The isotope selectivity of computed tomography (CT) imaging based on nuclear resonance fluorescence (NRF) transmission method using a quasi-monochromatic laser Compton scattering (LCS) gamma-ray beam in the MeV region was demonstrated at the Ultra Violet Synchrotron Orbital Radiation–III (UVSOR-III) Synchrotron Radiation Facility (Institute of Molecular Science, National Institute of Natural Science) for two enriched lead isotope rods (206Pb and 208Pb) implanted in an aluminum cylinder. Since these two rods show the same gamma-ray attenuation in atomic processes, it is impossible to differentiate between them using a standard Gamma-CT technique based on atomic attenuation of gamma rays. The LCS gamma-ray beam had a maximum energy of 5.528 MeV and an intensity of approximately 5.5 photons/s/eV at the resonance energy ( $J^{\pi } = 1^{-}$ at 5.512 MeV in 208Pb). A lead collimator with a hole diameter of 1 mm was used to define the size of the LCS gamma-ray beam at the CT target. The CT image of the 208Pb rod was selectively obtained with a 2-mm pixel size resolution, which was determined by the horizontal step size of the CT stage.

中文翻译：

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基于核共振荧光透射法的选择性同位素CT成像

基于核共振荧光 (NRF) 传输方法的计算机断层扫描 (CT) 成像的同位素选择性在 MeV 区域中使用准单色激光康普顿散射 (LCS) 伽马射线束在紫外线同步加速器轨道辐射–III 中得到证明(UVSOR-III) 同步辐射装置（国家自然科学研究所分子科学研究所），用于植入铝圆柱体中的两个富集铅同位素棒（206Pb 和 208Pb）。由于这两个棒在原子过程中表现出相同的伽马射线衰减，因此无法使用基于伽马射线原子衰减的标准伽马-CT 技术来区分它们。LCS 伽马射线束的最大能量为 5.528 MeV，在共振能量 ($J^{\pi } = 1^{-}$ at 5. 208Pb 中的 512 MeV）。使用孔径为 1 mm 的铅准直器来定义 CT 目标处 LCS 伽马射线束的大小。208Pb 棒的 CT 图像是选择性获得的，分辨率为 2 毫米，像素大小由 CT 阶段的水平步长决定。