Lee Sang Chul, Kim Ho Kyung, Chun In Kon, Cho Myung Hye, Lee Soo Yeol, Cho Min Hyoung
Graduate School of East-West Medical Science, Kyung Hee University, 1 Seochun, Kiheung, Yongin, Kyungki 449-701, Korea.
Phys Med Biol. 2003 Dec 21;48(24):4173-85. doi: 10.1088/0031-9155/48/24/014.
A dedicated small-animal x-ray micro computed tomography (micro-CT) system has been developed to screen laboratory small animals such as mice and rats. The micro-CT system consists of an indirect-detection flat-panel x-ray detector with a field-of-view of 120 x 120 mm2, a microfocus x-ray source, a rotational subject holder and a parallel data processing system. The flat-panel detector is based on a matrix-addressed photodiode array fabricated by a CMOS (complementary metal-oxide semiconductor) process coupled to a CsI:T1 (thallium-doped caesium iodide) scintillator as an x-ray-to-light converter. Principal imaging performances of the micro-CT system have been evaluated in terms of image uniformity, voxel noise and spatial resolution. It has been found that the image non-uniformity mainly comes from the structural non-uniform sensitivity pattern of the flat-panel detector and the voxel noise is about 48 CT numbers at the voxel size of 100 x 100 x 200 microm3 and the air kerma of 286 mGy. When the magnification ratio is 2, the spatial resolution of the micro-CT system is about 14 1p/mm (line pairs per millimetre) that is almost determined by the flat-panel detector showing about 7 1p/mm resolving power. Through low-contrast phantom imaging studies, the minimum resolvable contrast has been found to be less than 36 CT numbers at the air kerma of 95 mGy. Some laboratory rat imaging results are presented.
已开发出一种专门用于筛查小鼠和大鼠等实验小动物的小型动物X射线微型计算机断层扫描（micro-CT）系统。该微型CT系统由一个视野为120×120 mm²的间接检测平板X射线探测器、一个微焦点X射线源、一个旋转样本支架和一个并行数据处理系统组成。平板探测器基于通过互补金属氧化物半导体（CMOS）工艺制造的矩阵寻址光电二极管阵列，该阵列与作为X射线到光转换器的碘化铯铊（CsI:Tl）闪烁体耦合。已根据图像均匀性、体素噪声和空间分辨率对微型CT系统的主要成像性能进行了评估。已发现图像不均匀性主要来自平板探测器的结构非均匀灵敏度模式，并且在体素大小为100×100×200微米³且空气比释动能为286毫戈瑞时，体素噪声约为48个CT值。当放大倍数为2时，微型CT系统的空间分辨率约为14线对/毫米（每毫米线对数），这几乎由显示约7线对/毫米分辨能力的平板探测器决定。通过低对比度体模成像研究，发现在空气比释动能为95毫戈瑞时，最小可分辨对比度小于36个CT值。还展示了一些实验大鼠的成像结果。
