Specialised external radiotherapy techniques
Specialised techniques of external radiotherapy may be used to treat certain cancers.
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Many radiotherapy departments now use a technique known as conformal radiotherapy. Conformal radiotherapy uses the same radiotherapy machine as normal radiotherapy treatment. However, inside the machine is a device called a multi-leaf collimator, which allows the beam of radiation to be shaped very precisely so that it ‘conforms’ to the area of the cancer. As a result, the healthy surrounding cells and nearby structures receive a lower dose of radiation, so the possibility of side effects is reduced.
Conformal radiotherapy may be used to treat a number of different cancers, including cancers of the head and neck, prostate, gullet (oesophagus), some types of lung cancer, breast cancer and brain tumours. It is especially useful if the tumour is close to important organs or structures in the body, because high doses of radiotherapy can be given with minimal risk to the healthy tissue.
Although conformal radiotherapy is commonly used to treat some types of cancer, research is being carried out to see whether it can help to control other types of cancer better than standard radiotherapy, and cause fewer side effects. Your cancer specialist can tell you if conformal radiotherapy would be suitable in your situation.
Intensity-modulated radiotherapy (IMRT)
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High-resolution intensity-modulated radiotherapy, which is sometimes called three-dimensional IMRT (3D IMRT) also uses a multi-leaf collimator. During this treatment, parts of the multi-leaf collimator are moved while the treatment is given. This enables the treatment beams to be shaped very precisely and allows the dose of radiotherapy to be altered in different parts of the treatment area. Again, the aim is to reduce the side effects of treatment.
Total body irradiation (TBI)
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This type of radiotherapy is used much less often than other types of radiotherapy, but may be given to people who are having a stem cell transplant as part of their treatment.
A large single dose, or 6-8 smaller doses, of radiation is given to the whole body to destroy the cells of the bone marrow. Very high doses of chemotherapy are also given. The treatment is followed by giving stem cells (cells that develop into white blood cells, red blood cells and platelets) by a drip into a vein, to replace the bone marrow that has been destroyed.
This type of radiotherapy is described in our section about stem cell and bone marrow transplants.
Proton therapy can be used to treat cancers affecting the back of the eye, such as melanoma. It is given using a machine called a Cyclotron. The cyclotron uses proton radiation rather than x-rays to kill the cancer cells. The proton beam is aimed directly at the cancer and causes very little damage to surrounding healthy tissues.
Some very rare cancers, such as tumours affecting the base of the skull or the spine, can be treated with high-energy proton therapy. There are plans to develop this treatment in the UK, but it is not currently available. However, the Department of Health can arrange for people who need this type of radiation to have it at centres in the USA or Europe, paid for by the NHS.
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This treatment involves the use of many beams of radiation, each giving a low dose to the tumour. This is used instead of normal treatment that uses just one or a few beams of radiation giving much higher doses.
Again, the aim is to give a high dose of radiation to the cancer but a low dose to normal tissues, reducing side effects. There are also claims that the treatment targets the cancer more accurately than normal radiotherapy. The treatment is given by special types of radiotherapy machines, such as the CyberKnife® and Gamma Knife®. There are very few of these machines in the UK, and research is underway to see if they do offer any advantage over normal treatment.
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This uses a special machine to give a single dose of radiation in the operating theatre at the time a cancer is removed. A recent clinical trial has suggested this could be an alternative for women with early breast cancer who would normally have a course of radiotherapy over several weeks following surgery.
At the moment it’s only available at one hospital in the UK and it’s uncertain whether it will become more widely available in the future.