A Phase I/II Study of the Photon Radiosurgery System

The standard treatment for children with brain tumors is surgical removal of the tumor followed by radiation to the brain and chemotherapy (medicines) given to shrink any remaining tumor or to prevent tumor from growing back. There are very few treatment options available for children whose brain tumor grows back after receiving radiation treatment. There is a greater risk of complications and side effects when the brain is repeatedly treated with external radiation. The side effects of repeat radiation treatment are dependent on the amount of the brain that is radiated. Radiation given with PRS during surgery is focused to the specific area of the brain where the tumor is located. Therefore, the area of the brain affected by the radiation is smaller. It is hoped that this targeted radiation will lessen the side effects to the normal brain that is not affected by the tumor. It is also hoped that a lower occurrence of side effects will increase the quality of life of children with brain tumors. The optimal dose of targeted radiation is not known. Therefore, increasing doses will be given to treat different patients, starting with the lowest possible dose. The amount of radiation to be given will depend on whether or not your child received prior radiation therapy and where the tumor is located. The groups of patients will first be divided into 2 groups: Group A, who are those who received radiation as part of their prior treatment, and Group B, who are those who did not receive any radiation treatment. Each group will be then divided again into 2 groups depending on the location of the tumor. In each group, if the lowest dose is well-tolerated with only minimal side effects by 3 patients, then the next higher dose will be given to the next 3 patients. The purposes of this research are: * To evaluate the potential side effects of a single high dose of x-rays using the Photon Radiosurgery System (PRS) given to a small area of the brain. * To determine the maximum dose of targeted radiation that can be safely given to brain tumors with the fewest side effects. * To see how well this treatment works for children with recurrent brain tumors and newly-diagnosed glioblastoma multiforme.