Biologically effective dose ($\mathrm{BED}=Nd(1+d/(\alpha /\beta ))$)

An effect-equivalent dose derived from the linear-quadratic radiobiology model, with a subscript often indicating the tissue's assumed $\alpha /\beta$ in gray. It is distinct from the physical total absorbed dose $Nd$. Increasing fraction size at fixed tumour BED can increase the normal-tissue BED when the latter has smaller $\alpha /\beta$.