Flatness and Symmetric Problem

hi all

when I try to use the FlatSym module in Pylinac since my EPID image was inverted (background was 1 and the radiation field was 0), the results will be wrong (see attached image) the original image also was attached.
can you give me some solution?


RI.25698111.10_10-1_1_1.dcm (387 KB)

I do my analysis a bit differently, but I think you could do the following:

  • my_img = pylinac.FlatSym([insert image path here])

Then, if you suspect that it needs to be inverted you can do:

  • my_img.invert()
    Then you can analyze:

  • my_img.analyze()

Hi David

Thank you, but when I used ‘my_image.invert()’ and I received this error: "‘FlatSym’ object has no attribute ‘invert’".

**I think I should add some inversion property to it. could you share your '**flatsym.py’ file with me??

Best regards.


For the newest version of pylinac use my_img.image.invert()

Hi James

Thank you so much. it works well.

Another problem is that when calling StandardImagingQC3 , it returns: “ValueError: Unable to find the QC-3 phantom in the image.” error

I attached my image.

aS100 Image.dcm (1.5 MB)

Change this line in your local library: https://github.com/jrkerns/pylinac/blob/master/pylinac/planar_imaging.py#L511

change rtol=0.05 to rtol=0.07 and it works.

Thanks, James.

As you said I changed it but still get the previous error.

Is it possible for you to share the “planar_imaging.py” file with me?