[Gate-users] Problems with the simulation of LEHR collimator

[Leda Lorenzon]

Dear all,

I’m trying to simulate Infinia Hawkeye SPECT system with LEHR collimator.
When I run the geometry check /geometry/test/recursive_test I get the
following error message:

GeomTestError: SolidProblem

            Push fails to fix geometry inconsistency

                        Solid name=hole_solid

                        Local position=…..



GeomTest Error: Overshooting daughter volume

    The volume hole_phys[81780] appears to extend outside the mother volume
collimator_phys[0]

    at the following points in global coordinates: (list truncated)

       length (cm)    ---------- start position (cm) -----------   -----------
end position (cm) ------------

              1.75                 0           -20          24.3
1.75           -20          24.3

            0.0075             -1.61      -20.0075          24.3
-1.61           -20          24.3

            0.0075            -1.435      -20.0075          24.3
-1.435           -20          24.3

            0.0075             -1.26      -20.0075          24.3
-1.26           -20          24.3

            0.0075            -1.085      -20.0075          24.3
-1.085           -20          24.3

   ……….







I’m sure that the daughter (hole) does not extend outside the mother
(collimator).

I’m worried about this error message because when I try to validate my
simulation by comparing the simulated with the measured spectra I don’t
find a good agreement: for instance the number of detected counts in the
simulation is too low and also in the simulated spectra I can’t see  the
x-ray lead peak.



If you know how to solve this problem, please let me know.

Here is associated script for the definition of LEHR collimator and the
physics process.

Really thank you.



#####LEHR COLLIMATOR

/gate/SPECThead/daughters/name collimator

/gate/SPECThead/daughters/insert box

/gate/collimator/geometry/setXLength 3.5 cm

/gate/collimator/geometry/setYLength 40. cm

/gate/collimator/geometry/setZLength 54. cm

/gate/collimator/placement/setTranslation  -3.075 0. 0. cm

/gate/collimator/setMaterial Lead

/gate/collimator/daughters/name hole

/gate/collimator/daughters/insert hexagone

/gate/hole/geometry/setHeight 3.5 cm

/gate/hole/geometry/setRadius .075 cm

/gate/hole/placement/setRotationAxis 0 1 0

/gate/hole/placement/setRotationAngle 90 deg

/gate/hole/setMaterial Air

/gate/hole/repeaters/insert cubicArray

/gate/hole/cubicArray/setRepeatNumberX 1

/gate/hole/cubicArray/setRepeatNumberY 235

/gate/hole/cubicArray/setRepeatNumberZ 183

/gate/hole/cubicArray/setRepeatVector 0. 0.17  0.294  cm

/gate/hole/repeaters/insert linear

/gate/hole/linear/setRepeatNumber 2

/gate/hole/linear/setRepeatVector 0.  .085  0.147103 cm





####PHYSICS PROCESS

/gate/physics/addPhysicsList empenelope



/gate/physics/addProcess PhotoElectric

/gate/physics/processes/PhotoElectric/setModel PenelopeModel



/gate/physics/addProcess Compton

/gate/physics/processes/Compton/setModel PenelopeModel



/gate/physics/addProcess RayleighScattering

/gate/physics/processes/RayleighScattering/setModel PenelopeModel



/gate/physics/addProcess ElectronIonisation

/gate/physics/processes/ElectronIonisation/setModel StandardModel e-



/gate/physics/addProcess Bremsstrahlung

/gate/physics/processes/Bremsstrahlung/setModel StandardModel e-



/gate/physics/addProcess eMultipleScattering

/gate/physics/processes/eMultipleScattering/setModel Urban95Model e-



/gate/physics/processList Enabled

/gate/physics/processList Initialized



/gate/physics/Electron/SetCutInRegion   world 1. cm

/gate/physics/Gamma/SetCutInRegion      world 0.001 cm

/gate/physics/processes/PhotoElectric/setDeltaRayCut 1 keV

/gate/physics/processes/PhotoElectric/setXRayCut 1 keV

/gate/physics/displayCuts
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