Potential bug in castor-PetScannerLutEx

General Discussions
1

Hello All,

I’m working on adapting castor-PetScannerLutEx to match a Gate geometry that is incompatible with castor-GATEMacToGeo. However on my first run of castor-PetScannerLutEx (no changes) I get a seg fault.
I found there was a bug at line 342, the oMatrix needs to be initialized with nb_resctors +1 oMatrix *****crystal_center = new oMatrix [nb_rsectors+1];

After that seemed to get the program to compile alright, but I’m having some difficulty in getting sensible results out of it with my geometry. For now I’m using GATE with a cylindricalPET system with only a single ring of 28 rsectors, no layers and 16 x 16 crystal arrangement, nothing that castor-GateRootToCastor couldn’t handle. I end up with a non-sequential castor indexing, that I think is the cause of my problems.

Are there any further tutorials on using castor-PetScannerLutEx ?

Thanks,
-Peter Neilson

2

Hi Peter,

Thank you for noticing this.

This code is just an example on how to make a LUT following CASToR ring by ring detector indexation.

In order to adapt it to GATE indexing, you must change the last loop which attribute the crystal index to the cryID variable*.* For your example system, I believe it should be something like
int cryID = rsnb_axial_crystalnb_trans_crystal + l

…to index all the crystals in the first rsector, then the next one, etc. You should check that the ordering and position of the first rsector/crystal are consistent between CASToR and GATE indexing.

Hope this helps,
Thibaut

3

Hello Thibaut,

Thanks for your assistance, I’ve been able to get the script up and reconstructing images. However I’ve noticed something rather odd when I view them in amide.

In this case I’m still working with a single ring of axial modules and rsectors to keep things simple, with point sources at z=0. I would expect the produced image to be centered in amide when I view it, and do seem to have the correct X and Y coordinates, however I find the sources at z = -11.63 mm. Is there some form of metadata or option to set these coordinates?

Thanks,
-Peter Neilson

4

Hi Peter,
Did you center your ring of crystal at z=0 ? Because really the axial position just depends on where your ring is located.

Best,
Thibaut

Peter Neilson <neilson@txcorp.com> a écrit :