Proton beams have a unique characteristic called the “Bragg peak”, which enables emission of the highest radiation dose at the set depth. Thus, we are able to control the proton beam to deposit a large focused amount of radiation right into a tumour. In proton therapy, the shape and depth of the ‘Bragg peak’ are precisely controlled to conform to the shape and size of a tumour, which enables radiation oncologists to provide a focused treatment on the targeted area, with little radiation dose beyond it.
Unlike proton therapy, conventional radiation therapy uses photons which enter the body and deposit most of its energy in normal tissues near the body surface, and then the energy reduces as it goes towards the center of the body. They also continue to penetrate through the tumor and irradiate the healthy tissue behind it. This undesirable pattern of energy placement can result in unnecessary damage to healthy tissue, thus increasing the side effects.