[Gate-users] Lu177 Dosimetry: unexpected result in Air

[Manuel Bardiès]

My guess: few interactions in air, but very small mass -> high absorbed dose?

Envoyé depuis mon iPhone. Ca pousse à la concision...

> Le 25 août 2020 à 18:10, Francesca De Benetti <francesca.debenetti at gmail.com> a écrit :
> 
> Dear all,
> 
> I am computing Lu177 dosimetry using as input a CT and a PET. The conversion of the CT is done using the Schneider2000 table and the conversion of the PET is linear (1 Bq). The isotope used is Lu177 defined with a discrete spectrum and the number of primaries is 10^8. Overall the result looks ok, but there is unexpected high dose in some areas where there is Air. In the attachment you can find some examples and below the .mac file. Is that a known issue with GATE or is it due to an error in the .mac? Also, any other comment on how to improve the .mac file is welcome!
> 
> Best regards,
> 
> Francesca De Benetti
> 
> <Example 1.png>
> <Example 2.png>
> <Example 3.png>
> 
> #=========================================================================================================
> # GEOMETRY
> #=========================================================================================================
> /gate/geometry/setMaterialDatabase 								{dataDir}/GateMaterials.db
> 
> # World
> /gate/world/geometry/setXLength 									3 m
> /gate/world/geometry/setYLength 									3 m
> /gate/world/geometry/setZLength 									3 m
> /gate/world/setMaterial 											{worldMaterial}
> /gate/world/vis/setVisible 										0
> 
> # Automatic generation of the conversion values
> /gate/HounsfieldMaterialGenerator/SetMaterialTable                  			{dataDir}/{conversion}MaterialsTable.txt
> /gate/HounsfieldMaterialGenerator/SetDensityTable                   			{dataDir}/{conversion}DensitiesTable.txt
> /gate/HounsfieldMaterialGenerator/SetDensityTolerance              			0.1 g/cm3
> /gate/HounsfieldMaterialGenerator/SetOutputMaterialDatabaseFilename 	{dataDir}/{conversion}_CT-HUmaterials.db
> /gate/HounsfieldMaterialGenerator/SetOutputHUMaterialFilename       	{dataDir}/{conversion}_CT-HU2mat.txt 
> /gate/HounsfieldMaterialGenerator/Generate
> 
> # Daughter
> /gate/world/daughters/name                              						patient
> /gate/world/daughters/insert                           							ImageNestedParametrisedVolume
> 		
> /gate/geometry/setMaterialDatabase                                  				{dataDir}/{conversion}_CT-HUmaterials.db
> /gate/patient/geometry/setHUToMaterialFile              	      				{dataDir}/{conversion}_CT-HU2mat.txt
> 
> /gate/patient/geometry/setImage                        						{dataDir}/paddedCT.mhd
> 
> /gate/patient/placement/setTranslation       							0 0 0 mm
> 
> #=========================================================================================================
> # PHYSICS
> #=========================================================================================================
> 
> # Coulomb (do we need it?) scattering, multiple scattering, ionisation, Bremsstrahlung (change the version to add the pair production for electrons)
> /gate/physics/addPhysicsList 										emlivermore
> 
> /gate/physics/addProcess 										Compton
> /gate/physics/processes/Compton/setModel 							LivermoreModel
> 
> /gate/physics/addProcess 										RayleighScattering
> /gate/physics/processes/RayleighScattering/setModel 					LivermoreModel
> 
> /gate/physics/addProcess										RadioactiveDecay
> 		
> /gate/physics/addProcess 										HadronElastic
> /gate/physics/processes/HadronElastic/setModel 						G4HadronElastic
> /gate/physics/processes/HadronElastic/setDataSet 					G4HadronElasticDataSet
> 
> /gate/physics/processList 										Enabled 
> /gate/physics/processList 										Initialized
> 
> #=========================================================================================================
> # CUTS
> #=========================================================================================================
> 
> #/gate/physics/Electron/SetCutInRegion     							world  4 mm
> #/gate/physics/Positron/SetCutInRegion     							world  4 mm
> #/gate/physics/Gamma/SetCutInRegion     							world  4 mm
> #/gate/physics/Proton/SetCutInRegion     							world  4 mm
> 
> #=========================================================================================================
> # ACTOR
> #=========================================================================================================
> 
> /gate/actor/addActor                               								DoseActor  doseDistribution
> /gate/actor/doseDistribution/save                  							{outputFolder}/{outputDose}.mhd
> /gate/actor/doseDistribution/attachTo              						patient
> /gate/actor/doseDistribution/stepHitType           						random
> /gate/actor/doseDistribution/setSize               						416.88 348.82 1104 mm
> /gate/actor/doseDistribution/setPosition          						0 0 0 cm
> /gate/actor/doseDistribution/setResolution        						588 492 368      
> /gate/actor/doseDistribution/enableEdep            						false
> /gate/actor/doseDistribution/enableUncertaintyEdep 					false
> /gate/actor/doseDistribution/enableDose            						true
> /gate/actor/doseDistribution/enableSquaredDose     					false
> /gate/actor/doseDistribution/enableUncertaintyDose 					false
> /gate/actor/doseDistribution/enableNumberOfHits    					false
> /gate/actor/doseDistribution/saveEveryNSeconds     					60
> 
> 
> #=========================================================================================================
> # INITIALIZATION
> #=========================================================================================================
> 
> /gate/run/initialize
> /gate/physics/displayCuts
> 
> #=========================================================================================================
> # SOURCE
> #=========================================================================================================
> 
> /gate/source/addSource                                        						spect voxel
> /gate/source/spect/reader/insert                              					image
> 
> /gate/source/spect/imageReader/translator/insert              				linear
> /gate/source/spect/imageReader/linearTranslator/setScale      			1 Bq
> /gate/source/spect/imageReader/readFile                       				{dataDir}/paddedPET.mhd
> /gate/source/spect/imageReader/verbose                        				1
> 
> /gate/source/spect/setPosition                                					-208.44 -174.41 -552 mm
> /gate/source/spect/dump                                       						1
> 
> /gate/source/spect/gps/particle 									e-
> /gate/source/spect/gps/energytype 								UserSpectrum
> /gate/source/spect/gps/setSpectrumFile 							{dataDir}/{spectrumFile}.txt
> 	
> /gate/source/spect/setForcedUnstableFlag 							true
> /gate/source/spect/setForcedHalfLife 								581817 s
> 
> /gate/source/spect/gps/angtype 									iso
> /gate/source/spect/gps/centre  									0 0 0 mm
> /gate/source/list
> 
> #=========================================================================================================
> # START
> #=========================================================================================================
> 
> /gate/random/setEngineName 									MersenneTwister
> /gate/random/setEngineSeed 									default
> /gate/application/setTotalNumberOfPrimaries    						{nPrimaries}
> /gate/application/start
> 
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