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Air Kerma-rate constant Γ
δ
A
K r
δ
δ
&
⋅
=Γ
2
Consequently, and according to definition of air kerma rate at point P, is:
EA
r 4
1
EA
da
1
r 4
da
Ψ
2
2
⋅ ⋅
⋅
= ⋅ ⋅
⋅
⋅
=
π
π
&
E,
tr
2
E,
tr
EA
r 4
1
Ψ K
α
α
δ
ρ
μ
π
ρ
μ
⋅ ⋅ ⋅
⋅
=
⋅ =
&
&
with
Combining above equations, the air kerma-rate
constant
Γ
δ
for the mono-energetic
point source is given by
(multiplication by r² and division by A)
:
E,
tr
E
4
1
Γ
α
δ
ρ
μ
π
⋅ ⋅
=