Three dimensional (3-D) conformal radiation therapy is a technique where the beams of radiation used in treatment are shaped to match the tumor. Previously, radiation treatment matched the height and width of the tumor, meaning that healthy tissue had to be exposed to the beams. Advances in imaging technology make it possible to locate the tumor precisely. Conformal radiation therapy uses the targeting information to focus precisely on the tumor while avoiding the healthy surrounding tissue. This exact targeting makes it possible to use higher levels of radiation in treatment, which are more effective in shrinking and killing tumors.
3-D conformal therapy is in some ways similar to IMRT; both are used to target cancer while sparing healthy tissue. With IMRT, radiation intensity can be turned up or down during the treatment, but sometimes due to the tumor shape and location, 3-D conformal therapy is best suited to treating a cancer. This determination is made by the radiation oncologist.
The process begins with taking a 3-D image of the tumor, often using computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), or PET/CT imaging. The 3-D image is then analyzed by a computer program which designs radiation beams that follow the shape of the tumor. During treatment, beams from several directions precisely match the tumor's height, width and depth. The patient is immobilized in a foam mold to target the radiation more accurately to the tumor and not the adjacent tissues.
3-D conformal therapy has been shown to improve outcomes for a number of cancer types, including head and neck, lung, liver, prostate and brain cancers. This technique is widely used by radiation oncologists at UPMC Cancer Centers.
