ESTRO course Dose Modelling and Verification 2017

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40
Spectrum corrections of raytraced collision kerma
and scerma for attenuated beams (wedges)
Multiply cKERMA by
Multiply SCERMA by
   
PQ
0 0
ˆ
mod
P P
k open 
 
  
5 10 15 20 25 30
Depth in water [cm]
0.90
0.95
1.00
1.05
1.10
Beam quality corrections for a 1.5 cm lead attenuator
k PQ,
k SQ
0
0
4MV, k
PQ
4MV, k
SQ
24MV, kPQ
24MV, kSQ
 
 
 
 
 
1 KERMA
mod
,
1 KERMA
open
PQ
g
depth thickness
g
k 




 
 
 
SCERMA
mod
,
SCERMA
open
SQ depth thickness k 


i. e.
Where is the modulation.
ˆ

   
SQ
0 0
ˆ
mod
S S
k open 
 
  