Definitions

Question 1

Definition of Kerma

Answer 1

Kinetic Energy Released in MAtter.

Energy transferred to charged particles per unit mass of material by indirectly ionizing radiation (e.g. gamma rays, neutrons). Not defined for charged particle radiation.

1. the kerma is the first step in photon or neutron energy absorption. This step is energy transfer from the uncharged radiation.
2. kerma refers to the transfer of energy to the medium, not to the absorption in the medium.
3. kerma is the sum of the kinetic energy released including any secondary radiations that lose energy by collision, bremsstrahlung, or annihilation processes.
4. The second step of neutron or gamma energy absorption is the absorption of energy. If the energy leaves the mass, then the kerma and absorbed dose will differ.

Question 2

Definition of Absorbed Dose

Answer 2

Energy deposited per unit mass.

1. Absorbed dose refers to all ionizing radiation in any medium
2. absorbed dose is a measure of the energy imparted and not the ionizing ability of the radiation type

Question 3

What condition must exist for absorbed dose to be approximately equal to kerma

Answer 3

Whenever the mean energy imparted by ionizing radiation in a mass is equal to the initial kinetic energies of all the charged ionizing particles liberated by uncharged ionizing radiation in a material of mass.

Put another way, Electronic Equilibrium is achieved when as many electrons are stopped in a volume as are being put into motion.