The present invention relates to a thermoplastic composition suitable for manufacturing a thermoplastic sheet for producing a medical cast, such as a radiation mask. The composition has a polymeric component comprising a mixture of a styrene acrylonitrile copolymer and polycaprolactone, optionally together with a cross-linker and/or a filler, wherein the polymeric component comprises, 20 to 40 weight% of a styrene acrylonitrile copolymer and 80 to 60 weight% of a polycaprolactone, expressed in weight% of the polymeric component, wherein the thermoplastic composition has a glass transition temperature of 35 °C - 80 °C. The invention further relates to a thermoplastic sheet and to a medical cast, in particular a radiation mask, obtainable from said composition. In a final aspect, the invention relates to a method for producing said sheet and said radiation mask.
