显微CT(μ-CT)-医学CT未来的发展方向

Micro CT (μ-CT)-Further Development of The Medical CT In Future

病理学诊断是现代医学诊断的金标准。病理学诊断可分为宏观的尸检肉眼诊断和微观的切片显微诊断两大部份。宏观肉眼诊断的空间分辨率为ｍｍ数量级，而微观显微诊断的空间分辨率经为μｍ数量级，二者之间的差别为２至３个数量级。目前医学ＣＴ影像的空间分辨率已由第１代ＣＴ的ｃｍ数量级，进展为第５代高分辨ＣＴ的亚ｍｍ数量级（０３５ｍｍ）。２５年来，ＣＴ的空间分辨率已提高约两个数量级。目前ＣＴ（包括ＭＲＩ）影像的空间分辨率，已能满足宏观病理学诊断的要求。我们预期，最多再过２５年，如果ＣＴ的空间分辨率再提高２个数量级，达到μｍ水平，即由宏观ＣＴ进展至微观ＣＴ，即可满足现代医学诊断金标准的要求，从而使临床医学提高到一个崭新的水平。目前工业ＣＴ的空间分辨率已达到１０μｍ，比医学ＣＴ高一个数量级，这就为进一步提高医学ＣＴ的空间精度，提供技术上的借鉴。本文对提高医学ＣＴ空间分辨率所面临的技术问题，进行了详细的分析与讨论。我们认为；应用微焦点光源，Ｘ射线球管高压可调，双能束光锥扫描，虚拟式准直技术，缩小检测器探头尺寸，增加检测器探头的数目，采用集成光刻钨酸镉阵列ＣＣＤ（电荷耦合检测）技术，高速电子束扫描，亚毫米级超薄层成像，高灵敏度低噪声的?

Pathological diagnosis is the golden criteria of clinical medical sciences.Pathological diagnosis can be subdivided into two parts:the macro examination of autopsy and the microscopic diagnosis of cell pathology. The spatial resolution of the autopsy is about milimeter in magnitude,while that of the microscopic diagnosis is micrometer in magnitute, Since 1973,medical CT has gained great progress to improve its spatial and temporal resolution. Recently,the spatial resolution of the high resolution CT has reached 0.35mm.From now on and not more then 25 years later,if the CT spatial resolution can increase to 1～10 micrometers in magnitude, then cells and tissues can be visualized and the microscopic pathological diagnosis can be made by using the micro CT. On the other hand,the industrial computed tomography(ICT) has rapidly developedon non-destructive testing field and its spatial resolution has already reached 100～10 micrometers.Advanced technologies of the ICT is also available to improve the spatial resolution of medical CT In this paper,difficulties and strategies about the improvement of the micro CT spatial resolution were analysed and discussed in detail.We suggested that the micro CT should compose of the following properties and speculations:an antivibration ground base,small diameter(50～100μm) focus spot of the X- ray source,variable high voltage of the X-ray tube,double eneregy X- ray scanning,virtual collimation,integrated micro probe array detector (CCD)made of cadmium tungstate (CdWO4)crystal,(probe sige 10x50μm),high speed electronic beam scanning (1～10 milidecond per frame)hyper thin tomo section(10-50μm)high sensitivity and low noise signal amplification, super computer with large storage volume, sophisticatic image working station,rapid imaging technique of the segion of interest(ROI),image zooming technique,multi-window technique,special μ-CT color staining technique,μ- CT and 3D stereotaxic operation technique,etc.We forecast that the micro CT will give a great impact on the clinical medical sciences in the coming 21 century.