I am having issues with simulating with very small voxels. I input an egsphant into my program with a 0.1 mm x 0.1 mm x 1 mm rectangular scoring geometry. However, I get many stuck particle messages and the doses are recorded as zero. When I visualize the scoring geometry, the voxels are overlapped and only cover a small portion of the actual geometry. When I make the voxels bigger, the visualization of the voxels looks correct, but I still get the stuck particle messages.
I thought it could be that the tolerance value defining the accuracy of tracking on the surfaces was too large so I set it to be relative to my world volume and made the world slightly bigger than my volume so that they would be on the same scale. However, this did not change how the voxels overlap when they are very small.
I am not sure what is going on. Is there a lower limit on voxel size that is causing this or could it be something else? I am using version 10.02.p03. Below is an one of the stuck particle messages.
-------- EEEE ------- G4Exception-START -------- EEEE -------
*** G4Exception : GeomNav0003
issued by : G4Navigator::ComputeStep()
Stuck Track: potential geometry or navigation problem.
Track stuck, not moving for 26 steps
in volume -phantom_phys_real- at point (-0.166564,8.99999e-05,-11.5611)
*** Event Must Be Aborted ***
G4WT27 > G4Track (0x2b03a0391270) - track ID = 8, parent ID = 2
G4WT27 > Particle type : e- - creator process : RadioactiveDecay, creator model : Undefined
G4WT27 > Kinetic energy : 416.934 keV - Momentum direction : (-0.956312,0.00057387,0.292348)
G4WT27 > Step length : 1 Ang - total energy deposit : 0 eV
G4WT27 > Pre-step point : (-0.166564,8.99999e-05,-11.5611) - Physical volume : phantom_phys_real (Water__0.992752 g/cm3)
G4WT27 > - defined by : CoupledTransportation - step status : 1
G4WT27 > Post-step point : (-0.166564,8.99999e-05,-11.5611) - Physical volume : phantom_phys_real (Water__0.992752 g/cm3)
G4WT27 > - defined by : msc - step status : 7
G4WT27 > *** Note: Step information might not be properly updated.
-------- EEEE -------- G4Exception-END --------- EEEE -------
Thanks so much!