Inclusion Criteria:

- Histologically proven prostate adenocarcinoma.

- Gleason score 2-7 (reviewed by reference lab at UM).

- Biopsy within one year of date of enrollment.

- Clinical stage ≤T2 based on DRE and ≤T3a based on MRI; N0-Nx; M0-Mx (AJCC 7th
Edition)

- T-stage and N-stage determined by physical exam and available imaging studies
(CT, and/or MRI of the pelvis; see section 4.5). For MRI, questionable
extracapsular extension is permitted. To distinguish blood from tumor the ideal
study would be to acquire T2, T1 noncontrast and T1 dynamic contrast enhanced
sequence, although this is not required. A small amount of extracapsular
extension is permitted, as long as it can be included in the CTV and the
constraints are met.

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

- PSA ≤ 15 ng/ml, obtained no greater than 3 months prior to enrollment.

- Patients belonging in one of the following risk groups:

- Low:

- Clinical stage* T1-T2; Gleason ≤ 6, PSA ≤ 10 & <50% biopsy cores positive.

- Intermediate:

- Clinical stage T2b-T2c; Gleason ≤ 6, PSA ≤ 10 & <50% biopsy cores positive.

- Clinical stage T1-T2; Gleason ≤ 6, PSA ≤ 10 & ≥50% biopsy cores positive.

- Clinical stage T1-T2; Gleason = 7, PSA ≤ 10 & <50% biopsy cores positive
or T1-T2; Gleason ≤ 6 & PSA >10 and ≤15 & <50% biopsy cores positive.

- MRI stage T3a with evidence of extraprostatic extension is allowed.

- Clinical stage is based on digital rectal exam (DRE). Seminal vesicle invasion
on MRI is not eligible. T1a should be permitted if subsequent peripheral zone
biopsies show tumor.

- Prostate volume: ≤ 80 cc.

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

- Measured from CT or MRI ≤90 days prior to enrollment.

- Zubrod performance status 0-1.

- No prior total prostatectomy or cryotherapy of the prostate.

-- Prior suprapubic prostatectomy, transurethral resection and laser ablation are
permitted.

- No prior radiotherapy to the prostate or lower pelvis.

- No implanted hardware or other material that would prohibit appropriate treatment
planning or treatment delivery, in the investigator's opinion.

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

- No history of an invasive malignancy (other than this prostate cancer, or
nonmetastatic basal or squamous skin cancers) in the last 5 years.

- No androgen deprivation therapy (ADT) for six months prior to enrollment, and no
planned ADT during treatment or adjuvantly.

- Patient must be able to have gold fiducial markers placed in the prostate (if on
anticoagulants, must be cleared by a primary care physician or cardiologist).

- Ability to understand and the willingness to sign a written informed consent
document.

- Willingness to fill out quality of life/psychosocial forms.

- Age >= 35 and =< 85 years.

- IPSS (AUA) score ≤12

Exclusion Criteria:

- Does not have a diagnosis of prostate adenocarcinoma.

- Patient has clinical T3a or any evidence of T3b disease.

- Patient has stage N1 or M1 disease.

- Patients has a PSA of greater than 15 ng/ml.

- Patient does not meet any of the risk groups outlined in section 3.1.4.

- Prostate volume greater than 80 cc.

- Zubrod performance status 2 or greater.

- Prior total prostatectomy.

- Prior radiation therapy to the prostate or lower pelvis.

- Implanted hardware which limits treatment planning or delivery (determined by the
investigator).

- Chemotherapy within the past 5 years.

- Diagnosis of an invasive malignancy within 5 years (other than current prostate
cancer or non-metastatic basal or squamous skin cancers).

- The use of androgen deprivation therapy (ADT) within the past 6 months prior to
enrollment or the planned use of ADT during or after treatment.

- Inability to have gold fiducial markers placed in the prostate.

- Unwilling or inability to give informed consent.

- Not willing to fill out quality of life/psychosocial questionnaires.

- IPSS score > to 12.

- Age < 35 and > 85 years.