Parents' Glossary to Types of Radiation Therapy

St. Jude strives to give your family all the information you need regarding your child’s therapy, when you need it. We've made a guide for parents to explain common types of radiation therapy your child may receive.

Brachytherapy: This is a type of internal radiation therapy. It is used inside the body near or adjacent to the tumor. Doctors can place special wires or pellets with radiation inside the body to kill cancer cells over time.

Conformal Radiation Therapy (CRT): Sometimes called 3-D CRT, this is a type of external radiation treatment usually done to plan treatment for tumors. “Conformal” describes the way that radiation matches the exact shape of the tumor. It surrounds the outside and targets the entire inside area, too.

CRT is often used to treat brain tumors, along with surgery and chemotherapy.

Intensity modulated radiation therapy (IMRT): This is the most frequently used type of external radiation treatment. It is an advanced way of doing conformal radiation therapy (CRT). Radiation beams are sent from many directions and conform to match the shape of the tumor. Plus, radiation oncologists can control the intensity, which is the strength of the radiation. So, “intensity modulation” means the beams can be “turned up” to be stronger or “turned down” to be weaker in healthy areas.

Radiation Therapy: Any type of treatment that includes high-energy radiation to kill cancer cells, shrink tumors or provide pain relief. Types of radiation therapy can include X-rays, protons and other sources.

Stereotactic radiosurgery (SRS): This is a type of external radiation treatment. Doctors create a 3-D image to help them plan radiation treatment that will be the exact shape of the tumor. The word "stereotactic" means the radiation will be accurately aimed at the tumor using the 3-D guide. Even though “surgery” is part of the name, there’s no cutting, shots, IVs or scars.

SRS uses devices that precisely shape radiation beams, so it’s good for targeting small tumors in the brain or spinal tumor. SRS can be a safer alternative to traditional surgery. There are different types of SRS, including a linear accelerator, Gamma knife and proton beam therapy.

Stereotactic body radiation therapy (SBRT): This type of stereotactic radiosurgery is used to treat tumors in various parts of the body other than the brain, such as spine, liver and kidney. (See stereotactic radiosurgery.)

Proton beam therapy: This type of radiation uses protons, not X-rays, to treat cancer. Read more at Proton Beam Therapy at St. Jude.