Nuclear medicine is an important field of nuclear medicine, especially thanks to its role in in vivo imaging of important processes in human organism. An overwhelming majority of nuclear medicine examinations comprises of planar scintigraphy and single photon emission computed tomography, for decades relying on the labeling by metastable technetium nuclide (99mTc), used with a great diversity of ligands for various applications. Nuclear medicine departments utilize commercially available molybdenum- technetium generators, being able to elute the nuclide at any time and prepare the radiopharmaceutical. The mother nuclide, molybdenum-99 (99Mo), is produced in just a handful of places around the world. The production places are without exception research nuclear reactors working far past their life expectancy. A concurrent temporary shutdown of two of them in the year 2009 caused a critical worldwide shortage of 99mTc. An unavoidable permanent shutdown of part of these capacities in the second decade of the 21st century will cause the second, and this time rather permanent ”technetium crisis”. The article focuses on history, present, potential future and possible solutions in regard to SPECT diagnostics.