Radiation therapy is the use of a certain type of energy (radiation) from X-rays, gamma rays and electrons to destroy cancer cells. In high doses, radiation destroys cells in the area being treated. It does this by damaging the DNA in cancer cell genes, making it impossible for them to grow and divide. 

There are two major types of radiation treatments:

External beam radiation therapy:

In external beam radiation therapy, radiation is directed at the cancer and surrounding tissue from a machine outside the body. This type of treatment is used to treat most cancers.


In brachytherapy, sealed radioactive sources are placed inside the body, in or near the cancer. A sealed radioactive source is often called an implant. Brachytherapy makes it possible to treat the cancer with a high total dose of radiation in a concentrated area in a short period of time.

Cancer Care Ontario's Radiation Treatment Program sets provincial standards and guidelines for treatment and quality assurance, and supports and works with radiation experts and organizations to continually improve radiation therapy. This includes evaluating and advising on new technologies and techniques, setting standards and targets, and working to improve wait times. Cancer Care Ontario has been publicly reporting radiation wait times since 2004.

Your patients may experience side-effects from radiation treatment. These can include:

Cancer Care Ontario
Canadian Cancer Society