- The accelerator, which is housed in a 25,000-square-foot facility, funnels protons into a 40-foot-wide circular track known as a cyclotron. The cyclotron speeds up protons to higher energy levels.
- The patient enters one of three chambers, depending on the type of treatment, and lies on a gurney-like bed. A computer-controlled proton-firing nozzle positions itself over the target area.
- Meanwhile, magnets guide a beam of protons along the center of a long, narrow tube. The beam races toward a gantry, which rotates around the patient as its nozzle fires protons at the tumor.
- By changing the protons' speed, doctors can control when they release their energy. Faster protons "detonate" farther inside a patient; slower ones attack tumors just below the skin.
- The energy released by a proton beam, though not necessarily greater than that of an x-ray, is much more targeted. The key is that most of it zaps the tumor, not surrounding tissue.