|dc.contributor.advisor||Abdurrahman, Naeem M.||en
|dc.creator||Abdelrahman, Magdy Shehata||en
|dc.description.abstract||Neutron radiography and computed tomography are nondestructive
imaging techniques for the assessment of internal structure of objects. Neutron
scattering in such objects can cause image degradation and complicate image
interpretation. The removal of the scattering effect is one of the most challenging
problems in neutron imaging. In this work, a new method for scattering
correction is being developed. Experimental measurements and Monte Carlo
simulations were used to investigate the effect of thermal and fast neutron
scattering on neutron image degradation both qualitatively and quantitatively.
Neutron scattering degrades the quality of radiographs and in cases of severe
scattering, could blur sharp edges in neutron images. In addition, neutron
scattering imposes an error in neutron radiography quantitative measurements.
In this study, scattering correction was approached in two different ways.
The first consisted of image restoration using the Slow Evolution from the
Continuation Boundary (SECB) method. The SECB method was investigated
and implemented to deblur neutron images for such cases when neutron scattering
effect is severe enough to blur produced radiographs. The SECB method is a noniterative
linear image deblurring method based on the slow evolution constraint,
which is highly effective in suppressing noise amplification.
The second approach for a scattering correction, which has been developed
for the first time as part of this study, is based on the conjecture that there exists a
correlation between the pattern of scattered neutrons as observed from a given
side of the object as the object is irradiated from different sides. This suggests
rotating the sample with some angle to clear the direct neutron view and obtain an
image of pure scattering. The correlation between this side image and the
scattering component of the forward image could be used to obtain an estimate of
the forward scattering component. The estimated scattering component would
then be subtracted from the degraded image to get a scattering-free image.
Data manipulation of the scattering side-images was used to correlate the
scattering side-image to the forward scattering component utilizing the scattering
information outside of the neutron beam scope. Another approach was to
implement artificial neural networks to capture the correlations between scattering
side-images and the forward scattering components as obtained from numerical
simulations for typical samples and utilize these networks to get an estimate of the
forward scattering component for the object of interest.||
|dc.rights||Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.||en
|dc.title||Scattering correction and image restoration in neutron radiography and computed tomography||en
|thesis.degree.grantor||The University of Texas at Austin||en
|thesis.degree.name||Doctor of Philosophy||en