Shiying Zhao

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In this paper, we prove a generalized backprojection-filtration formula for exact cone-beam image reconstruction with an arbitrary scanning locus. Our proof is independent of the shape of the scanning locus, as long as the object is contained in a region where there is a chord through any interior point. As special cases, this generalized formula can be(More)
Image artifacts induced by multiple metallic objects pose a persistent problem in X-ray computed tomography (CT). Among existing CT methods for metal artifact reduction, the wavelet-based approach we recently developed is very promising in practice. In this paper, we report a major refinement to our earlier work [1]. The key component of this refinement is(More)
Yu and Wang [1, 2] implemented the first theoretically exact spiral cone-beam reconstruction algorithm developed by Katsevich [3, 4]. This algorithm requires a high computational cost when the data amount becomes large. Here we study a parallel computing scheme for the Katsevich algorithm to facilitate the image reconstruction. Based on the proposed(More)
In this paper, we present concise proofs of several recently developed exact cone-beam reconstruction methods in the Tuy inversion framework, including both filtered-backprojection and backprojection-filtration formulas in the cases of standard spiral, nonstandard spiral, and more general scanning loci. While a similar proof of the Katsevich formula was(More)
With the introduction of spiral/helical multislice CT, medical x-ray CT began a transition into cone-beam geometry. The higher speed, thinner slice, and wider coverage with multislice/cone-beam CT indicate a great potential for dynamic volumetric imaging, with cardiac CT studies being the primary example. Existing ECG-gated cardiac CT algorithms have(More)
In this article, we propose to develop the first clinical micro-CT (CMCT) system for human temporal bone imaging in vivo. This CMCT system consists of medical CT and micro-CT scanners either as separate components or in a combination, a cross-modality registration mechanism such as a facial surface scanner, and associated software. This system integrates(More)
A hot topic in cone-beam CT research is exact cone-beam reconstruction from a general scanning trajectory. Particularly, a nonstandard saddle curve attracts attention, as this construct allows the continuous periodic scanning of a volume-of-interest (VOI). Here we evaluate two algorithms for reconstruction from data collected along a nonstandard saddle(More)
RATIONALE AND OBJECTIVES A previous scan-regularized reconstruction (PSRR) method was proposed to reduce radiation dose and applied to lung perfusion studies. Normal and ultra-low-dose lung computed tomographic perfusion studies were compared in terms of the estimation accuracy of pulmonary functional parameters. MATERIALS AND METHODS A sequence of sheep(More)
Accurate and efficient simulation of an x-ray transform for representative structures plays an important role in research and development of x-ray CT, for the evaluation and improvement of CT image reconstruction algorithms, in particular. Superquadrics are a family of three-dimensional objects, which can be used to model a variety of anatomical structures.(More)
Two theorems are presented for wavelet decompositions of the two-dimensional Radon transform. The first theorem establishes an upper error bound in L-norm between the Radon transform and its wavelet approximation whose coefficients at different scales are estimated from Radon data acquired at corresponding sampling rates. The second theorem gives an(More)