8 Nicolas Karakatsanis GATE woskshop Chicago

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Information about 8 Nicolas Karakatsanis GATE woskshop Chicago

Published on January 10, 2008

Author: Mercede

Source: authorstream.com

Slide1:  GATE Overview and recent advances Nicolas Karakatsanis Irène Buvat National Technical University of Athens, Greece Laboratory of Functional Imaging, U678 INSERM, Paris, France Slide2:  Outline Evolution of the use of MC simulations in ET since 1996 OpenGATE motivation and short history New features in MC simulators in ET New applications for MC simulations Upcoming developments in MC simulations Conclusion Slide3:  Evolution of the codes used for MC simulations in ET since 1996 1996-2000 14 different codes: - 10 « home-made » - 4 publicly released or available from authors Slide4:  Motivation for developing GATE in 2001 Provide a public code based on a standard code to ensure reliability enabling SPECT and PET simulations (possibly even more) accommodating almost any detector design (including prototypes) modeling time-dependent processes user-friendly Developed as a collaborative effort Slide5:  The OpenGATE collaboration From 4 to 23 labs worldwide U601 Inserm, Nantes U650 Inserm, Brest U678 Inserm, Paris LPC CNRS, Clermont Ferrand IReS CNRS, Strasbourg UMR5515 CNRS, CREATIS, Lyon, CPPM CNRS, Marseilles Subatech, CNRS, Nantes SHFJ CEA, Orsay DAPNIA CEA, Saclay Joseph Fourier University, Grenoble Delft University of Technology, Delft, The Netherlands Ecole Polytechnique Fédérale de Lausanne, Switzerland Forschungszentrum Juelich, Germany Ghent University, Belgium National Technical University of Athens, Greece Vrije Universiteit Brussel, Belgium John Hopkins University, Baltimore, USA Memorial Sloan-Kettering Cancer Center, New York, USA University of California, Los Angeles, USA University of Massachusetts Medical School, Worcester, USA University of Santiago of Chile, Chile Sungkyunkwan University School of Medicine, Seoul, Korea Slide6:  Product of OpenGATE: GATE Publicly released on May 2004 http://www.opengatecollaboration.org An official publication: Jan S, Santin G, Strul D, Staelens S, Assié K, Autret D, Avner D, Barbier R, Bardiès M, Bloomfield PM, Brasse D, Breton V, Bruyndonckx P, Buvat I, Chatziioannou AF, Choi Y, Chung YH, Comtat C, Donnarieix D, Ferrer L, Glick SJ, Groiselle CJ, Guez D, Honore PF, Kerhoas-Cavata S, Kirov AS, Kohli V, Koole M, Krieguer M, van der Laan DJ, Lamare F, Largeron G, Lartizien C, Lazaro D, Maas MC, Maigne L, Mayet F, Melot F, Merheb C, Pennacchio E, Perez J, Pietrzyk U, Rannou FR, Rey M, Schaart D, Schmidtlein CR, Simon L, Song TY, Vieira JM, Visvikis D, Van de Walle R, Wiers E, Morel C. GATE: a simulation toolkit for PET and SPECT. Phys Med Biol 49: 4543-4561, 2004. More than 800 subscribers to the Gate users mailing list Slide7:  Tasks of the OpenGATE collaboration Upgrade GATE for following GEANT4 new releases (1 major release per year) Incorporate new developments in GATE (1 minor release per year) e.g.: variance reduction techniques (to be released soon) speed-up options (e.g., analytical modeling of the collimator response in SPECT) (to be released soon) tools for running GATE on a cluster or on a grid environment (to be released soon) extension of GATE for dosimetry applications tools for interfacing GATE output with other software (STIR) Organize training Slide8:  GATE today: technical features Based on GEANT 4 Written in C++ User-friendly: simulations can be designed and controlled using macros, without any knowledge in C++ Appropriate for SPECT and PET simulations Flexible enough to model almost any detector design, including prototypes Explicit modeling of time (hence detector motion, patient motion, radioactive decay, dead time, time of flight, tracer kinetics) Can handle voxelized and analytical phantoms Slide9:  GATE today: practical features Can be freely downloaded, including the source codes Can be run on many platforms (Linux, Unix, MacOs) On-line documentation, including FAQ and archives of all questions (and often answers) about GATE that have been asked so far Help about the use of GATE can be obtained through the gate-user mailing list Many commercial tomographs and prototypes have already been modeled (including validation of the model) Slide10:  www.opengatecollaboration.org Slide11:  PET systems already modeled by the OpenGATE collaboration Slide12:  Some examples Slide13:  Some examples Guez et al, DAPNIA and SHJF HRRT Slide14:  SPECT systems already modeled by the OpenGATE collaboration Slide15:  Example Schielding Backcompartment NaI(Tl) crystal Scanning table Phantom holder MEHR collimator DST Xli camera Assié et al, Phys Med Biol 2005 Slide16:  Some examples Counts (AU) Assié et al, Phys Med Biol 2005 Energy (keV) Counts (AU) 0 2 4 6 8 10 12 14 50 70 90 110 130 150 170 190 210 230 250 270 Indium 111 source in air Indium 111 source in water Slide17:  Prototypes already modeled by the OpenGATE collaboration Slide18:  Example PSPMT crystal collimator Experiment GATE Energy (keV) Number of counts Energy spectrum Lazaro et al, Phys Med Biol 2004 IASA CsI(Tl) gamma camera … Slide19:  Monte Carlo simulations today: what is new? Slide20:  Modeling time dependent processes SPECT and PET intrinsically involves time: Change of tracer distribution over time (tracer biokinetic) Detector motions during acquisition Patient motion Radioactive decay Dead time of the detector Time-of-flight PET GEANT 4 (hence GATE) is perfect in that regard Slide21:  Modeling of radioactive decay Santin et al, IEEE Trans Nucl Sci 2003 15O (2 min) 11C (20 min) Slide22:  Modeling of time of flight PET Groiselle et al, IEEE MIC Conf Rec 2004 Slide23:  Realistic phantoms can be easily used as GATE input NCAT Modeling realistic phantoms Segars et al, Mol Imaging Biol 2004 MOBY Segars et al, IEEE TNS 2001 Descourt et al, IEEE MIC Conf Records 2006 Slide24:  Modeling original detector designs Non-conventional geometries TEP/CT BIOGRAPH Siemens Spherical geometry of the Hi-Rez PET scanner Michel et al, IEEE Conf Records 2006 lead end-shielding detection block GEANT 4 is a very flexible tool Slide25:  Modeling original detector designs TEP/CT BIOGRAPH Siemens Sakellios et al, IEEE MIC Conf Records 2006 Small animal imaging Mouse-size gamma camera 2 Hamamatsu H8500 PSPMT NaI pixelized scintillator Tungsten collimator Mouse-size PET 1 Hamamatsu H8500 PSPMT pixelated LYSO scintillator (30 x 35 crystals per block, 1 head = 1 block) Slide26:  Modeling original detector designs Sakellios et al, IEEE MIC Conf Records 2006 Small animal imaging Simulated mouse gamma camera image (MOBY phantom) Simulated mouse PET image (MOBY phantom) Slide27:  New applications for Monte Carlo simulations Design and assessment of correction and reconstruction methods Study of an imaging system response Use in the very imaging process Data production for evaluation purpose Description and validation of a code 1995-1999 Slide28:  Optimizing detector design Michel et al IEEE MIC Conf Records 2006 NEC curves as a function of the crystal in the PET HiRez scanner Slide29:  Using Monte Carlo simulations for calculating the system matrix “Object” f Projection p p = R f GATE is very appropriate but slow Slide30:  Example: SPECT Tc99m phantom Simulated data El Bitar et al IEEE MIC Conf Records 2006 Slide31:  What next? Slide32:  Bridging the gap between MC modeling in imaging and dosimetry Dewaraja et al, J Nucl Med 2005 SIMIND DPM DPM The validity of the physics at low energy will have to be checked Problems in G4 have been identified, e.g., multiple scattering and corresponding energy deposit calculation Slide33:  Modeling hybrid machines (PET/CT, SPECT/CT, OPET) Integrating Monte Carlo modeling tools for: - common coordinate system - common object description - consistent sampling - convenient assessment of multimodality imaging GATE Brasse et al, IEEE MIC Conf Rec 2004 GATE Alexandrakis et al, Phys Med Biol 2005 OPET GATE TOAST PET/CT SPECT/CT On-going studies regarding the use of GATE for CT simulations Slide34:  Conclusion GATE is a very relevant tool for Monte Carlo simulations in ET Simulations will be more and more present in (nuclear) medical imaging in the future: as a invaluable guide for designing scanners, imaging protocols and interpreting SPECT and PET scans in the very imaging process of a patient Slide35:  Last but not least: next GATE training 3 days, March 7-9th, 2007 in Clermont-Ferrand, France GATE installation, GATE use through lectures and practical sessions given by GATE experts Registration will open on December, attendance will be limited Registration from mid-december on http://www.opengatecollaboration.org Slide36:  Acknowledgments The OpenGATE collaboration Thank you!!!:  Thank you!!! Slide38:  Throughput of the simulations The major problem with GATE and GEANT4! High throughput needed for efficient data production Large number of particles to be simulated low detection efficiency in SPECT, typically 1 / 10 000 is detected in PET, 1 / 200 is detected Big “World”: - detectors have a “diameter” greater than 1 m emitting object (e.g., patient) is large (50 cm up to 1.80 m) emitting object is finely sampled (typically 1 mm x 1 mm x 1 mm cells) voxelized objects are most often used At least 4 approaches can be used to increase the throughput of the simulations Slide39:  Using acceleration methods Variance reduction techniques such as importance sampling (e.g. in SimSET) speed-up factors between 2 and 15 Slide40:  Combining MC with non MC modeling increase in efficiency > 100 Song et al, Phys Med Biol 2005 Full MC Collimator Angular Response Function Slide41:  Parallel execution of the code on a distributed architecture PET old merger new merger Speed-up factor ~ number of jobs De Beenhouwer et al, IEEE MIC Conf Records 2006 Slide42:  Smart sampling Taschereau et al, Med Phys 2006

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