[Modern technics of irradiation of brain tumors in children]

Radiotherapy still represents with surgery the cornerstone in the management of pediatric brain tumors. Techniques of irradiation have benefited greatly from modern imaging, CT scan and MRI for tumor-volume delineation, as well as megavoltage equipment, mainly linear accelerators delivering both high-energy X-Rays and electrons, widely used in cranial-spinal irradiations. Furthermore, new modalities of doses and volumes have been tested in various tumors (medulloblastomas, germ cell tumors...), in studies frequently combining chemotherapy with conventional therapies. Nevertheless, local control remains a major concern in tumors such as brain stem and high grade supratentorial gliomas. Concerning iatrogenic neurological sequelae, particularly harmful in children, limited data suggest an improvement in recent years. This improvement is partly due to the reduced prophylactic doses for the treatment of medulloblastomas, but further long-term observations are necessary. For these reasons, multiple technical innovations have been investigated. Some of them concern irradiation selectivity: stereotactic pencil beams, interstitial brachytherapy, heavy charged particles, 3-dimensional treatment planning. Others aim to increase the irradiation "efficacy": multifractionation, high LET particles, radiation-sensitizers.