The potential role of proton beams in radiation oncology.

Historically, major gains in the local control of large, deep-seated tumors treated with radiation have occurred whenever dose distributions have become more localized to the tumor. Better dose localization permits the delivery of higher tumor doses while delivering less dose to dose-limiting normal tissues. High-energy protons, because they stop abruptly in tissue at the end of their range and deposit most of their energy there, provide dose distributions that are superior to x-rays when used in comparable beam configurations. The installation of a hospital-based proton therapy facility at the Massachusetts General Hospital in Boston, MA, and the existing facility at Loma Linda University Medical Center, Loma Linda, CA, provide a potential for achieving higher rates of local control in tumors throughout the body.