Calibration and evaluation of a system of total body in vivo activation analysis using 14 MeV neutrons.

A system has been established for determining the total body contents of calcium, phosphorus, sodium, chlorine and nitrogen by neutron activation analysis using sealed-tube neutron generators and a shadow-shield whole-body counter. The system was calibrated using three anthropomorphic phantoms of different sizes, filled with various mixtures of the activatable elements in amounts similar to those in man. The reproducibility determined from replicate measurements, was on average +/- 2.9% (SD). The average uncertainty in absolute measurements was estimated to be +/- 4.2% (68% confidence interval).