IMRT is an advanced form of 3D therapy used to treat cancer and noncancerous tumors. It uses a computer-driven radiation linear accelerator machine that moves around the patient as it delivers radiation. The goal is to target the radiation to limit side effects and damage to healthy tissue. Along with shaping the beams and aiming them at the target cancer site from several angles, the intensity (strength) of the beams can be adjusted to limit the doses reaching nearby normal tissues. This allows the radiation oncologist to deliver a higher dose to the tumor.

Some newer radiation machines have on board imaging scanners built into them. This technology advancement, known as image guided radiation therapy (IGRT), allows the radiation oncologist to obtain images of the tumor and make minor daily localization adjustments prior to delivering radiation.