Are there any volumetric constraints associated with toxicity in the dose range that is moderately above prescription (i.e. 30-35 Gy range), when planning hippocampal-sparing whole brain radiation?

This is an important question worth some discussion. As the question mentions, clinical trials of HA-WBRT have permitted a hot spot of 133% of the prescription dose of 30 Gy (or 40 Gy) to D2% of the whole-brain parenchyma as an acceptable protocol variation. Importantly, none of these trials have de...