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Reduction of motion blurring artifacts using respiratory gated CT in sinogram space: A quantitative evaluation
Author(s) -
Lu Wei,
Parikh Parag J.,
Hubenschmidt James P.,
Politte David G.,
Whiting Bruce R.,
Bradley Jeffrey D.,
Mutic Sasa,
Low Daniel A.
Publication year - 2005
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2074187
Subject(s) - imaging phantom , artifact (error) , computer vision , artificial intelligence , hounsfield scale , computer science , iterative reconstruction , medical imaging , diaphragm (acoustics) , nuclear medicine , computed tomography , physics , medicine , radiology , acoustics , loudspeaker
Techniques have been developed for reducing motion blurring artifacts by using respiratory gated computed tomography (CT) in sinogram space and quantitatively evaluating the artifact reduction. A synthetic sinogram was built from multiple scans intercepting a respiratory gating window. A gated CT image was then reconstructed using the filtered back‐projection algorithm. Wedge phantoms, developed for quantifying the motion artifact reduction, were scanned while being moved using a computer‐controlled linear stage. The resulting artifacts appeared between the high and low density regions as an apparent feature with a Hounsfield value that was the average of the two regions. A CT profile through these regions was fit using two error functions, each modeling the partial‐volume averaging characteristics for the unmoving phantom. The motion artifact was quantified by determining the apparent distance between the two functions. The blurring artifact had a linear relationship with both the speed and the tangent of the wedge angles. When gating was employed, the blurring artifact was reduced systematically at the air‐phantom interface. The gated image of phantoms moving at 20 mm ∕ s showed similar blurring artifacts as the nongated image of phantoms moving at 10 mm ∕ s . Nine patients were also scanned using the synchronized respiratory motion technique. Image artifacts were evaluated in the diaphragm, where high contrast interfaces intercepted the imaging plane. For patients, this respiratory gating technique reduced the blurring artifacts by 9%–41% at the lung‐diaphragm interface.