Hypofractionated Stereotactic Body Radiation Therapy (SBRT)

Inclusion Criteria: * 18 years of age or older * Histologically confirmed diagnosis of adenocarcinoma of the prostate within 180 days of enrollment * Signed informed consent * Gleason score ≤ 7 * If Gleason 7 (3+4=7 or 4+3=7) then \<50% of biopsy cores must be positive for any pathologic grade of prostate cancer * If Gleason score \<7 then there is no limit on the percentage of biopsy cores involved by prostate cancer * PSA (within 90 days prior to enrollment) * ≤ 15 ng/ml prior to start of therapy if Gleason ≤ 6 and * ≤ 10 ng/ml prior to start of therapy if Gleason 7 * No plan to use hormone therapy prior to evidence of biochemical failure(ie: No neoadjuvant or adjuvant ADT) * Tumor stage: T1a, T1b, T1c, T2a, T2b * ECOG Performance Status 0-1 Exclusion Criteria: * A history of other malignancy diagnosed within the previous 60 months except for non-melanoma skin cancer. * Any patients who have received other investigational therapy within the last 60 days * Individuals that have previously been implanted with permanent Beacon transponders * Patients that have any prosthetic implants in the pelvic region that contain metal or conductive materials (e.g., an artificial hip) * Patients with implanted pacemaker or defibrillators * Patients who are felt to have body habitus not conducive to tracking with Calypso beacons * Positive lymph nodes or metastatic disease from prostate cancer * Tumor stage: T2c, T3, or T4 * Previous pelvic radiation therapy * Previous surgery or chemotherapy for prostate cancer * Previous transuretheral resection of the prostate (TURP) or cryotherapy to the prostate * Prior hormone therapy or plans for concurrent or post treatment adjuvant hormonal therapy or chemotherapy * Hormone therapy to include LHRH agonist or oral anti-androgen * Finasteride and Dutasteride use not excluded * Concomitant antineoplastic therapy (including surgery, cryotherapy, conventionally fractionated radiation therapy, and chemotherapy) while on this protocol * History of Crohn's Disease or Ulcerative Colitis