CANCER: UNDERSTANDING RADIATION THERAPY
Radiation Therapy Explained
Radiation therapy, also known as radiotherapy, is a widely used method of orthodox cancer treatment. It is commonly employed as a modern treatment for persons afflicted with cancer, in an attempt to kill the malignant tissue that is involved with cancer. It can be used singularly, as the primary method of treatment, or it can be used prior or post surgery, or in conjunction with chemotherapy.
External beam therapy uses a complicated machine called a ‘linear accelerator’ to generate radioactive beams or rays, to damage and kill dividing cells.
Alternatively, a radioactive variant (isotope) of a common element, such as radium or iodine, can be implanted into or close to the cancerous tissue, or injected in. This type of internal treatment is called brachytherapy. It deals mainly with the problem site and therefore with one part of the body, usually where the tumour was first discovered.
Unlike surgery, radiation therapy does not involve an operation and removal of the part affected. It resembles chemotherapy in that it can damage tumour cells. Unfortunately damage to surrounding healthy tissue usually occurs, in particular to bone marrow and the mucosal lining of the gastrointestinal tract. Radiation acts at the cellular level, causing cell death. Radiation exerts its greatest effect on rapidly proliferating cells.
How Radiation Therapy Works
Radiation Therapy consists of an orderly arrangement of steps:
1. Planning
2. Treatment
3. Care and supervision during the course
4. Care and support of reactions and side-effects
5. Periodic review to check on progress
Radiotherapy uses a source of ionizing radiation, such as x-rays, gamma rays, radium or radioactive cobalt (Cobalt-60 or Iodine-131) delivered to the cancerous tissue to kill malignancies. The idea is to bombard the diseased tissue with radiation in the precise area that will destroy the tumour, and hopefully only cause minimal damage to surrounding tissues.
How Radiation Therapy is Given
Planning – In planning for radiation therapy, surface marks are drawn on the skin in red or purple so that the beam of radiation can be aimed at the tumour. These marks are miniature tattoos that are left on throughout the course of the treatment and may take a long time to disappear after treatment. Measurements are taken and doses calculated through diagnostic x-ray exposures with metallic markers. A prescription is then written for the radiographer to follow with treatment.
Treatment – The application of radiotherapy is painless and rapid (often only 30 seconds in length). The linear accelerator (most commonly used x-ray generator) is activated as all operators leave the room. The patient must lie perfectly still to ensure the radiation hits the correct area. Treatment is required several times and usually given daily for a period of three weeks or more. Alternatively, a radioactive variant can be inserted into the body, or injected. An example of this is the insertion of a radioactive element into the vagina for forty-eight hours to kill any cancerous cells.
Care and Supervision – It is recommended that the person receiving radiation therapy should see the doctor and radiographer every week, to check on side effects and results of treatment. Blood tests are taken regularly to monitor blood cell counts, as with chemotherapy.
Why Radiation Therapy is Given
Radiation therapy is commonly used before scheduled surgery to shrink tumours to more operable sizes. It is also used after surgery, to ensure removal of any remaining cancerous tissue and to prevent the onset of further cancerous growths in the future. It is also employed as a method of removing and shrinking small tumours present in the body. Some particular types of cancer respond better to radiation therapy rather than chemotherapy or other cancer drugs.
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