In the verification experiment , the materials with approximately linear attenuation coefficients
in the reconstructed images could be significantly distinguished.
The mass attenuation coefficient ([[mu].sub.m]/[rho]) can be obtained by dividing the linear attenuation coefficient
of the material ([[mu].sub.m]) by its density ([rho]).
The correlation between TU and the linear attenuation coefficient
of the different materials utilised for the CT calibration showed that a linear regression ([r.sup.2] coefficient 0.999) represented a very good adjustment for the data obtained experimentally.
In both cases, the relative probability of Ti x-ray emission ([approximately equal to]0.008) was estimated such that the measured apparent linear attenuation coefficient
would be close to the Loftus measured value of 0.0015 c[m.sup.-1].
As the linear attenuation coefficient
[[mu].sub.m]H[rho]H remains constant in different beam paths, from Equation  it is possible to calculate a value [t.sub.c] that corresponds to the equivalent distance traversed by the beam, based on the following relationship derived from Equation :
The (greylevel) intensity at each voxel in the final 3-D image corresponds to the linear attenuation coefficient
of the material contained in that voxel.
where [[mu].sub.w] is the linear attenuation coefficient