Author: Francis A Asamoah, David D. Campos, Jordan A Holmes, Ke Colin Huang, Omar Ishaq, Sook Kien Ng, Arpan Prabhu, Edwin Quashie, Yong Yue 👨🔬
Affiliation: Indiana University School of Medicine, Department of Radiation Oncology 🌍
Purpose: Evaluate a novel rectal spacer workflow with spacer injection during brachytherapy to streamline logistics, reduce hospital visits and costs, and compare the benefits of SpaceOAR Vue and Barrigel.
Methods: The study included two groups of 10 prostate cancer patients each received either SpaceOAR Vue or Barrigel spacers during combined HDR brachytherapy/EBRT treatment. SpaceOAR Vue was injected after brachytherapy to prevent interference with ultrasound-guided needle placement and treatment planning, enabling improved dosimetry and precise patient alignment during EBRT. For Barrigel, an initial 3cc was injected pre-brachytherapy to enhance brachytherapy dosimetry, with the remainder administered post-brachytherapy to optimize EBRT dosimetry. We evaluated spacer outcomes based on injection success rate, ease of use, spacer placement uniformity/symmetry, target coverage impact and rectal dose reduction in EBRT.
Results: SpaceOAR Vue: CT-only treatment planning and precise alignment using CBCT-based motion management remained effective. Despite four instances of minor leakage through brachytherapy needle tracts, all patients achieved optimal target coverage and significant rectal dose reduction during EBRT. However, achieving uniformity and symmetry in spacer placement was challenging due to its liquid form, making the process more time-consuming.
Barrigel: Barrigel seamlessly integrated into brachytherapy workflows, preserving the visibility of anatomical structures in ultrasound to allow precise needle placement and ultrasound-based planning. Barrigel's gel-like consistency facilitated sculptability, ensuring uniform placement and improved rectal sparing. No leakage was observed, and dosimetry enhancements were achieved for both brachytherapy and EBRT.
Conclusion: Rectal spacer injections during brachytherapy are feasible and effective. SpaceOAR Vue is ideal for workflows requiring CT-only planning and facilitated CBCT-based daily motion management, though minor leakage risks exist due to its liquid form during injection. Barrigel integrates seamlessly into brachytherapy procedures, enhancing dosimetry for both brachytherapy and EBRT while supporting ultrasound-guidance brachytherapy without the risk of leakage. Spacer selection should consider patient-specific needs, clinical workflows, and clinician expertise.