[Castor-users] Merging PET attenuation and sensitivity map for the reconstruction

[FILIPOVIC PIERUCCI Marina]

Hello,

If I have understood your problem right, you already have an attenuation image and a sensitivity map, and by sensitivity you mean the detector efficiency normalization?
In CASToR definition, the sensitivity is actually an image representing for each voxel the sum of system matrix elements for that voxel, where a system matrix element contains everything (the projection coefficient, detector efficiency normalization, dead time,  attenuation, calibration, etc.).
If the above is right, why can't you compute and write a CASToR normalization file (described in the documentation and used as input along the list-mode file for list-mode reconstruction), that contains both attenuation and detector efficiency correction coefficients for each projection line? Or maybe is there some detail I have missed?

Cheers

Marina Filipovic

________________________________________
De : Castor-users [castor-users-bounces at lists.castor-project.org] de la part de jbaran [jakub.baran at ifj.edu.pl]
Envoyé : lundi 15 juillet 2019 10:48
À : castor-users at lists.castor-project.org
Objet : [Castor-users] Merging PET attenuation and sensitivity map for the reconstruction

Dear Castor Users,

I am trying to reconstruct the PET data with Castor. To be more precise,
what I am trying to do is to reconstruct the data with provided
separately attenuation and sensitivity maps. What was suggest to me is
that Castor need those map merged together and used as one input. The
solution for doing that (as suggested by Castor developers) is to
produce high statistics list mode covers whole FOV (what we did) and
then using obtained list mode, attenuation maps and -opti SENS option in
castor-recon app (without sensitivity map) produce merged
attenuation+sensitivity map which will be then used in the final
reconstruction. However, the computing demands for handling that are
huge and overcome a little bit our computing capabilities.

I am wondering what other options do I have. Idealistically, I would
like to know if it is possible to merge both maps without the list-mode
data or give both them as an input to Castor in one castor-recon
command. Is there any external software or anyone of you developed
software to do that externally?

I would appreciate any help with that matter.

All the best,
Jakub
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