Equieffective dose

The total absorbed dose delivered by the reference treatment plan (fraction size $X$) that leads to the same biological effect as a test treatment plan that is conducted with absorbed dose per fraction $d$ and total absorbed dose $D$ according to the relation:
$EQDX_{\alpha/\beta} = D \cdot \frac{d+\alpha/\beta}{X + \alpha/\beta}$
where $\alpha/\beta$ is an endpoint- and radiation quality-specific parameter that describes the effect of changes in dose per fraction.