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

[Maxime Chauvin]

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] 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
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