Types of Radiation Therapy
How radiation therapy works
Radiation therapy uses invisible forms of high energy, such as X-rays and electron beams, to kill or damage cancer cells. Radiation is directed at tumors to damage the DNA of cancer cells, which prevents them from growing and dividing. Technological advancements have created radiation therapy techniques that precisely target cancer cells while minimizing radiation to nearby healthy cells.
Scripps MD Anderson specialists treat many types of cancer using the most appropriate type of radiation therapy based on each patient’s cancer type, how far it may have spread, their medical profile, overall health and more.
Scripps MD Anderson offers three main types of radiation therapy:
- External-beam radiation
- Internal radiation
- Systemic radiation
Keep reading for more information on each of these types. For more information on radiation therapy, visit radiation therapy FAQs and what to expect.
External-beam radiation therapy
External-beam radiation therapy treats cancer from outside of the body. Radiation beams are delivered by powerful, precise equipment in one of our hospitals or radiation therapy centers. Most patients need several treatments per week. The number of weeks depends on the type and stage of cancer.
Scripps MD Anderson cancer specialists use several types of external-beam radiation therapy, as described below.
Electron beam radiation therapy treats superficial tumors, such as skin cancers or other tumors near the surface of the body.
3-D conformal radiation therapy (3D-CRT)
3D-CRT uses advanced computer software that allows physicians to visualize a patient’s anatomy in 3-D, thereby more closely matching the radiation dose to the shape of the tumor while minimizing exposure to surrounding healthy tissues and organs.
Intensity-modulated radiation therapy (IMRT)
IMRT is an advanced form of 3-D CRT that enables radiation oncologist to specify the strength of the radiation beam to certain areas, allowing for stronger doses to some parts of the tumor and restricting the dose to surrounding healthy tissues.
Volumetric arc therapy (VMAT)
VMAT is an advanced form of IMRT that delivers radiation through a rotating device. Unlike IMRT, VMAT delivers the entire dose continuously, without stopping to adjust the angle.
Image-guided radiation therapy (IGRT)
IGRT is a type of 3-D CRT that takes patient motion and tumor movement into account during radiation treatments through repeated imaging. This allows the delivery of a more effective “real-time” radiation beam to the tumor. It is used for cancers in the body where motion occurs continuously (such as the lungs) when doses are delivered.
Stereotactic radiosurgery (SRS)
Stereotactic radiosurgery (SRS) delivers a single high dose of radiation to an extremely precise location to minimize exposure to healthy tissues surrounding the cancer. Scripps offers several types of SRS, including Gamma Knife.
Stereotactic body radiation therapy/stereotactic ablative radiotherapy (SBRT/SABR)
Stereotactic body radiotherapy (SBRT), also known as stereotactic ablative radiotherapy (SABR), treats tumors with multiple high-dose radiation treatments (typically two to five). Scripps uses leading-edge technology to deliver SBRT.
TrueBeam can treat tumors with volumetric arc therapy (VMAT), intensity-modulated radiation therapy (IMRT), stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT).
Edge is the newest radiation therapy machine that delivers volumetric arc therapy (VMAT), intensity modulated radiation therapy (IMRT), stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT).
Gamma Knife is a form of stereotactic radiosurgery (SRS) that uses a single dose of gamma rays to treat malignant and benign tumors of the brain.
Total body irradiation (TBI)
Total body irradiation (TBI) treats the whole body at once. It’s an essential part of bone marrow or stem cell transplant treatment for cancers of the blood (leukemia) and some types of lymphoma.
Internal radiation therapy (brachytherapy)
Internal radiation therapy, most commonly called brachytherapy or radioactive seed, delivers radiation by placing radioactive substances directly into or near a tumor. Radioactive beads, wires or other sources are placed into the body through catheters or small plastic tubes.
Scripps MD Anderson uses high-dose brachytherapy, which delivers a high dose of radiation internally for a very short time per treatment. The radioactive substance is placed into the body and removed after a few minutes. Treatments may be repeated for several days or weeks.
Systemic radiation therapy
Systemic radiation therapy uses radioactive substances that travel throughout the body via the blood to attack cancer cells. These are given as pills or injected into a vein.
Because the radioactive material may be present in saliva, sweat and other body fluids, patients may need to be in the hospital after receiving treatment for a day or so, and may need to take precautions to avoid affecting others. Although the radioactive substance travels through the entire body, it accumulates near the tumor, so the effect on the rest of the body is minimal.
Radioactive iodine is a systemic radiation therapy administered following surgery for thyroid cancer to eliminate any remaining cancer cells. The thyroid is the only organ that absorbs iodine, so the radiation does not affect other tissues.