[Gate-users] [BUG] FFDA - Displaced detector geometry and primary projections

Simon Rit simon.rit at creatis.insa-lyon.fr
Tue Mar 15 23:36:15 CET 2022

Hi Gabriele,
I have managed to reproduce the error and I think I have a fix
I probably never detected this because I normally don't use a source offset
and a detector offset together... Can you test the fix and let me know if
it works for you?

On Tue, Mar 8, 2022 at 11:37 AM Simon Rit <simon.rit at creatis.insa-lyon.fr>

> Hi Gabriele,
> If something is set to 0, it is probably because your collimated source is
> too small. Try adjusting the source size
> https://github.com/OpenGATE/GateContrib/blob/master/imaging/CT/fixedForcedDetectionCT/mac/fixedForcedDetectionCT.mac#L59-L73
> Simon
> On Tue, Mar 8, 2022 at 10:41 AM Gabriele Belotti <
> gabriele.belotti.bergamo at gmail.com> wrote:
>> Hello everyone,
>> I'm posting this to inquire on a possible bug in GATE.
>> I'm conducting some fixed forced detection simulations, with a voxelized
>> phantom and a moving gantry described by an RTK .XML geometry file.
>> The specific condition in my geometry file is that I have source and
>> detector offsets.
>> My simulation saves primary as well as attenuation images.
>> BUG(?):
>> When inspecting the primary images I have a vertical band of values that
>> is consistently put to 0. The position of this band is on the same side of
>> the detector offset (i.e. toward the center of the phantom being
>> projected). At the same time, the attenuation images have no such issue and
>> represent the complete projection consistently.
>> I tried changing phantom and the issue was reproduced in the same way.
>> While if I changed the RTK geometry to one with no offsets I get correct
>> primary and attenuation images. I will try to find a culprit with
>> further tests but I wanted to share this with you.
>> PS: Issue reproduced in vGATE (GATE 9.1 and GEANT4 10.7) and on a cluster
>> (with GATE master and GEANT4 11.0)
>> Gabriele Belotti
>> _______________________________________________
>> Gate-users mailing list
>> Gate-users at lists.opengatecollaboration.org
>> http://lists.opengatecollaboration.org/mailman/listinfo/gate-users
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