Radiation therapy is one of the most effective ways to combat cancer and is used to treat cancer by itself or in combination with the other forms of treatment, most often surgery or chemotherapy. It works by focusing a beam of ionizing radiation on the cancerous growth or implanting radioactive sources in the cancerous area.

In the Radiation Oncology, treatment programs are established by the Saint John's Health Center physicians to standardize the optimal care. The Treatment programs are reviewed periodically by all physicians in radiation oncology and are based on medical evidence and national standards, ensuring the highest level of care for every patient.

Before beginning radiation treatment, the radiation oncologist must plan a customized treatment program so that all the areas "at risk" (i.e., tumor or areas potentially harboring cancerous cells) are included in the radiation treatment field while sparing as much normal tissue as possible.