INCLUSION CRITERIA: Biopsy proven localized prostate cancer in whom stereotactic body radiation treatment (SBRT) with or without neoadjuvant androgen deprivation therapy (ADT) is planned for definitive management (NIH laboratory of pathology confirmation is not required). Must have at least 1 MRI detected, biopsy proven localized prostate cancer. Age >= 18 years ECOG performance status <= 2 For individuals with evidence of human immunodeficiency virus (HIV) infection, individuals must be on effective anti-retroviral therapy with undetectable viral load within the prior 6 months are eligible. For individuals with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy, if indicated. For individuals with a history of hepatitis C virus (HCV), the infection must have been treated and cured. For individuals with HCV infection who are currently on treatment, they are eligible if they have an undetectable HCV viral load. Ability of subject to understand and the willingness to sign a written informed consent document. Men must agree to use adequate contraception with their partner (hormonal or barrier method of birth control; abstinence) for the duration of study participation and 2 months after the last 18F-DCFPyL scan.  EXCLUSION CRITERIA:  Receiving prior androgen deprivation therapy, radiotherapy, or surgery for prostate cancer. Any condition that is likely to interfere with study procedures or results. Individuals in whom pelvic nodal irradiation is planned. Serum creatinine > 2 times the upper limit of normal. Weighing > 350 lbs (weight limit for scanner table), or unable to fit in imaging gantry. Evidence of tumor spread beyond the prostate/seminal vesicles (lymph nodes, metastases). Contraindications to radiation or SBRT.