Wavelet Filtering for Limited-Angle and Low-Dose Computed Tomographic Reconstruction

Computed tomography (CT) has gained extensive application in nondestructive testing and medical diagnosis. Most of the practical application of CT imaging applications demands the development of more efficient reconstruction techniques for low-dose and limited-angle scanning to avoid the risk of ionizing radiation associated with CT. The widely used reconstruction algorithms, filtered back-projection (FBP), fails to produce satisfactory results because of lacking the projection data. Statistical techniques have been recently introduced for low-dose CT but the success of these algorithms rely on the assumption of noise characteristics and makes clinical application difficult. Aiming to improve the quality of CT reconstruction, this work investigates the incorporation of an alternate filter for FBP reconstruction. To this end, a multi-resolution 1-D Gabor filter is employed due to its band-pass capability and texture segmentation nature. The proposed filter was developed as reusable software components using the object oriented and platform independent features of Java language. The feasibility and validity of Gabor filterfor FBP was evaluated for its potential on projection simulated from Shepp-Logan phantom image. The results demonstrate that the Gabor filter outperformed its counter parts in artifacts reduction, noise suppression, and structure preservation.