By Mayo Clinic Staff

Intensity-modulated radiation therapy (IMRT) is an advanced type of radiation therapy used to treat cancer and noncancerous tumors.

IMRT uses advanced technology to manipulate photon and proton beams of radiation to conform to the shape of a tumor.

IMRT uses multiple small photon or proton beams of varying intensities to precisely irradiate a tumor. The radiation intensity of each beam is controlled, and the beam shape changes throughout each treatment.

The goal of IMRT is to conform the radiation dose to the target and to avoid or reduce exposure of healthy tissue to limit the side effects of treatment.

April 09, 2015