title: A variation-based ring artifact correction method with sparse constraint for flat-detector CT.
abstract: The reconstructed slice quality of flat-detector computed tomography (CT) is often disturbed by concentric-ring artifacts. Since concentric rings in CT slices appear as straight stripes when transformed into polar coordinates, a variation-based model is proposed to suppress the stripes. The method is motivated by two observations about stripes in polar coordinates: (1) ring artifacts attenuate gradually along the radial direction, leading to a sparse distribution of stripes and (2) stripes greatly distort the image gradient across the stripes, while slightly affecting the image gradient along the stripes. Thus, a [Formula: see text]-norm-based data fidelity term and a [Formula: see text]-norm/[Formula: see text]-norm unidirectional variation-based regularization term are presented to characterize the stripes. The alternating direction method of multipliers is introduced to solve the resulting minimization problem. Moreover, we discuss the interpolation methods used in coordinate transformation and find that the nearest neighbor interpolation is optimal. Experimental results on simulated and real data demonstrate that our method can correct ring artifacts effectively compared with state-of-the-art coordinate transformation-based methods, as well as preserve the structures and details of slices.
authors.affiliation: Science and Technology on Multispectral Information Processing Laboratory, School of Automation, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
authors.forename: Luxin
authors.initials: L
authors.lastname: Yan
authors.forename: Tao
authors.initials: T
authors.lastname: Wu
authors.forename: Sheng
authors.initials: S
authors.lastname: Zhong
authors.forename: Qiude
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000465:Algorithms; D016477:Artifacts; D014057:Tomography, X-Ray Computed / Q000379:methods*