Study of PSMA PET/MR Guided Stereotactic Body Radiation Therapy With Simultaneous Integrated Boost (SBRT-SIB) for High-Intermediate and High Risk Prostate Cancer

Inclusion Criteria: * Male aged 21 years or older. * Ability to provide signed informed consent and willingness to comply with protocol requirements. * Pathologic confirmation of high-risk adenocarcinoma of the prostate gland as follows: a. Gleason 8-10 or tertiary component 5 disease and/or b. PSA of 20 ng/ml or greater and/or c. Tumor stage of T2c or greater; OR Unfavorable intermediate risk (Gleason 4+3=7, \>50% of cores involved, or 2 or more intermediate risk factors which include Gleason 7 disease, PSA 10-20, or T2b disease) * Participants must agree to use an acceptable form of birth control and utilize condoms for a period of seven days after each PSMA injection, if engaged in sexual activity. * No evidence of metastatic disease, including pelvic lymph nodes. Exclusion Criteria: * Clinical and/or technical factors that would compromise statistical analysis of the PET and/or MR. * Contraindications to PSMA IV administration * Contraindications to prostate SBRT (history of transurethral resection of prostate; prostate size greater than 150 cc; AUA score greater than 20; history of prior radiation to the prostate) * Other unspecified reasons that, in the opinion of investigators, make the subject unsuitable for enrollment * Patients on or intending to take abiraterone will be excluded