Radiation Therapy

Radiation therapy is a type of treatment used to treat different types of cancers

What is radiation therapy?

Radiation therapy is also known as radiotherapy. This is a type of therapy that is used to help treat many types of tumors, malignant as well as benign. In this type of treatment, doses of high energy radiation are carefully targeted to eliminate cancer cells[1]. Almost every cancer can be treated with radiation therapy, but limitations of treatment due to accessibility to the tissues or other reasons may make it difficult to treat some conditions. Radiation therapy is the most useful to treat tumors that are non-cancerous or benign.

Woman in radiographic machine

Who gets radiation therapy?

A majority of the people who are suffering from cancer receive radiation therapy as part of their treatment for the disease. Radiation therapy is also known as irradiation or radiotherapy and is a normal part of the treatment protocol followed for most cancers.

Radiation therapy is a name given to a procedure whereby high energy beams of radiation are focused and aimed at the site of the cancer. These beams are used for the destruction and elimination of abnormal cancerous cells. Gamma rays, X rays, neutrons and various other materials which are radioactive in nature are used as the source of radiation in this treatment therapy.

Radiation therapy is one of the most effective treatments used for the destruction of cancerous lesions, and is also used as palliative treatment in the later stages of the disease. There are several ways of administering radiation therapy in a cancer patient. By far the most common way of administering radiation therapy is external radiation whereby a machine, known as a linear accelerator, is used in the treatment. The accelerator is used to direct the radiation beams towards the cancerous lesion in the body as well as a minor margin surrounding the lesion. External radiation technique requires a few outpatient visits of short duration. In a majority of cases, this radiation therapy is administered on a daily basis, or on all working days of the week of a specific duration of time – which can either range from several days to almost eight weeks. There are a number of ways in which external radiation can be administered in a patient, depending upon the type of the tumor being treated.

  • Three-dimensional conformal radiation: In this type of therapy, computer stimulation is used for the production of a precise image of the cancer and all the organs surrounding this tumor. This is done so that several beams of radiation can be focused and shaped in accordance with the contour of the area that requires the treatment. This type of therapy is highly effective and safe because the precision allows for saving the healthy tissues of the body and not exposing them to radiation unnecessarily.
  • Intensity-modulated radiation therapy (IMRT): This is a type of three dimensional conformal radiation therapy. This form of therapy makes use of highly sophisticated software as well as hardware – in order to determine the exact shape and the intensity of the beam of radiation which will be focused and aimed onto the different areas of the body. This therapy is effective in terms of reducing the dose of radiotherapy which will be received by the healthy tissues of the body.
  • Stereotactic radiosurgery: This kind of radiation therapy is specifically used for the tumors that affect the brain. With the help of this technique, multiple beams of radiation are aimed onto the tumor through a specialized helmet. This helmet helps focus the radiation beams straight towards the targeted tumor from a number of different directions.
  • Cyber-Knife and the Peacock system: This particular technique is also used specifically for the tumors that affect the brain. In this therapy, specialized machinery is used which helps move around the head of the patient while the device aims regulated doses of the radiation from a few hundred directions at one time. The beams of radiation used in this particular technique have the ability to modify their size and shape in order to effectively conform to the form of the cancer itself. It also successfully helps in avoiding the exposure of radiation to the healthy tissues.

Cancer patients who have received external beam radiation do not possess any risks of having excess radiation within their bodies. They are not in any way radioactive and cannot cause any harm to any other individual.

Brachytherapy: Internal radiation therapy: This therapy involves the implantation of the radiation source within the body. In this technique, a radioactive material is placed within a small device – for instance a plastic tube, a metal seed, a thin wire or a capsule. This device is then placed near the cancerous lesion or in some cases, directly into the lesion itself. However, this technique requires the patients to spend a short duration at the hospital. Patients who have received internal radiation have the potential to give off an insignificant amount of radiation for a short time. Necessary precautions need to be taken in order to prevent visitors from being exposed to radiation unnecessarily. One of the most effective methods in this case is to keep the patient in a private hospital room and limit the number of visitors.

Additional Resources:

Cukier, Daniel, et al. 2005. Coping with Chemotherapy and Radiation. NewYork: McGraw-Hill. This book is written by radiation-oncology physicians with the goal ofhelping people prepare and manage their cancer treatment. It reviews thebasics of chemotherapy and radiation therapy and provides guidancewith regards to diet and lifestyle adjustment that may ease discomfort.Side effects of radiation therapy are reviewed by body part and by disease.


American Society for Therapeutic Radiology and Oncology (ASTRO). Radiation Therapy for Cancer.  This overview describes different types of radiation therapy; the membersof the treatment team; what happens before, during, and after treatment;side effects; and self-care during radiation treatment. Other brochures focusing on radiation therapy for specific cancer types are also available on this site in Adobe Acrobat (.pdf) and HTML formats. Access at: www.astro.org/


National Cancer Institute. Radiation Therapy and You.. A Guide to Self- Help during Cancer Treatment. This introduction to radiation therapy reviews external and internal radiation therapy – including what to expect, managing side effects, andfollow-up care. Access at:  www.cancer.gov/cancertopics/coping/radiation-therapy-and-you



This article was originally published on 7/12/2014 and last revision and update of it was 9/14/2015.