Cema is the acronym for converted energy per unit mass. It is a nonstochastic quantity applicable to directly ionizing radiations such as electrons and protons. The cema C is the quotient of dEc by dm, where dEc is the energy lost by charged particles, except secondary electrons, in collisions in a mass dm of a material:
C = dEc / dm
The unit of cema is joule per kilogram (J/kg). The name for the unit of cema is
the gray (Gy).
Radiation Oncology Physics A Handbook for Teachers And Students