如何显示voxelized phantom？

Gate里，voxelized phantom是可以显示的，voxelized source不可以。。。

 gate_v2.2.0/examples/example_PHAMTOM_SOURCE/Voxelized_Phantom_Source/range.dat
   5
   0      0       Air        false 0.0  0.0   0.0  0.2
   6      6       Lung       false 1.0  0.0  0.0  0.2
   6      16      Breast     false 0.0  1.0  0.0  0.2
   16     36      Plastic    true  0.0  0.0  1.0  0.2
   36     200     Air        false  0.0  0.0  0.0  0.2
 
 5 classes
 lld  uld  material flag a b c d
 
 The 'material' voxels are those for which lld < voxels < uld  where th e"material" is defined in GateMaterials.db
 The flag indicates whether to display the phantom when visualising the 'a,b,c,d' parameters are related to the colour/line-style/line-width etc. to  display the material. 

In order to view transparency, you need a viewer that supports it, like the G4RayTracer (for more info see geant4/source/visualization/RayTracer/README).  The alpha parameter controls 
the transparency level: 0-transparent, 1-opaque.