Evolution of Hypofractionated Stereotactic Irradiation for Radio-Resistant Brain Metastases From D1-3-5 to D1-2-3

Inclusion Criteria: * Age \> 18 years * Patients with one or more unoperated brain metastases (1-5) originating from radioresistant primary locations, including melanoma, kidney, digestive, sarcoma, and prostate \* * Karnofsky Performance Status (KPS) greater than 50% (Annex 3). * Absence of major psychiatric conditions in the medical history that may interfere with follow-up, based on the investigator's judgement. * Proficiency in understanding French. * Signed informed consent. * For the ancillary study only: Patients included in the SISMIC study at centers with adequate resources and who have agreed to participate in the optional ancillary study. * Note: Patients who have had one or more surgery for metastasis removal and also have unresectable metastases are eligible for inclusion. Irradiation of the operating bed will follow the same treatment regimen as existing metastases but will not be considered for the evaluation of local control. Exclusion Criteria: * Pregnant or breastfeeding women * An unoperated brain metastasis whose maximum diameter is \> 3.5 cm * Patients deprived of liberty or under guardianship (including curatorship). * Patients with a history of cerebral radiotherapy. * Patients with known allergy to gadolinium. * Contraindication to magnetic resonance imaging (MRI).