# Absorbed dose

The fundamental dose quantity absorbed dose, $D$, given by:
$D=\frac{d\bar{ϵ}}{dm}$
where $d\bar{ϵ}$ is the mean energy imparted to matter of mass $dm$ by ionising radiation. The SI unit for absorbed dose is joule per kilogram (J kg-1) and its special name is gray (Gy).