Low incidence of significant hydrogel spacer rectal wall infiltration: results from an experienced high-volume center - Woo, Sungmin; Becker, Anton S.; Katz, Aaron E.; Tong, Angela; Vargas, Hebert A.; Byun, David J.; Lischalk, Jonathan W.; Haas, Jonathan A.; Zelefsky, Michael J. (Frontiers in Oncology, 2025)