A profound understanding of dose response modeling of the putative biological effects of spatially fractionated radiation therapy (SFRT) is fundamentally important for the clinical implementation of heterogeneity dose radiation approaches. In chapter 14, Bartzsch et al discuss the role of the linear quadratic model, equivalent uniform dose, and relative biological effectiveness to be able to account for and compare the biological effects of different types of beams and beam geometries used in SFRT. Further, for clinical implementation, comprehensive commissioning and quality assurance processes are paramount in SFRT.