[Gate-users] Weird Blips in F18 data

[David Sarrut]

Hello Mark,

can you try with a single core (no merging), even with a "low" statistics,
to see if it also occurs ?

thanks
David

On Thu, Dec 2, 2021 at 4:52 PM BAKER, Mark (THE CLATTERBRIDGE CANCER CENTRE
NHS FOUNDATION TRUST) <mark.baker23 at nhs.net> wrote:

> Hi everyone
>
>
>
> I’m running a relatively simple simulation of a NEMA IQ phantom, looking
> at the dose deposited within it by F18. My sim has a CT scan loaded as the
> geometry (with HU determined from the StoichHU example) and the F18 scan as
> the source. Physics are loaded as GQSP_BERT_EMV.  The macro is split into 4
> to run on 4 separate cores, then merged together afterwards using hadd for
> the root files. My source definition is Fluor18 with e+ particle, 6585s
> setforcedhalflife and true for setforcedunstableflag (unfortunately my code
> is on a different machine to my emails so I can’t cope and paste directly).
>
>
>
> I’m getting some interesting results in my tracklength and edepspectrum
> root files (see attached). The tracklength seems to get a little bit of a
> blip at pretty much 1mm, which I’m finding hard to explain. Additionally,
> on the Edep there appears to be an event (or possibly several) which
> deposits 20GeV from an energy of around 0.5MeV. The reason that I think it
> might be several events is that the same point is visible on the individual
> root files as well as the merged file. My actual edep and dose images look
> pretty good.
>
>
>
> These examples are from merged root files from 4x25000 events so probably
> not amazing statistically but are quick enough for me to run and trouble
> shoot. I’ve ran slightly more events and still see the same effects, but I
> will run a longer simulation (4x200M or something) overnight to see if I
> get the same effects (and rule out a statistics related issue).
>
>
>
> Does anyone have any clues or suggests are to where to look to
> troubleshoot this?
>
>
>
> Thank you
>
>
>
> *Mark Baker*
>
> Principal Clinical Scientist (Interim)
>
> Imaging Physics (Ionising)
>
> The Clatterbridge Cancer Centre NHS Foundation Trust
>
> *(he, him)*
>
>
>
> CCCW Tel:  0151 556 5030
>
> CCCL Tel: 0151 318 8438
>
> Email: mark.baker23 at nhs.net
>
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>
>
> *Honorary Lecturer, Dept. of Physics*
>
> *University of Liverpool*
>
>
>
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-- 
David Sarrut, Phd
Directeur de recherche CNRS
CREATIS, UMR CNRS 5220, Inserm U1294
Centre de lutte contre le cancer Léon Bérard
28 rue Laënnec, 69373 Lyon cedex 08
Tel : 04 78 78 51 51 / 06 74 72 05 42
http://dsarrut.github.io
_________________________________
 "2 + 2 = 5,  for extremely large values of 2"
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