Grid line artifact formation: A comprehensive theory

Gauntt, David M.; Barnes, Gary T.

doi:10.1118/1.2184444

Cited by 33 publications

(19 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, when grids are used with these high resolution imaging detectors, the images contain a fixed-structure pattern noise or grid line artifacts and moiré patterns 5 . When these anti-scatter grids are used with a standard FPD, the grid lines are not very apparent because of the lower spatial resolution of the detector, which results in an averaging or blurring of the lines.…”

Section: Introductionmentioning

confidence: 99%

Scatter estimation and removal of anti-scatter grid-line artifacts from anthropomorphic head phantom images taken with a high resolution image detector

et al. 2016

View full text Add to dashboard Cite

In radiography, one of the best methods to eliminate image-degrading scatter radiation is the use of anti-scatter grids. However, with high-resolution dynamic imaging detectors, stationary anti-scatter grids can leave grid-line shadows and moiré patterns on the image, depending upon the line density of the grid and the sampling frequency of the x-ray detector. Such artifacts degrade the image quality and may mask small but important details such as small vessels and interventional device features. Appearance of these artifacts becomes increasingly severe as the detector spatial resolution is improved. We have previously demonstrated that, to remove these artifacts by dividing out a reference grid image, one must first subtract the residual scatter that penetrates the grid; however, for objects with anatomic structure, scatter varies throughout the FOV and a spatially differing amount of scatter must be subtracted. In this study, a standard stationary Smit-Rontgen X-ray grid (line density - 70 lines/cm, grid ratio - 13:1) was used with a high-resolution CMOS detector, the Dexela 1207 (pixel size - 75 micron) to image anthropomorphic head phantoms. For a 15 × 15cm FOV, scatter profiles of the anthropomorphic head phantoms were estimated then iteratively modified to minimize the structured noise due to the varying grid-line artifacts across the FOV. Images of the anthropomorphic head phantoms taken with the grid, before and after the corrections, were compared demonstrating almost total elimination of the artifact over the full FOV. Hence, with proper computational tools, anti-scatter grid artifacts can be corrected, even during dynamic sequences.

show abstract

Section: Introductionmentioning

confidence: 99%

Scatter estimation and removal of anti-scatter grid-line artifacts from anthropomorphic head phantom images taken with a high resolution image detector

et al. 2016

View full text Add to dashboard Cite

show abstract

“…However, when stationary grids are used with these high resolution imaging detectors, the images contain anti-scatter grid line artifacts because the lead septa dimension of the grid is a substantial fraction of the pixel size of the high resolution detector. Also, apart from anti-scatter grid line artifacts, moiré patterns 5 are also present in the image because of the minute misalignment of the grid septa pattern with that of the pixels of the detectors. The presence of this fixed-structure pattern noise diminishes the advantage of the usage of the grid with high resolution detectors, by masking the fine anatomic details present in the image.…”

Section: Introductionmentioning

confidence: 99%

Real time implementation of anti-scatter grid artifact elimination method for high resolution x-ray imaging CMOS detectors using Graphics Processing Units (GPUs)

Rana

Nagesh

Bednarek

et al. 2017

Medical Imaging 2017: Physics of Medical Imaging

View full text Add to dashboard Cite

Scatter is one of the most important factors effecting image quality in radiography. One of the best scatter reduction methods in dynamic imaging is an anti-scatter grid. However, when used with high resolution imaging detectors these grids may leave grid-line artifacts with increasing severity as detector resolution improves. The presence of such artifacts can mask important details in the image and degrade image quality. We have previously demonstrated that, in order to remove these artifacts, one must first subtract the residual scatter that penetrates through the grid followed by dividing out a reference grid image; however, this correction must be done fast so that corrected images can be provided in real-time to clinicians. In this study, a standard stationary Smit-Rontgen x-ray grid (line density – 70 lines/cm, grid ratio – 13:1) was used with a high-resolution CMOS detector, the Dexela 1207 (pixel size – 75 micron) to image anthropomorphic head phantoms. For a 15 × 15 cm field-of-view (FOV), scatter profiles of the anthropomorphic head phantoms were estimated then iteratively modified to minimize the structured noise due to the varying grid-line artifacts across the FOV. Images of the head phantoms taken with the grid, before and after the corrections, were compared, demonstrating almost total elimination of the artifact over the full FOV. This correction is done fast using Graphics Processing Units (GPUs), with 7–8 iterations and total time taken to obtain the corrected image of only 87 ms, hence, demonstrating the virtually real-time implementation of the grid-artifact correction technique.

show abstract

“…5,6 Grid ratios typically used in mammography are of the order of 5:1, and grid frequencies are typically ~30 lp/cm. 7 …”

Section: Introductionmentioning

confidence: 99%

Design and evaluation of a grid reciprocation scheme for use in digital breast tomosynthesis

et al. 2016

View full text Add to dashboard Cite

This work describes a methodology for efficient removal of scatter radiation during digital breast tomosynthesis (DBT). The goal of this approach is to enable grid image obscuration without a large increase in radiation dose by minimizing misalignment of the grid focal point (GFP) and x-ray focal spot (XFS) during grid reciprocation. Hardware for the motion scheme was built and tested on the dual modality breast tomosynthesis (DMT) scanner, which combines DBT and molecular breast tomosynthesis (MBT) on a single gantry. The DMT scanner uses fully isocentric rotation of tube and x-ray detector for maintaining a fixed tube-detector alignment during DBT imaging. A cellular focused copper prototype grid with 80 cm focal length, 3.85 mm height, 0.1 mm thick lamellae, and 1.1 mm hole pitch was tested. Primary transmission of the grid at 28 kV tube voltage was on average 74% with the grid stationary and aligned for maximum transmission. It fell to 72% during grid reciprocation by the proposed method. Residual grid line artifacts (GLAs) in projection views and reconstructed DBT images are characterized and methods for reducing the visibility of GLAs in the reconstructed volume through projection image flat-field correction and spatial frequency-based filtering of the DBT slices are described and evaluated. The software correction methods reduce the visibility of these artifacts in the reconstructed volume, making them imperceptible both in the reconstructed DBT images and their Fourier transforms.

show abstract

Grid line artifact formation: A comprehensive theory

Cited by 33 publications

References 3 publications

Scatter estimation and removal of anti-scatter grid-line artifacts from anthropomorphic head phantom images taken with a high resolution image detector

Scatter estimation and removal of anti-scatter grid-line artifacts from anthropomorphic head phantom images taken with a high resolution image detector

Real time implementation of anti-scatter grid artifact elimination method for high resolution x-ray imaging CMOS detectors using Graphics Processing Units (GPUs)

Design and evaluation of a grid reciprocation scheme for use in digital breast tomosynthesis

Contact Info

Product

Resources

About