Compact DD generator-based in vivo neutron activation analysis (IVNAA) system to determine sodium concentrations in human bone

Abstract

Objective: This study presents the development of a noninvasive method for monitoring Na in human bone. Many diseases, such as hypertension and osteoporosis, are closely associated with sodium (Na) retention in the human body. Na retention is generally evaluated by calculating the difference between dietary intake and excretion. There is currently no method to directly quantify Na retained in the body. Bone is a storage for many elements, including Na, which renders bone Na an ideal biomarker to study Na metabolism and retention. Approach: A customized compact deuterium–deuterium (DD) neutron generator was used to produce neutrons for in vivo neutron activation analysis (IVNAA), with a moderator/reflector/shielding assembly optimized for human hand irradiation in order to maximize the thermal neutron flux inside the irradiation cave and to limit radiation exposure to the hand and the whole body. Main results: The experimental results show that the system is able to detect sodium levels in the bone as low as 16 µg Na g−1 dry bone with an effective dose to the body of about 27 µSv. The simulation results agree with the numbers estimated from the experiment. Significance: This is expected to be a feasible method for measuring the change of Na in bone. The low detection limit indicates this will be a useful system to study the association between Na retention and related diseases.