如今CT——Computerized Tomography,即计算机化X射线造影术——已家喻户晓,成为医生强有力的诊断工具。它可以方便地将你全身“切片”拍照,通过一系列断面照片将你全身五脏六腑。拍得消清楚楚。又由于它是一种非侵入式诊断,对病人无痛苦无损伤,因而也深受病人欢迎。如今许多中型以上医院已普遍装备了CT,或者说不久的将来,它将会像今日的X光机那样普及。然而科学家却清楚了解,CT远非完善,下面介绍的MECT将让你领略一下未来的CT会是什么样的。 传统X光造影—CT—MECT 传统X光照像得到的照片实际是体内各层组织或病变物对X光吸收图像的重叠,它无法单独区分各层信息。CT则由于X光源及探测器进行了旋转扫描,并采用现代计算技术进行数据处理,得以逐层逐点重建整个横断面上X光吸收强度的图像,从而从根本上克服了传统X光照像术中器官组织重叠问题,这是CT所以能够大出风头的根本原因。但CT存在很根本的一个限制便是它所使用的X光源仍是传统的X光管,这种源所产生的X光实际是多种能量光子的混合物,也就是说是“多色”的X光,而不是“单色”光。然而物质对不同能量X光的吸收却是很不一样的,因此CT探测器所收到的信息实际上不过是各种能量X射线吸收图像的某种平均。这种平均效应无疑将降低图像细部的对比度(衬度 Now CT - Computerized Tomography, computerized X-ray angiography - has become a household name and a powerful diagnostic tool for doctors. It makes it easy to take a picture of your whole body “slice” and pass your entire body through a series of cross-sectional photographs. Shoot clearly. And because it is a noninvasive diagnosis that is painless and harmless to the patient, it is also well received by patients. Many mid-size and high-end hospitals are now equipped with CTs, or in the near future it will be as popular as today’s X-ray machines. However, scientists have clearly understood that CT is far from perfect. The MECT described below will give you a taste of what CT will look like in the future. Traditional X-ray - CT-MECT Traditional X-ray images are actually pictures of the various layers of tissue or lesions on the X-ray absorption image of the overlap, it can not distinguish between layers of information alone. CT is the result of X-ray source and detector rotation scanning, and the use of modern computing technology for data processing, can be layer by point reconstruction of the entire cross-section X-ray absorption intensity of the image, which fundamentally overcome the traditional X-ray In the organ tissue overlap problem, this is the root cause CT can be a big limelight. However, a fundamental limitation of CT is that the X-ray source it uses is still a conventional X-ray tube. The X-ray generated by this source is actually a mixture of a variety of energy photons, that is, “multicolored” X-rays, not “monochromatic” lights. However, the material’s absorption of X-rays of different energies is quite different, so the information received by the CT detector is actually just some sort of averaging of the various energy X-ray absorption images. This averaging effect will undoubtedly reduce the contrast of the image detail (contrast