William Paul Segars

Associate Professor in Radiology

Our current research involves the use of computer-generated phantoms and simulation techniques to investigate and optimize medical imaging systems and methods. Medical imaging simulation involves virtual experiments carried out entirely on the computer using computational models for the patients as well as the imaging devices. Simulation is a powerful tool for characterizing, evaluating, and optimizing medical imaging systems. A vital aspect of simulation is to have realistic models of the subject's anatomy as well as accurate models for the physics of the imaging process. Without this, the results of the simulation may not be indicative of what would occur in actual clinical studies and would, therefore, have limited practical value. We are leading the development of realistic simulation tools for use toward human and small animal imaging research.

These tools have a wide variety of applications in many different imaging modalities to investigate the effects of anatomical, physiological, physical, and instrumentational factors on medical imaging and to research new image acquisition strategies, image processing and reconstruction methods, and image visualization and interpretation techniques. We are currently applying them to the field of x-ray CT. The motivation for this work is the lack of sufficiently rigorous methods for optimizing the image quality and radiation dose in x-ray CT to the clinical needs of a given procedure. The danger of unnecessary radiation exposure from CT applications, especially for pediatrics, is just now being addressed. Optimization is essential in order for new and emerging CT applications to be truly useful and not represent a danger to the patient. Given the relatively high radiation doses required of current CT systems, thorough optimization is unlikely to ever be done in live patients. It would be prohibitively expensive to fabricate physical phantoms to simulate a realistic range of patient sizes and clinical needs especially when physiologic motion needs to be considered. The only practical approach to the optimization problem is through the use of realistic computer simulation tools developed in our work.

Appointments and Affiliations

  • Associate Professor in Radiology

Contact Information

  • Office Location: Hock Plaza Suite 302, 2424 Erwin Road, Durham, NC 27705
  • Office Phone: (919) 684-1473
  • Email Address: paul.segars@duke.edu
  • Websites:


  • Ph.D. University of North Carolina - Chapel Hill, 2001

Courses Taught

  • BME 791: Graduate Independent Study
  • BME 792: Continuation of Graduate Independent Study

In the News

Representative Publications

  • Gonzales, Matthew J., Gregory Sturgeon, Adarsh Krishnamurthy, Johan Hake, René Jonas, Paul Stark, Wouter-Jan Rappel, et al. “A three-dimensional finite element model of human atrial anatomy: new methods for cubic Hermite meshes with extraordinary vertices.” Med Image Anal 17, no. 5 (July 2013): 525–37. https://doi.org/10.1016/j.media.2013.03.005.
  • Hsu, Christina M. L., Mark L. Palmeri, W Paul Segars, Alexander I. Veress, and James T. Dobbins. “Generation of a suite of 3D computer-generated breast phantoms from a limited set of human subject data.” Med Phys 40, no. 4 (April 2013): 043703. https://doi.org/10.1118/1.4794924.
  • Segars, W. P., Jason Bond, Jack Frush, Sylvia Hon, Chris Eckersley, Cameron H. Williams, Jianqiao Feng, et al. “Population of anatomically variable 4D XCAT adult phantoms for imaging research and optimization.” Med Phys 40, no. 4 (April 2013): 043701. https://doi.org/10.1118/1.4794178.
  • Li, Xiang, Ehsan Samei, Cameron H. Williams, W Paul Segars, Daniel J. Tward, Michael I. Miller, J Tilak Ratnanather, Erik K. Paulson, and Donald P. Frush. “Effects of protocol and obesity on dose conversion factors in adult body CT.” Med Phys 39, no. 11 (November 2012): 6550–71. https://doi.org/10.1118/1.4754584.
  • Zhang, Yakun, Xiang Li, W Paul Segars, and Ehsan Samei. “Organ doses, effective doses, and risk indices in adult CT: comparison of four types of reference phantoms across different examination protocols.” Med Phys 39, no. 6 (June 2012): 3404–23. https://doi.org/10.1118/1.4718710.
  • Hsu, Christina M. L., Mark L. Palmeri, W Paul Segars, Alexander I. Veress, and James T. Dobbins. “An analysis of the mechanical parameters used for finite element compression of a high-resolution 3D breast phantom.” Med Phys 38, no. 10 (October 2011): 5756–70. https://doi.org/10.1118/1.3637500.
  • Veress, Alexander I., W Paul Segars, Benjamin M. W. Tsui, and Grant T. Gullberg. “Incorporation of a left ventricle finite element model defining infarction into the XCAT imaging phantom.” Ieee Trans Med Imaging 30, no. 4 (April 2011): 915–27. https://doi.org/10.1109/TMI.2010.2089801.
  • Li, Xiang, Ehsan Samei, W Paul Segars, Gregory M. Sturgeon, James G. Colsher, Greta Toncheva, Terry T. Yoshizumi, and Donald P. Frush. “Patient-specific radiation dose and cancer risk estimation in CT: part II. Application to patients.” Med Phys 38, no. 1 (January 2011): 408–19. https://doi.org/10.1118/1.3515864.
  • Li, Xiang, Ehsan Samei, W Paul Segars, Gregory M. Sturgeon, James G. Colsher, Greta Toncheva, Terry T. Yoshizumi, and Donald P. Frush. “Patient-specific radiation dose and cancer risk estimation in CT: part I. development and validation of a Monte Carlo program.” Med Phys 38, no. 1 (January 2011): 397–407. https://doi.org/10.1118/1.3515839.
  • Tward, Daniel J., Can Ceritoglu, Anthony Kolasny, Gregory M. Sturgeon, W Paul Segars, Michael I. Miller, and J Tilak Ratnanather. “Patient Specific Dosimetry Phantoms Using Multichannel LDDMM of the Whole Body.” Int J Biomed Imaging 2011 (2011): 481064. https://doi.org/10.1155/2011/481064.
  • Segars, W. P., G. Sturgeon, S. Mendonca, Jason Grimes, and B. M. W. Tsui. “4D XCAT phantom for multimodality imaging research.” Med Phys 37, no. 9 (September 2010): 4902–15. https://doi.org/10.1118/1.3480985.