Inclusion Criteria:

- Histologically proven prostate adenocarcinoma

- Gleason score 2-7

- Biopsy within one year of date of registration

- Clinical stage T1b-T2b, N0-Nx, M0-Mx (AJCC 6th Edition)

- T-stage and N-stage determined by physical exam and available imaging studies
(ultrasound, CT, and/or MRI)

- M-stage determined by physical exam, CT or MRI. Bone scan not required unless
clinical findings suggest possible osseous metastases.

- PSA ≤ 20 ng/dL

- Patients belonging in one of the following risk groups:

- Low: CS T1b-T2a and Gleason 2-6 and PSA ≤ 10, or

- Intermediate: CS T2b and Gleason 2-6 and PSA ≤ 10, or CS T1b-T2b, and Gleason 2-6 and
PSA ≤ 20 ng/dL, or Gleason 7 and PSA ≤ 10 ng/dL

- Prostate volume: ≤ 100 cc

- Determined using: volume = π/6 x length x height x width

- Measurement from CT or ultrasound ≤90 days prior to registration.

- ECOG performance status 0-1

- Completion of patient questionnaires:FACT-G questionnaire, AUA questionnaire, EPIC-26
questionnaire, SHIM questionnaire, Utilization of Sexual Medications/Devices
questionnaire

- Consent signed.

Exclusion Criteria:

- Prior prostatectomy or cryotherapy of the prostate

- Prior radiotherapy to the prostate or lower pelvis

- Implanted hardware or other material that would prohibit appropriate treatment
planning or treatment delivery, in the investigator's opinion.

- Chemotherapy for a malignancy in the last 5 years.

- History of an invasive malignancy (other than this prostate cancer, or basal or
squamous skin cancers) in the last 5 years.

- Hormone ablation for two months prior to enrollment, or during treat