Intensity-modulated radiation therapy (IMRT) is an advanced form of three-dimensional conformal radiotherapy (3DCRT). In addition to using multiple shaped portals from which the radiation beams emanate, the intensity of the beams within each portal is spatially modulated using sophisticated software and hardware. This enables an optimized dose distribution to be delivered to the three-dimensional tumor volume while maintaining constraints of avoiding close or overlapping normal structures. IMRT is often used for the treatment of tumors that are in close proximity to normal organs that are more sensitive to radiation. For example, IMRT is often used in the treatment of prostate cancer to achieve high tumor control with significantly reduced rectal toxicity.
|Courtesy of Varian Medical Systems|