Proton Beam Therapy is a type of radiation treatment that uses protons to treat cancer. A proton is a positively charged particle. At high energy protons can destroy cancer cells. Proton Beam Therapy may be used alone or may combine it with other treatments, such as standard radiation therapy, surgery, chemotherapy, and or immunotherapy. Proton therapy is a type of external-beam radiation therapy. It painlessly delivers radiation through the skin from a machine outside the body. A machine called a synchrotron or cyclotron speeds up the protons. The protons speed determines the energy level. High-energy protons travel deeper in the body than low-energy ones. The protons go to the targeted place in the body. There, they deposit the specific radiation dose in the tumor.