L-shell x-ray fluorescence (LXRF) is a non-invasive approach to lead (Pb) concentration measurements in human bone. The method is based on the detection of the characteristic x-ray photons of Pb at 10.5 and 12.6 keV and experimental studies were designed to perform in vivo human bone Pb measurements. In later studies, however, the initial LXRF methodology was shown to have poor accuracy and precision. In a recent publication, we investigated an optimal grazing-incidence position (OGIP) approach using a submillimeter x-ray beam from an integrated x-ray tube and polycapillary x-ray lens table-top system. The OGIP method effectively reduced the x-ray scatter and produced a Pb detection limit of ~5 μg/g for a 2 mm soft tissue phantom thickness. In this study, the OGIP methodology was improved by using 10 s x-ray spectra acquisitions at sequential positions 0.5 mm apart. The measured Sr Kα peak height versus position data was used to spectroscopically identify the bone phantom and the OGIP. The data was fitted with the analytical convolution between a Gaussian and an exponential decay. The position corresponding to the maximum of the fitted convolution function was then selected as the OGIP. Four phantom sets were used. A cylindrical plaster-of-Paris bone phantom doped with Pb in a concentration of 74 μg/g was used as a bare bone phantom or with one of the three overlying polyoxymethylene cylindrical shell soft tissue phantoms of 1, 2, and 3 mm thickness. The reproducibility of the OGIP method was assessed in five independent trials using each of the four phantom sets. The coefficient of variation (COV) percentage values of the Sr Kα peak height measurements were below 5%. The new procedure decreased by more than threefold the duration and radiation dose of the earlier approach.

中文翻译：

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对骨骼和软组织体模中铅的 L 壳 X 射线荧光测量的最佳掠入射位置方法的改进和再现性

L 壳 X 射线荧光 (LXRF) 是一种非侵入性方法来测量人体骨骼中的铅 (Pb) 浓度。该方法基于检测 10.5 和 12.6 keV 的 Pb 的特征 X 射线光子，并设计了实验研究以进行体内人体骨骼 Pb 测量。然而，在后来的研究中，最初的 LXRF 方法被证明具有较差的准确度和精确度。在最近的一份出版物中，我们使用来自集成 x 射线管和多毛细管 x 射线透镜桌面系统的亚毫米 x 射线束研究了最佳掠入射位置 (OGIP) 方法。OGIP 方法有效地减少了 X 射线散射，并且对于 2 mm 软组织体模厚度产生了 ~5 μg/g 的 Pb 检测限。在这项研究中，通过在相距 0.5 毫米的连续位置使用 10 秒 X 射线光谱采集改进了 OGIP 方法。测量的 Sr Kα 峰高与位置数据用于光谱识别骨模型和 OGIP。数据拟合了高斯和指数衰减之间的解析卷积。然后选择对应于拟合卷积函数最大值的位置作为OGIP。使用了四个幻影集。使用浓度为 74 μg/g 的 Pb 掺杂的圆柱形巴黎石膏骨模型作为裸骨模型或三个覆盖的聚甲醛圆柱壳软组织模型之一，厚度为 1、2 和 3 毫米。OGIP 方法的可重复性在五个独立试验中使用四个体模组中的每一个进行了评估。Sr Kα 峰高测量值的变异系数 (COV) 百分比值低于 5%。新程序的持续时间和辐射剂量比早期方法减少了三倍多。