Evaluation of the Efficacy and the Safety of a Stereotaxic Prostatic Radiotherapy Delivered With Linac MRI, in Patients With Prostate Adenocarcinoma

Inclusion Criteria: 1. prostate adenocarcinoma 2. WHO performance index ≤ 1 3. Patient presenting one of the following cases: * Low risk: ≤ T2a and Gleason 6 (3 + 3) and PSA \<10 ng / ml * Intermediate risk: T2b-T2c or Gleason 7 or PSA \<15 ng / ml * High localized risk: T3a and Gleason ≤7 and PSA \<15 ng / ml 4. Disease presenting a risk of lymph node involvement \<15% 5. Absence of pelvic or lumbar aortic lymphadenopathy 6. Absence of bone or visceral metastasis 7. IPSS score \<15 or ≤ 7 8. Prostate volume estimated by MRI or ultrasound \< 90cc 9. If hormonotherapy, hormone therapy must not have started for more than 60 days before inclusion. 10. Absence of prior pelvic radiotherapy 11. No surgical treatment for prostate cancer Exclusion Criteria: 1. Prostate cancer of histology other than adenocarcinoma 2. Contraindication to MRI including, but not limited to, patients with a pacemaker or defibrillator 3. Patient diagnosed N1 during imaging workup or pN1 4. Serum PSA level ≥ 15 ng / ml 5. IPSS score ≥ 15 or IPSS score\> 7 if alpha blocking urological treatment in progress 6. Prostate volume estimated on MRI or ultrasound\> 90 cc 7. Involvement of seminal vesicles on MRI 8. History of cancer in the 5 years preceding entry into the trial 9. History of transurethral resection of the prostate less than 6 months compared to the expected date of start of radiotherapy 10. rectal surgery 11. pelvic irradiation 12. Patient treated with antineoplastic or medication which may include Methotrexate 13. Hormone therapy started for more than 60 days at the time of inclusion 14. Severe uncontrolled hypertension 15. Patient followed or treated for severe or unstable angina, or having presented a myocardial infarction in the 6 months preceding the randomization 16. Patient on immunosuppressant 17. Patient with known hypersensitivity to gadoteric acid, meglumine or any drug containing gadolinium