[Gate-users] Attaching a dose actor to a wedge-shaped volume

[Elia Alessio]

Hi Sam!

I am not an expert but I would recommend you few basic things:

-        If you have an irregular shape do to not score the dose values directly but use rather the energy deposited and then post-process dose values. as far as I know, the dose actor dose not compute correctly the dose if you do not have a regular shape. Do you see the same behavior in your output-Edep.txt?

-        Run the command geometry/test/run in order to see if you have any overlap in your geometry. If this is the case your results are unpredictable

-        In some sense, an actor is like a virtual object that you must attached to a geometrical volume. In your specific case (wedge shape) I personally do not see other solutions than your "3bodies approach". Therefore you should attach a different actor to each of your wedge-volume

Hope this can help!

Cheers
Alessio

From: Gate-users [mailto:gate-users-bounces at lists.opengatecollaboration.org] On Behalf Of Manger, Sam
Sent: Dienstag, 14. März 2017 18:21
To: gate-users at lists.opengatecollaboration.org
Subject: Re: [Gate-users] Attaching a dose actor to a wedge-shaped volume


To add to this -



If I create a 2D/3D actor not attached to any volume, then I get a segmentation error. I feel like this is the right way of doing things but I'm not sure why I'm getting this error. There's no helpful debugging info that comes out if I switch verbosity on.



My dose actor definition in the macro is:


/gate/actor/addActor DoseActor test
/gate/actor/test/setPosition                   12.5 0. 10. mm
/gate/actor/test/setSize                           35.  50.  .028 mm
/gate/actor/test/setResolution               140  200  1
/gate/actor/test/stepHitType                  random
/gate/actor/test/enableEdep                  true
/gate/actor/test/saveEveryNSeconds          60
/gate/actor/test/save /home/user/GATE_Simulations/wedge/test.txt

Sam


________________________________
From: Manger, Sam <S.Manger at warwick.ac.uk<mailto:S.Manger at warwick.ac.uk>>
Sent: 14 March 2017 16:44
To: gate-users at lists.opengatecollaboration.org<mailto:gate-users at lists.opengatecollaboration.org>
Subject: [Gate-users] Attaching a dose actor to a wedge-shaped volume


Hi Gate users,



I'm trying to simulate the response of Gafchromic film to protons. I've done this previously using a rectangular volume with the material properties of EBT-3 and essentially produce a 2D voxelised dose output. However, in experiment, I've used a piece of film that looks almost D-shaped. To replicate this in Gate, I have produced 3 volumes; central rectangular volume that is a box, flanked by two wedges. I've tilted them at 1 degree to the x-axis and I think I've aligned them. Now, I'm struggling to get a sensible output!



[cid:image001.png at 01D29D64.1A6D0B10]



If I attach a dose actor to each volume, then I see dose being deposited in the film. The central region is fine, but the two wedge regions confuse me slightly. I've used /gate/actor/[actorname]/setResolution to define the resolution but I'm not sure how this works with the wedge-shapes. The whole dose matrix is full and there isn't any hint of structure. Should I expect that my dose volume is entirely contained within the film volume? This would mean that the voxels are different sizes.



Is there a better way of getting a dose actor to read out the film? I tried attatching an actor to the world volume and locating it at the same position as the active layer of the film but got no output!



Please let me know if I'm doing anything stupid!



Sam Manger


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