Local and global 3D noise power spectrum in cone-beam CT system with FDK reconstruction

Department of Radiology, Stanford University, Stanford, California 94305, USA.
Medical Physics (Impact Factor: 3.01). 04/2011; 38(4):2122-31. DOI: 10.1118/1.3556590
Source: PubMed

ABSTRACT The authors examine the nonstationary noise behavior of a cone-beam CT system with FDK reconstruction.
To investigate the nonstationary noise behavior, an analytical expression for the NPS of local volumes and an entire volume was derived and quantitatively compared to the NPS estimated from experimental air and water images.
The NPS of local volumes at different locations along the z-axis showed radial symmetry in the f(x)-f(y) plane and different missing cone regions in the f(z) direction depending on the tilt angle of rays through the local volumes. For local volumes away from the z-axis, the NPS of air and water images showed sharp transitions in the f(x)-f(y) and f(y)-f(z) planes and lack of radial symmetry in the f(x)-f(y) plane. These effects are mainly caused by varying magnification and different noise levels from view to view. In the NPS of the entire volume, the f(x)-f(y) plane showed radial symmetry because the nonstationary noise behaviors of local volumes were averaged out. The nonstationary sharp transitions were manifested as a high-frequency roll-off.
The results from noise power analysis for local volumes and an entire volume demonstrate the spatially varying noise behavior in the reconstructed cone-beam CT images.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Nonstationarity is an important aspect of imaging performance in CT and cone-beam CT (CBCT), especially for systems employing iterative reconstruction. This work presents a theoretical framework for both filtered-backprojection (FBP) and penalized-likelihood (PL) reconstruction that includes explicit descriptions of nonstationary noise, spatial resolution, and task-based detectability index. Potential utility of the model was demonstrated in the optimal selection of regularization parameters in PL reconstruction.
    Medical Physics 08/2014; 41(8):081902. DOI:10.1118/1.4883816 · 3.01 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this work was to develop an inexpensive phantom for simplified image quality assurance (IQA) together with algorithms for objective evaluation of image quality parameters and to integrate these components into an easy-to-use software package. This should help make quality control of dental cone beam computed tomography (CBCT) units accessible, easy, and affordable for any specialist or general practitioner. Our study developed an inexpensive polymethyl methacrylate (Plexiglas) phantom containing objects and structures for objective quantification of the most important image-quality parameters in CBCT imaging. It also paired the phantom with a software package, based on open-source software, for automatic processing and analysis. The software produces objectively measured IQA data for low- and high-contrast resolution, uniformity, noise characteristics, and geometric linearity. The authors consider the phantom and methods presented in this article to be a step toward helping clinical dental personnel perform regular quality assurance on CBCT units. Copyright © 2014 Elsevier Inc. All rights reserved.
    Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 11/2014; 118(5):603-11. DOI:10.1016/j.oooo.2014.08.003 · 1.46 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this work is to develop and demonstrate a set of practical metrics for CT systems optimization. These metrics, based on the Hotelling observer (HO) figure of merit, are task-based. The authors therefore take the specific example of optimizing a dedicated breast CT system, including the reconstruction algorithm, for two relevant tasks, signal detection and Rayleigh discrimination.
    Medical Physics 10/2014; 41(10):101917. DOI:10.1118/1.4896099 · 3.01 Impact Factor

Full-text (2 Sources)

Available from
Sep 3, 2014