have, and may include seeds, needles, wires, capsules or other devices.
- Radioisotope therapy - This uses radioactive liquid that is taken by mouth as a capsule or given by injection.
Your doctor may recommend internal radiotherapy alone or in combination with external radiotherapy.
How is the implant placed in the body?
The doctor may use an applicator to hold the implant against the surface of the tumour. This may require admission to hospital or it may be done as a day procedure. You may need anaesthetic while the doctor positions the applicators using an imaging test, such as an x-ray, to look at the exact area where they need to go.
The applicators come in different shapes and sizes, and can contain different radioactive materials. Once the applicators are in the right position, the radioactive sources are passed into the applicator by a machine.
How long will it be in place?
Implants can be temporary or permanent. Some implants deliver low doses of radiation; others deliver high doses.
- Temporary implants - These may be in place for 1-6 days before being taken out. You will stay in hospital during this time. In other cases, the implant delivers radiation over a few minutes during several sessions.
- Permanent implants - Seeds or pellets about the size of a grain of rice are left in place permanently to gradually decay. Over a period of weeks or months the radiation level drops but the seeds remain in place with no lasting effect.
Will the implant be painful?
You should not have any severe pain or feel ill during implant therapy. If your implant is being held in place by an applicator, it may be uncomfortable, but your doctor can prescribe medicine to relax you and relieve any pain.
Once the applicator is removed you may be sore or sensitive in the treated area for some time. In some cases, your doctor might suggest that you limit physical and sexual activity for a while.
Will I be radioactive?
While the radioactive applicator is in place, some radiation may pass outside your body. For this reason, hospitals take several safety precautions to avoid unnecessary exposure to hospital staff or your family and friends while the implant is in place. The hospital staff will explain any restrictions to you before you start treatment. These may include the following requirements:
- You may be nursed alone, or in a room away from the main ward.
- Hospital staff will only stay in the room for short periods of time, and visitors may be limited while the implant is in place - children under 18 or pregnant women usually can't enter the room.
- You can use an intercom to talk to hospital staff and visitors.
Once the temporary implant is removed, you are not radioactive and there is no risk to others.
If you have a permanent implant, you will be radioactive for a short while and may need to stay in an isolated room for a few days. You may have temporary restrictions placed on your activities such as being around small children or pregnant women.
- Let the staff know if you feel claustrophobic or lonely.
- Take in reading material and other items to keep you occupied while you're in the single room. You may also be able to watch television or listen to the radio.
This uses radioactive material that is taken by mouth as a capsule or given by injection.
Different radioisotopes are used to treat different cancers, including liver cancer and non-Hodgkin lymphoma. The most common radioisotope treatment is radioactive iodine, which is used to treat thyroid cancer.
This treatment requires a short stay in hospital. During this time you will be in an isolation room while you are temporarily radioactive. The radioactive iodine taken up by the thyroid cells becomes less radioactive each day. Any iodine not taken up by the thyroid cells is passed out of the body in urine, sweat or faeces.
The amount of radiation that is in your body is measured regularly during your hospital stay. Once the radiation level in your body reaches a safe level, you will be able to go home.
There may be some special precautions or care that you need to take for a short while after you are home. Talk to your radiation oncologist or nurse about what to bring to hospital with you, and about any special care that may be required after discharge.
Treating secondary bone cancer
Radioisotopes can be used to treat secondary bone cancer. The radioisotope is injected into a vein and circulates to the area of the cancer in the bone. This is a simple procedure and a hospital stay is usually not needed.
Selective internal radiotherapy treatment (SIRT)
SIRT is a way of delivering high doses of internal radiotherapy to treat liver tumours. It uses tiny pellets called microspheres, which contain a radioactive substance.
The pellets are injected into a thin tube called a catheter, which is inserted into the main artery that supplies blood to the liver (hepatic artery). The radiation from the microspheres damage the tumours' blood supply so the tumours can't get the nutrients they need and shrink. This process is sometimes called radioemobolisation.
Each pellet gives out radiation to a small area. This means normal liver cells should only receive a small amount of radiation. The pellets deliver radiotherapy continuously for 10-14 days. After they have stopped working, the pellets remain in the body permanently but don't cause any problems.