Correction to: Variability in lutetium-177 SPECT quantification between different state-of-the-art SPECT/CT systems - Steffie M. B. Peters; Sebastiaan L. Meyer Viol; Niels R. van der Werf; Nick de Jong; Floris H. P. van Velden; Antoi Meeuwis; Mark W. Konijnenberg; Martin Gotthardt; Hugo W. A. M. de Jong; Marcel Segbers (EJNMMI Physics, 2021)