Development of high-sensitive synchrotron x-ray micro CT

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）是近年来发展起来的一种无需特殊准备就能显示物体内部元素分布的新技术。特别是通过将X射线探测器定位在与光束成90°的位置，同步加速器X射线（SR）的线性偏振有助于显著减少与Kcc线重叠的康普顿散射，从而提高元素的最小可探测性。采用高效率、高计数率的Ge探测器，实现了高空间分辨率的FXCT，并应用FXCT对离体甲状腺中碘的截面分布进行了研究，空间分辨率为0.1 mm x 0.1 mm（层厚为0.1 mm）或0.025 mm x 0.025 mm（层厚为0.025 mm）。采用同步辐射的FXCT可以在0.1 mm层厚的0.1 x 0.1 mmz空间分辨率下清晰地显示10 mm直径3孔体模中的0.005 mg/ml碘溶液。对0.005 mg/ml碘溶液的观察表明，测量体素中的激发碘含量约为5 pg。在甲状腺癌中，FXCT显示一部分癌症具有高碘含量，而另一部分具有低碘含量。其变化范围很宽，从0.09 mg/g到0.005 mg/g。今年春天，FXCT的实验环（AR）得到了改进，因此计划使用这一新系统获得0.005 mm的高空间分辨率图像。, '

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 surface of object. Then for 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 inner element of object without specific preparation. Especially by positioning the x-ray detector at 90°to the beam, the linear polarization of synchrotron x-rays (SR) helps to significantly reduce the Compton scattering overlapping the Kcc line and thus improving the minimal detectability of elements. Using a Ge detector with high efficiency and high count-rate capability, FXCT was implemented with high spatial resolution in the order of tens of micrometers.FXCT was applied to depict the cross sectional distribution of iodine in the thyroid gland, in vitro, at the spatial resolution of 0.1mm x 0.1 mm with 0.1-mm slice thickness or of 0.025 mm x 0.025 mm with 0.025 mm slice thickness. FXCT with synchrotron radiation could clearly visualize the 0.005 mg/ml iodine solution in the 10-mm diameter 3-hole phantom at 0.1 x 0.1 mmz spatial resolution with 0.1mm slice thickness. Observation of the 0.005 mg/ml iodine solution indicated that the excited iodine content in the measured voxel is about 5 pg. In the thyroid cancer, FXCT revealed that a part of cancer had high content of iodine, whereas another part had low content of iodine. It varied wide ranges from 0.09 mg/g to 0.005 mg/g. Experimental ring (AR) for FXCT was improved this spring, so high spatial resolution images with 0.005mm is planned to obtain using this new system. , '