Gantry in Proton Therapy Unit (IMAGE) Children's Hospital of Philadelphia Caption Located inside the treatment room, a steel gantry can rotate around a patient to aim the proton beam at the correct angle to deliver treatment. Powerful magnets located outside the room guide the high-speed, high-energy protons into a beamline, an airless tube about as long as a football field. From the beamline, protons are channeled into the gantry. Credit The Children's Hospital of Philadelphia Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.