The purpose of this research study is to determine if radiation using proton beam therapy will kill the germ cell tumor in the participant's central nervous system. This type of radiation has been used previously on many patients with different types of cancers. There are two types of external radiation treatments, proton beam and photon beam. In this study we will be examining the effects of proton beam radiation therapy. Studies have suggested that this kind of radiation can spare normal tissue more than photon radiation therapy. The physical characteristics of proton beam radiation let the doctor safely increase the amount of radiation delivered to the tumor. We believe that proton beam therapy will potentially reduce side effects that participants would normally experience with photon radiation therapy.