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Development of fluorescent x-ray detection technique in FXCT

FXCT荧光X射线检测技术的发展

基本信息

批准号：
13470178
负责人：
TAKEDA Tohoru
金额：
$ 10.5万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13470178/
关键词：
Fluorescent x-ray Computed tomography Specific element in vivo imaging Fluorescent x-ray detection

项目摘要

Fluorescent x-ray technique is used to evaluate very low contents of specific elements in the order of picograms, however the measurement must be performed in the surfade of object. Then for in biological sample, the specimen is required to be cut into thin slices and scanned with a beam perpendicular to its surface. Fluorescent x-ray computed tomography (FXCT) have being developed to reveal the distribution of specific element in living state. By positioning the x-ray detector at 90° to the beam, the linear polarization of synchrotron x-rays helps to significantly reduce the Compton scattering overlapping the K_α line of specific elements. However, Compton scattering has increased markedly in large object, and highly purified germanium detector cannot measure the huge amounts of photon. To improve this problem, three experiments such as filter method, parallel collimator method and Laue-mirror method, were done to examine the reduction of Compton scattering from object.Filter method, which is firstly thought most easy and highly effective method to reduce Compton scattering, is not useful because secondary fluorescent x-ray was generated by filter itself and this fluorescent x-ray overlaps on the iodine K_α line. Intense parallel collimator method, which reduces the efficacy of fluorescent x-ray detection, is most effective to reduce Compton scattering and to detect small amounts of fluorescent x-ray. Most ideal Laue-mirror method is difficult to set up the mirror system, so further improvement of x-ray mirror and its dedicate control is needed.For in vivo FXCT imaging, collimator or Laue-mirror method appear to be an useful technique to reduce the huge amounts of Compton scattering from large object.

荧光X射线技术用于评估皮克量级的极低含量的特定元素，但测量必须在物体的表面进行。然后，对于生物样品，需要将样品切成薄片，并用垂直于其表面的光束进行扫描。荧光X射线计算机断层扫描（FXCT）已发展到揭示在生活状态下的特定元素的分布。将X射线探测器置于与光束成90°的位置，同步辐射X射线的线偏振有助于显著减少与特定元素K_α线重叠的康普顿散射。然而，康普顿散射在大物体中显著增强，高纯锗探测器无法测量大量光子。为了解决这一问题，我们分别用滤波器法、平行准直器法和劳厄镜法对康普顿散射进行了实验研究，滤波器法被认为是最简单、最有效的康普顿散射抑制方法，但由于滤波器本身产生的次级荧光X射线与碘K_α线重叠，因此滤波器法对康普顿散射的抑制作用不大。强平行准直器方法降低了荧光X射线检测的功效，对于减少康普顿散射和检测少量荧光X射线最有效。在体FXCT成像中，准直器或劳厄镜法是一种有效的方法，可以有效地降低大物体的康普顿散射。