What is Radiation Therapy

Cancer patient receiving radiation therapy What is Radiation Therapy?


Radiation therapy uses targeted energy (e.g. x-rays, radioactive substances) to destroy cancer cells, shrink tumors, and/or alleviate certain cancer-related symptoms. Radiation therapy may be used:


  • As a primary treatment to destroy cancer cells
  • In combination with other treatments to stop the growth of cancer cells
  • Before another treatment to shrink a tumor
  • After another treatment to stop the growth of any remaining cancer cells
  • To relieve symptoms of advanced cancer


Radiation oncologists are experienced in using advanced technologies to deliver targeted radiation therapy while also proactively managing side effects.


Types of Radiation Therapy


What are the types of radiation therapy? Delivery methods include:


External Beam Radiation Therapy

Radiation is directed from a machine outside of the body onto cancerous cells within the body. Examples include 3D conformal radiation therapy, IMRT, IGRT, TomoTherapy, and stereotactic radiosurgery. 


Internal Radiation Therapy

Radioactive material Is placed via a catheter or other carrier directly into or near a tumor. An example of internal radiation therapy is high-dose rate brachytherapy.


Systemic Radiation Therapy

A radioactive substance (that is swallowed or injected) travels through the blood to locate and destroy cancerous cells. Radioactive iodine therapy is an example of this.