Using preoperative MRI imaging to identify areas suspicious of local advancement in addition
      to identifying areas with a higher likelihood of a positive margin during RP due to the
      presence of high risk features, Civasheet® and its inherently flexible structure allow the
      sheet to be directly implanted on areas suspicious for local advancement and positive
      surgical margins for direct application of radiation to these areas. The custom, single
      planar layer, integrative gold shielding of Civasheet® also allows radiation to be provided
      unidirectionally to allow healthy tissue (i.e., bladder, rectum) to be shielded from
      radiation; possibly affording a lower rate of gastrointestinal (GI) and genitourinary (GU)
      toxicity and adverse events. During EBRT, radiation especially for high risk PCa is provided
      at high rates to the entire prostatic bed with the seminal vesicles, pelvic lymph nodes and a
      surrounding margin often targeted to eliminate positive margins and cancer from locally
      advanced areas in which the cancer may have spread (i.e., seminal vesicles, bladder neck).
      These high rates of radiation often damage surrounding tissue and result in rectal and
      bladder complications in addition to urethral strictures among other adverse complications.
      Since Civasheet® will provide radiation to the prostatic bed, a lower dose of EBRT will be
      used to treat the prostatic bed and potentially lower adverse bladder and rectal effects
      compared to RP + RT at 60 Gy. 103 Pd seeds of Civasheet® also illuminate on imaging.
      Therefore placing Civasheet® based on pre-operative identification of areas suspicious for
      local advancement and areas of likely positive surgical margins during RP will allow for
      targeted EBRT to the locally advanced areas. Since EBRT can be targeted using Civasheet®, a
      lower and more direct dose of radiation during EBRT may be used to treat local advancement
      and positive surgical margins which will potentially reduce toxicity and complications
      associated with higher doses of radiation.

      The above properties are likely to facilitate improved cancer control with more direct and
      local application of radiation to areas of local advancement surrounding the prostate. These
      features are also likely to facilitate a reduced complication and toxicity profile since
      Civasheet® allows EBRT to be applied more accurately and at a lower dose and also the
      unidirectional radiation applied directly by Civasheet® protects surrounding healthy tissue
      from receiving radiation.No other studies have attempted to use Civasheet® to improve PCa
      control and reduce toxicity and complications associated with radiation for participants with
      high-risk prostate cancer. The investigators anticipate that implanting Civasheet® on areas
      suspicious for local advancement and positive margins based on pre-operative MRI findings and
      identification of high risk features in addition to relying on the illumination provided by
      Civasheet® for targeted adjuvant EBRT will provide a safer complication profile and
      eventually provide evidence for superior cancer control, lower toxicity and less adverse
      events than EBRT+ RP alone in a future randomized controlled trial. The investigators
      therefore propose a phase I single-arm open label dose escalation study to evaluate the MTD
      and safety of Civasheet® with RP and adjuvant EBRT in a 3+3 dose escalation design among
      participants with high risk PCa.With this study, the investigators to better understand the
      MTD, safety and toxicity profile of Civasheet® in the setting of RP + adjuvant EBRT in the
      treatment of high-risk PCa.