External Beam Radiation Therapy


External beam radiation therapy uses a high-energy x-ray machine called a linear accelerator (linac) to direct radiation to the tumor. The procedure lasts several minutes, and is typically repeated several times a week over several months. Learn more about the different types of external beam radiation treatments.

Three-Dimensional (3D) Conformal Radiation Therapy 

Three-dimensional (3D) conformal radiation therapy is a technique where beams of radiation used in the treatment are shaped to match the tumor. This type of radiation therapy sculpts radiation beams to irregularly shaped tumors or tumors that are located close to healthy tissues and organs. With 3D conformal radiation, our radiation oncology experts can view a tumor in three dimensions with the help of advanced imaging and deliver radiation beams to the tumor from several directions.

Intensity-Modulated Radiation Therapy (IMRT)

Intensity-modulated radiation therapy (IMRT) is a treatment method in which the strength of the radiation can be changed during treatment. In conventional therapy, the intensity is set for the entire treatment session. IMRT sends tiny beams, or radiation beamlets, of radiation that conforms to the shape and the area of risk. This technique allows for different areas to receive different amounts of radiation as well as help protect healthy tissue and nearby critical organs from unnecessary radiation exposure.


Halcyon™ is leading-edge technology that precisely targets the tumor while providing treatment in half the time and in an environment that’s more comfortable than ever before. The radiation and oncology experts at MedStar Health are proud to be the only healthcare system serving Washington, D.C., Maryland, and Virginia to offer the latest linear accelerator, Halcyon™. Click here to learn more about Halcyon™.


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