Department of Physics

Experience/Research

My research objective is to extend the experiments to develop a clinical diagnostic tool for detection of aluminum stored in human bone.

Aluminum (Al), the third most abundant element in the earth's crust, is known for its harmful biological effects. The Al load in human body can inhibit bone mineralization. Clinical exposure to aluminum present in dialysis fluid and the use of aluminum phosphate binders in patients with kidney and renal failure diseases are associated with dialysis encephalopathy syndrome and bone related secondary ailments like osteodystrophy, osteoarthritis and osteomalacia. The relationship between chronic Al exposure and the risk of Alzheimer's disease remains controversial. It is documented that the exposure to Al compounds and dusts in aluminum plants leads to neurological syndromes in occupationally exposed people. Al levels are routinely monitored by sampling blood and urine however these give only information about the recent exposure of the elements. The clinical method of detection of cumulative levels of Al in bone is iliac crest bone biopsy, which is painful and thus invasive and cannot be used as a routine monitoring approach.

My research project aims in developing a non-invasive, in vivo technique for the measurement of cumulative levels of Al stored in human bone. The technique of In-Vivo Neutron Activation Analysis (IVNAA) at McMaster University Accelerator laboratory (MAL) that has been in use for trace element analysis is adapted for this need. In IVNAA, neutrons from the thick lithium target (⁷Li (p, n) ⁷Be) in Tandetron accelerator is used to activate the human hand containing ²⁷Al, a 100% abundant isotope of aluminum. The ²⁷Al absorbs the thermal neutrons and undergoes the nuclear reaction, ²⁷Al(n, γ)²⁸Al, to form ²⁸Al, with the cross-section of 0.23barn. The nuclear product ²⁸Al is radioactive and has a half life of 2.35 minutes disintegrating rapidly to ²⁸Si with the emission of high energy γ rays (1.78 MeV). The induced gamma rays are detected using an array of 4π NaI (Tl) detectors and the amount of Al is measured using spectral decomposition method. The dose accompanying IVNAA of Al is 17.6 mSv with the corresponding effective dose of 14.4 µSv. This effective dose is comparable to that delivered in conventional chest and dental x-rays.

I hope my research will contribute to better measure Al levels in human bone and therefore, improve monitoring toxic effects of Al in dialysis patients as well as in the occupationally exposed population. Furthermore, this research has potential to provide additional physiological information of the effects of Al on human bone.

List of Selected Publications/Presentations

K. Davis , Aslam, A. Pejović-Milić, S. H. Byun, D. R. Chettle (2007), Bone Aluminum Measurement with Accelerator-based In Vivo Neutron Activation Analysis, Annual Conference of Canadian Association of Physicists, June 2007, Saskatoon, Saskatchewan, Canada.