Patient description: The patient is a 63-year-old man presenting to the Emergency Department with a history of acute urinary retention in the past 2 days. Abdominopelvic CT scan revealed a large prostate and a bladder filled with urine. He is a candidate for urethral catheterization and TURP. Further evaluation revealed: Post-void residual: 71 mL Prostate volume (TRUS): 63 mL Prostate-specific antigen (PSA) level: 3.5 ng/mL His recent blood chemistry (3 days ago) was normal: Hgb: 13.6 g/dl WBC: 133000 /mm3 Plt: 370000 /ml PT: 12 second PTT: 34 second INR: 0.9 Creatinine: 0.5 mg/dl BUN: 10 mg/dl U/A: Color: yellow Appearance: cloudy PH: 5.3 Specific gravity: 1.010 Glc: 100 Nitrite: negative Ketone: none Leukocyte esterase: negative RBC: negative WBC: 2 WBCs/hpf U/C: negative

Clinical trial eligibility criteria: eligible ages (years): 35.0-85.0,  Prostate Cancer Prostate Adenocarcinoma Biopsy confirmed adenocarcinoma of the prostate. 2. T1-T3a disease based on digital rectal exam (DRE) T3a disease based on MRI is acceptable (no evidence of frank (clear cut) seminal vesicle (SV) involvement or invasion of bladder or rectum). 3. Gleason score 6-10. 4. Patients with Gleason score ≥8 must be offered long term androgen deprivation therapy (ADT) and refuse such treatment because only 4-6 months (+/ months) (short term ADT) is permitted (not required) on this protocol. The ADT is recommended to begin after fiducial marker placement; however, ADT is permitted to have been started up to two months prior to the signing of consent. All patients in this protocol may (not required) be treated with 4-6 months (+/ months) of ADT, at the discretion of the treating physician Gleason ≥ 8 must have < 40% of the tissue involved with Gleason 8 in the biopsy specimen. 5. Prostate-specific antigen (PSA) ≤ 30 ng/mL within 3 months of enrollment. If PSA was above 30 and dropped to ≤ 30 with antibiotics, this is acceptable for enrollment. 6. No previous pelvic radiotherapy. 7. No previous history of radical/total prostatectomy (suprapubic prostatectomy is acceptable). 8. No concurrent, active malignancy, other than nonmetastatic skin cancer or early stage chronic lymphocytic leukemia (well-differentiated small cell lymphocytic lymphoma). If a prior malignancy is in remission for ≥ 5 years then the patient is eligible. 9. Identifiable multiparametric-MRI tumor lesion or lesions, that total in volume < 33% of the prostate Multiparametric MRI of prostate and pelvis is required prior to protocol consideration If contrast not given, the point dose on the apparent diffusion coefficient (ADC) map should be < 1000. 10. Ability to understand and the willingness to sign a written informed consent document. 11. Zubrod performance status < 2. 12. Willingness to fill out quality of life forms. 13. Bone scan negative if PSA > 15 ng/mL or Gleason ≥ 8 disease. A questionable bone scan is acceptable if other imaging tests are negative for metastasis. 14. Serum testosterone is within 40% of normal assay limits (e.g., x=0.4*lower assay limit and x=.04*upper assay limit + upper assay limit), and taken within 4 months of enrollment. Patients who have been started on ADT prior to signing consent are not required to have a serum testosterone at this level prior to signing consent; but, a serum testosterone prior to fiducial marker placement is recommended. 15. Serum liver function tests (LFT) are taken within 3 months of enrollment. 16. Complete blood counts are taken within 3 months of enrollment. 17. Age ≥ 35 and ≤ 85 years  > T3a disease on digital rectal exam or >T3a disease clearly identified by MRI. 2. Gleason score < 6. 3. ≥ 40% Gleason 8-10 tumor, over the total tissue including other tumor and normal tissue. For example: (Gleason 8-10 tumor length/other biopsy tissue length)*100 = ≥ 40%. 4. Androgen deprivation therapy longer than 8 months. Androgen deprivation timing is for the Luteinizing hormone-releasing hormone (LHRH) agonist portion only and not when anti-androgen is started beforehand with the purpose of counteracting the surge in testosterone from the LHRH agonist PSA > 30 ng/mL within 3 months of enrollment. 5. PSA > 30 ng/mL within 3 months of enrollment 6. Unable to obtain a 1.5T or 3.0T multiparametric MRI of the pelvis and prostate with contrast. 7. Unidentifiable multiparametric MRI tumor lesion. 8. Identifiable multiparametric-MRI tumor lesions, that total in volume ≥ 33% of the prostate. 9. Previous pelvic radiotherapy. 10. Previous history of radical prostatectomy. 11. Concurrent, active malignancy, which is not nonmetastatic skin cancer or early stage chronic lymphocytic leukemia (well-differentiated small cell lymphocytic lymphoma). If a prior malignancy is in remission for < 5 years then the patient is not eligible. 12. Zubrod performance status ≥ 2. 13. Inability to understand or unwilling to sign a written informed consent document 14. Unwilling to fill out quality of life/psychosocial forms. 15. Bone scan is positive and other imaging tests confirm a suspicion of metastasis from prostate cancer. 16. Serum testosterone is not within 40% of normal assay limits taken within 4 months of enrollment (only applicable to patients not started on ADT prior to signing consent). 17. Serum liver function tests (LFTs) are not taken within 3 months of enrollment. 18. Complete blood counts are not taken within 3 months of enrollment. 19. Age < 35 and > 85 years