About projection & limits on USRBIN 2D plot

Dear FLUKA experts,

I have some questions about the projection and limitations of USRBIN’s 2D plot.I used a 50kev photon beam to simulate a fixed energy X-ray, and directed the beam towards the leg mode. My goal was to get the spatial distribution of the rays after passing through the leg mode.

I added two usrbin cards, one for the volume behind the leg model with a thickness of 2cm, and the other for the volume containing the entire cone beam and leg model.

1、For usrbin21 cards,flair failed 2D drawing in either projection direction,and gives the error “Geometry Problem or empty plot at the specified location.Try to change the location or enlarge the plot.”,I don’t know why this mistake happened?

2、For usrbin22 cards,I’ve restricted the z axis to 108cm to 110cm, and I can get a 2D projection plot in the x and y directions, like this:

But I still can’t get a 2D plot in the z direction,because this will result in the same error message, Can you tell me what the reason is? I want to look at the spatial distribution of the rays in the z direction.

3、If I change the minimum limit of the z axis to 109cm, then the 2D plot of the x and y projection direction is also wrong, but the z direction is the same,So, what causes this?

4、I notice that the difference between the second case and the third case is does the Z-axis minimum limit touch the leg model? I don’t know if my speculation is the cause of the error.
XraySystem005.flair (3.9 KB)
XraySystem005.inp (2.3 KB)

I’m sorry for raising so many questions. This is my fluka and flair file. I would really appreciate it if you could help me answer it

Dear @chen2019 ,

Thank you for your questions. After analysing them, it seems all of the problems share the same root: the region boundaries that are plotted together with the .bnn files. If you use the Default/Auto configuration, FLAIR will plot the region boundaries found in the central plane of your 2D projection region. If no boundaries are found there, the error “Geometry problem or empty plot” will arise. To solve this, you can either select the position of a plane where boundaries can be found (Geometry: Pos: ) or simply deactivate the region boundary plot (Geometry: Use: No).

I comment below on the different points you mention:

  1. In the region defined at usrbin21 there are no boundaries, so the only option would be setting Geometry: Use: No.
  2. When you select the projection along Z axis for usrbin22, the default configuration tries to find boundaries in Z=51, where there is none. Hence, try selecting another Z in Geometry: Pos: <new_Z>, or simply disable it.
  3. Again, changing the axis and limits, modifies the location where FLAIR looks by default the boundaries, and errors will arise in some cases.
  4. Similar.

Last of all, I would suggest you edit the aspect ratio of the plots by clicking “Title:”, so that the usrbin plots have symmetrical axes.

I hope this helps.

Mario Sacristan

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Dear @msacrist
I’m sorry for replying so late.I have redone the 2D projection plot according to your method,and it is successful.Thank you for your advice, which helped me a lot.
Best ragard,

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