The purpose of this study is to evaluate the tolerability and toxicity of combining two radiation therapy methods for prostate cancer: Elective Pelvic Ultra Hypofractionated Irradiation Treatment (ePUHRT), which is an external beam radiotherapy with High Dose Rate Brachytherapy Boost (form of internal radiation where a cancer doctor implants a small plastic tube or balloon (catheter) in the tumor).

Progression free survival from irradiation dose escalation has been demonstrated across multiple prospective randomized studies. Irradiation dose escalation delivered by dual therapy (consisting of external beam irradiation treatment with brachytherapy boost, a type of internal radiation) offers improved survival. Brachytherapy boost makes it possible to safely deliver higher irradiation dose to the prostate gland than can be achieved with dose escalation by standard fractionated external beam treatment.

Inclusion Criteria:

1. ≥ 18 years old at the time of informed consent
2. Capable of providing informed consent and HIPAA authorization
3. Karnofsky performance score ≥ 70
4. Pathologically confirmed unfavorable intermediate, high, and very high-risk prostate cancer per treating physician
5. Candidate plans to undergo the standard of care prostate high dose brachytherapy boost procedure

Exclusion Criteria:

1. Prior pelvic irradiation treatment
2. Prior rectal surgery which precludes instrumentation with rectal ultrasound probe.
3. Evidence of nodal or distant disease on screening diagnostic work up.
4. Prior prostatectomy, Holmium laser enucleation of the prostate or transurethral resection of the prostate procedure
5. International Prostate Symptom Score (IPSS) score > 16 despite medical therapy