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Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/17424

Title: Intrinsic Artefacts of Circular Cone-beam Computed Tomography
Authors: Bartolac, Steven
Advisor: Jaffray, David A.
Department: Medical Biophysics
Keywords: cone-beam
computed tomography
artefacts
artifacts
Defrise
circular
Fourier
Issue Date: 14-Jul-2009
Abstract: Circular source and detector trajectories in cone-beam computed tomography (CT) are known to collect insufficient data for accurate object reconstruction. One model predicts that the lacking information corresponds to a shift-variant cone of missing spatial frequency components in the local Fourier domain. These predictions were experimentally verified by imaging small, localized objects and observing their Fourier transforms. Measurements indicated that the internal angle of the ‘missing cone’ varies as the angle of locally intersecting x rays with respect to the horizontal plane, as expected. Object recovery was also found to depend greatly on the distribution of the object’s frequency spectrum relative to the missing cone, as predicted. Findings agreed with more anatomically relevant phantoms, which showed preferential intensity discrepancies at gradients oriented within or near the missing cone. Methods for artefact correction are in general limited to approximation unless a priori information is incorporated.
URI: http://hdl.handle.net/1807/17424
Appears in Collections:Master
Department of Medical Biophysics - Master theses

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