Biological observation with fluorescent X-ray CT

点击翻译按钮获取中文摘要

In recent biomedical research, the innovation of the new imaging techniques with high-contrast and high-spatial resolution is required for molecular imaging. Fluorescent x-ray technique used in the planar mode is one of the most sensitive methods for detecting trace elements of large atomic numbers in the order of picogram. However, the specimen must be cut into thin slices and be scanned with a beam perpendicular to its surface. Fluorescent x-ray CT (FXCT) method described here combines the sensitivity of fluorescence x-ray technique and the cross-sectional description of CT. Here, we describe the in-vivo FXCT imaging and related experimental results.FXCT system consists of a silicon (111) double crystal monochromator, an x-ray slit system, a scanning table, two high purity germanium (HPGe) detectors, and pin-diode detectors. The experiment was carried out at the bending-magnet beam line of the Tristan accumulation ring in Tsukuba, Japan. Monochromatic x-ray energy was set 37keV, The incident monochromatic x-ray was collimated into a pencil beam of 1 x 0.1mm^2 for the live objects, and less than 0.5 x 0.2 mm^2 for the pathological specimens, respectively. The data acquisition time was set 5 sec for each scanning step.I-127 labeled IMP inside the brain of a live mouse was clearly imaged by FXCT at a 1 mm spatial resolution and a 0.1 mm slice thickness. Transmission x-ray CT that demonstrate geometrical structure of skull, can be simultaneously obtained with FXCT, so the anatomical position corresponding functional changes can be understood easily. Thus, in-vivo FXCT imaging of cerebral perfusion has succeeded for the first time in the world. FXCT could reveal the distribution of 1-127 IMP within ex-vivo brain and BMIPP within myocardium of hamster. Thus, the success of FXCT imaging at in-vivo and ex-vivo, allows starting new approach to bio-imaging research.