Differential reconstruction for planar object in computed tomography.

Traditional reconstruction algorithm in computed tomography (CT) requires a square reconstruction matrix, regardless of the particular object shape. This becomes inefficient when reconstructing planar objects such as IC chips which have a large area-to-thickness ratio. This article presents a differential reconstruction algorithm for planar object CT scan. By automatically determining the scanning start orientation of the object and its tilting angle with respect to the rotation axis, a reconstruction matrix with different dimensions and/or different reconstruction resolutions is employed to reconstruct the object area only. For demonstration, a low-temperature co-fire ceramic (LTCC) component is scanned and reconstructed. It shows that the new method requires much less computation time and storage, can achieve higher reconstruction resolution in the thickness dimension, and makes layer separation much easier for multilayer objects.