The main goal of this study is to evaluate and to determine the dose of a highly accurate irradiation (allowing to increase the dose delivered while restricting the risk of complication) in association with temozolomide.

Inclusion Criteria:

• Histopathologically proven diagnosis of glioblastoma (WHO grade IV astrocytoma)
• Diagnosis must be obtained by a stereotactic or surgical biopsy
• Age between 18 and 70
• Total or partial surgical resection deemed as not possible by a neurosurgeon
• OMS performance status 0 or 1
• Adequate blood function : absolute neutrophil count > 1.5 x 109/L, platelets count > 100 x 109/L platelets;
• Adequate liver function: bilirubin < 1.5 ULN (upper limit of normal), ALT and AST < 3 ULN,
• Adequate renal function: creatinine < 1.5 ULN
• Patient must have been informed and must have signed the specific informed consent form.

Exclusion Criteria:

• other malignancy histology
• resection of the brain tumor complete on MRI exploration
• patient unable to give informed consent
• patient presenting counter-indication to MRI exploration
• patient must not have received neither radiotherapy nor chemotherapy for that affection
• concomitant malignancy
• patient already enrolled in another biomedical study with an experimental molecule
• pregnant, nursing woman, or without contraception
• private individuals of freedom or under tutelage (including legal guardianship)
• psychiatric, behavioural disorders or geographical situation precluding the administration or follow-up of the protocol (including claustrophobia)