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Recipe:
Minimize the difference between measured depth dose and spectral
weighted monoenergetic Monte Carlo calculated depth dose. Explicitly
consider electron contamination depth dose in the buildup region (or
exclude the buildup zone from depth doses!):
( ) ( ) ( ) electron cont
1 2 1 2 fsize depth, fsize ebin 1 2 depth, fsize, ebin depth 1 2
fsize depth ebin
, ..., , ... c , ... , ... s s e e D s s d d e e  
   
= −  +
   
   
 
Ahnesjö & Andreo, 1989 PMB 34, p 1451-64
Beam energy spectra
Constrained unfolding of spectra from depth dose measured in water
Measured depth
dose, phantom
scatter normalized
Spectrum model,
constrained to a
“physical” shape
MC calc depth doses
for monoenergetic
photons
Electron
contamination
model
Error norm to minimize
by varying parameters