Jefferson Health plans to build a proton therapy cancer treatment center at its Torresdale campus in North Philadelphia. The facility would be just the second site in Philadelphia to ofter the minimally invasive treatment option alongside Penn Medicine's Roberts Proton Therapy Center. Proton therapy, a relatively new type of radiation therapy, often is used to treat cancers as well as benign tumors. Instead of using X-rays, which also touch non-cancer cells, proton beams enter the body at low doses of radiation that spare healthy tissue and produce fewer side effects.