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Kerma, collision kerma
Kerma is the expectation value of the energy
transferred by photons to the medium per unit
mass
[ ]
Gy
dm
d
K
tr
ε
=
ρ
µ
Ψ=
ρ
µ
Φ=
tr
tr
E K
Monoenergetic photon beam
V
Collision Kerma: energy
transferred to charged particles
(
)
g K K
col
− =
1
rad
col
K K K
+ =
K includes all energy transferred to
collision and radiation losses
ρ
µ
Ψ=
ρ
µ
ρ
µ
=
en
col
K K
tr
en