Impact of Structured Visual Feedback on Bladder Volume Consistency In Prostate EBRT: A Medical Physics 3.0 Inspired Trial.
Abstract
Purpose
A single institution clinical trial evaluated the efficacy of structured patient education and individualized CBCT-based visual feedback on the consistency and magnitude of bladder volume relative to the planning simulation baseline for prostate EBRT patients.
Methods
Data from 35 patients was analyzed (23 controls, 12 subjects). The subjects received individualized education about the importance of both total bladder volume and volume consistency during their treatment course. Sessions were conducted by medical physics learners. Additionally, they received individualized weekly feedback sessions using their daily CBCTs, overlaid with their simulation contours. Patient bladder volumes were manually contoured on all daily CBCTs (MIM Maestro). Anatomical variation was accounted for by normalizing each patient to their own simulation baseline (Vnorm= Vtx/Vsim). Patient specific median normalized volumes were utilized to assess consistency. Variability was measured via standard deviation from individual normalized volumes. Inter-group comparisons were performed using Welch’s t-test and Cohen’s d.
Results
The subjects receiving feedback demonstrated significantly higher bladder volume consistency compared to the controls (mean normalized volume: 1.052 vs. 0.766, p = 0.0131) with a large effect size (Cohen’s d = 0.88). They also exceeded their simulation volumes during 51.5% of their fractions, compared with 25.7% for the control group (p<.0322). Notably, the intentional increase in volume did not significantly increase inter-fraction variability (p = 0.475, d = 0.24), which suggests that the feedback improved patient bladder volume without sacrificing reproducibility between fractions.
Conclusion
Providing visual feedback to patients is a low-resource strategy that significantly improves protocol adherence. Improved bladder volumes are known to facilitate dose sparing to the OARs, and this intervention has been shown to do so without increasing inter-fractional variability or disrupting standard clinical workflow.