INTENSITY MODULATED RADIATION THERAPY
Intensity modulated radiation therapy (IMRT) is a sophisticated, new radiation treatment planning technology that can shape and deliver a high dose of radiation to a tumor while sparing surrounding healthy tissues. The fundamental difference between conventional radiation treatment and IMRT is beam intensity. In conventional radiation therapy the beam intensity is uniform, but in IMRT, the beam intensity varies across the treatment field. During IMRT treatment, where the tumor is the thickest, the beam intensity is at its greatest, and where the tumor is thinnest, the intensity is at its minimum. In many situations, this allows for the high dose region of the radiation plan to more closely conform to the shape of the tumor, and also often allows for greater sparing of adjacent normal tissues.
Treatments are given on the linear accelerator in a similar fashion to conventional external beam radiation (see External Beam Radiation page). Treatment time is usually slightly longer, because of the increased complexity of the treatment delivery. IMRT is used for cancers throughout the body including the prostate, brain, head + neck, lung, GI tract and others.