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

The purpose of this study is to evaluate the efficacy of hypofractionated stereotactic radiation treatments (SBRT) on children, teenagers and young adults malignant tumors.

SBRT (Stereotactic Body Radiation Therapy) is a radiotherapy treatment which involves the delivery of a single high dose radiation treatment or a few fractionated radiation treatments (usually up to 5). A high potent biological dose of radiation is delivered to the tumor improving the cure rates for the tumor, in a manner previously not achievable by standard conventional radiation therapy. For adult patients, the "Haute Authorité de Santé" (HAS) validates some indications for this treatment which are the followings : * Few primary or secondary brain tumors, which cannot be surgically removed * Spinal tumors * Primary bronchopulmonary tumors T1 T2 N0 M0 and pulmonary metastasis with slow growth and controled primary tumor. For pediatrics patients, no indication is now validated by HAS. Indications validated for adults are rare in pediatrics but not exceptional, and in such cases efficient alternative treatments does not exist. In consequence, and regarding the good results obtained in adult patients, it seems very important to validate the efficacy of this treatment on pediatrics population