Optimal slice thickness for object detection with longitudinal partial volume effects in computed tomography.

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State: Public
Version: Final published version
Serval ID
serval:BIB_42DCF7850104
Type
Article: article from journal or magazin.
Publication sub-type
Review (review): journal as complete as possible of one specific subject, written based on exhaustive analyses from published work.
Collection
Publications
Institution
Title
Optimal slice thickness for object detection with longitudinal partial volume effects in computed tomography.
Journal
Journal of applied clinical medical physics
Author(s)
Monnin P., Sfameni N., Gianoli A., Ding S.
ISSN
1526-9914 (Electronic)
ISSN-L
1526-9914
Publication state
Published
Issued date
01/2017
Peer-reviewed
Oui
Volume
18
Number
1
Pages
251-259
Language
english
Notes
Publication types: Journal Article
Publication Status: ppublish
Abstract
Longitudinal partial volume effects (z-axial PVE), which occur when an object partly occupies a slice, degrade image resolution and contrast in computed tomography (CT). Z-axial PVE is unavoidable for subslice objects and reduces their contrast according to their fraction contained within the slice. This effect can be countered using a smaller slice thickness, but at the cost of an increased image noise or radiation dose. The aim of this study is to offer a tool for optimizing the reconstruction parameters (slice thickness and slice spacing) in CT protocols in the case of partial volume effects. This optimization is based on the tradeoff between axial resolution and noise. For that purpose, we developed a simplified analytical model investigating the average statistical effect of z-axial PVE on contrast and contrast-to-noise ratio (CNR). A Catphan 500 phantom was scanned with various pitches and CTDI and reconstructed with different slice thicknesses to assess the visibility of subslice targets that simulate low contrast anatomical features present in CT exams. The detectability score of human observers was used to rank the perceptual image quality against the CNR. Contrast and CNR reduction due to z-axial PVE measured on experimental data were first compared to numerical calculations and then to the analytical model. Compared to numerical calculations, the simplified algebraic model slightly overestimated the contrast but the differences remained below 5%. It could determine the optimal reconstruction parameters that maximize the objects visibility for a given dose in the case of z-axial PVE. An optimal slice thickness equal to three-fourth of the object width was correctly proposed by the model for nonoverlapping slices. The tradeoff between detectability and dose is maximized for a slice spacing of half the slice thickness associated with a slice width equal to the characteristic object width.

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Create date
21/03/2017 17:55
Last modification date
20/08/2019 13:45
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