[Gate-users] nanoparticles with bismuth, 0Gy deposited dose values

[Sarah Blind]

Dear Gate users, 

I'm working with a very simple model : 1 sphere of G4-WATER (my cell) with at its center a repeater of smaller spheres (my nanoparticles) each composed as follows: 




AGuIX_bis: d=1.58 g/cm3 ; n=6 ; state=Solid 
+el: name=Bismuth ; f=0.16 
+el: name=Silicon ; f=0.10 
+el: name=Carbon ; f=0.25 
+el: name=Nitrogen ; f=0.08 
+el: name=Oxygen ; f=0.21 
+el: name=Hydrogen ; f=0.20 




I'm looking at the deposited dose on the nanoparticles focci and on water areas through a doseActor while changing the number of nanoparticles. 
Running multiple times my simulation with 15625 nanoparticles, I obtain mean values on the nanoparticles focci in Gy like 


    * 0 
    * 6.246 
    * 0.049 
    * 0 
    * 0.898 
    * 0 
    * 2.548 

I don't understand the zero values... ? 

I have a gamma beam and I send 300 000 Bq for a 60 secondes irradiation simulation. 
My source is an histogram that looks like that 
I'm not a physicist but with 300 000 (Bq) / 40 (my surface) = 7500 photons per um^2 , isn't it strange to obtain no gray at all ? 

Here is my code: 

MAIN.MAC 


BQ_BEGIN

/gate/geometry/setMaterialDatabase ../data/GateMaterials.db 

/control/execute world.mac 
/control/execute physics.mac 
/control/execute detectors.mac 

/gate/run/initialize 

/control/execute 5sourceSpectrumMeV.mac 

/gate/application/setTimeSlice 60. s 
/gate/application/setTimeStart 0. s 
/gate/application/setTimeStop 60. s 

/gate/random/setEngineName MersenneTwister 
/gate/random/setEngineSeed auto 
/gate/application/start 

BQ_END


WORLD.MAC 


BQ_BEGIN

/gate/world/geometry/setXLength 30 um 
/gate/world/geometry/setYLength 30 um 
/gate/world/geometry/setZLength 30 um 
/gate/world/setMaterial Air 

/gate/world/daughters/name cell 
/gate/world/daughters/insert sphere 
/gate/cell/geometry/setRmin 0.0 mm 
/gate/cell/geometry/setRmax 10 um 
/gate/cell/placement/setTranslation 0 0 0 um 
/gate/cell/setMaterial G4_WATER 
/gate/cell/vis/setVisible 1 
/gate/cell/vis/setColor blue 
/gate/cell/vis/forceSolid false 


/gate/cell/daughters/name NP 
/gate/cell/daughters/insert sphere 
/gate/NP/geometry/setRmin 0 mm 
/gate/NP/geometry/setRmax 0.5 um 
/gate/NP/placement/setTranslation 0 0 0 mm 
/gate/NP/setMaterial AGuIX_bis 

/gate/NP/repeaters/insert cubicArray 
/gate/NP/cubicArray/setRepeatNumberX 30 
/gate/NP/cubicArray/setRepeatNumberY 30 
/gate/NP/cubicArray/setRepeatNumberZ 30 
/gate/NP/cubicArray/setRepeatVector 5 5 5 nm 

BQ_END


PHYSICS.MAC 

BQ_BEGIN


/gate/physics/addPhysicsList QGSP_BERT_EMV 

/gate/physics/Gamma/SetCutInRegion world 50 nm 
/gate/physics/Electron/SetCutInRegion world 50 nm 

/gate/physics/Gamma/SetCutInRegion cell 20 nm 
/gate/physics/Electron/SetCutInRegion cell 20 nm 

/gate/physics/Gamma/SetCutInRegion NP 0.5 nm 
/gate/physics/Electron/SetCutInRegion NP 0.5 nm 

/gate/random/setEngineName MersenneTwister 

/gate/physics/addAtomDeexcitation 

/gate/physics/addProcess PhotoElectric gamma 
/gate/physics/processes/PhotoElectric/setModel LivermoreModel 
/gate/physics/processes/PhotoElectric/setAugerElectron true 
/gate/physics/processes/PhotoElectric/setDeltaRayCut 10 eV 
/gate/physics/processes/PhotoElectric/setXRayCut 10 eV 
/gate/physics/processes/PhotoElectric/setStepFunction e- 0.2 0.1 nm 

/gate/physics/addProcess Compton gamma 
/gate/physics/processes/Compton/setModel LivermoreModel 
/gate/physics/processes/Compton/setStepFunction e- 0.2 0.1 nm 

/gate/physics/addProcess RayleighScattering 
/gate/physics/processes/RayleighScattering/setModel LivermoreModel 

/gate/physics/addProcess GammaConversion 
/gate/physics/processes/GammaConversion/setModel LivermoreModel 

/gate/physics/addProcess ElectronIonisation 
/gate/physics/processes/ElectronIonisation/setModel LivermoreModel e- 
/gate/physics/processes/ElectronIonisation/setModel PenelopeModel e+ 
/gate/physics/processes/ElectronIonisation/setStepFunction e- 0.2 0.1 nm 

/gate/physics/addProcess Bremsstrahlung e- 
/gate/physics/addProcess Bremsstrahlung e+ 
/gate/physics/processes/Bremsstrahlung/setModel LivermoreModel e- 
/gate/physics/processes/Bremsstrahlung/setModel PenelopeModel e+ 

/gate/physics/addProcess eMultipleScattering e- 
/gate/physics/addProcess eMultipleScattering e+ 
/gate/physics/processes/eMultipleScattering/setModel UrbanModel e- 
/gate/physics/processes/eMultipleScattering/setModel UrbanModel e+ 

/gate/physics/SetMinKineticEnergyInRegion world 1 eV 
/gate/physics/SetMinKineticEnergyInRegion cell 1 eV 
/gate/physics/ActivateSpecialCuts gamma 

BQ_END


DETECTOR.MAC 


BQ_BEGIN

/gate/actor/addActor DoseActor dose 
/gate/actor/dose/save output/dose1.hdr 
/gate/actor/dose/attachTo cell 
/gate/actor/dose/stepHitType random 
/gate/actor/dose/setPosition 0.0 0.0 0.0 mm 
/gate/actor/dose/setSize 20 20 20 um 
/gate/actor/dose/setResolution 400 400 400 
/gate/actor/dose/saveEveryNSeconds 30 

BQ_END


SOURCE.MAC 


BQ_BEGIN

/gate/source/addSource mybeam gps 
/gate/source/mybeam/gps/particle gamma 
/gate/source/mybeam/gps/ene/type User 
/gate/source/mybeam/gps/hist/type energy 
/gate/source/mybeam/setActivity 300000. becquerel 


[histogram] 

/gate/source/mybeam/gps/position 0 0 15 um 
/gate/source/mybeam/gps/pos/type Volume 
/gate/source/mybeam/gps/pos/shape Cylinder 
/gate/source/mybeam/gps/pos/inner_radius 0 mm 
/gate/source/mybeam/gps/pos/radius 10 um 
/gate/source/mybeam/gps/pos/halfz 0.01 um 
/gate/source/mybeam/gps/ang/type beam2d 



BQ_END

Thank you for your help, 

Sarah Blind 








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