RecruitingDevice studyRectal Spacers Use in Prostate Cancer Radiation TherapyThis prospective, 2-arm clinical trial aims to evaluate the use of rectal spacers in patients with localized prostate cancer scheduled for Proton Beam Therapy (PBT). Up to 50 subjects will be enrolled in this study. Study visits will include screening, spacer placement, treatment planning, end-of-treatment assessment, and follow-up visits at 1, 3, and 6 months.