CT诊断学余开湖CT总论.ppt

计算机体层成像原理
Lecturer: yue zhi wen
Computed Tomography Principle
咸宁学院医学院影像系
puter tomography)是Hounsfield 1969年设计成功,1972年公诸于世的。CT不同于X线成像,它是用X线束对人体层面进行扫描,取得信息,经计算机处理而获得的重建图像。所显示的是断面解部图像,其密度分辨力明显优于X线图像。由于CT大大促进了医学影像学的发展。Hounsfield获得了1979年的诺贝尔奖金。
一概述
CT的发展概况
1969
1972
1973
1974
1979
Hounsfield
Ambroser
Ambroser
Ledley
Hounsfield
计算机横断体层成像设计成功
应用于临床并在英国放射学会发表
在英国放射学杂志上报道
全身CT机设计成功
Hounsfield获得诺贝尔奖
My name is Godfrey Hounsfield
I work for the Central Research
Labs. of EMI, Ltd in England
I developed the the first clinically
useful CT scanner in 1971
History puted Tomography
Early 1970s
1963 - Alan Cormack developed a mathematical method of reconstructing images from x-ray projections
For the first time we could view:
CT Broke the Barrier
- Tomographic or “Slice” anatomy- Density difference
But it's time consuming
And resolution needs to be improved
puted Tomography,即计算机体层成像,是用X线束对人体某部一定厚度的层面进行扫描,由探测器接收透过该层面的X线,扫描所得信息经计算机处理后形成的图像。
CT定义
线性衰减系数
CT的工作原理
体素、数字矩阵、像素
数据处理与重建
数据的计算方法
二 CT基本原理及基本概念
线性衰减系数
由物理学的吸收定律(或称朗伯定律)可知,当X线穿过任何物质时,其能量与物质的原子相互作用而减弱,X线穿过物质时其强度按指数规律衰减:
I=I0e-μd
式中 I0为入射X线强度,I为穿过物体衰减后X线强度,d为物体厚度,μ为组织线性吸收系数或衰减系数μ与X线的能量,物质的厚度、原子序数Z以及密度有关。
How does CT Work?
Recon. & postpro.
Data acquisition
X-ray generation
Patient is placed in the center of the measurement field
X-ray is passed through the patient’s slice from many direction along a 360° path
The transmitted beams are captured by the detectors which digitizes these signals
These digitized signals called raw data are sent to puter which create the CT image
How does CT Work?