1. A method for determining the distributions of density and atomic number in an object to be examined, comprising: recording a first distribution of X-ray absorption values of the object to be examined for a first X-ray spectrum, and recording at least a second distribution of X-ray absorption values of the object to be examined for a second X-ray spectrum; determining a first functional dependence recorded first distribution, of a first X-ray absorption value of the first distribution of X-ray absorption values on density and atomic number; determining at least a second functional dependence, from the recorded second distribution, of a second X-ray absorption value, assigned to the first X-ray absorption value, of the second distribution of X-ray absorption values on density and atomic number; and ascertaining a value for the density and the atomic number from a comparison of the first functional dependence with at least one of the second functional dependence and at least one further functional dependence.