multi-leaf collimator (MLC)
Intensity modulated radiation therapy (IMRT) is a specialized 3D conformal radiation treatment plan where thousands of tiny beams from several beam angles are used to target a tumor. These tiny beams are produced by using a highly sophisticated computer program that will dissect the cancer tissue from normal tissue, and assign the radiation beam intensity differently to the tiny areas, as directed by the doctors.The radiation intensity of these beams is modulated, or controlled, with a system of movable leaves called a multi-leaf collimator (MLC). The leaves conform to the shape of the tumor and block out unwanted radiation. With sophisticated dose calculation methods each leaf can move independently to create tiny beamlets of radiation that specifically target a tumor.
This treatment technique provides the means to escalate tumor doses while significantly sparing normal tissue. Less radiation to normal tissues translates into fewer complications for patients. IMRT is ideal for tumors situated near critical structures such as the spinal cord, heart and eyes. Some typical treatment sites include the prostate, brain and breast. As with 3D conformal treatments, IMRT is planned by our radiation oncology team using the advanced Eclipse treatment planning system.