The NCI Common Terminology Criteria for Adverse Events (NCI-CTCAE) is a descriptive terminology that can be utilized for Adverse Event (AE) reporting. A grading (severity) scale is provided for each AE term. Grade 1 Mild; asymptomatic or mild symptoms; clinical or diagnostic observations only; intervention not indicated. Grade 2 Moderate; minimal, local or noninvasive intervention indicated; limiting age-appropriate instrumental Activities of Daily Living (ADL). Grade 3 Severe or medically significant but not immediately life-threatening; hospitalization or prolongation of hospitalization indicated; disabling; limiting self-care ADL. Grade 4 Life-threatening consequences; urgent intervention indicated. Grade 5 Death related to AE. Number of participants with Grade 3 or higher adverse events associated with hyaluronic acid-based rectal spacer placement will be presented.

Patient assessments of symptom characteristics will be surveyed based on the Patient Reported Outcome Report, based on the Expanded Prostate Cancer Index Composite (EPIC) Bowel Assessment. Each item in the EPIC bowel domain uses a 5-point Likert scale. The responses are numerically coded and then converted to a 0-100 scale, where higher scores = better function / less bother. No problem=1, very small problem =2, small problem=3, moderate problem=4, big problem=5

The PRO-CTCAE survey, focused on gastrointestinal and genitourinary symptoms, will be used assessment of toxicity. The PRO-CTCAE Measurement System characterizes the frequency, severity, interference, and presence/absence of symptomatic toxicities reported from the patient perspective. PRO-CTCAE uses 5-point Likert scales to assess the frequency, severity, and daily life interference of patient-reported symptoms, with higher scores indicating more frequent, severe, or bothersome experiences.

The distance between the uterus, cervix, proximal vagina, and rectum will be measured using images acquired during brachytherapy.

Time required to complete gel placement will be reported.

Difficulty of Barrigel Procedure Insertion will be graded based on provider response to a 4-point scale survey. Higher scores represent difficult insertions. 1- Very Easy: All anatomical landmarks were easy to spot on transrectal ultrasonogram (TRUS), and Barrigel was well-visualized during injection. The tissue is separated well with Barrigel. Visible spacing between the cervix and rectum was achieved. The implant was positioned well and sculpted to the desired (symmetric) shape. 2- Easy: Most landmarks were easily seen, Barrigel was well-visualized, tissue separated reasonably well overall, although the shape may not be ideal. 3- Difficult: Some anatomy or Barrigel was difficult to visualize on TRUS, and/or the tissue didn't separate well in places with Barrigel. Spacing goals were notably not achieved, but some useful space was provided. 4- Very Difficult: The TRUS visibility was compromised, and/or the gel didn't get injected as planned due to tissue.