The present invention relates to a method for manufacturing a polymer sheet for use as an immobilization element, wherein the sheet is at least partly made of a polymer material comprising a polymer from the group of polycaprolactone, a copolymer of polyethylene with at least one α-olefin having 3-10 C atoms, or a mixture of two or more of the aforementioned polymers, a photo-initiator, and a photo-cross-linker, wherein the polymer sheet has a thickness of 1.0 to 5 mm and wherein the polymer sheet is at least partially cured by exposing to UV radiation for the at least partially cross-linking of the polymer.
