In 3DCRT, a computed tomography (CT) scan is used to design a radiation therapy treatment. Radiation target volumes and critical structures are defined on CT images. The radiation beams from different directions are designed to match the shape of the tumor. This helps to deliver a conformal dose of radiation to the tumor while sparing the normal tissue surrounding the tumor as much as possible. A number of cancer types have seen improved outcomes from 3D conformal radiation therapy, including Brain cancer, Head and neck cancer, Liver cancer, lung cancer and Prostate cancer.