Why Do Both Mean Dose and V≥x Often Predict Normal Tissue Outcomes?

Abstract

In the Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC), High Dose per Fraction, Hypofractionated Treatment Effects in the Clinic (HyTEC), and Pediatric Normal Tissue Effects in the Clinic (PENTEC) reviews, the mean dose was identified as a reasonable predictor for risk of toxic effects in some normal organs,1-5 particularly in organs classically considered to have a parallel-like architecture, such as the lung, liver, and parotid. The utility of the mean dose as a predictive metric is puzzling, because an underlying biological basis is challenging to define.