External Beam Radiation Therapy (EBRT)
External beam radiation therapy comes from a machine that aims radiation at your cancer. The machine is large and may be noisy. It does not touch you, but can move around you, sending radiation to a part of your body from many directions. External beam radiation therapy is a local treatment, which means it treats a specific part of your body. For example, if you have cancer in your lung, you will have radiation only to your chest, not to your whole body.
Three-Dimensional (3D) Conformal Radiation Therapy
Three-Dimensional (3D) conformal radiation therapy is a common type of external beam radiation therapy. It uses images from CT, MRI and PET scans to precisely plan the treatment area, a process called simulation. A computer program is used to analyze the images and to design radiation beams that conform to the shape of the tumor. 3-D conformal radiation conforms to the shape of the tumor by delivering beams from many directions. The precise shaping makes it possible to use higher doses of radiation to the tumor while sparing normal tissue.
Intensity Modulated Radiation Therapy (IMRT)
IMRT is is a type of 3D conformal radiation therapy. Like 3-D conformal radiation, radiation beams are aimed at the tumor from several directions.
IMRT uses many more smaller beams than 3-D conformal and the strength of the beams in some areas can be changed to give higher doses to certain parts of the tumor.
Image-Guided Radiation Therapy (IGRT)
IGRT is a type of IMRT. However, it uses imaging scans not only for treatment planning before radiation therapy sessions but also during radiation therapy sessions. During treatment, you will have repeated scans, such as CT, MRI or PET scans. These scans are processed by computers to detect changes in the tumor’s size and location. The repeated imaging allows for your position or the radiation dose to be adjusted during treatment if needed. These adjustments can improve the accuracy of treatment and help spare normal tissue.
Adaptive Radiation Therapy (ART)
Adaptive therapy provides the ability to adapt the treatment plan based on tumor and anatomical changes.
External Beam Radiation Therapy for Cancer was originally published by the National Cancer Institute.