[Castor-users] Problem with sensitivity computed from normalization datafile

[Julien Salvadori]

Dear Castor users,

I can reconstruct without problem a list mode from an IEC phantom recorded
on the Philips Vereos TEP (with and without correction) when the
sensitivity is calculated from the .geom scanner. However, when the
sensitivity is generated from a normalization file, it does not work
anymore. I have no idea where the problem may come from, especially since
the sensitivity image generated from the normalization file seems correct
to me.

Here in attachement :

“SensiScan” : Sensitivity calculated from the scanner element without
taking into account attenuation and normalization.

“ReconWithSensiScan” : MLEM reconstruction with sensitivity “SensiScan”
without any correction

è Gets reconstructed images which seems to me coherent considering the
absence of correction

“SensiNorm”: Sensitivity calculated from the normalization datafile without
taking into account attenuation and normalization (attenuation and
normalization factor set to 1)

ReconWithSensiNorm : MLEM reconstruction with sensitivity “SensiNorm”
without any correction

è Gets an almost uniform image with values very close to 0

Do you think that the sensitivity image calculated with the normalization
file seems correct? Have you ever encountered a similar problem?

Any help will be welcome!

Kind regards

Julien Salvadori

Phd student, IADI


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