“…The isotropic radiation shows a dose decline rate of approximately 1/r 3 and has a similar dosimetry compared with Linac radiosurgery and proton beam in small spherical intracranial tumors (11,12). The radiobiological effects of PRS irradiation, such as an early cell death through a nonapoptotic pathway, were demonstrated at several rodent and human cell lines (13)(14)(15). Focal radionecrotic lesions were demonstrated in animal models, and hyperthermia as a possible tumoricidal factor has been excluded (16).…”