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

[Julien Salvadori]

Thank you Simon for the quick reply.

I disabled the attenuation and normalization in the calculation of the
sensitivity and i always get strictly the same result. To make sure, i also
reiterated the sensitivity computation by forcing the variable
lor_sensitivity to 1 in the ProcessThisLine function of
oSensitivityGenerator, with again the same result !

Indeed,i use prompt coincidences to generate the normalization datafile,
it's not what is necessary to do ? and yes normalization coefficients are
provided by Philips.

Julien

2018-07-23 10:40 GMT+02:00 Simon Stute <simon.stute at cea.fr>:

> Hi Julien,
>
> Looking at the SensiNorm, you are taking normalization and/or attenuation
> into account, because we can see your object in the sensitivity image.
> If you really want to disable it, even if it is present in your
> normalization data file, just use the "-ignore-corr attn,norm" option, as
> you did in the reconstruction.
> Otherwise, the attenuation is still present in the sensitivity image, even
> if you ask for ignoring it in the reconstruction, as you provide the
> sensitivity image.
> I suggest you try this, until you get an almost similar image to the one
> built with the scanner elements.
>
> Also, when looking at the SensiNorm, it is quite noisy and we can see the
> inserts which looks like as if you used the prompt data as the
> normalization coefficients.
> I am wondering what kind of normalization coefficients are you using ? Are
> you using the one provided by Philips ?
>
> Best
> Simon
>
>
>
>
>
> Le 22/07/2018 à 17:18, Julien Salvadori a écrit :
>
> 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
>
>
> ​
>  1.zip
> <https://drive.google.com/file/d/1oU9veGi2I5sE8fS0-aeutq0HsUeTFn-Y/view?usp=drive_web>
> ​
>
>
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