[Gate-users] Dose actor shows zero valuesand STL file not in the center of defined geometry

Maikol Salas Ramirez mmsalas at gmail.com
Mon Jul 2 15:59:27 CEST 2018

Hi Emmanuel,

Some possibles solution.

1- I had the same problem a couple of times, I use Freecad to change the
position of the STL structure. STL are tricky because they keep the space
localization. What I do, normally is:
A- I use Freecad, I open a new file.
B- Import STL file.
C- Measure the SLT size (https://www.freecadweb.org/wiki/Mesh_BoundingBox)
D- Translate the MESH using the first set of coordinates (but using
negative values). This procedure moves your STL to a (0,0,0) position. (see
attached image)
E- Always is useful (at lest for me) to create a box with the same STL
dimensions if the STL is totally hiddenby the box is because the
translation was fine. (see attached image)
F- Anyway always you have to check visually what is going in the simulation
space. But at least this procedure will improve the localization.
G- EXTRA: If you want, you can apply a angular translation in freecad to
change the orientation of your phantom.

2- I also faced this problem. One option is create a vacuum volume (box)
("miniworld"), then include your source there (daughter of  "miniworld" ),
then your mesh structure (also daughter of "miniworld"). Try this and let
see. If I am not wrong it will resolve the problem.
In general avoid to link the source and the phantom directly to the world
volume, and play with the hierarchy and order.

Best regards

El El lun, 2 jul 2018 a las 2:19, Emmanuel Marfo <
emmanuel.marfo at postgrad.otago.ac.nz> escribió:

> Dear Sir/Gate Uers,
> Please, I have two main challenges
>    1. STL file not in the centre of the defined geometry
>    2. Dose actor showing zero value results
> I have attached a couple of STL files created with different procedures. I
> believed the attached STL files should work in the GATE simulation for dose
> scoring. However, the imported STL in the simulation is not located in the
> centre. I used placement/translation to get it in the right position for
> the simulation to run. Furthermore, the dose actor shows zeros values.
> Please, I need some help to figure it out where the problem might be,
> possibly from the STL files which I have attached. thanks.
> Best regards,
> Emmanuel Marfo
> Student
> University of Otago
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