Study of SBRT Efficacy on Intra and Extra -Cranial Tumors or Metastasis in Pediatrics Population (SBRT Pediatrics)

INCLUSION CRITERIA: * 18 months ≤ age ≤ 20 years * Malignant primary tumor, histologically or cytologically proven * Systemic disease under control or with slow evolution * Written indication of SBRT according to local pediatrics meeting and national Radiotherapy (RT) web conference * Performance Status ≤ 2 according to Eastern Cooperative Oncology Group (ECOG) * Sites * Brain metastasis (≤ 3 on MRI) not suitable for surgery, without hemorrhage, less than 3 cm each, not in the brain stem * Primary or secondary spinal/para spinal metastasis (≤ 3), not suitable for surgery or with a non operable macroscopic residue, less than 5 cm * Lung metastasis (≤ 3), less than 5 cm, not eligible for surgery, or macroscopic residue not suitable for surgery * Previously irradiated relapsing isolated primitive/secondary tumor (intra cranial or extra cranial), with no possible surgery, or macroscopic residue. * Affiliation to a social security scheme * Signed Informed consent by patient or parents and patient IN ADDITION FOR RELAPSING EPENDYMOMA: * Histologically proven local ependymoma at diagnosis * Previously irradiated ependymoma * Exclusive local relapse in previously irradiated site * Review of operability at time of relapse by a multidisciplinary staff * Relapse must be confirmed by a neuro-oncology multidisciplinary staff, on MRI evolutivity characteristics * Time to relapse after previous irradiation ≥ 1 year NON-INCLUSION CRITERIA : * Concomitant chemotherapy * No evalu…