Published clinical evidence confirms that a single dose of 24 Gy provides unprecedented long-term local control in primary and metastatic prostate cancer with safe toxicity profiles, provided that exposure of surrounding healthy tissues is critically assessed with fulfillment of strict constraints and dose distribution is accomplished using image guidance and tracking tools. In the present trial, intermediate unfavorable and selected high-risk organ-confined prostate cancer patients will undergo Single Dose Radiation Therapy (SDRT) With Focal Boost to the MRI-defined Macroscopic Tumor Volume by means of image-guided volumetric intensity-modulated arc radiotherapy (IGRT-VMAT) and state-of-the-art treatment-planning and quality assurance procedures. Androgen Deprivation Therapy (ADT) type and duration has been set as per standard of care, in accordance with current recommendations and guidelines. The results of the study will enable us to find out if the new, shorter treatment (1 doses of radiotherapy), has a similar level of side effects as the 5 dose treatment and is suitable for further study.