Development of a simulator for tomographic images generated by radiation transmission

Abstract

A computer program to simulate tomographic images generated by transmitted radiation was developed. The algorithm uses a deterministic approach to generate the projections, which supply an existing image reconstruction software. A dispersion associated with the counting statistics is also incorporated into the algorithm, in order to simulate the influence of the detector effi ciency and counting time on the fi nal image quality. The detector resolution is also included in the algorithm by assuming a gaussian shape for its line spread function -LSF. The program deals with cylindrical objects containing any desired number of cylindrical rods inside and requires their positions, dimensions and attenuation properties as input data. Images of such objects, acquired with a thermal neutron tomograph equipped with a position sensitive detector, have been compared with those simulated by the developed program in order to evaluate its ability to reproduce those images.

Forecasting the effect of neutron beam divergence on the quality of tomographic images

“…In order to accomplish this task, a simulator for tomographic images has been developed based on an earlier written code [1], incorporating beam divergence. A divergent but isotropic beam emitted by a point or line source would not spoil the final image and even could improve it [2], provided that the reconstruction algorithm is written to deal with this feature.…”

Evaluation of the divergence of a thermal neutron beam using a Position Sensitive Detector

“…The knowledge of the beam divergence is specially important whenever the direction of the incoming neutron plays a significant role in an experiment or measurement process, as in the Computer Assisted Tomography -CAT for instance, a growing field of non-destructive analysis in science and engineering where the image-reconstructing algorithms need this information to perform their tasks properly. Recent works [1][2][3][4][5] concerning the development and application of a Position Sensitive Detector -PSD to thermal neutron tomographic systems stimulated a work [6] which has shown the need to determine the divergence of the neutron beam and the viability to accomplish this task by using that kind of detector.…”