Principles of Tomographic Measurements and Reconstruction

X-ray computed tomography (CT) plays a crucial role in enhancing national security through its use in active interrogation of any miscellaneous object across various environments. The use of x-ray active interrogation can give insight on the structure of an object and its material density to provide an effective means of detecting potential threats in a wide range of objects. A small and lightweight portable CT device that can address highly sensitive inputs is constructed to perform active interrogation. Preprocessing analysis is performed to calibrate for irregularities in pixel values, detector current, tilt corrections, and more. Full image acquisitions are obtained with different x-ray source energy levels, two separate spot sizes, and different placements of the imaging object, aiming to assess the optimal parameters for achieving high image resolution. The Feldkamp-Davis-Kress (FDK), the Regularized Weighted Least Squares (RWLS), and the Adaptive Steepest Descent Projection onto Convex Sets (ASD-POCS) were the various reconstruction algorithms examined and compared to assess which yielded the highest spatial resolution in the resulting outputs. These algorithms are compared for a range of images acquired between 10 and 600 from 0° to 360°. Ideal parameters were identified and applied to enhance the tomographic reconstruction output, considering these variations in the number of images per acquisition.