A radiation detector is disclosed for the detection of ionizing radiation, preferably in a medical diagnosis and/or therapy system, having at least one detector element which is at least partially enclosed by an encapsulation compound. The encapsulation compound at least partially reflects light which is produced during the absorption of the ionizing radiation in the at least one detector element. Further, the detection of the radiation is carried out indirectly by detection of the generated light, wherein the encapsulation compound is made of a multicomponent mixture which converts compounds produced because of radiation, which generate color changes of the encapsulation compound, at least partially into colorless nonabsorbing compounds.