COCORIVO is an interventional study evaluating the impact of body composition on dosimetry of 177Lu-PSMA radioligand therapy in patients with metastatic castration-resistant prostate cancer (mCRPC). Body composition (muscle, lean, visceral fat, subcutaneous fat and total fat masses) will be automatically quantified from whole-body CT images acquired at 72-96h after 177Lu-PSMA injection using the Anthropometer3DNet software. Dosimetry will be evaluated for tumors and organs at risk (salivary glands, bone marrow, kidneys). The study also evaluates the impact of body composition on SUV quantification, the feasibility of single-timepoint dosimetry, and the evolution of body composition during treatment.