How Radiotherapy works
Radiotherapy is a way of treating or managing cancer using radiation. It works by damaging cells in the area being treated. Normal cells are able to repair this damage, but cancer cells can’t and are destroyed.
Cancer patients will be given radiotherapy for different reasons and for some patients it is the only treatment that they require.
Radical radiotherapy is used to try to get rid of cancer cells completely. The radiotherapy is given in small doses five days a week, often for four to five weeks.
Types of Radiotherapy
Prophylactic radiotherapy is given to stop cancer coming back in the same area after surgery and to reduce the risk of the cancer spreading (metastasising) to other organs. The radiotherapy is given in small doses five days a week for several weeks.
Palliative radiotherapy is used when cancer can’t be cured and is given to treat symptoms from cancer or to control the growth of the cancer. It is given in a single dose or a few doses over a much shorter period of time.
Method of Radiotherapy
External Beam Radiotherapy (Teletherapy)
Radiotherapy can be given as teletherapy (also known as external beam radiotherapy), when a beam of radiation is aimed at the area to be treated from a machine located away from the patient.
High or Low-Dose Brachytherapy
Other forms of radiotherapy are high or low-dose brachytherapy, which involves a radioactive source being placed on or in a tumour.
Radiotherapy Treatment Planning
All patients who are to have radiotherapy need individually tailored treatment so it is given accurately. A lot of information is needed so the doctor can target the tumour while minimising damage to the healthy tissue. This is called treatment planning and there are a number of ways of doing this.
Simulator planning is done using a specialised x-ray machine that can do the same things as the treatment machines except deliver treatment. The simulator allows the doctor to carefully look at the area that needs treatment and plan it precisely. During the planning, the radiographer will draw some marks on the skin using a pen; when the doctor and radiographer are happy they have an accurate plan, the radiographer may need to make two to three permanent marks called tattoos. These tattoos are the size of a pinhead and are used to ensure the radiotherapy is given to exactly the right place.
ACQSIM planning is done using a scanner. Some patients may need to have an intravenous injection before the scan to show up the area to be treated better. The scan usually takes about 15 minutes and the information from the scan is used to produce a treatment map. Sometimes it’s necessary to take some x-rays and measurements to check the treatment map and this is done on the simulator.
What Radiotherapy Involves
When radiotherapy treatment is being given by external beam radiation, it’s important the patient is in exactly the same position each time. The radiographers will often use pillows and wedges to make sure the patient is comfortable and in the correct position.
Patients having radiotherapy to the head or neck area may need to have a mould made to keep them in the right position. Moulds are made from clear Perspex after a plaster cast has been made of the head and neck. Once the Perspex mould has been made, the radiotherapy is planned while the patient is wearing the mould and marks are drawn on the mask instead of the skin.
Once the radiographers are happy that the patient is in the correct position they will leave the room to switch the treatment machine on. When the machine is on it makes a buzzing noise. The radiographers watch closely on a television screen. Treatment only lasts a few minutes and does not hurt.
Radiotherapy Side Effects
Side effects are different depending on the part of the body being treated. Most side effects are temporary but some may continue for weeks or months after treatment is finished. They include:
- Hair loss (alopecia)
- Cerebral oedema (excess fluid accumulating in the brain) can cause changes in mental state, restlessness, irritability, impaired pupil reactions, headache, increase in blood pressure, decrease in pulse and respiration, and nausea
- Dry or sore mouth or throat, changes in taste sensation, skin thickening
- Inflammation of the gullet, indigestion, nausea, lung inflammation
- Nausea and vomiting, diarrhoea, cystitis
- Sexual dysfunction. In males treatment of the abdomen area can cause impotence, sterility. In females it can cause sterility, loss of sexual desire.
- Irradiation of the pelvis may cause tightening of the vagina, loss of vaginal lubrication, inflammation or ulceration of the vagina. Some women may find intercourse painful
- Treatment of red bone marrow may cause infection and impaired healing, anaemia, increased tiredness, bruising and bleeding
As well as treating cancer the radiotherapy temporarily damages the outer layers of skin. During treatment the skin cannot repair itself as it normally would and it can become sore. But once treatment has finished the skin generally recovers quite quickly – usually within a month. The level of reaction can depend on your skin type, the type and number of treatments you have, and how you would normally react to the sun.
Skin side effects usually happen later on in the course of radiotherapy treatment or sometimes a few weeks after treatment has finished. Many patients do not have any skin changes at all. Skin care advice will be given to the patients by the staff treating them.
A common side effect of radiotherapy is tiredness and fatigue, which often prevents patients from doing normal everyday activities. Fatigue and tiredness are normal results of having radiotherapy and begin in the first week of treatment, reaching a peak after two weeks of treatment and gradually disappearing a few weeks after treatment has finished.
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