الفهرس 
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Abstract
The potential of computerized tomography by neutrons and gamma
rays as a main technique for non-destructive assay of materials and
components of prime importance in nuclear and general industries are
given and discussed. Both Fast Fourier Transform (FFT) and Algebraic
Reconstruction Technique (ART) techniques are introduced and
discussed. Shepp and Logan human head phantom is used for theoretical
testing and studying the effective measuring parameters and image
reconstruction parameters for both techniques. An experimental verification
of successful of both techniques for image reconstruction is
performed by using transmitted gamma rays projected data through
standard test sample. Comparison between the two techniques has
been carried out for the examined object.
The artifacts, caused in the reconstructed image due to the spectrum
shift to higher energies, spectrum hardening and to lower energies,
spectrum softening of the transmitted fast neutrons and gamma
rays have been corrected by the two-channel spectroscopy technique.
In this technique, the two-channel spectroscopy device was coupled
with the neutron/gamma discriminator unit and the correction treatments
were performed on-line during the measurement. Some neutron
and gamma CT-images, which have been be reconstructed from the
projected data measured with and without spectral correction have
been given to show the effect of this correction method.