[Gate-users] Regarding Voxelized Dosimetry

[Arun Gupta]

Dear all,

I have been working on voxelized dosimetry using GATE version 7.0. I am
using preclinical PET imaging data (mouse PET) for voxelized source and
Mouse CT atlas images for voxelized phantom. .
The PET imaging was done for 8 different time points (8 PET scans
altogether) post injection of nearly 1.50 MBq of 64Cu labelled compound.
I performed the simulation by preparing voxlizedphantom and voxelizedsource
macros based on CT atlas image and PET images respectively.I have matched
the resolution of both CT and PET images and I used Interfile image format
for both phantom and source images.
I used Attenuation_range.dat based on CT atlas but used linear translator
for source based on the activity injected which was calculated as the
product of scaling factor of PET image and Conversion factor.
I used emstandard physics macro by defining the CUTS parameters but used
manually.
I used the simulation time as 1/10th of the scan duration of each PET scans
and performed the simulations for all 8 PET scans separately.
I got the ouput dose map and uncertianity in dose for 8 simulations for 8
PET scans.

Now I would like to know whether the voxel value on dosemap image is in
Gray and energy deposition is in MeV? I am using MRIcro for image
processing.
I drew the 3D ROIs of organ of interest on CT images and imported the save
3D ROIs on Dose map image for Absorbed Dose calculation.
I would like to know how should I get the total absorbed dose of any organ
in this case?

The following are the macros I used.
#========================================================================================
#    VOXELIZED GEOMETRY
#========================================================================================
# World
/gate/world/geometry/setXLength 50 cm
/gate/world/geometry/setYLength 50 cm
/gate/world/geometry/setZLength 50 cm
/gate/world/setMaterial Air
#/gate/world/vis/setVisible 1
#/gate/world/vis/forceWireframe

### Image Regular Parameterized volume

/gate/world/daughters/name mouse
/gate/world/daughters/insert ImageRegularParametrisedVolume
/gate/mouse/geometry/setImage data/m000-CT_reorient.h33
/gate/mouse/geometry/setRangeToMaterialFile data/Atten_Range.dat

/gate/mouse/placement/setTranslation  0. 0. 0. mm

/gate/mouse/attachPhantomSD

#=====================================================================================================================
#    VOXELIZED SOURCE
#=====================================================================================================================

/gate/source/addSource PET_UCNP voxel

/gate/source/PET_UCNP/reader/insert interfile
/gate/source/PET_UCNP/interfileReader/translator/insert linear
/gate/source/PET_UCNP/interfileReader/linearTranslator/setScale
0.0012725287 Bq
/gate/source/PET_UCNP/interfileReader/readFile data/m003-UCNP_PET_1.h33
/gate/source/PET_UCNP/setPosition   -21.93 -21.93 -47.515 mm

/gate/source/PET_UCNP/gps/particle ion
/gate/source/PET_UCNP/gps/ion 29 64 0 0
/gate/source/PET_UCNP/gps/energytype Mono
/gate/source/PET_UCNP/gps/monoenergy 0. MeV
/gate/source/PET_UCNP/setForcedUnstableFlag true
/gate/source/PET_UCNP/setForcedHalfLife 45723.6 s
/gate/source/PET_UCNP/dump 1

###################################################################################
#    PHYSICS
###################################################################################

/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 GammaConversion
/gate/physics/processes/GammaConversion/setModel StandardModel

/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 MultipleScattering e+
/gate/physics/addProcess MultipleScattering e-

## In case of Ion source ##

/gate/physics/addProcess IonIonisation
/gate/physics/addProcess RadioactiveDecay

/gate/physics/setEMin 0.1 keV
/gate/physics/setEMax 10 GeV

/gate/physics/processList Enabled
/gate/physics/processList Initialized

#####################################################################################
#    CUTS
#####################################################################################

/gate/physics/Gamma/SetCutInRegion      world 0.1 mm
/gate/physics/Electron/SetCutInRegion   world 0.1 mm
/gate/physics/Positron/SetCutInRegion   world 0.1 mm

/gate/physics/Gamma/SetCutInRegion      mouse 0.01 mm
/gate/physics/Electron/SetCutInRegion   mouse 0.01 mm
/gate/physics/Positron/SetCutInRegion   mouse 0.01 mm

/gate/physics/SetMaxStepSizeInRegion    mouse 0.001 mm

#=============================================================================
#    RANDOM
#=============================================================================

/gate/random/setEngineName MersenneTwister

/gate/random/setEngineSeed default
/gate/random/verbose 0

#=============================================================================
#    START
#=============================================================================

/gate/application/noGlobalOutput

/gate/application/setTimeSlice   10 s
/gate/application/setTimeStart   0 s
/gate/application/setTimeStop    90 s

/gate/application/startDAQ

It will be highly appreciated if you help me in this case.

Thank you.


Arun Gupta

Ph.D. Student

Functional and Molecular Imaging System Lab

Nuclear Medicine department

College of Medicine

Seoul National Univ. Hospital

103 Daehakro, Jongno-gu, Seoul, 110-799, Korea
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