3 Types of Radiation Therapy Explained

Learn about 3 types of Radiation Therapy - Intraoperative Radiation Therapy (IORT), Intensity Modulated Radiation Therapy (IMRT), External Beam Radiation Therapy (EBRT). Understand how each type works and its side effects.

3 Types of Radiation Therapy Explained

Radiation therapy is a common treatment for cancer, and there are several types of radiation therapy available. Intraoperative radiation therapy (IORT) is used to treat a tumor exposed during cancer surgery. During this type of radiation therapy, detailed three-dimensional images of the cancer are created from computed tomography (CT) scans or magnetic resonance imaging (MRI). The treatment team uses these images to point the beam, allowing them to safely use higher doses of radiation therapy and reduce damage to healthy tissue.

This reduces the risk of side effects. Another type of radiation therapy is intensity-modulated radiation therapy (IMRT). With IMRT, radiation intensity varies, which is different from conventional 3D CRT, which uses the same intensity with each beam. IMRT targets the tumor and prevents healthy tissue better than conventional 3D-CRT. Peter Mac uses several different types of radiation therapy at five radiation therapy centers in Victoria to treat all different types of cancer. The most common type of radiation therapy used to treat cancer is external radiation (or external beam radiation).

A machine is used to direct high-energy beams or particles from outside the body to the tumor. External beam radiation is most often delivered as beams of photons (X-rays) and less often as beams of particles (protons, neutrons) or electrons. Three-Dimensional Conformal Radiation Therapy (3D-CRT) delivers beams of radiation from different directions designed to adapt to the shape of the tumor. This helps reduce radiation damage to normal tissues and better kill cancer by focusing the radiation dose on the exact shape and size of the tumor. This treatment, also called external beam radiation therapy (EBRT), does not make the person radioactive.

You can be safely close to other people, including children. This type of radiation therapy is offered only for certain types of gynecological and prostate cancer. William Powers, MD, the first director of radiation therapy, developed a process in which custom-made blocks made of cerrobend alloy could be used to block radiation delivery to areas outside the treatment site. The machines focus the radiation beam at the exact location to maximize the radiation that reaches the cancer, but also to limit the effect on normal tissues as little as possible. Unlike photons, which pass through the body and expose tissues to radiation before and after hitting the tumor, protons only travel a certain distance, so the tissues behind the tumor are exposed to very little radiation. A machine called a linear accelerator, or linac, creates the radiation beam for X-ray or photon radiation therapy. For example, a surgeon or radiation oncologist inserts a specially designed tube or applicator into the lumen, or opening, of the esophagus to treat cancer.

Other names for radiation therapy are irradiation and radiotherapy. For this treatment, the radiation machine delivers many small beams of radiation to the tumor from different angles around the body. Low-energy radiation does not penetrate very deeply into the body and is mainly used to treat superficial tumors, such as skin cancer. These radiation beams start outside the body and are directed toward the body, where cancer cells are located. External radiation therapy is usually given with a machine called a linear accelerator that delivers a beam (or several beams) of radiation. The department is one of the largest in the United States and a national leader in developing the latest radiation treatments for cancer patients. If the area receiving radiation in your body includes the ovaries, the radiation dose may cause the ovaries to stop working (infertility) and you may not be able to have children.

Most types of radiation therapy don't reach all parts of the body, which means they aren't useful for treating cancer that has spread to many parts of the body. There are many different types of radiation therapy, and they all work a little differently to kill cancer cells. If the area receiving radiation includes the testicles, the radiation dose may cause the testicles to stop working (infertility) and you may not be able to have children.