I have heard that IMRT radiation is used often for prostate cancer treatment. What is IMRT?
A. IMRT is intensity modulated radiation therapy. IMRT represents a significant advance in radiation therapy and we use IMRT both for treatment of the prostate alone and in coordination with a brachytherapy boost. There are two aspects of IMRT that improve radiation delivery. First, we can alter the fluence of any individual beam. Think of 3D conformal radiation as delivering say 4 to 9 beams all shaped uniquely to treat the tumor. Each beam however, like a flashlight, has the same strength across the beam. With IMRT we are not restricted to having one strength for each beam. Leaves can move into and out of the field while the beam is on to alter the fluence. In its most elegant form, IMRT can even allow treatment of a doughnut where a rim of radiation can be delivered while sparing the center. The second advance is inverse planning. Altering fluence requires computing speed and mathematical calculations far beyond what a human could envision. With inverse planning, we can tell the com
