俄亥俄州63岁的Bob Pierson右眼有一个菜豆大的恶性肿瘤。他面临着两种选择:切除右眼或者到哈佛大学回旋加速器实验室用高能质子束辐射治疗。Pierson选择了后一种治疗方法,从而保住了右眼。为了帮助物理学家研究原子核,1937年在该实验室建立了一个巨大的粒子加速器。哈佛大学医学院眼科专家Evangelas Gragoudas把质子束调到16亿伏,测定肿瘤的实际大小和形状。如果质子束不能准确地集中投射,那 Bob Pierson, 63, Ohio, has a large kidney bean cancer. He faces two choices: to excise his right eye or to use Harvard’s cyclotron laboratory with high-energy proton beam radiation therapy. Pierson chose the latter treatment to keep his right eye. To help physicists study the nucleus, a giant particle accelerator was established in the laboratory in 1937. Evangelas Gragoudas, an ophthalmologist at Harvard Medical School, adjusted the proton beam to 1.6 billion volts to determine the actual size and shape of the tumor. If the proton beam cannot focus on the projection accurately, then