Hydrogel injection outside of prostate radiation: an overview.

As radiotherapy has evolved and improved, it has become possible to apply higher doses of radiation more safely. However, adjacent structures and the associated collateral damage remains an important consideration. Creating separation between a target organ and these organs at risk (OAR) is fundamental to allowing greater and potentially more effective radiation coverage using external beam radiation. This technique has initially been described in the setting of prostate cancer with hydrogel being injected to separate the prostate from the rectum. The purpose of this manuscript is to describe both prostate and non-prostate techniques for utilizing hydrogel for OAR displacement in the setting of high dose radiation therapy with the intention of increasing target dose while limiting off target radiation to safe levels.