Abstract
High-energy proton beams of 7 mm. diameter or less were used to irradiate monkey eyes. When the Bragg peak was positioned immediately in front of the retina, it was possible to apply an acute radiation burn to a discrete area of the retina and choroid while delivering much smaller doses to other ocular and orbital tissues. The minimal scatter, finite penetration, and advantageous dose-distribution curve for soft tissues make this mode of radiotherapy very attractive for the treatment of ocular and orbital tumors.