Development of high-sensitive synchrotron x-ray micro CT

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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. , '