A tomography installation is configured to carry out a first scan along a first helix-segment-shaped trajectory section and to carry out a second scan along a second helix-segment-shaped trajectory section. A first data set is obtained during the first scan, and a second data set is obtained during the second scan. Taken by themselves in each case, both the first data set and the second data set are too incomplete for a reconstruction of a volume image without a partial revolution artifact. From the two data sets, a fused three- or four-dimensional data set is generated that is sufficiently complete for a reconstruction of a volume image without a partial revolution artifact.