ESTRO course Dose Modelling and Verification 2017

380-381 / 1245

Stoichiometric calibration: An improved approach U. Schneider et al PMB 1996
   
i
i i
A
i
g g A
Zw
NN N
   
    K
I c m
I cm
e
w e
m e
e s 
  
  
  
 
 

2 2 2 2
2 2 2 2
1 2 log
1 2 log
Calculate Relative Electron Density: Relative proton stopping power
water
g
water
g
e N
N


 
w
H


1000 
 
KN coh ph
g K ZK ZKA ZN    86.1 62.3 ˆ ~
) , (  
By making measurements of H for different tissue substitutes of known composition
one can get a fit of data to derive values for Kph/coh/KN which characterize the CT scanner
From this can plot a curve to predict H for range of tissues substitutes and real tissue
Rutherford et al 1976
Using chemical composition: