PhD, University of Cincinnati, 2013, Engineering and Applied Science: Nuclear and Radiological Engineering

This research improves the measurement of activity deposited in the axillary lymph nodes through the following specific aims:A. Determine the confounding influence of 241Am deposited in organs adjacent to the axillary lymph nodes by simultaneous solution of response functions for measurement of 241Am deposited in the liver, lungs, and skeleton.Hypothesis: A series of direct, organ-specific measurements can be used to account for measurement interference for the axillary lymph nodes from activity deposited in other organs.Radioactive material deposited in multiple organs of the body is likely to confound a result of an in vivo measurement performed over the lungs for routine occupational exposure monitoring. The significance of this interference was evaluated by measuring anthropometric torso phantoms containing lungs, liver, skeleton and axillary lymph nodes, each with a precisely known quantity of 241Am uniformly distributed in the organs. Arrays of multiple high resolution germanium detectors were positioned over organs within the torso phantom containing 241Am or over proximal organs without activity to determine the degree of measurement confounding due to photons emitted from other source organs. A set of four mathematical response functions describe the measured count rate with detectors positioned over each of the relevant organs and 241Am contained in the measured organ or one of the other organs selected as a confounder. Simultaneous solution of these equations yields the activity deposited in each of the relevant organs. The matrix solutions described represent a technically valid method for adjusting a result of 241Am measured in one organ for interferences that may arise from 241Am deposited elsewhere, so internal dose from radioactive materials known to deposit in multiple organs may be evaluated based upon in vivo measurements.B. Select the size and type of detector that offers the greatest sensitivity for 241Am in axillary lymph nodes measurements wit (open full item for complete abstract)

Committee: Henry Spitz Ph.D. (Committee Chair); Sam Glover Ph.D. (Committee Member); J. Kim Ph.D. (Committee Member); Paul Succop Ph.D. (Committee Member) Subjects: Nuclear Engineering