For Covid-19 lung tissue, the scans were recorded at the GINIX endstation of the PETRA III storage ring (DESY, Hamburg). The projections were acquired at two different photon energies Eph, 8⁢keV and 13.8⁢keV, using the first and third harmonic of the 5 m P10 undulator and a Si(111) channel-cut monochromator, respectively. Data are shown here only for 8⁢keV, which gave highest contrast for the unstained lung tissue. Two tomography configurations were combined to cover a larger range of length scales: