Abstract:
Introduction: The photoelectric attenuation coefficient of substances is known
to depend upon the energy E of the photon and the effective atomic number of substances
(Zeff) as (Zeff
x/Ey). No definitive values about these indices x, y are given in
the literature. The index x is said to lie between, 3.0 and 4.0, while for ‘y’ different
values have been assigned, between 3.0 and 4.0.
Methodology: We followed a methodology to find both the exponent y explicitly,
from a formula which does not contain x. Through this way, the risk of one
parameter leading to an estimation error for the other is automatically eliminated.
With the value of y being unmistakably established, we determined the exponent x
for different elements.
Results: It was found from the NIST data that ‘y’ = 3.0669 for most substances
with low atomic number but no single value can be assigned for the exponent ‘x’.
Conclusions: These results help us to perform model calculations for the
attenuation coefficients of different substances. They can also provide important
inputs for the diagnostic purposes in the DECT method.
