The Goal: Deliver a Proper Dose of Radiation
Both X-ray and proton therapy can be equally effective for treating cancer. However, proton therapy has several benefits. Patients typically experience fewer side effects, less dose to healthy tissue, and reduced risk of developing secondary tumors.
To deposit the proper amount of energy into the tumor, X-rays must irradiate much of the healthy tissue in front of it. Then, they penetrate the tumor and irradiate much of the healthy tissue behind it.
Protons interact in a very different way. They deliver a low dose to the healthy tissue then, at a precise depth, deliver a large burst of energy to the tumor. Shortly after this burst, they stop completely. To treat the entire tumor, additional protons are sent in at lower doses. In this way, protons completely irradiate the tumor while limiting the dose affecting the nearby healthy tissue.