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

Thu Mar 16 09:19:59 CET 2017

Hi,

yes your're right. The wiki is not very clear on this point. To modify it, I think you could write an email to this address and require the access: Albertine DUBOIS adubois at imnc.in2p3.fr<mailto:adubois at imnc.in2p3.fr>

Cheers,
Alessio

From: Manger, Sam [mailto:S.Manger at warwick.ac.uk]
Sent: Mittwoch, 15. März 2017 10:14
To: Elia Alessio <alessio.elia at medaustron.at>
Cc: gate-users at lists.opengatecollaboration.org
Subject: Re: [Gate-users] Attaching a dose actor to a wedge-shaped volume

Hi Alessio,

thanks for your advice. I will check for overlap and use the 3-body approach. I anticipate that there will be some post-processing on the results if I use setResolution, as along the wedges each bin will have a different x-size.

On a side note, the wiki (http://wiki.opengatecollaboration.org/index.php/Users_Guide_V7.2:Readout_parameters_for_Radiotherapy_applications:_Actors#3D_matrix_actor_.28Image_actor.29) states that "if no attach command is provided then the actor is activated in any volume", implying that it is posssible to use an actor that isn't attached to a volume. Considering the segmentation violation I saw,  I do believe you that I must attach the actor to a volume. Is it possible to update the wiki, or can I contribute in some way? As I have come across a few pieces of advice/instructions on the wiki that seem outdated.

Sam

________________________________
From: Elia Alessio <alessio.elia at medaustron.at<mailto:alessio.elia at medaustron.at>>
Sent: 15 March 2017 07:22
To: Manger, Sam
Cc: gate-users at lists.opengatecollaboration.org<mailto:gate-users at lists.opengatecollaboration.org>
Subject: Re: [Gate-users] Attaching a dose actor to a wedge-shaped volume

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<mailto: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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