776-777 / 2239
Modelling charged particle contamination
Needed when pencil beams kernels are derived from MC simulations
( )
2
,
r z
c
e e zr
p
γ− β−
α=
ρ
±
The parameters
α
,
β
,
and
γ
can be determined
through fitting to the
difference between
measurements and
calculated photon dose.
Charged particle contamination kernel
4MV
24MV
20
×
20 cm
2
5
×
5 cm
2
Contaminant dose per incident
primary photon fluence at depth z
A Ahnesjö et al (1992)
Med Phys
19, 263-273
A Ahnesjö and P Andreo (1989)
Phys Med Biol 34
, 1451-64.