METHODS FOR IN-VIVO MEASUREMENT OF MERCURY IN HUMAN KIDNEYS.

As mercury levels in the human kidney may be related to subclinical mercury poisoning, two methods of in-vivo measurement of mercury have been investigated. Earlier work detecting prompt gamma emission following thermal neutron capture from a neutron source of mean energy 2. 8 MeV gave a lower detection limit of 108 ppm for a dose of 1 rem (10mSv), well above the 10 ppm level necessary for the method to be of any value. However, the computer studies reported here indicate that the use of a 2 keV neutron source could improve the lower detection limit by a factor of 7. The alternative approach investigated was to use X-ray fluorescence, stimulating the characteristic mercury X-rays with a **1**0**9Cd gamma -ray source. Here the detection limit is very sensitive to the thickness of overlying tissue.