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Computer Simulation Computer Simulation for Emission for Emission Tomography:Tomography:Geant4 and GATEGeant4 and GATE
Xiao HanXiao Han
Aug. 2006Aug. 2006
OutlineOutline
IntroductionIntroduction Geant4Geant4 GATEGATE ConclusionConclusion
IntroductionIntroduction
Computer simulation is a necessary Computer simulation is a necessary step in designing modern emission step in designing modern emission tomography instrumentstomography instruments
Evaluation of simulation packages Evaluation of simulation packages – History and purposeHistory and purpose– FeaturesFeatures– User interfaceUser interface– How it worksHow it works– Validation and reliabilityValidation and reliability– Cost and accessibilityCost and accessibility– Current usersCurrent users
Geant4 ToolkitGeant4 Toolkit
Created by GCreated by GEANTEANT4 Collaboration (1998), 4 Collaboration (1998), to provide simulation for any area where to provide simulation for any area where particle interacts with matterparticle interacts with matter
Provides C++ classes for users to choose Provides C++ classes for users to choose to assemble their own packagesto assemble their own packages
Main featureMain feature– Software engineeringSoftware engineering– Object-oriented technologyObject-oriented technology
GATEGATE
Created by OpenGate Collaboration in 2002Created by OpenGate Collaboration in 2002 GATE – Geant4 Application for TomographiGATE – Geant4 Application for Tomographi
c Emissionc Emission FreeFree InterfaceInterface
– Input: scriptInput: script– Output:Output:
online plotteronline plotter ASCIIASCII Root …Root …
FeaturesFeatures
Well validated physics modelWell validated physics model Sophysticated geometry descriptionSophysticated geometry description Powerful visualization & 3D renderingPowerful visualization & 3D rendering Original features specific to emission tomOriginal features specific to emission tom
ography (temporal synchronization)ography (temporal synchronization)
GATE work flowGATE work flow
Scanner
Phantom
Physics
Source
Digitization
Acquisition
Scanner geometryScanner geometry
ScannerScanner
Volume shape:Volume shape:– BoxBox– SphereSphere– CylinderCylinder– ConeCone– Ellipse, etc.Ellipse, etc.
Material:Material:Geant4 database & Geant4 database &
user modifiableuser modifiable
PhantomPhantom
Similar to definition of Similar to definition of scanner geometryscanner geometry
or:or: Voxellized phantom (e.Voxellized phantom (e.
g. real patient data)g. real patient data)
SourceSource
Geant4 class Geant4 class ‘General Particle ‘General Particle Source’Source’
Source propertiesSource properties– ActivityActivity– Type of particleType of particle– Energy distributionEnergy distribution– Angular emissionAngular emission– Spatial distributionSpatial distribution– Half-lifeHalf-life
Hoffman brain phantom
Physics modelingPhysics modeling
Photon:Photon:– PhotoelectricPhotoelectric– Compton scatteringCompton scattering– Rayleigh scatteringRayleigh scattering
Electron: Electron: – IonizationIonization– Moller scatteringMoller scattering– BremsstrahlungBremsstrahlung
Electron-positron annElectron-positron annihilation:ihilation:– Gamma pair non-collinGamma pair non-collin
earityearity
Gamma photon Gamma photon emissionemission
Positron Positron emissionemission
Positron rangePositron range Positron-electron Positron-electron
annihilationannihilation Residual Residual
momentummomentum
radionuclide
e+
hv=511keV
hv=511keV
Gamma photon Gamma photon transporttransport
Rayleigh scaRayleigh scatteringttering
Compton scCompton scatteringattering
PhotoelectriPhotoelectricc
hv<511keV
hv=511keV
recoil e-
photoelectron
Electron transport & Electron transport & energy depositionenergy deposition
IonizationIonization Moller scatteringMoller scattering BremsstrahlungBremsstrahlung
e-
secondary electron
hve-
Optical photon generation and Optical photon generation and transporttransport
ScintillationScintillation TransportTransport SurfaceSurface
– ReflectionReflection– TransmissionTransmission
Physics modelingPhysics modeling
Positron decay
Optical photon transport
(before PMT)
DigitizationDigitization
A particle-matter interaction event
A physical observable
AcquisitionAcquisition
Set time sliceSet time slice Update time-dependent Update time-dependent
properties (geometry, activity) at properties (geometry, activity) at the beginning of time-slicesthe beginning of time-slices
Proceed particle transport and Proceed particle transport and data acquisition within time-data acquisition within time-slices, while system is kept staticslices, while system is kept static
ValidationValidationScanner type Studied FOM Agreement References
ECAT EXACT HR+, CPS
Spatial resolutionSensitivity
Count rates
Scatter fraction
about 3 %< 7 %
good at activityconcentrations < 20 kBq/ml
about 3 %
Jan et al 2005
Hi-Rez, Siemens
Scatter fractionCount rates
NEC curves
about 1 %good at activity
concentrations < 40 Bq/mlgood at activity
concentrations < 40 Bq/ml
Michel et al 2006
Allegro, PhilipsCount rate
Scatter fraction< 8 %8 %
Lamare et al 2006
GE Advance, GEMSEnergy spectraScatter fraction
not reported< 1 %
Schmidtlein et al 2006
MicroPET P4, ConcordeSpatial resolution
SensitivityMiniature Derenzo phantom
about 7 %< 4 %
visual assessmentJan et al 2003
MicroPET Focus, ConcordeSpatial resolution
Sensitivityabout 5 %about 3 %
Jan et al 2005
http://opengatecollaboration.healthgrid.org/physics/validation.html
Current users of GATECurrent users of GATE Ecole Polytechnique Fédérale de Lausanne (Ecole Polytechnique Fédérale de Lausanne (LPHELPHE), Lausanne), Lausanne
University of Clermont-Ferrand (University of Clermont-Ferrand (LPCLPC))University of Ghent (University of Ghent (ELISELIS))U678 INSERMU678 INSERM, CHU Pitié-Salpêtrière, Paris, CHU Pitié-Salpêtrière, ParisVrijeVrije UniversiteitUniversiteit BrusselBrussel (IIHE) (IIHE)Centre d'Exploration et de Recherche Médicales par Emission de Positons (Centre d'Exploration et de Recherche Médicales par Emission de Positons (CERMEPCERMEP), Lyon), LyonService Hospitalier Frédéric Joliot (Service Hospitalier Frédéric Joliot (SHFJSHFJ), CEA-Orsay), CEA-OrsayU601 INSERMU601 INSERM, CHU Nantes, CHU NantesSungkyunkwan University School of Medicine (Division of Nuclear Medicine), Sungkyunkwan University School of Medicine (Division of Nuclear Medicine), SeoulSeoulUniversity Louis Pasteur (University Louis Pasteur (IRESIRES), Strasbourg), StrasbourgUniversity Joseph Fourier (University Joseph Fourier (LPSCLPSC), Grenoble), GrenobleForschungszentrum-JuelichForschungszentrum-Juelich (IME), Juelich (IME), JuelichUniversity of Massachusetts Medical School (University of Massachusetts Medical School (Division of Nuclear MedicineDivision of Nuclear Medicine), Wo), WorcesterrcesterU650 INSERMU650 INSERM, LATIM, CHU Morvan, Brest, LATIM, CHU Morvan, BrestUniversity of California (University of California (Crump Institute for Molecular ImagingCrump Institute for Molecular Imaging), Los Angeles), Los AngelesDAPNIADAPNIA, CEA-Saclay, CEA-SaclayMemorial Sloan-Kettering Cancer Center (Department of Medical Physics), NMemorial Sloan-Kettering Cancer Center (Department of Medical Physics), New Yorkew YorkJohn Hopkins University (Division of Medical Imaging Physics), BaltimoreJohn Hopkins University (Division of Medical Imaging Physics), BaltimoreUniversity of Santiago of Chile (USACH)University of Santiago of Chile (USACH)NIMgroup, BIOSIM, National Technical University of AthensNIMgroup, BIOSIM, National Technical University of AthensCentre de Physique des Particules de Marseille (CPPM), Marseille Centre de Physique des Particules de Marseille (CPPM), Marseille Laboratoire de Physique Subatomique et des technologies associées (SUBATLaboratoire de Physique Subatomique et des technologies associées (SUBATECH), NantesECH), Nantes
ConclusionConclusion
GATE is capable to simulate from GATE is capable to simulate from source decay to optical photon source decay to optical photon transporttransport
GATE Simulation for Optical GATE Simulation for Optical photon generation & transport is photon generation & transport is time-consumingtime-consuming