Developmental Scientific Research of Radiograph with Elemental Selectivity

x射线透射强度取决于组成元素的线性吸收系数和样品厚度。因此，透射的x射线强度形成样品内部投影的图像。这种技术被称为射线照相，并应用于许多不同的领域。在含有几个原子序数相似的元素的样品中，不期望样品图像中有明显的对比。为了解决这一问题，我们利用边缘附近线性吸收系数的剧烈变化来获得与当前吸收边缘对应的某元素的透射图像。在目前的新x射线照片中，使用样品中一个成分的吸收边缘下方和上方的两个入射能量拍摄了两个x射线透射图像。由于在这两个能量处线性吸收系数有很大的跳跃，两张x光片显示出不同的对比。通过取它们之间的差值，我们只能得到包含相应元素的区域的射线图。即实现了具有元素选择性的射线照相。在本方法中，两个点被通知。首先，为了定量分析，必须精确地监测两种能量下的入射x射线强度。其次，利用成像板测量透射光强。这样，观测到的图像很容易数字化，便于进一步分析。

X-ray transmission intensity depends on a linear absorption coefficient of a constituent element and a sample thickness. Thus, transmitted x-ray intensity forms an image of a projection of an interior of a sample. This technique has been known as a radiograph and applied to many different fields. In a sample containing several elements of similar atomic numbers, a clear contrast in a sample image is not expected. In order to solve this problem, we use a drastic change of linear absorption coefficient near the edge to obtain the transmitted image of a certain element correspond to the present absorption edge. In the present new radiograph, two x-ray transmission images have been taken using the two incident energies just below and above the absorption edge of one of the constituents in the sample. Because of a large jump of the linear absorption coefficient at these two energies, the two radiographs show a different contrast. By taking a difference between them, we only obtain a radiograph of the region containing the corresponding element. Namely, the radiograph with the element selectivity is realized. In the present method, a couple of points are notified. Firstly, for the quantitative analysis, the incident x-ray intensities at the two energies must be accurately monitored. Secondly, the transmitted intensity is measured with an imaging plate. In this way, the observed image is easily digitized for the further analyses.