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基本原理 CT(Computed Tomography)全称是“电子计算机X线体层扫描”。其原理是将X线管环绕人体作圆周运动,使经过准直的细束X线从各个不同角度投射身体的同一横断面。在X线管的对侧,由高度灵敏的检测器接收穿过人体后残余的X线作为信号,输入电子计算机,计算出各个象素的线性衰减系数(μ值,即X线在单位长度的物质中失去能量的自然对数),并将μ值换算成GT值。由阴极射线管按CT值的高低,以不同灰阶亮度显示在荧屏上,构成人体横断解剖的图象(见图)。 CT图象是由160×160(或更多)个小格
Fundamentals CT (Computed Tomography) full name is “computer tomography.” The principle is the X-ray tube around the human body for circular motion, so that after the alignment of the fine beam X-ray projection from different angles the same body cross-section. On the opposite side of the X-ray tube, the highly sensitive detector receives the residual X-rays passing through the human body as signals and inputs them to a computer to calculate the linear attenuation coefficient of each pixel (μ value, that is, X-ray at unit length The natural logarithm of energy lost in matter), and the μ value is converted to a GT value. The cathode ray tube according to the level of CT values, with different gray scale brightness displayed on the screen, constitute the human body transected images (see Figure). The CT image is composed of 160 × 160 (or more) cells