[Gate-users] use of doseactor, voxelized phantom and source to generate dose and edep map
Matthew Strugari
matthew.strugari at dal.ca
Sat May 30 16:39:29 CEST 2020
Hi Park,
I hope others may provide additional info, but from a quick glance at your code, everything appears reasonable in terms of your settings.
Your confusion with “non-sense results” may stem from your configuration with total number of primaries since your simulation output does not take time into consideration. Setting 500000 total primaries will generate particles without any respect to decay time. So, if you linearly increase the number of primaries, you will linearly increase the dose deposited. In other words, your dose and Edep output are a total based on the total number of primaries generated. If you divide your output by 500000 then you would have dose in terms of Gy/decay, for example, which could then be scaled according to the number of decay events in your PET acquisition. An alternative approach would be to use the setTimeStart, setTimeSlide, and setTimeStop commands which would generate the number of primaries based on radioactive decay and time. This would again produce the total dose and Edep output as described above for the total number of primaries generated.
In case there is any confusion on your linear translator scale, note that 1 Bq means that pixel values are represented directly in Bq. The total number of primaries are then distributed amongst the source voxels according to their activity. So, if you only had two non-zero voxels in your source image with values of 2 and 3, your simulation in the current configuration would generate 200000 and 300000 primaries in each voxel, respectively.
To measure dose to a specific organ, you could use a segmentation of a region of interest (ROI) to mask the dose. All dose outside the ROI would be zero which would allow for computation of the dose volume histogram for any organ of interest.
Positively,
Matthew
From: Gate-users <gate-users-bounces at lists.opengatecollaboration.org> on behalf of Hyun Soo Park <hyuns at snu.ac.kr>
Date: Saturday, May 30, 2020 at 09:43
To: "gate-users at lists.opengatecollaboration.org" <gate-users at lists.opengatecollaboration.org>
Subject: [Gate-users] use of doseactor, voxelized phantom and source to generate dose and edep map
CAUTION: The Sender of this email is not from within Dalhousie.
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
<mailto: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<mailto:hyuns at snu.ac.kr>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.opengatecollaboration.org/pipermail/gate-users/attachments/20200530/57d13366/attachment-0001.html>
More information about the Gate-users
mailing list