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

"For Brain metastasis the SBRT treatment consists on 3 fractions of 8 Gy or 5 fractions of 7 Gy or 1 fraction of 18 Gy for a single metastasis which is less than 20 mm.~For primary or secondary pulmonary tumors the SBRT treatment consists on 3 fractions of 15 Gy or 5 fractions of 10 Gy for peripheral lesions and on 5 fractions of 8 Gy for proximal lesions.~For primary or secondary spinal or para-spinal tumors the SBRT treatment consists on 3 fractions of 9 Gy or 5 fractions of 7 Gy.~For previously irradiated tumors (same locations) the SBRT treatment consists on 5 to 8 fractions of 5 Gy.~For relapsed Ependymoma previously irradiated the SBRT treatment will be allocated by surgical stratified randomization and consists on either 3 fractions of 8 Gy or 5 fractions of 5 Gy."