Mr. Nicholas A. Shkumat Profile

Nicholas A. Shkumat

at Univ Health Network

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Author

Publications (3)

Proceedings Article | 20 March 2007 Paper

Development and implementation of a high-performance cardiac-gated dual-energy imaging system

N. Shkumat, J. Siewerdsen, A. Dhanantwari, D. Williams, S. Richard, D. Tward, N. Paul, J. Yorkston, R. Van Metter

Proceedings Volume 6510, 651006 (2007) https://doi.org/10.1117/12.713680

KEYWORDS: Imaging systems, X-rays, Radiography, Lung, Heart, Diagnostics, Oximeters, Image filtering, Image processing, Sensors

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Proceedings Article | 2 March 2006 Paper

High-performance dual-energy imaging with a flat-panel detector: imaging physics from blackboard to benchtop to bedside

J. Siewerdsen, N. Shkumat, A. Dhanantwari, D. Williams, S. Richard, M. Daly, N. Paul, D. Moseley, D. Jaffray, J. Yorkston, R. Van Metter

Proceedings Volume 6142, 61421E (2006) https://doi.org/10.1117/12.658080

KEYWORDS: Imaging systems, Sensors, Image acquisition, Oximeters, Dual energy imaging, Lung, Radiography, Diagnostics, Silver, X-rays

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The application of high-performance flat-panel detectors (FPDs) to dual-energy (DE) imaging offers the potential for dramatically improved detection and characterization of subtle lesions through reduction of "anatomical noise," with applications ranging from thoracic imaging to image-guided interventions. In this work, we investigate DE imaging performance from first principles of image science to preclinical implementation, including: 1.) generalized task-based formulation of NEQ and detectability as a guide to system optimization; 2.) measurements of imaging performance on a DE imaging benchtop; and 3.) a preclinical system developed in our laboratory for cardiac-gated DE chest imaging in a research cohort of 160 patients. Theoretical and benchtop studies directly guide clinical implementation, including the advantages of double-shot versus single-shot DE imaging, the value of differential added filtration between low- and high-kVp projections, and optimal selection of kVp pairs, filtration, and dose allocation. Evaluation of task-based NEQ indicates that the detectability of subtle lung nodules in double-shot DE imaging can exceed that of single-shot DE imaging by a factor of 4 or greater. Filter materials are investigated that not only harden the high-kVp beam (e.g., Cu or Ag) but also soften the low-kVp beam (e.g., Ce or Gd), leading to significantly increased contrast in DE images. A preclinical imaging system suitable for human studies has been constructed based upon insights gained from these theoretical and experimental studies. An important component of the system is a simple and robust means of cardiac-gated DE image acquisition, implemented here using a fingertip pulse oximeter. Timing schemes that provide cardiac-gated image acquisition on the same or successive heartbeats is described. Preclinical DE images to be acquired under research protocol will afford valuable testing of optimal deployment, facilitate the development of DE CAD, and support comparison of DE diagnostic imaging performance to low-dose CT and radiography.

Proceedings Article | 20 April 2005 Paper

Achieving high-resolution soft-tissue imaging with cone-beam CT: a two-pronged approach for modulation of x-ray fluence and detector gain

S. Graham, J. Siewerdsen, D. Moseley, H. Keller, N. Shkumat, D. Jaffray

Proceedings Volume 5745, (2005) https://doi.org/10.1117/12.595886

KEYWORDS: Sensors, Modulation, Head, X-rays, X-ray computed tomography, Image filtering, X-ray detectors, X-ray imaging, Liver, Visualization

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