Proceedings of the 16th Virtual International Meeting on Fully 3D Image Reconstruction in Radiology and Nuclear Medicine.

These proceedings contain the presented papers at the 16th International Meeting on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine 2021, which was to be held in Leuven, Belgium, but had to be transformed in a virtual meeting because of the covid-19 pandemic. Fully3D is one of the major forums for presentation of new results in the field of 3D image reconstruction, primarily with applications in x-ray computer tomography, PET and SPECT. Over the life-time of the meeting the focus has shifted to reflect recent developments in the field. Many of the major developments in fully 3D PET and SPECT imaging were first presented at Fully3D, as were the key results for analytic reconstruction methods in cone beam x-ray CT. Similarly, in the 2021 meeting a broad range of topics has been presented. As expected, deep learning methods are being used increasingly: they are used as post-processing tools or incorporated in the reconstruction, often aiming at improved noise and/or artifact suppression.