A geometric calibration approach for an industrial cone-beam CT system based on a low-rank phantom

Abstract

Precise alignment of the system scan geometry is crucial to ensure the reconstructed image quality in a cone-beam computed tomography (CT) system. A calibration method that depends on the local features of a multi-sphere phantom is probably affected by local image variations. In addition, multiple projections with circular scanning are usually required by this type of method to derive misaligned parameters. In contrast to previous works, this paper proposes a method that depends on the global symmetric low-rank feature of a novel phantom, which can accurately represent the system geometrical misalignment. All the misaligned parameters of the cone-beam CT system can be estimated from a single perspective direction without circular scanning. Meanwhile, since the global low-rank feature of the phantom is utilized, the proposed method is robust to noise. We study the performance of the proposed method through simulations and real experiments. The experimental results demonstrate that the proposed method can estimate the system geometric parameters accurately, leading to superior image quality, with the modulation transfer function of our method (0.22) higher than that of the competing method (0.13) at the spatial resolution of 10 lp mm−1.