Kerma (physics)

Kerma is a physical quantity of radiation physics. The term is an abbreviation for the words Kinetic Energy released per unit mass or Kinetic Energy released in matter. The Kerma is the power transmitted to the offspring of first-generation kinetic energy Ekin divided by the irradiated mass m:

The Kerma is always of the irradiated medium dependent. It is only indirectly ionizing radiation (neutrons, photons) calculated or measured. Offspring at photon interaction are secondary electrons. In the secondary electron equilibrium, the absolute value is equal to the absorbed dose. For dosimetry in humans only the absorbed dose is interesting, but approximately equal to the Kerma.

Unit

The SI unit of kerma is the gray ( Gy), in other words joules / kg.

Kermaleistung

The Kermaleistung is the derivative with respect to time of the Kerma.

The SI unit is the gray / second or watts / kilogram.