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Stoichiometric calibration: An improved approach
U. Schneider et al PMB 1996
∑ ∑
=
=
i
i
i
A
i
g
g
A
Zw
N N N
(
)
[
]
(
)
[
]
K
I
cm
I
cm
e
w
e
m
e
e
s
ρ
β β
β
β β
β
ρ ρ
=
− −
− −
=
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
ρ
ρ
ρ
=
µ
Using chemical composition:
w
H
µ
1000
=
{
}
KN
coh
ph
g
K ZK ZKAZN
+
+
=
86.1
62.3
ˆ
~
) , (
ρ µ
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