Inclusion Criteria:

          1. Histologically proven adenocarcinoma of the prostate a. Gleason score (2-10) b. Biopsy
             within six months of date of registration

          2. Clinical stage (American Joint Committee on Cancer 7th Edition) a. T-stage determined
             by physical exam i. MRI findings (e.g. extracapsular extension) should not influence
             T-staging, but should be noted for later analysis b. N-stage determined using
             abdominopelvic CT scan c. M-stage determined by physical exam, CT and/or MRI, and bone
             scan

          3. Patients must belong to one of the following risk groups: a. Very High risk: Stage cT3
             and Gleason 8-10 and prostate-specific antigen less than 150 b. High risk: Stage
             cT1-T2 and Gleason 8-10 and prostate-specific antigen less than 150 c. Moderate high
             risk: Stage cT3 and Gleason 7 and any prostate-specific antigen. Intermediate to high
             risk (a) Stage cT3 and Gleason 6 and prostate-specific antigen at least 30 e.
             Intermediate to high risk (b): Stage cT1-T2 and Gleason 7 and prostate-specific
             antigen at least 30

          4. Patient is planned to undergo standard androgen deprivation therapy and initial
             Intensity Modulated Radiation Therapy (IMRT) to the prostate and at-risk lymph nodes.

          5. Prostate volume greater than 20 cc and less than 100 cc

          6. Eastern Cooperative Oncology Group (ECOG) performance status 0-1

          7. Patient has agreed to complete questionnaires

          8. Signed Institutional Review Board (IRB) approved informed consent

        Exclusion Criteria:

          1. No prior prostate surgery or prostate cancer treatment

          2. No prior radiotherapy to the pelvis

          3. No implanted hardware or other material that would prohibit appropriate treatment
             planning or treatment delivery

          4. No chemotherapy for a malignancy in the last 5 years.

          5. No history of an invasive malignancy (other than basal or squamous skin cancers) in
             the last 5 years.

          6. No history of a horseshoe kidney

          7. No diagnosis of inflammatory bowel disease

          8. No heart pacemaker, No metallic foreign body (metal sliver) in the eye, No aneurysm
             clip in the brain

          9. Must be able to tolerate the confinement of an MRI procedure