Inclusion Criteria

Inclusion Criteria [applicable to both Cohorts 1 (control) and Cohort 2 (Experimental)
unless otherwise specified]:

1. Histological evidence of prostate adenocarcinoma.

2. Discrete intra‐prostatic tumor that can be confidently visualized on MRI prior to
radiotherapy (>5mm maximum diameter but <33% of prostate volume, biopsy confirmed)

3. At least 18 years old

4. ECOG performance status 0 or 1 with > 10‐year life expectancy

5. Informed consent: All patients must sign a document of informed consent indicating
their understanding of the investigational nature and risks of the study before any
protocol related studies are performed (this does not include standard care
laboratory tests or imaging studies).

6. Patients will be one of the following risk groups prior to therapy:

- Low‐risk disease (Gleason 6 and PSA <10 and T1) AND >50% of biopsy cores
involved with tumor

- Intermediate‐risk disease (Gleason 7 or PSA 10‐20 or T2)

- High‐risk disease (Gleason >8 or T3 or PSA >20)

7. Risk of LN involvement <30% (Roach formula = 2/3PSA([G‐6]x10))

8. Patients who received 78Gy RT to the prostate gland 3‐4.5 years prior to enrollment
(Cohort 1 only)

Exclusion Criteria [applicable to both Cohorts 1 (control) and Cohort 2(Experimental)
unless otherwise specified]:

1. Previous history of radiation therapy to the prostate (Cohort 2)

2. Diagnosis of another cancer not being skin cancer within the last 5 years (Cohort 2)

3. Patients weighing >136kgs (weight limit for the scanner tables)

4. Patients with contraindications to MRI: this includes patients with pacemakers,
cerebral aneurysm clips, shrapnel injury or implantable electronic devices not
compatible with MRI determination. Exceptions will be allowed if deemed sage and
appropriate by the MRI technologist.

5. Severe claustrophobia

6. Bleeding diathesis and anti‐coagulative therapy that cannot be temporarily ceased
precluding biopsy

7. Current hormonal therapy (Cohort 1) or initiated >2 weeks prior to enrollment (Cohort
2)

8. Radiological evidence of regional or distant metastases (Cohort 2)

9. Other urinary or medical conditions deemed by the PI or associates to make the
patient ineligible for MRI‐guided prostate biopsy

10. Contraindications to the endorectal coil, surgically absent rectum, severe
hemorrhoids or previous colorectal surgery

11. Contraindications to conscious sedation

12. Latex allergy

13. History of Ulcerative Colitis, Crohn's Disease, Ataxia Telangiectasia, or SLE (Cohort
2)

14. Other medical conditions deemed by the PI to make patient ineligible for study
intervention