Pencil beam scanning, also called scanning beam, is the most advanced type of proton therapy. Only a few millimeters wide (the width of a pencil), pencil beam scanning is used to treat complex cancers with unparalleled precision. It’s used to treat head and neck, gynecologic, lung, prostate, breast, brain, liver, lymphoma, sarcoma and tumors in children. Proton therapy may also be used for tumors that recur in areas that have previously...