[Gate-users] physics list builders vs Ch-TOF-PET

[Dania Consuegra]

Dear Gate User:

Using Geant 4.10.04.p02 and gate_v8.1.p01, I’m testing the influence of
using differences “Physics” for the EM processes and see how change the
coincidence detection deficiency and the TOF of my Cherenkov-TOF-PET using
a point source. For the optical processes I always used the same physics
and cuts....

- Using the EM for the benchmarkPET: 7.44 % of coincidence detection
efficiency and 66 ps for the TOF….

/gate/physics/addProcess PhotoElectric

/gate/physics/processes/PhotoElectric/setModel StandardModel

/gate/physics/addProcess Compton

/gate/physics/processes/Compton/setModel StandardModel

/gate/physics/addProcess RayleighScattering

/gate/physics/processes/RayleighScattering/setModel PenelopeModel

/gate/physics/addProcess ElectronIonisation

/gate/physics/processes/ElectronIonisation/setModel StandardModel e-

/gate/physics/processes/ElectronIonisation/setModel StandardModel e+

/gate/physics/addProcess Bremsstrahlung

/gate/physics/processes/Bremsstrahlung/setModel StandardModel e-

/gate/physics/processes/Bremsstrahlung/setModel StandardModel e+

/gate/physics/addProcess PositronAnnihilation

/gate/physics/addProcess eMultipleScattering e+

/gate/physics/addProcess eMultipleScattering e-

- Using a Combination of different models 1: 7.39 % of coincidence
detection efficiency and 66 ps for the TOF….

/gate/physics/addProcess PhotoElectric

/gate/physics/processes/PhotoElectric/setModel StandardModel

/gate/physics/addProcess Compton

/gate/physics/processes/Compton/setModel StandardModel

/gate/physics/addProcess RayleighScattering

/gate/physics/processes/RayleighScattering/setModel LivermoreModel

/gate/physics/addProcess ElectronIonisation

/gate/physics/processes/ElectronIonisation/setModel StandardModel e-

/gate/physics/processes/ElectronIonisation/setModel StandardModel e+

/gate/physics/addProcess Bremsstrahlung

/gate/physics/processes/Bremsstrahlung/setModel StandardModel e-

/gate/physics/processes/Bremsstrahlung/setModel StandardModel e+

/gate/physics/addProcess PositronAnnihilation

/gate/physics/addProcess eMultipleScattering

/gate/physics/processes/eMultipleScattering/setGeometricalStepLimiterType
e- distanceToBoundary

/gate/physics/processes/eMultipleScattering/setGeometricalStepLimiterType
e+ distanceToBoundary

/gate/physics/addAtomDeexcitation

/gate/physics/addProcess RadioactiveDecay

- Using a Combination of different models 2: 7.60 % of coincidence
detection efficiency and 66 ps for the TOF….

/gate/physics/addProcess Compton gamma

/gate/physics/addProcess PhotoElectric

/gate/physics/processes/Compton/setModel PenelopeModel

/gate/physics/processes/PhotoElectric/setModel PenelopeModel

/gate/physics/addProcess ElectronIonisation e-

/gate/physics/addProcess ElectronIonisation e+

/gate/physics/processes/ElectronIonisation/setModel PenelopeModel

/gate/physics/addProcess eMultipleScattering e-

/gate/physics/addProcess eMultipleScattering e+

/gate/physics/processes/eMultipleScattering/setGeometricalStepLimiterType
e- distanceToBoundary

/gate/physics/processes/eMultipleScattering/setGeometricalStepLimiterType
e+ distanceToBoundary

/gate/physics/addProcess Bremsstrahlung

/gate/physics/processes/Bremsstrahlung/setModel PenelopeModel e-

/gate/physics/processes/Bremsstrahlung/setModel PenelopeModel e+

/gate/physics/addProcess GammaConversion

/gate/physics/processes/GammaConversion/setModel PenelopeModel

#/gate/physics/addProcess IonIonisation

/gate/physics/addProcess RadioactiveDecay

/gate/physics/addAtomDeexcitation

- Using different physics list builders:

/gate/physics/addPhysicsList emstandard : 11.09 % of coincidence detection
efficiency and 69 ps for the TOF….

/gate/physics/addPhysicsList emstandard1 : 10.77 % of coincidence detection
efficiency and 95 ps for the TOF….

/gate/physics/addPhysicsList emstandard2 : 10.74 % of coincidence detection
efficiency and 93 ps for the TOF….

/gate/physics/addPhysicsList emstandard3 : 11.09 % of coincidence detection
efficiency and 68 ps for the TOF….

/gate/physics/addPhysicsList emstandard4 : 11.08 % of coincidence detection
efficiency and 78 ps for the TOF….

/gate/physics/addPhysicsList emlivermore : It is not possible to conclude
the simulation (Memory Leak)….

/gate/physics/addPhysicsList emlivermore_polar : 11.03 % of coincidence
detection efficiency and 68 ps for the TOF….

/gate/physics/addPhysicsList empenelope : 11.00 % of coincidence detection
deficiency and 68 ps for the TOF….

As it is recommended in
http://wiki.opengatecollaboration.org/index.php/Users_Guide:Setting_up_the_physics:
I switch all my simulations to the “physic list builder” mechanism for the
EM processes, specifically to the (/gate/physics/addPhysicsList
emstandard3) recommended for Medical Physics Application getting reasonable
results….

However, I would like to know why change in more than 3 % the Cherenkov
Photon Coincidences detection efficiency when I use any of the “physic list
builder” instead of the EM Physics used in the Benchmark PET and also why
using different “physics list builders” I can get discrepancies for the
Ch-TOF of more than 10 ps….

If some user/developer of GATE, GEANT4 can help me to understand this
differences, I would appreciate it….

Regards,

Dania Consuegra Rodríguez

PhD student, Jožef Stefan Institute
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