Anatomy-Driven Rectal Spacer Placement

In this segment, the expert faculty discuss how patient-specific anatomy significantly influences rectal spacer placement and subsequent radiotherapy planning. They illustrate how uncommon anatomical variants—such as prostate tumors extending deep into the sphincteric complex—require careful pre-procedure MRI review and direct communication to identify safe windows for gel placement. They explain that anatomical considerations shift depending on treatment technique: SBRT demands maximal spacing near the apex, whereas disease involving the prostate base or seminal vesicles necessitates targeted superior placement. They also note cases in which small bowel positioning or low perirectal fat complicates safe radiation delivery, making tailored spacer sculpting essential. They emphasize the value of a moldable spacer like Barrigel, which allows deliberate contouring around sensitive structures and irregular tumor extensions. Together, they highlight how continuous dialogue, shared imaging review, and individualized planning enable optimized rectal protection, precise dosing, and safer, more effective treatment outcomes.