Dr. Raj Shekhar Profile

Dr. Raj Shekhar

Principal Investigator at Children's National Health System

SPIE Involvement:

Editorial Board Member: Journal of Medical Imaging | Author

Publications (26)

SPIE Journal Paper | 3 February 2021 Open Access

Hybrid electromagnetic-ArUco tracking of laparoscopic ultrasound transducer in laparoscopic video

Xinyang Liu, William Plishker, Raj Shekhar

JMI, Vol. 8, Issue 01, 015001, (February 2021) https://doi.org/10.1117/12.10.1117/1.JMI.8.1.015001

KEYWORDS: Laparoscopy, Cameras, Transducers, Video, Ultrasonography, Zoom lenses, Detection and tracking algorithms, Sensors, Imaging systems, Augmented reality

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Proceedings Article | 8 March 2019 Paper

Segmentation of surgical instruments in laparoscopic videos: training dataset generation and deep-learning-based framework

Xinyang Liu, Eung-Joo Lee, Shuvra Bhattacharyya, Raj Shekhar, William Plishker, Timothy Kane

Proceedings Volume 10951, 109511T (2019) https://doi.org/10.1117/12.2512994

KEYWORDS: Data modeling, Magnetic resonance imaging, Image segmentation, Image processing, Video, Robotics, Neural networks, Binary data, Laparoscopy, Instrument modeling

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Proceedings Article | 8 March 2019 Presentation + Paper

Magnetically anchored pan-tilt stereoscopic robot with optical-inertial stabilization for minimally invasive surgery

Reza Monfaredi, Mojtaba Karimi, Saeed Shiry Ghidary, Raj Shekhar, Timothy Kane

Proceedings Volume 10951, 109511E (2019) https://doi.org/10.1117/12.2513019

KEYWORDS: Surgery, Imaging systems, Cameras, Sensors, Video, Robotics, Control systems, Stereoscopic cameras, Telecommunications

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SPIE Journal Paper | 10 October 2016

Laparoscopic stereoscopic augmented reality: toward a clinically viable electromagnetic tracking solution

Xinyang Liu, Sukryool Kang, William Plishker, George Zaki, Timothy Kane, Raj Shekhar

JMI, Vol. 3, Issue 04, 045001, (October 2016) https://doi.org/10.1117/12.10.1117/1.JMI.3.4.045001

KEYWORDS: Laparoscopy, Sensors, Calibration, Visualization, Ultrasonography, Video, Electromagnetism, Imaging systems, Optical tracking, Cameras

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Proceedings Article | 18 March 2016 Paper

Accurate tracking of tumor volume change during radiotherapy by CT-CBCT registration with intensity correction

Seyoun Park, Adam Robinson, Harry Quon, Ana Kiess, Colette Shen, John Wong, William Plishker, Raj Shekhar, Junghoon Lee

Proceedings Volume 9786, 97860P (2016) https://doi.org/10.1117/12.2217047

KEYWORDS: Image processing algorithms and systems, Neck, Tumors, Graphics processing units, Image segmentation, Image registration, Radiotherapy, Computed tomography

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Proceedings Article | 20 March 2015 Paper

Deformable registration of CT and cone-beam CT by local CBCT intensity correction

Seyoun Park, William Plishker, Raj Shekhar, Harry Quon, John Wong, Junghoon Lee

Proceedings Volume 9413, 941333 (2015) https://doi.org/10.1117/12.2082485

KEYWORDS: Cancer, Tissues, Surgery, Image registration, Radiotherapy, Medical imaging, Optical flow, Computed tomography, Radiation oncology, Image-guided intervention

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Proceedings Article | 18 March 2015 Paper

Application of single-image camera calibration for ultrasound augmented laparoscopic visualization

Xinyang Liu, He Su, Sukryool Kang, Raj Shekhar, Timothy Kane

Proceedings Volume 9415, 94151T (2015) https://doi.org/10.1117/12.2082194

KEYWORDS: Visualization, Imaging systems, Cameras, Calibration, Ultrasonography, Distortion, Corner detection, Optical tracking, Autoregressive models, Laparoscopy

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Proceedings Article | 12 March 2014 Paper

Stereoscopic augmented reality using ultrasound volume rendering for laparoscopic surgery in children

Jihun Oh, Xin Kang, Emmanuel Wilson, Craig Peters, Timothy Kane, Raj Shekhar

Proceedings Volume 9036, 90360Y (2014) https://doi.org/10.1117/12.2043929

KEYWORDS: Visualization, Surgery, Imaging systems, Calibration, Ultrasonography, Video, Volume rendering, Transducers, 3D image processing, Laparoscopy

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Proceedings Article | 12 March 2010 Paper

Parallel image registration with a thin client interface

Tabassum Ahmad, Ganesh Saiprasad, Raj Shekhar, Peng Lei, William Plishker, Yi-Jung Lo

Proceedings Volume 7628, 76280V (2010) https://doi.org/10.1117/12.844457

KEYWORDS: Image fusion, Tumors, Magnetic resonance imaging, Image processing, Image restoration, Image registration, Computed tomography, Rigid registration, Neuroimaging, Positron emission tomography

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Proceedings Article | 21 March 2007 Paper

Development of continuous CT-guided minimally invasive surgery

Adrian Park, Ivan George, Omkar Dandekar, Steven Kavic, Reuben Mezrich, Raj Shekhar

Proceedings Volume 6509, 65090D (2007) https://doi.org/10.1117/12.708783

KEYWORDS: X-ray computed tomography, Visualization, Surgery, Scanners, Image registration, Optical tracking, Computed tomography, 3D visualizations, 3D image processing, Laparoscopy

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Proceedings Article | 21 March 2007 Paper

PET guidance for liver radiofrequency ablation: an evaluation

Peng Lei, Omkar Dandekar, Faaiza Mahmoud, Raj Shekhar, David Widlus, Patrick Malloy

Proceedings Volume 6509, 650918 (2007) https://doi.org/10.1117/12.709683

KEYWORDS: Image fusion, Liver, Tumors, Tissues, Scanners, Image registration, Computed tomography, Radiofrequency ablation, Algorithm development, Positron emission tomography

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Proceedings Article | 21 March 2007 Paper

Automatic prostate localization using elastic registration of planning CT and daily 3D ultrasound images

Vivek Walimbe, Jianzhou Wu, Omkar Dandekar, Raj Shekhar, Warren D'Souza

Proceedings Volume 6509, 650913 (2007) https://doi.org/10.1117/12.711598

KEYWORDS: 3D acquisition, X-ray computed tomography, Ultrasonography, Image registration, Radiotherapy, Image filtering, Prostate, Computed tomography, 3D image processing, Automatic alignment

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Proceedings Article | 19 March 2007 Paper

A statistical approach to high-quality CT reconstruction at low radiation doses for real-time guidance and navigation

Avanti Shetye, Raj Shekhar

Proceedings Volume 6510, 65105U (2007) https://doi.org/10.1117/12.710107

KEYWORDS: X-ray computed tomography, Detection and tracking algorithms, CT reconstruction, Visualization, Metals, Scanners, X-rays, Image quality, Computed tomography, Reconstruction algorithms

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Proceedings Article | 16 March 2006 Paper

A scalable beamforming architecture for real-time 3D ultrasonic imaging using nonuniform sampling

Carlos Castro-Pareja, Raj Shekhar, Omkar Dandekar

Proceedings Volume 6147, 61470M (2006) https://doi.org/10.1117/12.653714

KEYWORDS: Point spread functions, Apodization, 3D acquisition, Ultrasonography, Image resolution, Field programmable gate arrays, Transducers, Phased arrays, Nonuniform sampling, 3D image processing

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Proceedings Article | 16 March 2006 Paper

Fully automatic segmentation of left ventricular myocardium in real-time three-dimensional echocardiography

Raj Shekhar, Vivek Walimbe, Vladimir Zagrodsky

Proceedings Volume 6144, 61444H (2006) https://doi.org/10.1117/12.654050

KEYWORDS: Image processing algorithms and systems, 3D acquisition, Image segmentation, Image restoration, 3D modeling, Image registration, Medical imaging, Algorithm development, Echocardiography, 3D image processing

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Purpose: We report a deformable model (DM)-based fully automatic segmentation of the left ventricular (LV) myocardium (endocardium + epicardium) in real-time three-dimensional (3D) echocardiography. Methods: Initialization of the DM is performed through automated mutual information-based registration of the image to be segmented with a 3D template (image + corresponding endo-epicardial wiremesh). The initialized endocardial and epicardial wiremesh templates are then simultaneously refined iteratively under the joint influence of mesh-derived internal forces, image-derived external (gradient vector flow-based) forces, and endo-epicardium mesh-interaction forces. Incorporation of adaptive mesh-interaction forces into the DM refinement, a novelty of the current work, ensures appropriate relative endo-epicardial orientation during simultaneous refinement. Repeating for the entire cardiac sequence provides the segmented myocardium for all phases. Preliminary comparison is presented between automatic and expert-defined myocardial segmentation for five subjects imaged in clinical settings using a Philips SONOS 7500 scanner. Results: Root mean square (rms) radial distance error between the algorithm-determined and expert-traced endocardial and epicardial contours in six predetermined planar views was 3.86 ± 0.72 mm and 4.0 ± 0.63 mm in end-diastole, 3.9 ± 0.51 mm and 4.04 ± 0.65 mm in systole, respectively. Mean absolute error between average myocardial thickness calculated using automatic and expert-defined contours was 1.64 ± 0.56 mm (apical), 1.3 ± 0.58 mm (mid) and 1.46 ± 0.45 mm (basal). The absolute difference in ejection fraction calculated using our algorithm and by the expert using the TomTec software was 7.2 ± 0.84 %. Conclusion: We demonstrate successful segmentation of LV myocardium, which allows clinically important LV structure and function (e.g. wall thickness, LV volume and ejection fraction) to be tracked over the entire cardiac cycle.

Proceedings Article | 10 March 2006 Paper

Elastic registration using 3D ChainMail: application to virtual colonoscopy

Barry Daly, Raj Shekhar, Carlos Castro-Pareja

Proceedings Volume 6144, 61442Y (2006) https://doi.org/10.1117/12.653644

KEYWORDS: 3D applications, Image resolution, 3D modeling, Image registration, Medical imaging, Colorectal cancer, Computed tomography, Colon, Optimization (mathematics), Virtual colonoscopy

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Proceedings Article | 15 February 2006 Paper

A cubic interpolation pipeline for fast computation of 3D deformation fields modeled using B-splines

Raj Shekhar, Carlos Castro-Pareja

Proceedings Volume 6063, 606301 (2006) https://doi.org/10.1117/12.650801

KEYWORDS: Clocks, Surgery, Image processing, Computing systems, Field programmable gate arrays, Control systems, 3D modeling, Image registration, Medical imaging, 3D image processing

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Proceedings Article | 15 February 2006 Paper

A hardware-accelerated approach to computing multiple image similarity measures from joint histogram

Carlos Castro-Pareja, Raj Shekhar

Proceedings Volume 6063, 60630N (2006) https://doi.org/10.1117/12.643206

KEYWORDS: Surgery, Magnetic resonance imaging, Image processing, Image restoration, Field programmable gate arrays, Iris, Image registration, Computed tomography, Optimization (mathematics), Positron emission tomography

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Proceedings Article | 29 April 2005 Paper

Adaptive reduction of intensity levels in 3D images for mutual information-based registration

Carlos Castro-Pareja, Raj Shekhar

Proceedings Volume 5747, (2005) https://doi.org/10.1117/12.595499

KEYWORDS: Image processing algorithms and systems, Detection and tracking algorithms, Magnetic resonance imaging, Image segmentation, Image registration, Quantization, Computed tomography, Rigid registration, Positron emission tomography, 3D image processing

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Proceedings Article | 25 February 2005 Paper

FPGA-based real-time anisotropic diffusion filtering of 3D ultrasound images

Carlos Castro-Pareja, Omkar Dandekar, Raj Shekhar

Proceedings Volume 5671, (2005) https://doi.org/10.1117/12.586198

KEYWORDS: Clocks, 3D acquisition, Anisotropic filtering, Ultrasonography, Image processing, Diffusion, Gaussian filters, Image filtering, 3D image processing, Anisotropic diffusion

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Proceedings Article | 18 May 2004 Paper

FPGA-based acceleration of mutual information calculation for real-time 3D image registration

Raj Shekhar, Jogikal Jagadeesh, Carlos Castro-Pareja

Proceedings Volume 5297, (2004) https://doi.org/10.1117/12.525412

KEYWORDS: Image fusion, Photovoltaics, Clocks, Image processing, Diagnostics, Field programmable gate arrays, Image registration, Medical imaging, Computer architecture, 3D image processing

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Proceedings Article | 12 May 2004 Paper

Elastic registration of 3D whole body CT and PET images by quaternion-based interpolation of multiple piecewise linear rigid-body registrations

Shanker Raja, Raj Shekhar, Bohdan Bybel, Vivek Walimbe, Mangesh Kanvinde, Vladimir Zagrodsky

Proceedings Volume 5370, (2004) https://doi.org/10.1117/12.535501

KEYWORDS: Tumors, Visualization, Image segmentation, 3D modeling, Image registration, Computed tomography, Algorithm development, Positron emission tomography, 3D image processing, Affine motion model

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Proceedings Article | 9 May 2002 Paper

Segmentation of 830- and 1310-nm LASIK corneal optical coherence tomography images

Yan Li, Raj Shekhar, David Huang

Proceedings Volume 4684, (2002) https://doi.org/10.1117/12.467123

KEYWORDS: Eye, Cornea, Surgery, Ultrasonography, Optical coherence tomography, Image segmentation, Image processing, Interfaces, Ultrasonics, LASIK

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Proceedings Article | 3 July 2001 Paper

Multifunction extension of simplex optimization method for mutual information-based registration of ultrasound volumes

Vladimir Zagrodsky, J. Fredrick Cornhill, Raj Shekhar

Proceedings Volume 4322, (2001) https://doi.org/10.1117/12.431124

KEYWORDS: MATLAB, 3D acquisition, Speckle, Ultrasonography, Image registration, Quantization, 3D scanning, Data conversion, Optimization (mathematics), 3D image processing

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Proceedings Article | 6 June 2000 Paper

Mutual information-based registration of cardiac ultrasound volumes

Vladimir Zagrodsky, Raj Shekhar, J. Fredrick Cornhill

Proceedings Volume 3979, (2000) https://doi.org/10.1117/12.387674

KEYWORDS: Signal to noise ratio, 3D acquisition, Speckle, Ultrasonography, Heart, Image registration, Data conversion, Electrocardiography, Echocardiography, 3D image processing

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Proceedings Article | 20 May 1999 Paper

Quantification of coronary arterial plaque volume using 3D reconstructions formed by fusing intravascular ultrasound and biplane angiography

Raj Shekhar, J. Fredrick Cornhill, Barry Kuban, Jon Klingensmith, David Vince, E. Tuzcu

Proceedings Volume 3660, (1999) https://doi.org/10.1117/12.349604

KEYWORDS: Visualization, Tissues, Calibration, Image segmentation, Arteries, 3D modeling, Transducers, Angiography, Intravascular ultrasound, 3D image processing

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Showing 5 of 26 publications

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