[Rtk-users] SPECT reconstruction issue

[Simon Rit]

Hi,
I'm not sure we actually ever checked this but it's a good check. Are you
using attenuation correction? If not, I expect that the total number of
counts in one projection should be equal to the integral of the SPECT image
as this is the Radon transform model. So you may want to average the number
of counts and not sum it (i.e., divide 8E+6 by your number of projections).
Can you check this?
Simon

On Tue, Jun 27, 2023 at 8:48 AM Nathan Sinsoilliez <n.sinsoilliez at gmail.com>
wrote:

> Hello everyone,
>
> I'm currently using rtk to reconstruct SPECT images using OSEM and I have
> an issue after the reconstruction. The total count of the image is
> completely changed (like 8E+6 in the projections VS 2E+4 when
> reconstructed). Also most of the pixels now have decimal values.
> Graphically everything seems to be alright though.
>
> Do you have an idea about what could cause this problem ?
>
> Best Regards
> Sinsoilliez Nathan
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