title: Towards clinical application of a Laplace operator-based region of interest reconstruction algorithm in C-arm CT.
abstract: It is known that a reduction of the field-of-view in 3-D X-ray imaging is proportional to a reduction in radiation dose. The resulting truncation, however, is incompatible with conventional reconstruction algorithms. Recently, a novel method for region of interest reconstruction that uses neither prior knowledge nor extrapolation has been published, named approximated truncation robust algorithm for computed tomography (ATRACT). It is based on a decomposition of the standard ramp filter into a 2-D Laplace filtering and a 2-D Radon-based residual filtering step. In this paper, we present two variants of the original ATRACT. One is based on expressing the residual filter as an efficient 2-D convolution with an analytically derived kernel. The second variant is to apply ATRACT in 1-D to further reduce computational complexity. The proposed algorithms were evaluated by using a reconstruction benchmark, as well as two clinical data sets. The results are encouraging since the proposed algorithms achieve a speed-up factor of up to 245 compared to the 2-D Radon-based ATRACT. Reconstructions of high accuracy are obtained, e.g., even real-data reconstruction in the presence of severe truncation achieve a relative root mean square error of as little as 0.92% with respect to nontruncated data.
authors.forename: Yan
authors.initials: Y
authors.lastname: Xia
authors.forename: Hannes
authors.initials: H
authors.lastname: Hofmann
authors.forename: Frank
authors.initials: F
authors.lastname: Dennerlein
authors.forename: Kerstin
authors.initials: K
authors.lastname: Mueller
authors.forename: Chris
authors.initials: C
authors.lastname: Schwemmer
authors.forename: Sebastian
authors.initials: S
authors.lastname: Bauer
authors.forename: Gouthami
authors.initials: G
authors.lastname: Chintalapani
authors.forename: Ponraj
authors.initials: P
authors.lastname: Chinnadurai
authors.forename: Joachim
authors.initials: J
authors.lastname: Hornegger
authors.forename: Andreas
authors.initials: A
authors.lastname: Maier
mesh_terms: D000465:Algorithms; D016477:Artifacts; D006257:Head / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000379:methods*