[Gate-users] Simulated energy spectrum not same as actual energy spectrum

[Adolf Nordin]

Hi Matthew

Indeed that was one of the problems (at least I hope).

I had it as 1mm, changed it to 0.5mm and got low values. I also inserted a piece of metal under the source to create back scatter, as this is the actual setup as well. I will play around with the settings now to get comparable spectra.

Next question (for you or anyone else).

Up to now my comparison of the spectra was visual.

I can see the spectrum via root, but have not found a way (yet) to export the data as a text file so that I can plot it in excel.

Do I use "/gate/actor/addActor EnergySpectrumActor" or can I extract from normal root output as well?

Just point me in the right direction, the trial and error I will do.

Adolf

From: Matthew Strugari <matthew.strugari at dal.ca>
Sent: Tuesday, June 15, 2021 8:27 PM
To: Adolf Nordin <Adolfn at axim.co.za>; gate-users at lists.opengatecollaboration.org
Subject: Re: [Gate-users] Simulated energy spectrum not same as actual energy spectrum

Hi Adolf,

Have you adjusted your production thresholds/cuts? It's likely that you're missing secondary and tertiary interactions due to the default cut off value of the world (1.0 mm).

Regards,
Matthew

--
Matthew Strugari
PhD Candidate at Biomedical Translational Imaging Centre - BIOTIC,
5890 University Ave, Halifax, NS, B3K 6R8


From: Gate-users <gate-users-bounces at lists.opengatecollaboration.org<mailto:gate-users-bounces at lists.opengatecollaboration.org>> on behalf of Adolf Nordin <Adolfn at axim.co.za<mailto:Adolfn at axim.co.za>>
Date: Tuesday, June 15, 2021 at 10:29
To: gate-users at lists.opengatecollaboration.org<mailto:gate-users at lists.opengatecollaboration.org> <gate-users at lists.opengatecollaboration.org<mailto:gate-users at lists.opengatecollaboration.org>>
Subject: [Gate-users] Simulated energy spectrum not same as actual energy spectrum
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Hi

I've hit 2 walls, bit want to sort the first.

I have a simple geometry for a SPECT system:

SPECTHEAD
Lead shielding
Al cover under the crystal
Crystal
Back cover
No collimator (doing intrinsic tests).

Source

The simulation runs fine.

However, when I compare the energy spectrum from the simulation with an actual energy spectrum from the camera, I get very little low energy counts.

So I cannot say that the simulation is a true reflection of the actual system.

Is this a known issue, or am I missing something.

Thanks.
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