Fan-beam-tomography noise theory

Bennett, Keith; Byer, Robert L.

doi:10.1364/josaa.3.000624

Cited by 22 publications

(14 citation statements)

References 16 publications

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“…A global scalar measure to investigate the amount of fluctuation in CT values is the standard deviation over an area. 44 Recently several studies concerned with the level of noise in parallel-, 45 fan-, 46…”

Section: B3 Image Noisementioning

confidence: 99%

A quality assurance framework for the fully automated and objective evaluation of image quality in cone‐beam computed tomography

2014

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Section: B3 Image Noisementioning

confidence: 99%

A quality assurance framework for the fully automated and objective evaluation of image quality in cone‐beam computed tomography

2014

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“…To describe the noise in reconstructed CT images, the image variance has been studied for parallel-beam, 1-4 fan-beam, [5][6][7][8][9] and cone-beam CT systems. 10,11 While the image variance provides information on the noise magnitude, it cannot characterize the noise correlation introduced by the reconstruction algorithm and detector blurring and therefore the performance in object or feature detection tasks cannot be fully described by the variance alone.…”

Section: Introductionmentioning

confidence: 99%

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

Baek

Pelc

2011

Medical Physics

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Purpose:The authors examine the nonstationary noise behavior of a cone-beam CT system with FDK reconstruction. Methods: 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. Results: 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. Conclusions: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.

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“…To quantify image noise, the pixel value variance is commonly used and much research has been done to study the image variance for parallel beam filtered backprojection ͑FBP͒ 2,3 and fan beam FBP reconstruction. [4][5][6][7][8] However, while the image variance is relatively easy to calculate, it may not fully reflect the impact that the noise will have on a diagnostic task ͑e.g., lesion detection͒. For example, smoothing can lower the image variance while not changing the information content of the image.…”

Section: Introductionmentioning

confidence: 99%

The noise power spectrum in CT with direct fan beam reconstruction

Baek

Pelc

2010

Medical Physics

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The noise power spectrum ͑NPS͒ is a useful metric for understanding the noise content in images. To examine some unique properties of the NPS of fan beam CT, the authors derived an analytical expression for the NPS of fan beam CT and validated it with computer simulations. The nonstationary noise behavior of fan beam CT was examined by analyzing local regions and the entire field-of-view ͑FOV͒. This was performed for cases with uniform as well as nonuniform noise across the detector cells and across views. The simulated NPS from the entire FOV and local regions showed good agreement with the analytically derived NPS. The analysis shows that whereas the NPS of a large FOV in parallel beam CT ͑using a ramp filter͒ is proportional to frequency, the NPS with direct fan beam FBP reconstruction shows a high frequency roll off. Even in small regions, the fan beam NPS can show a sharp transition ͑discontinuity͒ at high frequencies. These effects are due to the variable magnification and therefore are more pronounced as the fan angle increases. For cases with nonuniform noise, the NPS can show the directional dependence and additional effects.

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Fan-beam-tomography noise theory

Cited by 22 publications

References 16 publications

A quality assurance framework for the fully automated and objective evaluation of image quality in cone‐beam computed tomography

A quality assurance framework for the fully automated and objective evaluation of image quality in cone‐beam computed tomography

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

The noise power spectrum in CT with direct fan beam reconstruction

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