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Dosimetric comparison of implantable rectal spacers for low-dose-rate prostate brachytherapy
Vishesh Agrawal1, Jinesh Shah1, Molly B Shapiro1
1Advanced Radiation Centers of New York, Lake Success, 11042 NY.
Introduction:
Brachytherapy is utilized for both definitive and salvage radiotherapeutic management of prostate cancer. We compared current FDA-approved rectal spacers, including hyaluronic acid (HA), polyethylene glycol hydrogel (PEG), and an absorbable balloon, to evaluate rectal dosimetry in low-dose-rate brachytherapy (LDR-BT).
Methods:
53 patients undergoing low-dose-rate brachytherapy (LDR-BT) with or without rectal spacer placement were analyzed. Post-implant dosimetry was performed, and rectal spacers were compared to assess for effect on rectal dosimetry parameters, including V100%, D2cc, and D1cc. The Mann-Whitney test was used to assess for statistical significance.
Results:
Rectal spacers were implanted following brachytherapy without complication. The mean rectal separation at the midgland for patients with no spacer, HA, PEG, and Balloon was 1.8, 9.2, 10.5, and 15.5 mm, respectively. The rectal D2cc and D1cc were significantly improved for all spacers. The mean rectal D2cc and D1cc for no spacer, HA, PEG, and balloon were 40.8%, 20.5%, 24.1%, 11.8%, and 55.2%, 25.4%, 33.0%, 13.8%. Balloon-based spacing had statistically decreased rectal dose compared to HA- and PEG-based spacing.
Conclusion:
Balloon-based rectal spacing is feasible for prostate cancer patients undergoing low-dose-rate brachytherapy (LDR-BT) and results in statistically significant reduction in rectal dose compared to other available spacing modalities.
