ESTRO course Dose Modelling and Verification 2017
Flattening filter scatter, semi-analytical approach
c c
0 1
C
f
k k
A
d
2
z
z
0
area as
calc
filt
viewed backward through the aperture
Assumptions (Med. Phys. 21 p 1227-1235): • Predominantly first order scatter • Triangular source distribution over the *visible* filter area - Fit parameters c 0 and c 1 from measured output factors. • Correction factors for: - Energy loss in Compton scattering. - Klein-Nishina cross section angular variation. • Modulate the resultant fluence if modulators are present
dA
( X,Y )
( x,y )
35
, X Y
i
i
i
i
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