Development of fluorescent x-ray CT with synchrotron radiation

Fluorescent x-ray technique is usually used to evaluate very low contents of specific elementsthe order of picograms，however the measurement must be performed in the surface of object. Then for biological sample，specimen is required to be cut into thin slices and scanned with a beam perpendicular to itssurface. The fluorescent x-ray computed tomography （FXCT）which can reveal the distribution of inner element of object and do not require the specificpreparation, have being developed. Especially by positioning the x-ray detector at 90 to the beam，linear polarization of synchrotron x-rays (SR) helps to significantly reduce the Comptonscattering overlapping the K - D2α - D2 line and thus improving the minimal detectability of elements。Using a detector with high efficiency and high count-rate capability and highly precise x-raycollimator system,我们implemented FXCT with high spatial resolution in the order of tens of micrometers.FXCT wasapplied to depict the cross sectional distribution of iodine in the thyroid gland, in vitro，at the spatial resolution of 0.1 mm x 0.1 mm with 0.1-mm slice thickness or of 0.025 mm x 0.025 mmwith 0.025 mm slice thickness FXCT with SR could clearly visualize the 0.005 mg/ml iodine solutionin the 10-mm diameter 3-hole phantom at 0.1 x 0.1 mm D12 - D1 spatial resolution with 0.1 mm slicethickness. Observation of the 0.005 mg/ml iodine solution indicated that the excited iodine contentin the measured voxel is about 5 pg (0.005 mg/ml x 1.0 x 10维D1-6维D1 ml). in the thyroid cancer，FXCT revealed that一part of cancer had high content of iodinewhereas另一部分had low content of iodine. It varied wide ranges from 0.09 mg/g to0.005mg/g.FXCT can obtain the image of specific elements by selecting the K - D2α - D2 fluorescentx-ray line so many other elements such as zinc and cupper for enzyme function of tumor，platinum for the cancer therapy will be imaged quantitatively。

Fluorescent x-ray technique is usually 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. The fluorescent x-ray computed tomography (FXCT), which can reveal the distribution of inner element of object and do not require the specific preparation, have being developed. 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 KィイD2αィエD2 line and thus improving the minimal detectability of elements. Using a detector with high efficiency and high count-rate capability and highly precise x-ray collimator system, we implemented FXCT 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 0.1 mm 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 SR could clearly visualize the 0.005 mg/ml iodine solution in the 10-mm diameter 3-hole phantom at 0.1 x 0.1 mmィイD12ィエD1 spatial resolution with 0.1 mm 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 (0.005 mg/ml x 1.0 x 10ィイD1-6ィエD1 ml). 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 0.005mg/g.FXCT can obtain the image of specific elements by selecting the KィイD2αィエD2 fluorescent x-ray line, so many other elements such as zinc and cupper for enzyme function of tumor, and platinum for the cancer therapy will be imaged quantitatively.