[Gate-users] possible bug

Ananth Ravi ananth.ravi at swri.ca
Tue Jan 30 00:18:55 CET 2007


Hello All,

 

I have been trying to simulate the imaging of a brachytherapy seed using a
CZT linear array detector.  I am sweeping the linear array to create a 2D
image of the seed.  However in the process I have run into a very
interesting phenomenon.  I don't know whether it is a bug or if it is a
problem with my install.

 

The seed is positioned vertically at (0,0,0) cm  and the detector moves from
-4 mm to + 4 mm as we move from -4 mm to 0 we slowly see the seed is
resolved in the projection images.  However as we go from 0 to +4 mm the
seed continues to be resolved.  This is a problem because the SPECThead is
perfectly symmetric, (or at least I think it is in my macro), so I should
expect similar results on either side of 0 cm in the x-direction.

 

This graph compares the projections from the -4 mm, which is what is
expected, to the + 4 mm, which doesn't make any sense in this context and
appears to be an erroneous result of the simulation.

 



 

I am currently using:

Clhep-1.8.1.0

Geant4.7.0.p01

Root_v4.04.02

Gate_v2.2.0

CC built on GNU gcc version 3.3.1

 

This macro is run 100 times on a cluster, so that I can get 2 minute images
per projection.  I then move the camera by 0.8 mm and take another image for
2 minutes.

 

I am attaching my macro below:

The only text that I change between each image is 

/gate/SPECThead/placement/setTranslation  -4. 0. 70. mm {where -4. goes to
+4. in increments of 0.8 mm}

 

Any help that anyone might be able to provide would be really appreciated.

 

Later Gaters, 

 

Ananth Ravi

 

 

/control/verbose 0

# COMMENT  TO DISABLE THIS  V I S U A L I S A T I O N

#/vis/open OGLSX

#/vis/viewer/reset

#/vis/viewer/set/style surface

#/vis/drawVolume

#/gate/geometry/enableAutoUpdate

#/vis/viewer/zoom 2

#/vis/viewer/set/viewpointThetaPhi 120 30 

 

/gate/world/geometry/setXLength 50 cm

/gate/world/geometry/setYLength 50 cm

/gate/world/geometry/setZLength 50 cm

/gate/world/setMaterial Air

 

####### Scanner Head

/gate/world/daughters/name SPECThead

/gate/world/daughters/insert box

/gate/SPECThead/geometry/setXLength 4 cm

/gate/SPECThead/geometry/setYLength 6 cm

/gate/SPECThead/geometry/setZLength 4 cm

/gate/SPECThead/placement/setTranslation  -4. 0. 70. mm

/gate/SPECThead/setMaterial Air

/gate/SPECThead/attachPhantomSD

/gate/SPECThead/vis/forceWireframe

/gate/world/describe

 

###### Collimator

/gate/SPECThead/daughters/name collimator

/gate/SPECThead/daughters/insert box

/gate/collimator/geometry/setXLength 4. cm

/gate/collimator/geometry/setYLength 6. cm

/gate/collimator/geometry/setZLength 1.6 cm

/gate/collimator/placement/setTranslation  0 0.0 -1.2 cm

/gate/collimator/setMaterial Brass

/gate/collimator/vis/setColor red

/gate/collimator/vis/forceSolid 

/gate/collimator/attachPhantomSD

 

 

######  HOLE

/gate/collimator/daughters/name hole

/gate/collimator/daughters/insert box

/gate/hole/geometry/setXLength 0.65 mm

/gate/hole/geometry/setYLength 0.65 mm

/gate/hole/geometry/setZLength 1.6 cm

/gate/hole/setMaterial Air

/gate/hole/vis/setColor yellow

/gate/hole/vis/forceWireframe

/gate/hole/repeaters/insert linear

/gate/hole/linear/setRepeatNumber 64

/gate/hole/linear/setRepeatVector 0. 0.8 0.   mm

/gate/hole/linear/autoCenter true

 

##### Crystal

/gate/SPECThead/daughters/name block

/gate/SPECThead/daughters/insert box

/gate/block/geometry/setXLength 3.3 mm

/gate/block/geometry/setYLength 51.2 mm

/gate/block/geometry/setZLength 3.0 mm

/gate/block/placement/setTranslation  0. 0. -1.35 mm

/gate/block/setMaterial Silicon

/gate/block/vis/setColor blue

/gate/block/vis/forceWireframe 

 

/gate/block/daughters/name crystal

/gate/block/daughters/insert box

/gate/crystal/placement/setTranslation 0.0 0.0 0.0 mm

/gate/crystal/geometry/setXLength 0.7 mm #2.3

/gate/crystal/geometry/setYLength 0.7 mm

/gate/crystal/geometry/setZLength 3.0 mm

/gate/crystal/setMaterial CZT

/gate/crystal/repeaters/insert linear

/gate/crystal/linear/setRepeatNumber 64

/gate/crystal/linear/setRepeatVector 0. 0.8 0 mm

/gate/crystal/linear/autoCenter true

/gate/crystal/vis/setColor grey

 

 

########     breast   P H A N T O M 

/gate/world/daughters/name phantom

/gate/world/daughters/insert box

/gate/phantom/geometry/setXLength 5 cm

/gate/phantom/geometry/setYLength 5 cm

/gate/phantom/geometry/setZLength 2 cm

/gate/phantom/setMaterial Lucite

/gate/phantom/vis/forceWireframe

/gate/phantom/placement/setTranslation 0.000000 0.000000 -9.6 mm

/gate/phantom/attachPhantomSD

 

/gate/phantom/daughters/name seed

/gate/phantom/daughters/insert cylinder

/gate/seed/geometry/setRmax .4  mm

/gate/seed/geometry/setRmin 0.0 mm

/gate/seed/geometry/setHeight 5. mm

/gate/seed/placement/alignToY

/gate/seed/placement/setTranslation 0.000000 0.000000 +9.6 mm

/gate/seed/setMaterial Titanium

/gate/seed/vis/setColor magenta

/gate/seed/attachPhantomSD

/gate/seed/vis/forceWireframe

 

/gate/seed/daughters/name marker

/gate/seed/daughters/insert cylinder

/gate/marker/geometry/setRmax .32  mm

/gate/marker/geometry/setRmin 0.0 mm

/gate/marker/geometry/setHeight 1.2 mm

/gate/marker/placement/setTranslation 0.000000 0.000000 0 mm

/gate/marker/setMaterial Tungsten

/gate/marker/attachPhantomSD

 

/gate/seed/daughters/name airgap

/gate/seed/daughters/insert cylinder

/gate/airgap/geometry/setRmax .32  mm

/gate/airgap/geometry/setRmin 0.0 mm

/gate/airgap/geometry/setHeight 1.82 mm

/gate/airgap/repeaters/insert linear

/gate/airgap/linear/setRepeatNumber 2

/gate/airgap/linear/setRepeatVector 0. 0. 3.02 mm

/gate/airgap/setMaterial Air

/gate/airgap/attachPhantomSD

 

###### SYSTEM

/gate/systems/SPECThead/crystal/attach crystal

/gate/crystal/attachCrystalSD

 

###### PHYSICS

/gate/physics/gamma/selectRayleigh lowenergy

/gate/physics/gamma/selectPhotoelectric standard

/gate/physics/gamma/selectCompton standard

/gate/physics/setElectronCut 1. m

/gate/physics/setXRayCut 1. GeV

/gate/physics/setDeltaRayCut 1. GeV

 

###### INITIALIZE

/gate/geometry/enableAutoUpdate

/run/initialize

 

##### DIGITIZER

/gate/digitizer/Singles/insert adder

 

/gate/source/addSource seed_1

/gate/source/seed_1/setActivity 0.00208800 Ci

/gate/source/seed_1/gps/particle gamma

/gate/source/seed_1/gps/type Volume

/gate/source/seed_1/gps/shape Ellipsoid

/gate/source/seed_1/gps/halfx 0.32 mm

/gate/source/seed_1/gps/halfy 2.42 mm

/gate/source/seed_1/gps/halfz 0.32 mm

/gate/source/seed_1/gps/energytype Mono

/gate/source/seed_1/gps/monoenergy 21  keV

/gate/source/seed_1/gps/confine airgap_P

/gate/source/seed_1/gps/centre 0 0 0 cm

 

###### OUTPUT

#/gate/output/root/disable

/gate/output/root/setRootHitFlag 0

/gate/output/root/setRootSinglesFlag 0

/gate/output/root/setRootNtupleFlag 0

/gate/output/root/setRootSinglesAdderFlag 0

/gate/output/ascii/setOutFileHitsFlag 0

/gate/output/ascii/setOutFileSinglesFlag 1

/gate/output/ascii/setOutFileSinglesAdderFlag 0

 

 

###### RANDOM

/gate/output/root/setSaveRndmFlag 1

/random/resetEngineFrom endOfRun.rndm

 

###### PROJECTION

/gate/output/projection/pixelSizeX 0.8 mm

/gate/output/projection/pixelSizeY 0.8 mm

/gate/output/projection/pixelNumberX 1

/gate/output/projection/pixelNumberY 64

/gate/output/projection/projectionPlane XY

 

###### VERBOSITY

/control/verbose 0

/grdm/verbose 0

/run/verbose 0

/event/verbose 0

/tracking/verbose 0

/gate/application/verbose 0

/gate/generator/verbose 0

/gate/stacking/verbose 0

/gate/event/verbose 0

/gate/source/verbose 0

/gate/output/projection/verbose 0

/gate/output/verbose 0  

 

 

###### EXPERIMENT

/gate/application/setTimeSlice    1.200  s

/gate/application/setTimeStart    0.000  s

/gate/application/setTimeStop     1.200  s

 

 

###### LET'S RUN THE SIMULATION!

/gate/application/startDAQ

 

exit

 

 

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