Manganese has been so far mainly used for in-vivo animal studies of tissue anatomy of liver, kidneys, heart and pancreas, as well as to monitor cellular activity, cytoarchitecture and neuronal tract tracing in the brain by using the so-called Manganese-Enhanced Magnetic Resonance Imaging (MEMRI)-based techniques. However, the large amount of manganese necessary for MEMRI may induce neurotoxic effects that result in manganism, a neurological syndrome similar to Parkinson\u2019s disease. The much higher sensitivity of positron emission tomography (PET) over MRI enables, instead, the use of non-toxic trace level concentrations of Mn. The radioisotopes 52Mn (t1/2= 5.591 d, \u3b2+= 29.4%, E(\u3b2+)avg= 241.6 keV) and 51Mn (t1/2= 45.59 min, \u3b2+=97.1%, E(\u3b2+)avg = 970.2 keV) have already been used for preclinical PET imaging in the past, mainly administered in free ionic form as MnCl2 1-2. However, internal radiation dose assessment due to the administration of 52MnCl2 to humans is still missing, while only one study has been reported for 51MnCl2 dosimetry calculations2. The aim of this work is to fill this gap by assessing the radiation effective dose (ED) of 51MnCl2 and 52MnCl2
