[Gate-users] use of doseactor, voxelized phantom and source to generate dose and edep map

[Hyun Soo Park]

Hello, Gate users,

We just have a  relatively simple task of estimating internal radiation
dosimetry of 18F-labeled PET tracer using doseactor, voxelized phantom and
source. However, me and my colleagues are struggling with this beautiful
research tool because of lack of experiences and not enough understandings
about it.

We acquired PET/CT images using the radiotracer at varying time points to
describe the biodistribution of the tracer. CT images were the voxelized
phantom and PET images were the matched voxelized source.

By following to many contributors’ exercices and examples, we’ve finally
generated following macro that returns common outputs of internal dosimetry
by GATE (i.e., Dose and Edep, etc).

Our questions are obvious:

1) is the following macro defined well to generate Dose and Edep map for
given voxelized phantom and source?

2) definition of the fluorine-18 was appropriate?

3) how could we measure dose of a specific organ, such as kidney, using
dose map? Could it be done by common VOI analysis measuring voxel mean
value?

4) the latest simulation gave us non-sense results of showing continuously
increasing dose in a organ, while the radioactivity is apparently
decreasing as time. how could it be explained?

Best wishes, and have a great weekend!

Park

#=====================================================
# VEROBOSITY
#=====================================================

/control/execute  mac/verbose.mac

#=====================================================
# VISUALISATION
#=====================================================

/control/execute mac/visu.mac

#=====================================================
# GEOMETRY
#=====================================================

/gate/geometry/setMaterialDatabase data/GateMaterials.db

# World
/gate/world/geometry/setXLength 10 cm
/gate/world/geometry/setYLength 10 cm
/gate/world/geometry/setZLength 10 cm
/gate/world/setMaterial Air
/gate/world/vis/setVisible 1
/gate/world/vis/forceWireframe

# Voxel phantom
/gate/world/daughters/name                      ct
/gate/world/daughters/insert
 ImageRegularParametrisedVolume
/gate/ct/geometry/setRangeToMaterialFile     data/range_geo.dat
/gate/ct/geometry/setImage                   data/ct-gate.mhd
/gate/ct/setSkipEqualMaterials 1
/gate/ct/vis/setVisible 1
# /gate/ct/vis/setColor blue
/gate/ct/vis/forceWireframe

# /gate/geometry/rebuild

#=====================================================
# PHYSICS
#=====================================================

/gate/physics/addPhysicsList emstandard_opt3
/gate/physics/addProcess RadioactiveDecay #to generate decay process of F-18

#=====================================================
# DETECTORS
#=====================================================

/gate/actor/addActor                                DoseActor
 doseDistribution
/gate/actor/doseDistribution/attachTo       ct
/gate/actor/doseDistribution/stepHitType            random
/gate/actor/doseDistribution/setSize                30 28.8 99 mm #Size in
mm
/gate/actor/doseDistribution/setPosition            0 0 0 cm # Origin
/gate/actor/doseDistribution/setResolution          58 48 165 #Size (pixel)
/gate/actor/doseDistribution/enableEdep             true
/gate/actor/doseDistribution/enableUncertaintyEdep  true
/gate/actor/doseDistribution/enableSquaredEdep      false
/gate/actor/doseDistribution/enableDose             true #from true
/gate/actor/doseDistribution/setDoseAlgorithm VolumeWeighting
# /gate/actor/doseDistribution/enableDoseToWater      true #new set
/gate/actor/doseDistribution/enableUncertaintyDose  true #from true
/gate/actor/doseDistribution/enableSquaredDose      false
/gate/actor/doseDistribution/enableNumberOfHits     true
/gate/actor/doseDistribution/save                   output/output.mhd

/gate/actor/addActor               SimulationStatisticActor stat
/gate/actor/stat/save               output/stat.txt
/gate/actor/stat/saveEveryNSeconds 60

#=====================================================
# INITIALISATION
#=====================================================

/gate/run/initialize

#=====================================================
# SOURCE :
#=====================================================

#Description

#Ion
/gate/source/addSource ion voxel
/gate/source/ion/reader/insert image
/gate/source/ion/imageReader/translator/insert linear
/gate/source/ion/imageReader/linearTranslator/setScale 1. Bq
/gate/source/ion/imageReader/readFile data/pt-gate.mhd
/gate/source/ion/imageReader/verbose 1
/gate/source/ion/setPosition -15.0 -14.4 -49.5 mm

/gate/source/ion/gps/particle ion
/gate/source/ion/gps/ion 9 18 0 0 #F-18
/gate/source/ion/gps/energytype Mono
/gate/source/ion/gps/monoenergy 0. keV
/gate/source/ion/gps/angtype iso
/gate/source/ion/setForcedUnstableFlag true
/gate/source/ion/useDefaultHalfLife 6586 s


/gate/source/ion/dump                                   1

# /gate/source/list

#=====================================================
# RANDOM
#=====================================================
/gate/random/setEngineName MersenneTwister
/gate/random/setEngineSeed auto

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

/gate/application/noGlobalOutput
/vis/enable
/gate/application/setTotalNumberOfPrimaries 500000 #acceptable uncertainty
is at 500000
/gate/application/start

-- 
*연구중점교수, 분당서울대학교병원*
*전화번호:*
(사무실) +82-31-787-2936
(휴대전화) +82-10-8833-2806
*팩스:* +82-31-787-4018
*이메일:* hyuns at snu.ac.kr

*Hyun Soo Park, PhD*
*--*
*Research professor*
Department of Nuclear Medicine
Seoul National University Bundang Hospital, Seongnam, Korea
*Telephone:*
(Office) +82-31-787-2936
(Mobile) +82-10-8833-2806
*Fax:* +82-31-787-4018
*email:* hyuns at snu.ac.kr
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