The invention is based on the fact that a representation of an object can be improved by means of an irradiation, in view of an ensuing reconstruction of the object based on the representation. In order to achieve this, simulated data corresponding to a simulated irradiation of the object is used, before a reconstruction, as prior information for measuring an irradiation of the object and/or for producing the representation from a measured irradiation. The invention relates to a method for representing an object (10) by means of an irradiation. Said method involves preparing simulated data corresponding to a simulated irradiation of the object (10), in a memory (20) for example; using the simulated data for measuring an irradiation of the object (10) by means of a control mechanism (24), in a CT scanner (12) for example, in order to obtain the irradiation of the object; and/or using the simulated data for producing the representation from a measured irradiation by means of a data preparation device (26).