Quantification of Sodium (Na) in Bone with in Vivo Neutron Activation Analysis (IVNAA) and Its Implications on Na Retention Studies
Abstract
The locations of Na storage and its exchange mechanisms in different tissues in the body are not well known. This information is important for understanding the impact of Na intake, absorption, and retention on human health, especially on the risk of developing chronic diseases like hypertension. In order to non-invasively quantify Na in bone, a compact deuterium-deuterium (DD) neutron generator-based IVNAA system was developed for use in Na nutrition studies. This thesis will first discuss the optimization of the system using MCNP to maximize the thermal neutron flux inside the irradiation cave while limiting radiation exposure to the hand and the whole body. With optimized assembly in place, an animal study was conducted to investigate the storage and exchange of Na in the body. The right posterior legs of two live pigs, one on a low Na diet and one on a high Na diet, were irradiated inside the customized assembly and then measured with a 100% high efficiency high purity germanium detector (HPGe). The results show that the difference in concentration between the pigs on high vs low Na diets was distinguishable with the system. Analysis also shows rapid exchange of Na in the leg during the first 2 hour measurements (with an exchange decay time of 1.3 hours) while the exchange was minimal at the second and third 2 hour measurements, taken 7 and 21 hours post irradiation. With these results, we conclude there is a non or low exchangeable compartment (likely to be bone) for Na storage and that the DD neutron generator-based IVNAA is a useful method in Na nutrition studies.
Degree
M.S.
Advisors
Nie, Purdue University.
Subject Area
Health sciences|Nuclear physics
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