[Gate-users] Bug when using RadioactiveDecay in GATE 7.1
Jared Strydhorst
jared.strydhorst at gmail.com
Tue Sep 15 11:38:00 CEST 2015
When I originally encountered the problem while simulating just the LSO
contribution to a PET system, I noticed that there was only a single peak
around 300 keV, and none near 200 keV. I wrote a test simulation, attached,
with not detector, but that simulates a single decay of Lu176. If you look
at the verbose output produced with v7.0 vs. v7.1, the difference in the
decay is apparent. I've excerpted the relevant portions of the output below.
GATE 7.0
========================================================================
*********************************************************************************************************
* G4Track Information: Particle = Hf176[597.0], Track ID = 2, Parent
ID = 1
*********************************************************************************************************
Step# X(mm) Y(mm) Z(mm) KinE(MeV) dE(MeV) StepLeng TrackLeng
NextVolume ProcName
0 0 0 0 1.96e-06 0 0 0
world_phys initStep
1 -0.000751 -0.000973 0.000396 0 1.96e-06 0.00129 0.00129
world_phys ionIoni
2 -0.000751 -0.000973 0.000396 0 0 0 0.00129
world_phys RadioactiveDecay
:----- List of 2ndaries - #SpawnInStep= 2(Rest= 2,Along= 0,Post= 0),
#SpawnTotal= 2 ---------------
: -0.000751 -0.000973 0.000396 0 Hf176[290.2]
: -0.000751 -0.000973 0.000396 0.307 gamma
:-----------------------------------------------------------------
EndOf2ndaries Info ---------------
*********************************************************************************************************
* G4Track Information: Particle = Hf176[290.2], Track ID = 12, Parent
ID = 2
*********************************************************************************************************
Step# X(mm) Y(mm) Z(mm) KinE(MeV) dE(MeV) StepLeng TrackLeng
NextVolume ProcName
0 -0.000751 -0.000973 0.000396 0 0 0 0
world_phys initStep
1 -0.000751 -0.000973 0.000396 0 0 0 0
world_phys RadioactiveDecay
:----- List of 2ndaries - #SpawnInStep= 2(Rest= 2,Along= 0,Post= 0),
#SpawnTotal= 2 ---------------
: -0.000751 -0.000973 0.000396 0 Hf176[88.4]
: -0.000751 -0.000973 0.000396 0.202 gamma
:-----------------------------------------------------------------
EndOf2ndaries Info ---------------
*********************************************************************************************************
* G4Track Information: Particle = Hf176[88.4], Track ID = 14, Parent
ID = 12
*********************************************************************************************************
Step# X(mm) Y(mm) Z(mm) KinE(MeV) dE(MeV) StepLeng TrackLeng
NextVolume ProcName
0 -0.000751 -0.000973 0.000396 0 0 0 0
world_phys initStep
1 -0.000751 -0.000973 0.000396 0 0 0 0
world_phys RadioactiveDecay
:----- List of 2ndaries - #SpawnInStep= 5(Rest= 5,Along= 0,Post= 0),
#SpawnTotal= 5 ---------------
: -0.000751 -0.000973 0.000396 0 Hf176[0.0]
: -0.000751 -0.000973 0.000396 0.00162 e-
: -0.000751 -0.000973 0.000396 0.00789 gamma
: -0.000751 -0.000973 0.000396 0.0559 gamma
: -0.000751 -0.000973 0.000396 0.0231 e-
:-----------------------------------------------------------------
EndOf2ndaries Info ---------------
GATE 7.1
===========================================================================
*********************************************************************************************************
* G4Track Information: Particle = Hf176[596.820], Track ID = 2,
Parent ID = 1
*********************************************************************************************************
Step# X(mm) Y(mm) Z(mm) KinE(MeV) dE(MeV) StepLeng TrackLeng
NextVolume ProcName
0 0 0 0 2.88e-07 0 0 0
world_phys initStep
1 -9.46e-309 -3.16e-309 -9.73e-309 0 2.88e-07 1.39e-308
1.39e-308 world_phys RadioactiveDecay
:----- List of 2ndaries - #SpawnInStep= 3(Rest= 0,Along= 0,Post= 3),
#SpawnTotal= 3 ---------------
: -9.46e-309 -3.16e-309 -9.73e-309 0 Hf176
: -9.46e-309 -3.16e-309 -9.73e-309 0.29 gamma
: -9.46e-309 -3.16e-309 -9.73e-309 0.307 gamma
:-----------------------------------------------------------------
EndOf2ndaries Info ---------------
Jared
============================Lu176_test.mac===================================
# VISUALIZATION
/vis/open OGLSX
/vis/viewer/reset
/vis/viewer/set/viewpointThetaPhi 20 30
/vis/viewer/set/style surface
/vis/drawVolume
/tracking/storeTrajectory 1
/vis/scene/endOfEventAction accumulate
/vis/viewer/update
/vis/scene/add/trajectories
/gate/geometry/setMaterialDatabase GateMaterials.db
# WORLD
/gate/world/geometry/setXLength 4. cm
/gate/world/geometry/setYLength 4. cm
/gate/world/geometry/setZLength 4. cm
/gate/world/setMaterial Air
/gate/world/vis/forceWireframe
/gate/geometry/rebuild
# PHYSICS
/gate/physics/addPhysicsList emstandard_opt3
/gate/physics/addProcess RadioactiveDecay GenericIon
#/gate/physics/addProcess IonIonisation GenericIon
# INITIALIZATION
/gate/run/initialize
/gate/source/addSource Lu176
/gate/source/Lu176/setActivity 1 Bq
/gate/source/Lu176/gps/particle ion
/gate/source/Lu176/gps/ion 71 176 0 0
/gate/source/Lu176/gps/energytype Mono
/gate/source/Lu176/gps/energy 0 MeV
/gate/source/Lu176/gps/type Point
/gate/source/Lu176/gps/centre 0. 0. 0. cm
/gate/source/Lu176/gps/angtype iso
# OUTPUT
/gate/output/allowNoOutput
/tracking/verbose 2
/gate/random/setEngineName MersenneTwister
/gate/random/setEngineSeed auto
/gate/application/SetNumberOfPrimariesPerRun 1
/gate/application/start
===========================================================================
2015-09-15 11:16 GMT+02:00 Pietrzyk, Uwe <u.pietrzyk at fz-juelich.de>:
>
> Hi Jared,
>
> let me briefly ask what the detector looked like?
> Since there are emission lines of 202 and 88 keV, the 290 keV
> is likely to be a "summation peak”.
>
> I have checked the RadioactiveDecay in 7.1 for our EduGATE
> examples and did not find anything wrong. So I am a little bit
> puzzled by the statements in your eMail.
>
> Kind regards,
>
> Uwe Pietrzyk
>
> /----------------------------------------------------------------------
> Prof. Dr. Uwe Pietrzyk
> Diplom-Physiker
> Institut für Neurowissenschaften und Medizin / INM-4
> Forschungszentrum Jülich GmbH
> 52425 Jülich
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> eMail: U.Pietrzyk at fz-juelich.de
> http://www.fz-juelich.de/inm/inm-4/DE/Home/home_node.html
> &
> Bergische Universität Wuppertal
> Fachbereich C - Physik / D.08.01
> Gaußstr. 20
> 42097 Wuppertal
> Tel: +49-(0)202-439-3523
> Fax: +49-(0)202-439-2811
> eMail: Uwe.Pietrzyk at physik.uni-wuppertal.de
> http://www.medizinphysik.uni-wuppertal.de
> ----------------------------------------------------------------------/
>
> On 15 Sep 2015, at 11:05, Jared Strydhorst <jared.strydhorst at gmail.com>
> wrote:
>
> If you're using RadioactiveDecay with GATE 7.1, there is a bug in Geant4
> v10.1.1 that causes the emissions from the nuclear de-excitation to be
> simulated incorrectly. For example, I've found that after Lu-176 decays to
> Hf-176, it emits a 307 keV gamma, correctly, but then goes to the ground
> state by emitting an unphysical 290 keV gamma, instead of a 202 keV
> followed by a 88 keV gamma, or the competing conversion electrons. I don't
> know how other isotopes are affected, though it seems from the relevant
> Geant4 forum that the problem isn't specific to Hf de-excitation.
>
> The bug has been fixed in G4 v10.2 (still in beta), and doesn't seem to be
> present in earlier versions, so if you use GATE 7.0 or earlier it shouldn't
> affect you.
>
> Jared STRYDHORST
>
> Laboratoire Imagerie Moléculaire In Vivo (IMIV)
> UMR 1023 Inserm/CEA/Université Paris Sud - ERL 9218 CNRS
> CEA/I2BM/Service Hospitalier Frédéric Joliot
> 4, place du Général Leclerc
> 91401 ORSAY Cedex
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