Inclusion Criteria:  Ability to understand a written informed consent document, and the willingness to sign it Age >= 18 years Eastern Cooperative Oncology Group (ECOG) performance status 0-2 History/physical examination with digital rectal examination of the prostate within 8 weeks prior to registration Histologically confirmed intermediate- to high-risk prostate adenocarcinoma (T1c-T3b, PSA > 10, and/or Gleason score >= 7 No evidence of disease beyond the prostate and/or seminal vesicles (i.e., no suspicious pelvic lymph nodes or presence of metastatic disease outside the pelvis) Prostate size =< 60cc International Prognostic Scoring System (IPSS) score =< 15 Able to safely receive moderate sedation or general anesthesia  Exclusion Criteria:  Patients with neuroendocrine or small cell carcinoma of the prostate Prior or concurrent invasive malignancy (except non-melanomatous skin cancer) or lymphomatous/hematogenous malignancy unless continually disease free for a minimum of 5 years Regional lymph node involvement Evidence of distant metastases Previous radical surgery (prostatectomy) or cryosurgery or high-intensity focused ultrasound for prostate cancer Previous pelvic irradiation or prostate brachytherapy Previous or concurrent cytotoxic chemotherapy for prostate cancer Patients with history of inflammatory bowel disease (i.e., Crohn's disease, ulcerative colitis), high predisposition for radio-toxicity compared to general population (i.e., ataxia telangiectasia), or at risk for major bowel surgery Transurethral resection of the prostate (TURP) procedure within 6 months of radiation treatment