[Gate-users] Moving point source simulation in GATE 9.0

[Satyajit Ghosh]

Dear Gaters,

                      I want to simulate a moving source in GATE 9.0. The
point source is supposed to move in a predefined trajectory (see the
attached image file - trajectory.png (red coloured path)). I am taking help
from the benchSPECT example; and for the trajectory, I am using 'Generic
move' feature (
https://opengate.readthedocs.io/en/latest/defining_a_geometry.html#moving-a-volume).
Although there is some WARNING specified in documentation about use of
'Generic move', right now, I am relying on this. The script segment I am
using is given hereunder.








































*# Static phantom definition/gate/world/daughters/name
Phantom/gate/world/daughters/insert cylinder/gate/Phantom/geometry/setRmax
10.0  cm/gate/Phantom/geometry/setRmin 0.
cm/gate/Phantom/geometry/setHeight 30. cm/gate/Phantom/setMaterial
Water/gate/Phantom/vis/setColor
blue/gate/Phantom/vis/forceWireframe/gate/Phantom/attachPhantomSD# A small
moving phantom to hold the moving source/gate/Phantom/daughters/name
movsource/gate/Phantom/daughters/insert
cylinder/gate/movsource/geometry/setRmax 1.
 cm/gate/movsource/geometry/setRmin 0. cm/gate/movsource/geometry/setHeight
1. cm/gate/movsource/moves/insert
genericMove/gate/movsource/genericMove/setPlacementsFilename
data/movsource.placements/gate/movsource/setMaterial
Water/gate/movsource/vis/setColor magenta/gate/movsource/attachPhantomSD#
Point source definition/gate/source/addSource
SourceConfinement/gate/source/SourceConfinement/gps/type
Point/gate/source/SourceConfinement/gps/centre 0. 0. 0.
cm/gate/source/SourceConfinement/gps/particle
gamma/gate/source/SourceConfinement/gps/energy 140.
keV/gate/source/SourceConfinement/setActivity 30000.
Bq/gate/source/SourceConfinement/gps/angtype iso# Confining the point
source inside moving phantom volume -
movsource/gate/source/SourceConfinement/gps/confine movsource*

In movsource.placements file, I have not defined all the detailed steps to
have a trajectory like trajectory.png. Rather, simple four steps are added
for testing. The contents of movsource.placements is pasted hereunder.












*###### List of placement (translation and rotation) according to
time###### Column 1 is Time in s (second)###### Column 2 is rotationAngle
in degree###### Columns 3,4,5 are rotation axis###### Columns 6,7,8 are
translation in mmTime sRotation degTranslation mm0.000000 0 0 1 0 10 10
00.000025 0 0 1 0 0 -10 00.000050 0 0 1 0 -10 10 00.000075 0 0 1 0 -10 -10
0*

Finally, the data acquisition was performed using below lines -





*/gate/application/setTimeSlice      0.0001
 s/gate/application/setTimeStart      0  s/gate/application/setTimeStop
  0.0001  s/gate/application/startDAQ*

*QUESTION 1*
Gate (v 9.0) shows this error when I am running the code.















*[Acquisition-0] Slice 0 from 0 to 0.0001 s [slice=0.0001 s][G4-cerr]
-------- EEEE ------- G4Exception-START -------- EEEE -------***
G4Exception : ConstructOwnPhysicalVolume      issued by :
GateVVolume::ConstructOwnPhysicalVolumeCan not complete placement
update.*** Fatal Exception *** core dump ***[G4-cerr]  **** Track
information is not available at this moment[G4-cerr]  **** Step information
is not available at this moment[G4-cerr] -------- EEEE --------
G4Exception-END --------- EEEE -------[G4-cerr] [G4-cerr] *** G4Exception:
Aborting execution ***Aborted (core dumped)*


*QUESTION 2*
I don't understand the implementation in movsource.placements file. I want
a gradual change of position of source point with time. Can the above
implementation provide that? It seems like it is a discrete instantaneous
change.

Thanking you
Satyajit Ghosh
14-June-2021



-- 
*Satyajit Ghosh, M.Sc.*
*PhD Student*

*Nuclear Spectroscopy and Molecular Imaging Lab,*
*Physics Department, IIT Bombay,*
*Mumbai-400076, INDIA*
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