Dr. Samuel J. LaRoque Profile

Dr. Samuel J. LaRoque

Science Advisor at Robins, Kaplan, Miller & Ciresi LLP

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Publications (6)

Proceedings Article | 18 March 2008 Paper

Image reconstruction from sparse data samples in MRI accounting for phase roll

Samuel LaRoque, Emil Sidky, Gregory Karczmar, Xiaochuan Pan

Proceedings Volume 6913, 69130E (2008) https://doi.org/10.1117/12.769568

KEYWORDS: Magnetic resonance imaging, Image restoration, Reconstruction algorithms, Fourier transforms, Magnetism, Medical imaging, Algorithm development, Compressed sensing, Statistical analysis, Data acquisition

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Proceedings Article | 6 March 2008 Paper

Accurate computation of the Hotelling template for SKE/BKE detection tasks

Emil Sidky, Samuel LaRoque, Xiaochuan Pan

Proceedings Volume 6917, 69170W (2008) https://doi.org/10.1117/12.772715

KEYWORDS: Signal to noise ratio, Reconstruction algorithms, Computing systems, Computed tomography, Algorithm development, CT reconstruction, Detection theory, Optimization (mathematics), Medical imaging, Signal detection

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Proceedings Article | 6 March 2008 Paper

Comparison of variable and fixed focal length cone beam CT in diagnostic imaging

Samuel LaRoque, Junguo Bian, Emil Sidky, Xiaochuan Pan

Proceedings Volume 6917, 69170V (2008) https://doi.org/10.1117/12.769559

KEYWORDS: Sensors, Head, Diagnostics, X-ray computed tomography, Computed tomography, Spherical lenses, X-ray sources, X-rays, Reconstruction algorithms, Medical imaging

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We use a task-based study to objectively evaluate the effect of variable versus fixed focal length in determining the position of a lesion in helical cone-beam computed tomography (HCBCT). This method will be used to assess whether variable focal length CBCT scans provide a measurable improvement in estimating lesion position relative to fixed focal length CBCT in diagnostic applications. In this simulation study a 1 cm diameter spherical lesion is placed at four different positions within a three-dimensional Shepp-Logan head phantom. The axial plane is taken to point along the z-axis, which is also the central axis of the helix. The lesion is placed at the center of the Shepp-Logan phantom, at positions displaced ±5 cm in x, and at a position displaced 5 cm in y. Four different scans of pitch length 10 cm are then performed using 128 views over 360° with a 100×300 pixel (20 cm×60 cm) detector. Two scans have a fixed focal length of 50 cm between the X-ray source and the center of rotation (COR), varying only in the starting angle of the source (0° and 90°). We call this the circular configuration. The other two scans have a variable focal length following the curvature of the head phantom and ranging from 37.5 cm to 50 cm. We call this the elliptical configuration. The detector rotates with the source but maintains a constant distance of 30 cm from the COR. A likelihood gridding technique is used to assess bias and variance in the position estimates determined from each scan configuration. We find that the biases are small relative to the variances, and have no apparent preferred direction. Of the 24 circular to elliptical comparisons made, we find that in 14 cases the elliptical scan has a smaller variance that is statistically significant(p ≤ 0.05). By contrast, we find no statistically significant cases in which the circular scan gives a smaller variance compared to the elliptical scan. We conclude that using a variable focal length adapted to the contours of the head phantom provides more precise results, but caution that this is a limited pilot study and many more factors will be accounted for in future work.

Proceedings Article | 20 March 2007 Paper

Evaluation of the channelized Hotelling observer for signal detection in 2D tomographic imaging

Samuel LaRoque, Emil Sidky, Darrin Edwards, Xiaochuan Pan

Proceedings Volume 6515, 651514 (2007) https://doi.org/10.1117/12.710112

KEYWORDS: Signal to noise ratio, Reconstruction algorithms, Image restoration, Signal detection, Tomography, CT reconstruction, Detection and tracking algorithms, Data modeling, Systems modeling, Computed tomography

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Proceedings Article | 16 March 2007 Paper

Image reconstruction from sparse data samples along spiral trajectories in MRI

Samuel LaRoque, Emil Sidky, Xiaochuan Pan

Proceedings Volume 6510, 651054 (2007) https://doi.org/10.1117/12.710240

KEYWORDS: Magnetic resonance imaging, Image restoration, Reconstruction algorithms, Fourier transforms, Statistical analysis, Cardiac imaging, Medical imaging, Image analysis, Imaging systems, Data modeling

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Proceedings Article | 6 March 2007 Paper

Accurate image reconstruction from sparse data in diffraction tomography using a total variation minimization algorithm

Samuel LaRoque, Emil Sidky, Xiaochuan Pan

Proceedings Volume 6513, 651302 (2007) https://doi.org/10.1117/12.710195

KEYWORDS: Reconstruction algorithms, Image restoration, Diffraction, Tomography, Fourier transforms, Inverse scattering, Data modeling, Algorithm development, Solids, Image filtering

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Showing 5 of 6 publications

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