There have been considerable technical improvements in radiation therapy for the past two decades. In children affected with cancer, these have been likely overshadowed by concommittant major chemotherapy-based advances, and at least in part ignored and misused. This article outlines principles, technological requirements, and clinical applications of innovations that aim at improving ballistical selectivity (such as conformal, intensity modulation, stereotactic photons, charged particles, and intraoperative therapies), as well as at influencing tumors and normal tissues sensitivity to radiations (such as high LET particles, and altered fractionations).