Parameters for applying materials to CT

Dear FLUKA experts,
I am trying to simulate a simple CT calibration phantom in FLUKA.
I have implemented the relevant DICOM files through FLAIR, using the provided body.mat file. However, I should update the file, to my understanding.
I have the HU to electron density from the CT scan, and the electron density of the calibration phantom.

1. How should I update the file? Should I create a new file, based on the my HU ranges?
2. What is the meaning of the Crho_min/Chro_max and CdEdx_rel_min/CdEdx_rel_max parametes? I saw that in the provided file the CdEdx_rel_min/CdEdx_rel_max parameters were set to 1. Should I change it? if so, how to?

1. The head.mat and body.mat are provided as an example for a specific machine. The HU → MATERIALS correspond to the Schneider parametrisation, but for your CT you might need some adjustments. You can copy the body.mat or head.mat (which ever fits better to your case) and modify it, either with a text editor or inside flair.