An analytical algorithm for skew-slit collimator SPECT with uniform attenuation correction

Tang, Qinghua; Zeng, G.L.; Huang, Qiu

doi:10.1088/0031-9155/51/23/018

Cited by 11 publications

(9 citation statements)

References 21 publications

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“…By positioning the slit along the axial direction and the slats perpendicular to it, this type of collimator displays the high spatial resolution typical of a single pinhole in the transaxial direction, each transaxial plane being independent of each other. Skew slat collimators, consisting of two perpendicular slits located at different distances from the detector [24], have been also proposed as a way to reach better spatial resolution in the transaxial direction, while reducing axial artifacts, when compared to single pinhole collimators.…”

Section: Discussionmentioning

confidence: 99%

“…In order to reduce blurring at planes away from the center of the object, some authors have proposed to use multiple orbit scans with single pinhole collimators [18], but equivalently good results can be reached with circular and helical scans with multipinhole [28], [29], skew-slit [24] and slit-slat collimators [21], [22].…”

Section: Discussionmentioning

confidence: 99%

“…So, for example, slit-slat [21]- [23] and skew-slit [24] collimators have been proposed to reach high spatial resolution in the transaxial direction, high sensitivity and reduction of the axial artifacts. In the first case, the slit behaves as a pinhole collimator along the transaxial direction, providing good spatial resolution, while the slats behave as parallel collimators, which makes that axial slices become independent one from the other.…”

Section: Introductionmentioning

confidence: 99%

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Planar and tomographic (SPECT) imaging of small volume targets using a Cross-Slit collimator

Mejía

Galvis-Alonso

Braga

et al. 2010

IEEE Nuclear Science Symposuim &Amp; Medical Imaging Conference

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In vivo imaging techniques applied to small animals are important tools in basic research. Scintigraphic planar and tomographic images allow in vivo functional expression of the protocol's effect on the animal's organs to be assessed. In that way, long term dynamical studies can be developed on the same animal, which can be used as its own control, helping to reduce statistical uncertainties, to cut costs and to improve ethical aspects of the experiment. Considering the small size of those animals' organs, specially adapted instruments must be used in order to reach, simultaneously, good spatial resolution and sensitivity. Because of the intrinsic magnification factor, smallsize pinhole-like collimators seem to be the obvious option to reach good spatial resolution. However, sensitivity is limited by the aperture's size. In this work, we propose the use of a combination of two 11-mm long, 0.8-mm width, mutually perpendicular slits as the collimator, in combination with appropriate restoration algorithms. By being narrow, information on high resolution is encoded on the recorded image, while, by being long, a large effective open area allows for good sensitivity. The slits are short enough such that individual open elements produce almost identical projections of the target. In a pre-processing stage, an implementation of the Maximum Likelihood Expectation Maximization algorithm was used to decode individual projections, producing high resolution planar images of the target. The same algorithm was used to combine those pre-processed individual projections, this time as if they would be obtained with a small size single pinhole collimator, obtaining a three-dimensional (3D) model of the target's radiotracer distribution. Monte Carlo simulations and physical phantoms were used to test the proposed methodology. Spatial resolution, equivalent to the one obtained with a 1.5-mm diameter pinhole collimator, was reached. Considering the collimator's open area, sensitivity should increase by a factor nearly 9, when compared with the same 1.5-mm diameter pinhole collimator. The experimental results are consistent with that theoretical value. Additionally, the pre-processing stage does not introduces a significant increase in the total processing time necessary for convergence to the reconstructed 3D object model. In this way, this kind of collimator appears as a good alternative ).to reduce the acquisition time, improving ethical aspects on animal management, as well as to allow the 3D target emission model to be obtained with no increased machine burden.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Planar and tomographic (SPECT) imaging of small volume targets using a Cross-Slit collimator

Mejía

Galvis-Alonso

Braga

et al. 2010

IEEE Nuclear Science Symposuim &Amp; Medical Imaging Conference

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“…1. When the vertical slit is closer to the object than the horizontal slit, this aperture configuration produces images with high transaxial resolution, and also reduces the extent of the axial artifacts seen in reconstructions from circular-orbit pinhole-acquired images [10], [11]. This crossed-slit aperture has been implemented in an adjustable system configuration.…”

Section: Anamorphic Imagingmentioning

confidence: 99%

High-Resolution Anamorphic SPECT Imaging

Durko

Barrett

Furenlid

2014

IEEE Trans. Nucl. Sci.

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We have developed a gamma-ray imaging system that combines a high-resolution silicon detector with two sets of movable, half-keel-edged copper-tungsten blades configured as crossed slits. These apertures can be positioned independently between the object and detector, producing an anamorphic image in which the axial and transaxial magnifications are not constrained to be equal. The detector is a 60 mm × 60 mm, one-millimeter-thick, one-megapixel silicon double-sided strip detector with a strip pitch of 59 μm. The flexible nature of this system allows the application of adaptive imaging techniques. We present system details; calibration, acquisition, and reconstruction methods; and imaging results.

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“…When the vertical slit is closer to the object than the horizontal slit, the configuration produces images with increased transaxial resolution, and resulting reconstructions have been shown to possess fewer axial artifacts than reconstructions from pinhole-based systems. 4, 5 …”

Section: Imaging Concept and System Designmentioning

confidence: 99%

Adaptive SPECT imaging with crossed-slit apertures

Durko

Furenlid

2014

SPIE Proceedings

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Preclinical single-photon emission computed tomography (SPECT) is an essential tool for studying the progression, response to treatment, and physiological changes in small animal models of human disease. The wide range of imaging applications is often limited by the static design of many preclinical SPECT systems. We have developed a prototype imaging system that replaces the standard static pinhole aperture with two sets of movable, keel-edged copper-tungsten blades configured as crossed (skewed) slits. These apertures can be positioned independently between the object and detector, producing a continuum of imaging configurations in which the axial and transaxial magnifications are not constrained to be equal. We incorporated a megapixel silicon double-sided strip detector to permit ultrahigh-resolution imaging. We describe the configuration of the adjustable slit aperture imaging system and discuss its application toward adaptive imaging, and reconstruction techniques using an accurate imaging forward model, a novel geometric calibration technique, and a GPU-based ultra-high-resolution reconstruction code.

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An analytical algorithm for skew-slit collimator SPECT with uniform attenuation correction

Cited by 11 publications

References 21 publications

Planar and tomographic (SPECT) imaging of small volume targets using a Cross-Slit collimator

Planar and tomographic (SPECT) imaging of small volume targets using a Cross-Slit collimator

High-Resolution Anamorphic SPECT Imaging

Adaptive SPECT imaging with crossed-slit apertures

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