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Proceedings Paper

Exact reconstruction for unequally spaced triple-source helical cone-beam CT
Author(s): Yannan Jin; Jun Zhao; Ming Jiang; Tiange Zhuang; Ge Wang
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Paper Abstract

In a previous study, we proposed a helical scanning configuration with triple X-ray sources symmetrically positioned and established its reconstruction algorithm. Although symmetrically positioned sources are convenient in practice, artifacts can be produced in a reconstructed image if the physical sources are not equally spaced. In this work, we develop an exact backprojection filtration (BPF) type algorithm for the configuration with unequally spaced triple sources to reduce the artifacts. Similar to the Tam-Danielsson window, we define the minimum detection window as the region bounded by the most adjacent turns of two helices. The sum of the heights of the three consequent minimum detection windows is equal to that of the traditional Tam-Danielsson window for a single source. Furthermore, we prove that inter-helix PI-lines satisfy the existence and uniqueness properties (i.e., through any point inside the triple helices, there exists one and only one inter-helix PI-line for any pair of helices). The proposed algorithm is of the backprojection-filtration (BPF) type and can be implemented in three steps: 1) differentiation of the cone-beam projection from each source; 2) weighted backprojection of the derivates on the inter-helix PI-arcs; 3) inverse Hilbert transformation along one of the three inter-helix PI-lines. Numerical simulations with 3D Shepp-Logan phantoms are performed to validate the algorithm. We also demonstrate that artifacts are generated when the algorithm for the symmetric configuration is applied to the unequally spaced helices setting.

Paper Details

Date Published: 7 September 2006
PDF: 9 pages
Proc. SPIE 6318, Developments in X-Ray Tomography V, 63181Q (7 September 2006); doi: 10.1117/12.681398
Show Author Affiliations
Yannan Jin, Shanghai Jiao Tong Univ. (China)
Jun Zhao, Shanghai Jiao Tong Univ. (China)
Ming Jiang, Peking Univ. (China)
Tiange Zhuang, Shanghai Jiao Tong Univ. (China)
Ge Wang, Univ. of Iowa (United States)


Published in SPIE Proceedings Vol. 6318:
Developments in X-Ray Tomography V
Ulrich Bonse, Editor(s)

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