In vivo study of an x-ray fluorescence system to detect bone strontium non-invasively.

Medical Physics and Applied Radiation Science, McMaster University, Hamilton, L8S 4K1, Canada.
Physics in Medicine and Biology (Impact Factor: 2.7). 04/2007; 52(8):2107-22. DOI: 10.1088/0031-9155/52/8/005
Source: PubMed

ABSTRACT An x-ray fluorescence (XRF) system using 125I as the source was developed to measure strontium in bone in vivo. As part of an in vivo pilot study, 22 people were measured at two bone sites, namely the index finger and the tibial ankle joint. Ultrasound measurements were used to obtain the soft tissue thickness at each site, which was necessary to correct the signal for tissue attenuation. For all 22 people, the strontium peak was clearly distinguishable from the background, proving that the system is able to measure Sr in vivo in people having normal bone Sr levels. Monte Carlo simulations were carried out to test the feasibility and the limitations of using the coherently scattered peak at 35.5 keV as a means to normalize the signal to correct for the bone size and shape. These showed that the accuracy of the normalized Sr signal when comparing different people is about 12%. An interesting result arising from the study is that, in the measured population, significantly higher measurements of bone Sr concentration were observed in continental Asian people, suggesting the possibility of a dietary or race dependence of the bone Sr concentration or a different bone biology between races.

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    ABSTRACT: Ten female volunteers were recruited as part of the Ryerson and McMaster University Strontium (Sr) in Bone Research Study to have their bone Sr levels measured as they self-supplemented with Sr supplements of their choice. Of the ten volunteers, nine were suffering from osteopenia and/or osteoporosis. Non-invasive bone Sr measurements were performed using an in vivo x-ray fluorescence (IVXRF) I-125 based system. Thirty minute measurements were taken at the finger and ankle, representing primarily cortical and trabecular bone, respectively. For analysis, the 14.2keV Sr K-alpha peak normalized to the Coherent peak at 35.5keV was used. Baseline readings, representing natural bone Sr levels were acquired since all volunteers had no previous intake of Sr based supplements or medications. Once Sr supplements were started, a 24hr reading was taken, followed by frequent measurements ranging from weekly, biweekly to monthly. The longest volunteer participation was 1535 days. The mean baseline Sr signal observed for the group was 0.42±0.13 and 0.39±0.07 for the finger and ankle, respectively. After 24hrs, the mean Sr signal rose to 1.43±1.12 and 1.17±0.51, for the finger and ankle, respectively, representing a statistically significant increase (p=0.0043 & p=0.000613). Bone Sr levels continued to increase throughout the length of the study. However the Sr signal varied widely between the individuals such that after three years, the highest Sr signal observed was 28.15±0.86 for the finger and 26.47±1.22 for the ankle in one volunteer compared to 3.15±0.15 and 4.46±0.36, for the finger and ankle, respectively in another. Furthermore, while it was previously reported by our group, that finger bone Sr levels may plateau within two years, these results suggest otherwise, indicating that bone Sr levels will continue to rise at both bone sites even after 4 years of Sr intake.
    Bone 01/2014; · 4.46 Impact Factor
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    ABSTRACT: The use of an energy-dispersive X-ray fluorescence spectrometry (EDXRF) system equipped with an 125I source was validated for in vivo and ex vivo quantification of strontium in human teeth. The mean concentration of enamel strontium for an area with a high influx of immigration (Toronto, Ontario, Canada) is also reported. It was found that the mass attenuation of the strontium and calcium X-rays allows for a probing depth of 1.8 mm (SrKα) allowing the front central incisors to act as the site for the in vivo or ex vivo quantification of strontium as well as for molars to be used ex vivo for the quantification of enamel strontium. The calcium signal for all teeth studied (n = 42) was found to have a relative standard deviation of 5.7% which allowed for successful normalization of the strontium signal to that of calcium. Validation of the EDXRF method was performed on human molars (enamel thickness of (1.9 ± 0.7) mm, p < 0.05), by graphite furnace atomic absorption spectrometry (GFAAS). The EDXRF method was found to produce equivalent strontium determinations to that of GFAAS (p < 0.05). Our results also demonstrate that for a sample from a large metropolitan area, the fresh enamel strontium concentrations range from 42–301 ppm with a mean strontium concentration of (169 ± 80) ppm (p < 0.05).
    Journal of Analytical Atomic Spectrometry 01/2008; 23(4). · 3.40 Impact Factor
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    ABSTRACT: X-ray fluorescence has been used to measure several elements noninvasively within living human subjects. Some description is given of the constraints imposed by this rather unusual form of analysis together with a brief listing indicating the range of elements for which such analyses have been developed. Measurements of two elements are then presented in more detail. Lead is measured in bone and has become a well-established tool in continuing research into the long term effects of lead. Strontium is also measured in bone and, although presently not in widespread use, offers the potential for essential information in the study of the reported benefits of strontium supplementation.
    Pramana 01/2011; 76:249-259. · 0.56 Impact Factor


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