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Characterization of a New D-D Neutron Generator System for Neutron Activation of Manganese in Bone In-Vivo

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posted on 27.04.2022, 14:20 by Elizabeth Helen JayeElizabeth Helen Jaye

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 usedindustrial 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  Mnas  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 systemusing 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  yieldfor the  D-D  109M  generator  wasestimated to be2.24E+09+/-2.15E+07neutrons per secondfor this work. The Mn detection limit for the system was estimatedto be 0.442 ppm. The equivalent dose received by the sampleduring the standard 10-minute irradiation was estimated to be 8.45 +/-2.05rem. The results found for the human cadaver bones weremixed. It was found that the system was able to successfully detect Mn incadaver 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.Thereforethe 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.

History

Degree Type

Master of Science

Department

Medical Physics

Campus location

West Lafayette

Advisor/Supervisor/Committee Chair

Linda Nie

Additional Committee Member 2

Aaron Bowman

Additional Committee Member 3

Keith Stantz

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