Proton beam is one of the charged particle beams, which can produce radiation by accelerating protons (hydrogen nuclei) to high energy. When the proton beam shines on the human body, according to its physical characteristics, the energy can be released at a certain depth and disappear suddenly (called "Bragg Peak").
X-rays used in general radiation therapy could not find the physical properties. In proton therapy, the depth and width of the Bragg Peak can be adjusted to match the shape of the cancer cells, inhibiting its impact on nearby vital organs and normal cells; and injecting a sufficient dose into the cancer cells to achieve a therapeutic on cancer.
Multiple treatments have been reported for diseases such as head-and-neck cancer, lung cancer, liver cancer, esophageal cancer, pancreatic cancer and prostate cancer.
(Data source: Sumitomo Heavy Machinery Statistics)