The invention relates to an iterative method of determining a spatial distribution of values of a property of an object, and particularly values of its absorption, in an examination region, on the basis of measured values that values are acquired with a measuring device, and particularly with a computer tomograph. The reliability of each measured value is taken into account when this is done. The measured values can each be represented as a sum of values of the property that have each been multiplied by a proportional factor, the proportional factor being a measure of the proportion that a value of the property forms of the measured value. Each value of the property is approached by one iteration value at a time by setting each iteration value to a starting value and, in an iteration step, generating for each measured value a reference measured value, forming the difference between each reference measured value and the corresponding measured value, and multiplying this difference by a reliability parameter and projecting it backward into the examination region.