Patients must have histologically-proven prostate cancer

Patients must meet either: a. National Comprehensive Cancer Network (NCCN) definition of high-risk disease or b. Intermediate-risk disease with at least 3 points using the following scale: One point each for clinical stage = T2b-c, iPSA \>7 ng/mL, and Gleason grade group 2 (overall Gleason sum 3+4 =7), Two points for Gleason grade group 3 (overall Gleason sum 4+3 =7).

Patients must have N0 M0 status on the basis of technetium bone scan and computed tomography (CT) scan of the pelvis

Minimum age: 18

Those with pre-intervention prostate specific antigen (iPSA) above 100 ng/mL.

Those who have received prior surgical treatment for prostate cancer including transurethral resection of the prostate (TURP), transurethral resection of the bladder neck (TURB), cryotherapy, laser ablation, or high frequency ultrasound (HIFU)

Those with an estimated life expectancy of less than 5 years with an Eastern Cooperative Oncology Group (ECOG ) performance status above 0-2

Those with prior radiation therapy to the pelvis.

Those who have received androgen deprivation therapy (ADT) prior to registration.

Contraindication to high-dose pelvic irradiation, Luteinizing hormone-releasing hormone (LHRH) agonists, or nonsteroidal antiandrogen therapy

Those who are not able to participate in an MRI scan (i.e. significant renal impairment that would preclude the use of contrast agent, some patients with cardiac pacemaker, wires, or defibrillator; artificial heart valve; brain aneurysm clip; electrical stimulator for nerves or bones; ear or eye implant; implanted drug infusion pump; coil; catheter, or filter in any blood vessel. Some men with metallic prosthesis; shrapnel, bullets, or other metal fragments retained in the body)

Those who are not able to participate in a PET/CT scan

Cancer survivors who do not meet all three of the following criteria: a) The patient has undergone potentially curative therapy for all prior malignancies. b) There has been no evidence of recurrence for at least five years following potentially curative therapy. (For non-melanoma skin cancer the five-year requirement does not apply.) and c) The patient is considered by the treating physician to be at low risk of recurrence from prior malignancies.

Those who are on anticoagulation therapy (blood thinners) and are unable stop this medication safely for at least 5 days.