109Cd源激发的X射线荧光法无创伤测定人体骨铅含量

建立了用以体内测定骨铅含量的109Cd源作为激发源的X射线荧光测量系统. 该系统采用高纯锗探测器(10 mm×7 mm), 检测人体胫骨中铅被109Cd的88.0 keV的γ射线激发后产生的特征K层X射线. 采用铅的K层X射线对相干散射归一化的方法, 根据铅的K层X射线强度与相干散射强度的比值对胫骨模型铅含量之间的校正曲线, 便可得到人体骨铅的含量. 这种归一化的方法, 使测量结果的精确度不受骨外组织层厚度、骨的形状、大小、密度以及被测者位移的影响. 用含铅石膏制作的一组胫骨模型得到的校正曲线呈现良好的线性关系. 对急性铅中毒工人的试验性测量结果表明, 他们的骨铅含量明显高于对照组.

Non-Invasive Determination of Bone Lead in Human Body Using X-Ray Fluorescence Excited by 109Cd

A measurement system of X-ray fluorescence excited by 109Cd was set up for the in vivo measurement of bone lead. In the system, a HPGe detector (phi 10 mm x 7 mm) was used to detect the characteristic K X-rays of lead in tibia excited by gamma rays of 88.0 keV from 109Cd. By the normalization of lead X-rays to the coherent scatter, the content of bone lead was calculated from the calibration curves of the ratio (X-ray intensity: coherent intensity) against the lead concentration in tibia phantoms. The normalization technique rendered the measurement accuracy independent of tissue overlay thickness, bone shape, size, mass, and subject motion. Calibration curves obtained from a set of tibia phantoms with lead-doped plaster of Paris were linear. The results of pilot measurements showed that the contents of bone lead in the occupationally exposed workers were higher than those in the control group.