The feasibility of in vivo detection of lanthanum using a 241Am K x-ray fluorescence system.

OBJECTIVE: Lanthanum (La) is commonly used in phosphate binders in the form of lanthanum carbonate in patients with end-stage kidney disease undergoing hemodialysis treatments. With this administration, there is the potential for La storage in the body with bone being the main site of concern. However, the long-term effects of residual La in the body on bone health are not yet known. In this work, we investigate the feasibility of using a K x-ray fluorescence (K-XRF) spectroscopy system to measure bone La in vivo. APPROACH: A series of hydroxyapatite (HAp) bone mineral phantoms were created to represent human bone. A 1.09 GBq 241Am source was used to excite the HAp phantoms doped with various known concentrations of La placed in a 90° geometry relative to the photon source and high-purity germanium (HPGe) detector. MAIN RESULTS: For a detector live time of 2000 s, the minimum detection limit was calculated to be 1.7 µg La g-1 Ca or 0.7 µg La g-1 HAp and is comparable to previously reported in vivo bone La concentrations. SIGNIFICANCE: The technique developed in this study shows promising results and provides an alternative method to invasive biopsy sampling techniques to monitor the accumulation of bone La. To the best of our knowledge, this is the first reported work that seeks to non-invasively measure bone La via in vivo XRF.