264-265 / 1359
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
Z
K ZK
A
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 K
ph/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: