Changes

The unit for entrance surface air kerma is the Gy. Entrance surface air kerma <mathmmath>K_e</math> can be calculated from incident air kerma <math>K_i</math> using suitable backscatter factor <math>B</math>, or determined directly using small dosimeters (thermoluminescent or semiconductor) positioned at the representative point on the skin of the patients. (Adapted from [[ICRP Publication 117]], 2010)