Dear Castor community,
I am doing PET simulations on Gate but I have encountered a problem in one of my reconstructions of a cilindrical phantom with 6 cilindrical capilars with different diameters inside.
The reconstructed image by Castor is not correct.
My phantom has an activity of 5.3kBq/mL in the big compartment, and a 4:1 ratio in the four smaller capilars (hot rods in background); the two larger capilars have water and air.
So I would expect to see a reconstructed image of 4 intense circles and 2 empty on a sligtly lighter background**.
Instead I got the following: which looks like all volumes have roughly the same activity (except for the cold rods)
I have intermediate results that correspond to what was expected. I cannot post more than one image for now but I have: image of source in root, visualization of emitted particles in Gate; and a transverse view of a real acquisition on a siemens PET, with the same activity as simulated.
They all show the capilars with more activity than the background.
So, I don´t understand what could have been wrong with the reconstruction in Castor.
I tried doing more interactions, but it didn´t help. The sensitivity matrix seems ok.
This is the command I used for reconstruction:
castor-recon -vb 2 -df path/file_df.Cdh -dout path -it 10:1 -dim 260,260,153.6 -fov 260,260,153.6 -proj multiSiddon,2,3 -opti MLEM
I would appreciate any help!