In-Vivo Neutron Activation Analysis for Aluminium in Bone: System Upgrade and Improve Data Analysis

An existing NaI(Tl) multidetector array at McMaster University used for in vivo measurement of aluminum by means of neutron activation has been recently upgraded with an in-house built pulse processing system. The new system is capable of collecting spectra in coincidence and anticoincidence modes which allows for better discrimination between the 1.78 MeV 28 Al peak and the interfering 38 Cl peak. The system is interfaced with Matlab and controlled using a custom graphical user interface, which provides periodic spectral data storage during the acquisition. This feature makes it possible to validate the acquired data and the spectral fitting routines through half-life analysis of the radionuclides. A new set of calibration phantoms spanning a narrower range of aluminum concentrations than employed in the previous study, has also been developed. The combined effect of the new improvements resulted in the minimum detectable level of aluminum in aqueous solutions containing Na, Cl, and Ca in physiological levels, equal to approximately 3 µgAl/gCa.