The feasibility of measuring manganese concentrations in human liver usingneutron activation analysis

Manganese is an element which is required by the human body. However, as wi th most metals, in large amounts manganese can be toxic. People who suffer from severe manganese intoxication have symptoms similar to those of Parkin son's disease. Preclinical symptoms of manganese intoxication have recently been detected in individuals working in industries which have manganese di oxide dust in the air. The concentration of many toxic elements can be meas ured in vivo using neutron activation. A small dose of neutrons is delivere d to the organ of interest, the neutrons are readily captured by the target nuclei, and the gamma rays given off can be detected outside of the body. A neutron activation analysis system is being developed to measure manganes e concentrations in humans. The McMaster KN-accelerator supplies the neutro n beam and the thermal neutron capture reaction Mn-55(n,gamma)Mn-56 is used . The half-life of Mn-56 is 2.58 hr and thus counting can occur after irrad iation. The 847 keV gamma ray given off when 56Mn decays is detected using a Nal detector. Calibration curves are made using phantoms with known conce ntrations of Mn. This system will be used to monitor manganese levels in in dividuals who have occupational exposure to the element. Preliminary measur ements, using liver phantoms, give a minimum detectable limit for Mn in the liver of less than one part per million, which is well below normal levels . (C) 1999 Inter Press, Inc.