Characterization of a New D-D Neutron Generator System for Neutron Activation of Manganese in Bone in-Vivo
Abstract
Neutron Activation Analysis (NAA) is a non-invasive method for assessing the qualitative and quantitative elemental composition of a sample. One application of this technique is in-vivo quantification of specific elements in the human body. An important element in terms of human exposure assessment is Manganese (Mn). Mn is the fourth most used industrial metal and can be an inhalation exposure hazard specifically for welders. Over exposure to Mn can lead to neurological degeneration issues similar to Parkinson’s disease. It has been found that bone is a good biomarker for Mn as Mn is deposited in the bone and remains for long periods of time, allowing for an assay to reveal long term exposure information. The method of using NAA to quantify levels of Mn in-vivo using the bones in the human hand is being explored in this work. The NAA system used, involves a deuterium-deuterium neutron generator and an N-type High Purity Germanium Detector. It is critical to have the performance of the entire system characterized using phantoms and cadaver bones before the system can be used for in-vivo measurements. The goal of this work is to determine the neutron yield of the generator system, the neutron and photon dose received by a sample, the detection limit of Mn with this system, and to evaluate the Mn detection capability of the system using cadaver bones from occupationally exposed Mn miners. The parameters were determined through a combination of simulation with Monte Carlo N-Particle Code (MCNP), experiments using Mn doped bone phantoms and cadaver bones, and various dosimetry tools such as TLDs and EPDs. The neutron yield for the D-D 109M generator was estimated to be 2.24E+09 +/- 2.15E+07 neutrons per second for this work. The Mn detection limit for the system was estimated to be 0.442 ppm. The equivalent dose received by the sample during the standard 10-minute irradiation was estimated to be 8.45 +/- 2.05 rem. The results found for the human cadaver bones were mixed. It was found that the system was able to successfully detect Mn in cadaver bones. Unexpectedly, however, three of the samples showed little to no Ca signal. In addition, significant amounts of soft tissue and bone marrow exist in the samples. Therefore the Mn concentration in the bones was not able to be accurately estimated. A relative metric of Mn concentration was used instead and showed a slight positive increase from the unexposed to exposed samples but was not statistically significant.
Degree
M.Sc.
Advisors
Nie, Purdue University.
Subject Area
Energy|Aquatic sciences|Atomic physics|Neurosciences|Physics|Thermodynamics
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