Sufficient radiation can destroy any type of cancer. However, because of the
inability to selectively irradiate the cancer with conventional means of treatment,
normal tissues that receive a high radiation dose can also be damaged. As a
consequence, a less-than-optimal dose is frequently used in order to reduce
damage to the normal tissue. This precaution reduces the likelihood of cure
for many patients.
Proton differs from conventional radiation in that the beam enters the body at a low
absorption rate and increases in intensity at a specific point, called the Bragg peak. A
series of peaks are focused on the tumor, giving it the highest concentration of radiation,
killing the cells of the tumor. Not only is the dose of radiation to normal tissue sharply
reduced compared to conventional radiation therapy, but the energy of the proton beam completely
dissipates within the tumor, causing no damage to normal tissues beyond the tumor.