As seen online:
“Potential toxicity to normal tissue is further reduced by injecting a synthetic hydrogel called SpaceOAR (manufactured Boston Scientific) as a spacer between the prostate and rectum. This moves the rectum away from the prostate by a small amount (usually 10-12mm) which is just enough for the rectum to be moved out of the high dose area of the radiation field.”
— from Prostate cancer treatment Intensity Modulated Radiation Therapy (IMRT) - Prostate Matters as of 12 July 2026