Use of a sheet-like composite material for the manufacture of an immobilization element, wherein the sheet-like composite material is made from a material comprising a thermoplastic polymer containing carbon nanotubes as a fibrous reinforcing material, obtainable by dispersing carbon nanotubes in a dispersing liquid in which the thermoplastic polymer does not dissolve, subjecting the dispersion to an ultrasonic treatment, adding of particles thermoplastic polymer to the dispersion and mixing of the thermoplastic polymer with the dispersion of carbon nanotubes, removing of the dispersing liquid, forming of the thermoplastic polymer impregnated with carbon nanotubes into a sheet.
