Adaptive assay of radioactive pulmonary aerosols with an external detector

The accuracy of the assay of radioactive pulmonary aerosols is influenced by the spatial distribution of the aerosol in the lungs. In general, there is considerable uncertainty in the spatial distribution of the aerosol beginning a few months after inhalation. This paper develops an adaptive approach for optimizing the assay of non-uniform spatial distributions of pulmonary aerosols. An adaptive assay is one in which the design of the assay system is modified during operation in response to measurements obtained on-line. Experimental results are presented which compare the performance of an adaptive assay with that of the standard measurement procedure. We study the assay of 241Am distributed in the lungs of a Lawrence Livermore realistic phantom using a NaI-CsI Phoswich detector.