Upgraded in vivo counting for plutonium, americium and uranium

Significant advances in the measurement of 239Pu, 241Am, 235U, and 238U have been obtained over the past several years due to the availability of the Livermore Lung phantom and the ''mock'' plutonium study. Further improvements have been obtained through the use of arrays of high-purity planar germanium detectors. Even further improvements are needed if we are to achieve the ability to reliably measure pure 239Pu lung burdens of 16 nCi or less in the average size radiation worker. Although there are many approaches that could provide improved measurement capability, only five of the more important ones will be discussed in this paper. 8 refs., 7 figs