In vivo determination of nitrogen using Pu-Be sources

Abstract
A method of measuring [human] body N by neutron capture .gamma.-analysis is described. The neutron flux is provided by 4 collimated 5 Ci Pu-Be sources, placed to give a bilateral irradiation of the subject. The 10.83 MeV thermal neutron capture .gamma.-rays from 14N were detected by 2 heavily shielded 5 in .times. 4 in NaI(Tl) detectors. There was a reproducibility of .+-. 3% (1 SD) for a 10 min irradiation of the chest area, while giving a radiation dose equivalent of 50 mrem.