The present invention relates to an immobilization mask comprising a first layer comprising a low temperature thermoplastic material, the first layer having a first side and a second side at least one dimensionally stable attachment section connected to the first layer and at least one deformable molding member connected to the first side or to the second side of the first layer. The present invention also relates to a method of immobilizing a patients body part, comprising the steps of applying an immobilization mask comprising a first layer having a low temperature thermoplastic material and at least one dimensionally stable attachment section connected to the first layer, wherein at least one deformable molding member is placed between the first layer and the patients head and molding the first layer tightly to the patients head and to the molding member.