Subjects: Nuclear Science and Technology >> Other Disciplines of Nuclear Science submitted time 2023-05-31
Abstract： Tomographic Gamma Scanner (TGS), an advanced γ-ray nondestructive analysis technique, can locate and analyze nuclides in radioactive nuclear waste, and TGS can be categorized into two types: e.g., transmission measurement and emission measurement). Specifically, transmission measurements provide the basis for accurate measurement of nonuniform radionuclide content in TGS scanning. The scan data were obtained using the Monte Carlo tool Geant4 simulation, and 25 voxels were divided into five lengths and five widths in a square barrel. In this study, an encoding cropping algorithm based on draped foot vector judgment was adopted to rapidly calculate the voxel trace matrix within a square bucket of nuclear waste, and the transmission images were reconstructed using ordered subset expectation maximization (OSEM). The results indicated that the cropping speed of the improved coding algorithm was significantly higher than that of the original algorithm, and the relative mean deviation (RMD) and root mean square error (RMSE) between the reconstructed attenuation coefficient and the reference standard value tended to decrease with an increase in the cropped line segments in the voxel; the Pearson correlation coefficient (PCC) tended to converge to 1.0. The image quality evaluation parameters of the high media-density materials were better than those of the low media-density materials in the above three indexes. The reconstruction effect was relatively poor for more complex filling materials. When there were more than 10 cropped line segments in the voxel, the reconstruction data generally tended to be stable. The graphical trimming algorithm can rapidly calculate the trace matrix of the scanned voxels; it exhibits the advantages of speed and efficiency and can serve as a novel method to solve the trace matrix of TGS nuclear waste transmission scans.
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