602 / 1609
Photons are here considered to be gamma rays, characteristic x rays and internal
bremsstrahlung.
The air kerma-rate constant is defined for an ideal point source and is
characteristic for each radionuclide.
Considering a real source of finite size, attenuation and scattering in the source
itself occur and annihilation radiation and external bremsstrahlung may be
produced.
Considering the energy cut-off
its value depends on the specific application. For
simplification and standardisation it is recommended that
is expressed in keV.
The notation Γ
10
for the air kerma-rate constant means that a value of 10 keV for
the energy cut-off
is used
.
Air Kerma-rate constant Γ
δ
A
K r
2