Intensity-Modulated Radiotherapy (IMRT) is an advanced approach to 3-D conformal radiation therapy. The IMRT technique is very precise; it uses computer-generated images to plan and then deliver tightly focused radiation beams to prostate cancer tumors. With this capability, clinicians can vary the beam's intensity to "paint" a precise radiation dose to the shape and depth of the tumor, while significantly reducing the radiation's harmful effects on healthy tissue.