The Proton Therapy Cooperative Group discussed various machine designs and proton delivery systems. In fact, conventional radiation deposits more energy just under the surface of the skin than it does in a deep-lying tumor, which may be near the center of the patient's body. This is done to bypass vital organs and good tissues, as much as possible, and to concentrate the radiation on the tumor. Still, because physicians cannot focus the radiation enough to avoid the surrounding tissues, they fail to control the local disease in 225,000 patients every year in the United States. The proton beam dramatically reduces these negative factors by decreasing injury to the healthy tissues it passes through, and by penetrating no farther than the tumor.
Protons are subatomic, positively charged particles, found in the nuclei of atoms.
In contrast to conventional radiation, they enter the body at a very low absorption rate and go through good tissues rapidly. By focusing the Bragg Peak on a patient's tumor, the deadly radiation causes most of its damage to the tumor. Damage to the tissues in front of the tumor is significantly reduced in comparison to the damage caused by conventional radiation. And there is no measurable damage to normal tissues beyond the tumor. The superior controllability of the proton beam has allowed for the delivery of higher radiation doses than is possible with conventional radiation and promises, therefore, better results.