Post-processing to reduce missing wedge effect using total variation minimization

The use of X-ray inspection for analyzing faults in printed circuit board components is becoming more important with the ongoing development of 3D integrated circuits. Achieving optimal X-ray inspection for a slab-like flat object depends on selecting an appropriate computed tomography (CT) geometry, such as an off-centered cone-beam geometry. However, because the use of flat components in tomographic reconstruction restricts the range of viewing angles, CT leads to the missing wedge problem, which causes missing angle artifacts in reconstructed 3D data. In this paper, we propose the use of post-processing to reduce the missing wedge effect via total variation minimization, when sinogram images have equal quality at all viewing angles and the accessible tilt range is restricted only by the physical limits of the oblique-view CT system. We demonstrate that axial slice reconstruction using the proposed processing method substantially reduces the missing wedge effect and that the proposed method provides overall image quality superior to that achieved with existing denoising methods.