Guillem Pratx
Status
PhD Candidate, Stanford, Electrical Engineering (Graduating 10/2009)
Education
Thesis: "Novel strategies for practical reconstruction in high-resolution positron emission tomography"
Adviser: Craig S. Levin, PhD
Work and Research Experience
Doctoral Student. Researched and implemented novel image reconstruction solutions for positron emission tomography (PET) systems.
The framework combines the two following features: ultra fast processing by using graphics processing units (GPU), and high image quality
and quantitative accuracy by using a precise shift-varying model within the reconstruction, as well as new strategies for positioning
high-energy photons in high-resolution PET detectors. The approach was successfully applied to commercially-available pre-clinical
(high-resolution) and clinical (time-of-flight) PET systems.
Supervisor: Craig S. Levin, PhD
2007-present, Cancer Center, Stanford University, CA
Research Assistant. Implemented a software package for calibration and real-time operation of a surgical gamma camera prototype.
Helped conduct clinical study on the efficacy of the gamma camera for guiding sentinel lymph node biopsy in breast cancer and melanoma
(50 patients).
Supervisor:Denise L. Johnson, MD
Visiting Researcher. Investigated novel non-linear optimization methods for maximum-likelihood
PET image reconstruction based on the conjugate gradient method.
Supervisor:Andew J. Reader, PhD
Summer 2004, LIAMA, Chinese Academy of Sciences, Beijing, China
Research Intern. Designed and implemented methods to automatically extract buildings from
high-resolution satellite images.
Summer 2001, Kick Start Ventures, London, UK
Consulting mission for a company which manages an online marketplace
for road freight in the UK. Marketing for British phone operator.
Summer 2000, Alcatel Space Industries, Toulouse, France
Industrial drawing and software development.
A one year project aiming at launching Serbia's first job-search website
Honors & Awards
Fellowships
Awards
Top Student Paper Award, IEEE Medical Imaging Conference, Dresden, Germany, 2008
Society of Nuclear Medicine Travel Award to attend Annual Meeting, Toronto, ON, 2009
IEEE Travel Award to attend IEEE Medical Imaging Conference, Dresden, Germany, 2008
Society of Nuclear Medicine Travel Award to attend Annual Meeting, New Orleans, LA, 2008
IEEE Travel Award to attend IEEE Medical Imaging Conference, Honolulu, HI, 2007
Bio-X Travel Grant to attend Fully 3D Meeting in Lindau, Germany, 2007
Philips Travel Award to attend IEEE Medical Imaging Conference, San Diego, CA, 2006
Teaching
IEEE Short Course, Honolulu, HI, 2007
Programming and Medical Applications Using Graphics Hardware
Miscellaneous
Engineering and Computer Skills
C, C++, OpenGL, CG, CUDA, Linux, Matlab, OpenCV, LATEX
Optimization (linear & non-linear)
Statistical signal processing, estimation, Monte-Carlo simulation
Image processing, computer vision, computer graphics
Languages
English (fluent), French (fluent), Spanish (basic), Mandarin (basic)
Professional Activities
Service
President, French Stanford Student Association, Stanford University, 2007-2008
Refereeing
IEEE Transactions in Nuclear Science
IEEE Transactions in Medical Imaging
Publications and Conference Presentations
Peer-Reviewed Publications
Pratx G, Chinn G, Olcott PD & Levin CS, "Fast, accurate and shift-varying line projections for
iterative reconstruction using the GPU", IEEE Trans. Med. Imag., vol 28(3), pp. 435-445, Mar 2009
Pratx G & Levin CS, "Bayesian reconstruction of photon interaction sequences for high-resolution
PET detectors", Phys. Med. Bio., vol 54(17), pp. 5073-5094, Sept 2009.
Pratx G & Levin CS, "Resolution recovery in PET via online detector response calculations",
to be submitted
Pratx G, Surti S & Levin CS, "GPU-accelerated list-mode reconstruction for 3-D time-of-flight
PET", in preparation
Olcott PD, Pratx G, Johnson DL, Mansouri MA & Levin CS, "Clinical feasibility of an intra-
operative hand-held gamma camera for sentinel lymph node biopsy for the surgical staging of
melanoma and breast cancer", in preparation
Reynolds PD, Olcott PD, Pratx G, Lau FWY & Levin CS, "Convex optimization of coincidence
time resolution for a high resolution PET system", to be submitted
U.S. Patents
Pratx G, Olcott PD & Levin CS, "Method of reconstructing a tomographic image using a graphics
processing unit", US 2007/0201611 A1
Pratx G & Levin CS, "Method and apparatus for imaging using robust Bayesian sequence reconstruction", provisional filed
Invited Talks
Molecular Imaging Program at Stanford (Stanford, CA), September 24, 2007. "Accelerating
tomographic image reconstruction for PET using computer graphics hardware"
Service Hospitalier Frederic Joliot (Orsay, France), September 4, 2007. "Preconditioned conjugate
gradient algorithm for ML"
Manchester Institute for Mathematical Science (Manchester, UK), September 10, 2007. "Ultra-
fast tomography using off-the-shelf graphics cards"
Molecular Imaging Program at Stanford (Stanford, CA), March 27, 2006. "Real-time imaging
algorithms for surgical gamma camera"
Conference Presentations
Pratx G, Surti S & Levin CS, "GPU-accelerated list-mode reconstruction for 3-D time-of-flight
PET", Soc Nucl Med Annual Meeting, 2009
Olcott PD, Pratx G, Johnson DL, Mansouri MA & Levin CS, "Clinical feasibility of an intra-
operative hand-held gamma camera for sentinel lymph node biopsy for the surgical staging of
melanoma and breast cancer", Soc Nucl Med Annual Meeting, 2009
Pratx G, Chinn G, Olcott PD & Levin CS, "Fast, accurate and shift-varying line projections for
iterative reconstruction using the GPU", IEEE Medical Imaging Conference, Dresden, Germany, 2008
Pratx G, Reader AJ & Levin CS, "Faster maximum-likelihood reconstruction via explicit conjugation
of search directions", IEEE Medical Imaging Conference, Dresden, Germany, 2008
Gu Y, Pratx G, Lau FWY & Levin CS, "Effects of photon multiple interactions in a high
resolution PET system that uses 3-D positioning detectors", IEEE Medical Imaging Conference,
Dresden, Germany, 2008
Reynolds PD, Olcott PD, Pratx G, Lau FWY, Levin CS, "Convex optimization of coincidence
time resolution for high resolution PET systems", IEEE Medical Imaging Conference, Dresden,
Germany, 2008
Pratx G & Levin CS, "Maximum a posteriori event positioning in high-resolution PET CZT
detectors", oral presentation, Soc Nucl Med Annual Meeting, New Orleans, LA, 2008
Pratx G, Reader AJ & Levin CS, "Fast maximum likelihood image reconstruction via PCG
without a line search", oral presentation, Soc Nucl Med Annual Meeting, New Orleans, LA, 2008
Peng H, Olcott PD, Pratx G, Foudray AMK, Chinn G & Levin CS, "Design study of a high-
resolution breast-dedicated PET system built from CZT detectors", IEEE Medical Imaging Conference,
Honolulu, HI, 2007
Pratx G & Levin CS, "Accurately positioning events in a high-resolution PET system that uses
3D CZT detectors", oral presentation, IEEE Medical Imaging Conference, Honolulu, HI, 2007
Pratx G, Chinn G, Olcott PD & Levin CS, "Fully 3D list-mode OSEM on PC graphics hardware:
Quantitative studies", IEEE Medical Imaging Conference, Honolulu, HI, 2007
Pratx G, Chinn G, Habte F, Olcott PD & Levin CS, "Acceleration of fully 3-D list-mode OSEM
with system modeling for high-resolution PET using graphics processing units", oral presentation,
International Meeting on Fully 3-D Image Reconstruction in Rad. and Nuclear Medicine,
Lindau, Germany, 2007
Pratx G, Chinn G, Habte F, Olcott P & Levin CS, "Fully 3-D list-mode OSEM accelerated by
graphics processing units", IEEE Medical Imaging Conference, San Diego, CA, 2006
Olcott PD, Buss SR, Levin CS, Pratx G & Sramek CK, "GRAY: High energy photon ray tracer
for PET applications", IEEE Medical Imaging Conference, San Diego, CA, 2006
Pratx G, Chinn G, Olcott P & Levin CS, "Accelerated list-mode 3D-OSEM reconstruction for
PET on a graphics processing unit", oral presentation, Soc Nucl Med Annual Meeting, San
Diego, CA, 2006
Education
profile
Curriculum Vitae