[Gate-users] Problems with scoring edep and dose in non rectangular geometries and CAD geometries

[Maikol Salas Ramirez]

Hi Leoni,

Just going back to this sentence "When scoring edep we obtain a value of
about 3000 MeV in the geometry built with Gate, when scoring in the CAD
geometry we obtain a value of about 370 MeV".

This difference can come from the "finish" of your mesh, it is important to
remember that the mesh representation is not the same that the 3D volume
with perfect curves. I would say that it is a good idea to play with the
level of detail of the finish of the mesh surfaces. Also depending of the
size of your geometries and  if you are simulation electrons, you could
have big differences, because electron are very sensible to this surface
changes.

Best regards
Maikol

El lun., 8 oct. 2018 a las 12:36, Leonie Brodbek (<
leonie.brodbek at uni-oldenburg.de>) escribió:

> Dear Maxime,
>
>
> Thank you!
>
> Unfortunately we already checked this and it seems that both geometries
> fit well and that this does not cause the problem.
>
>
> Kind regards
>
> Leonie
> ------------------------------
> *Von:* Maxime Chauvin <maxime.chauvin at inserm.fr>
> *Gesendet:* Montag, 8. Oktober 2018 12:01:11
> *An:* Leonie Brodbek
> *Cc:* Elia Alessio; gate-users at lists.opengatecollaboration.org
> *Betreff:* Re: [Gate-users] Problems with scoring edep and dose in non
> rectangular geometries and CAD geometries
>
> Dear Léonie,
>
> something you could check is the position of the geometry. Importing a
> .stl file can result in a unwanted shift due to a different reference frame
> from CAD compared to how GATE build a box or a cylinder. And this can cause
> a difference in Edep and absorbed dose.
>
> As a rough check you can use the visualisation (Gate --qt) to see if your
> geometries are identical between your 2 simulations.
>
> Kind regards,
>   Maxime Chauvin
>
> On 8 Oct 2018, at 11:26, Leonie Brodbek <leonie.brodbek at uni-oldenburg.de>
> wrote:
>
> Hi Alessio,
>
> thanks a  lot!
>
> We tried to create geometries with a CAD program to import more complex
> geometries and tested it with scoring in a box that is built inside Gate
> and with the same geometry built in the CAD program.
> When scoring edep we obtain a value of about 3000 MeV in the geometry
> built with Gate, when scoring in the CAD geometry we obtain a value of
> about 370 MeV. We imported the CAD geometries via a .stl file and the
> insert specification "tessellated". We obtained the same behavior when
> scoring Edep in cylinders built in gate and with the help of a CAD programm.
>
>
> Kind regards
> Leonie
>
> ------------------------------
> *Von:* Elia Alessio <alessio.elia at medaustron.at>
> *Gesendet:* Montag, 8. Oktober 2018 10:58:37
> *An:* Leonie Brodbek
> *Cc:* gate-users at lists.opengatecollaboration.org
> *Betreff:* RE: Problems with scoring edep and dose in non rectangular
> geometries and CAD geometries
>
> Hi Leonie,
>
> thanks for your email. Concerning the first point you spotted could you be
> more precise? (for example what do you mean with “different results with
> different order of magnitude”?). With respect to the second point, this is
> a known behavior of the dose actor. At the moment, it cannot handle
> correctly non-regular geometries as far as I know. I would recommend you to
> work with the edep and then post-process the dose.
>
> Hope it can help!
>
> Best
> Alessio
>
> *From:* Gate-users [
> mailto:gate-users-bounces at lists.opengatecollaboration.org
> <gate-users-bounces at lists.opengatecollaboration.org>] *On Behalf Of *Leonie
> Brodbek
> *Sent:* Montag, 08. Oktober 2018 10:31
> *To:* Gate-users at lists.opengatecollaboration.org
> *Subject:* [Gate-users] Problems with scoring edep and dose in non
> rectangular geometries and CAD geometries
>
> Dear all,
>
> we try to perform simulations of different detectors with Gate and have
> some problems when scoring dose and edep in different volumes, perhaps
> anyone can help us with these issues:
>
> - When we score dose and edep in a gate constructed geometry and in the
> same CAD geometry we obtain different results with different orders of
> magnitude (even in rectangular geometries).
>
> - When we score dose and edep in non rectangular geometries we cannot
> recalculate the dose out of edep and it seems that the dose in Gate is
> calculated by a geometry surrounding the real geometry but having
> rectangular corners, e.g. for a sphere of radius 0.5 cm the dose can be
> recalculated out of edep  by a cube with side length 1 cm.
>
> We would be very thankful for any help!
>
> Kind regards
> Leonie Brodbek
> *Disclaimer:*
> Please notice our E-Mail Disclaimer
> http://www.medaustron.at/email-disclaimer/
>
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