dMRIprep ! Tissue Segmentation - Freesurfer or FSL?

I am considering implementing dMRIprep in the lab I work in, but I couldn’t understand from the documentation if the brain segmentation is done with FSL or Freesurfer tools ?
I see that in the GitHub script recon-all is activated, thus using Freesurfer, but I’m not sure if it’s possible to disable it and use FSL instead. We work with brain tumors, so FSL would be better.
Could someone please help me with that?