显微动态与功能CT-未来的21世纪CT

病理宏观肉眼诊断的空间分辨率为毫米数量级，而微观病理显微诊断的空间分辩为微米数量级。目前医学CT影像的空间分辨率已达到0.35mm已能满足宏观病理学诊断的要求。如果医学CT的空间分辩率再提高到微米水平，即可清晰显示细胞和组织的微细结构，从而满足现代医学临床病理诊断金标准的要求。目前工业CT(ICT)的空间分辨率已达到5－10微米，从而为提高医学CT的空间分辨率提供技术依据。本文给出用工业微焦点CT机首次对生物组织进行显微成像的结果。认为，应用微焦点X线源，以及采用钨酸镉集成电路CCD检测技术，进一步缩小检测器元件探头的尺寸和增加检测器探头的数目，可以提高医学CT的空间分辨率；应用电子束快速扫描技术，可以提高医学CT的时间分辨率，达到动态的水平：应用双能X线束扫描技术，可以进一步提高密度分辩率。如果未来医学CT的空间分辨率达到微米级(显微CT)，时间分辨率达到毫秒级(动态CT)，密度分辨率能观察到神经细胞有兴奋时胞内钙离子浓度的瞬态上升1000倍，即成为显微动态和功能CT，就可以观测人脑神经元在不同功能状态下的动态兴奋和时空编码过程，对进一步研究人脑的学习记忆和思维认知过程有重要意义。

MICRO CT－THE NEW GENERATION CT IN THE 21CENTURY

The spatial resolution of the autopsy is about milimeter in magnitude, while the resolution of the microscopic diagnosis is micrometer. Since 1973, medical CT has gained a great progress to improve its spatial and temporal resolution. We suggest that if the spatial resolution of medical CT can increase to 1 or 10 micrometers in magnitude, then cells and tissues can be visualized and then the microscopic pathological diagnosis can be made by using the medical micro CT(μ CT). On the other hand, the industrial computed tomography (ICT) has been developed rapidly on the non-destructive testing fields and its spatial resolution has already reached 10 ～ 100 μm We have already applied the micro ICT to examine the tissues of rats and obtained the distinct microscopic CT images of tissues and cells. Micro CT images of the pyramidal neurons of the cerebral cortex, the Bowman's capsule of the glomerulus of kidney and the structure of the hepatic lobules were first reported in this paper. Results were very exciting. It means that the advanced technologies of ICT can be available to improve the spatial resolution of the medical CT and that the micro CT is feasible. We suggested that the medical micro CT should composed of the following properties and speculations: an anti-vibration ground base, a small diameter focus spot (1～10 μm)of x-ray source, variable high voltage x ray tube, double energy x ray scanning, micro CCD detector, high speed electronic beam scanning (1～10ms per flame), hyper thin tomo section (10～50 μnthick), super computer with vast storage volume, rapid imaging technique of the region of interest (ROI), image zooming technique, special μ- CT color staining technique, μCT and 3D stereotaxic operation technique, etc. It is obvious that the micro CT will give a great impact on the clinical medicine in the 21 century.