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Dose per MU formalisms:
factor-based dose calculations
Inhomogeneities
Effective depth
to a calculation point is the thickness of water equivalent tissue that
would attenuate the radiation by the same amount as the actual tissue along a fan-line
between the calculation point and the surface
If the radiation passes through
n
different
tissues each if thickness
d
i
and density
ρ
i
=
=
n
i
d
d
1
i i
eff
Note:
TPSs usually report an effective depth for a calculation point, but
how exactly this is derived is not always apparent
d