title: Anti-scatter grid artifact elimination for high resolution x-ray imaging CMOS detectors.
abstract: Higher resolution in dynamic radiological imaging such as angiography is increasingly being demanded by clinicians; however, when standard anti-scatter grids are used with such new high resolution detectors, grid-line artifacts become more apparent resulting in increased structured noise that may overcome the contrast signal improvement benefits of the scatter-reducing grid. Although grid-lines may in theory be eliminated by dividing the image of a patient taken with the grid by a flat-field image taken with the grid obtained prior to the clinical image, unless the remaining additive scatter contribution is subtracted in real-time from the dynamic clinical image sequence before the division by the reference image, severe grid-line artifacts may remain. To investigate grid-line elimination, a stationary Smit Röntgen X-ray grid (line density: 70 lines/cm, grid ratio 13:1) was used with both a 75 micron-pixel CMOS detector and a standard 194 micron-pixel flat panel detector (FPD) to image an artery block insert placed in a modified uniform frontal head phantom for a 20 × 20cm FOV (approximately). Contrast and contrast-to-noise ratio (CNR) were measured with and without scatter subtraction prior to grid-line correction. The fixed pattern noise caused by the grid was substantially higher for the CMOS detector compared to the FPD and caused a severe reduction of CNR. However, when the scatter subtraction corrective method was used, the removal of the fixed pattern noise (grid artifacts) became evident resulting in images with improved CNR.
authors.affiliation: Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY 14214.
authors.forename: R
authors.initials: R
authors.lastname: Rana
authors.affiliation: Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY 14214.
authors.forename: V
authors.initials: V
authors.lastname: Singh
authors.affiliation: Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY 14214.
authors.forename: A
authors.initials: A
authors.lastname: Jain
authors.affiliation: Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY 14214.
authors.forename: D R
authors.initials: DR
authors.lastname: Bednarek
authors.affiliation: Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY 14214.
authors.forename: S
authors.initials: S
authors.lastname: Rudin
keywords: CMOS detectors; CNR; anti-scatter grid; grid artifacts; high resolution detector; scatter; x-ray imaging