Quality improvement of X-ray Ct images by estimation of the mechanical misalignment in a projection image using an iterative method

An X-ray computed tomography (CT) apparatus is required for the inspection of semiconductor packages to detect fine voids with high accuracy. However, obtaining high-quality CT images stably is difficult because of object misalignment. In this paper, we propose a method for improving the X-ray CT image quality by estimating the mechanical misalignment of each projection image. The estimation is conducted by using an iterative method based on the characteristic features obtained from the reconstructed image. In experiments, we verified the effectiveness of proposed method by using projection images with simulated misalignments added. The results indicated that the proposed method may be useful for improving the quality of CT imaging.