电子信息工程专业英语课件TechnicalEnglish07.ppt
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1、Technical EnglishTechnical EnglishFor Information and Communication Engineering 2024/4/16Unit SevenComputerized Tomographic Imaging 概述n n计算机层析成像的基本原理计算机层析成像的基本原理计算机层析成像的基本原理计算机层析成像的基本原理n nHounsfieldHounsfield的发明及其意义的发明及其意义的发明及其意义的发明及其意义n nX X射线射线射线射线CTCT和衍射和衍射和衍射和衍射CTCTn nCTCT技术的应用领域技术的应用领域技术的应用领域技术
2、的应用领域2tomographytomography断层成像术断层成像术断层成像术断层成像术transmissiontransmission透射透射透射透射reflectionreflection反射反射反射反射diagnosticdiagnostic诊断诊断诊断诊断unprecedentedunprecedented前所未有的,空前的前所未有的,空前的前所未有的,空前的前所未有的,空前的attenuationattenuation衰减衰减衰减衰减coefficientcoefficient系数系数系数系数radioisotoperadioisotope放射性同位素放射性同位素放射性同位素放射
3、性同位素resonanceresonance共振共振共振共振lend oneself tolend oneself to有助于,适宜于有助于,适宜于有助于,适宜于有助于,适宜于boreholeborehole钻孔钻孔钻孔钻孔celestialcelestial天空的天空的天空的天空的integralintegral积分积分积分积分diffractdiffract衍射,绕射衍射,绕射衍射,绕射衍射,绕射cross-sectionalcross-sectional断面的,截面的断面的,截面的断面的,截面的断面的,截面的3breakneckbreakneck极快的,很危险的极快的,很危险的极快的,很
4、危险的极快的,很危险的algebraicalgebraic代数的代数的代数的代数的backprojectionbackprojection反向投影反向投影反向投影反向投影unambiguousunambiguous不模糊的,不含糊的不模糊的,不含糊的不模糊的,不含糊的不模糊的,不含糊的anatomicalanatomical解剖学的解剖学的解剖学的解剖学的cylindercylinder柱体,圆柱柱体,圆柱柱体,圆柱柱体,圆柱isotopeisotope同位素同位素同位素同位素viz.viz.(拉丁语拉丁语拉丁语拉丁语videlicetvidelicet)就是说(可读就是说(可读就是说(可读就
5、是说(可读namelynamely)scatterscatter散射散射散射散射inhomogeneityinhomogeneity不均匀性不均匀性不均匀性不均匀性refractive indexrefractive index折射率折射率折射率折射率variationvariation变种变种变种变种avalancheavalanche雪崩雪崩雪崩雪崩bibliographybibliography参考书目参考书目参考书目参考书目citecite引述,引用引述,引用引述,引用引述,引用4通过从许多不同方向照射物体,根据透通过从许多不同方向照射物体,根据透通过从许多不同方向照射物体,根据透通过
6、从许多不同方向照射物体,根据透射或反射的数据对物体断面成像射或反射的数据对物体断面成像射或反射的数据对物体断面成像射或反射的数据对物体断面成像它使医生能以前所未有的精度看到体它使医生能以前所未有的精度看到体它使医生能以前所未有的精度看到体它使医生能以前所未有的精度看到体内的器官而对病人十分安全。内的器官而对病人十分安全。内的器官而对病人十分安全。内的器官而对病人十分安全。TomographyTomography refers to refers to the cross-sectional imaging of an object the cross-sectional imaging of
7、an object from either transmission or reflection data collected by from either transmission or reflection data collected by illuminating the object from many different directionsilluminating the object from many different directions.The.The impact of this technique in diagnostic medicine has been im
8、pact of this technique in diagnostic medicine has been revolutionary,since revolutionary,since it has enabled doctors to view internal it has enabled doctors to view internal organs with unprecedented precision and safety to the patient.organs with unprecedented precision and safety to the patient.U
9、nit 7Unit 75后来利用放射性同位素、超声、磁共振后来利用放射性同位素、超声、磁共振后来利用放射性同位素、超声、磁共振后来利用放射性同位素、超声、磁共振也成功地获得了医学图像,在每一种情也成功地获得了医学图像,在每一种情也成功地获得了医学图像,在每一种情也成功地获得了医学图像,在每一种情况下用不同的参数成像。况下用不同的参数成像。况下用不同的参数成像。况下用不同的参数成像。The first medical application utilized x-rays for forming The first medical application utilized x-rays for
10、forming images of tissues based on their x-ray attenuation coefficient.images of tissues based on their x-ray attenuation coefficient.More recently,however,medical imaging has also been More recently,however,medical imaging has also been successfully accomplished with radioisotopes,ultrasound,and su
11、ccessfully accomplished with radioisotopes,ultrasound,and magnetic resonance;the imaged parameter being different in magnetic resonance;the imaged parameter being different in each case.each case.Unit 7Unit 76还有大量的非医学应用也可使还有大量的非医学应用也可使还有大量的非医学应用也可使还有大量的非医学应用也可使用计算机层析成像方法。用计算机层析成像方法。用计算机层析成像方法。用计算机层析
12、成像方法。1.1.通过钻孔成像测绘地下资源通过钻孔成像测绘地下资源通过钻孔成像测绘地下资源通过钻孔成像测绘地下资源2.2.无损检测中断面成像的某些特殊案例无损检测中断面成像的某些特殊案例无损检测中断面成像的某些特殊案例无损检测中断面成像的某些特殊案例3.3.确定天球面上的亮度分布确定天球面上的亮度分布确定天球面上的亮度分布确定天球面上的亮度分布4.4.电子显微镜三维成像电子显微镜三维成像电子显微镜三维成像电子显微镜三维成像 There are numerous non-medical imaging applications which There are numerous non-medic
13、al imaging applications which lend themselves tolend themselves to the methods of computerized the methods of computerized tomographytomography.Researchers have already applied this methodology to Researchers have already applied this methodology to the the mapping ofmapping of underground resources
14、 via cross-borehole underground resources via cross-borehole imaging,imaging,some specialized cases ofsome specialized cases of cross-sectional imaging for cross-sectional imaging for nondestructive testing,nondestructive testing,the determination ofthe determination of the brightness the brightness
15、 distribution over a celestial sphere,distribution over a celestial sphere,and three-dimensional and three-dimensional imagingimaging with electron microscopy.with electron microscopy.1 1 Unit 7Unit 7lend themselves tolend themselves to有助于,适宜于有助于,适宜于有助于,适宜于有助于,适宜于7某一角度的投影是图像在该角度所某一角度的投影是图像在该角度所某一角度的
16、投影是图像在该角度所某一角度的投影是图像在该角度所定义的方向上的积分定义的方向上的积分定义的方向上的积分定义的方向上的积分 Fundamentally,Fundamentally,tomographictomographic imaging deals with imaging deals with reconstructing an image from its projections.In the strict reconstructing an image from its projections.In the strict sense of the word,sense of the
17、word,a projection at a given angle is the integral a projection at a given angle is the integral of the image in the direction specified by that angleof the image in the direction specified by that angle,as,as illustrated in illustrated in Figure 7.1Figure 7.1.Unit 7Unit 78在宽泛的意义上在宽泛的意义上在宽泛的意义上在宽泛的意
18、义上 若辐射源是衍射性的如超声波或微波,若辐射源是衍射性的如超声波或微波,若辐射源是衍射性的如超声波或微波,若辐射源是衍射性的如超声波或微波,可使用可使用可使用可使用“衍射投影衍射投影衍射投影衍射投影”一词。一词。一词。一词。However,However,in a loose sensein a loose sense,projection means the information,projection means the information derived from the transmitted energies,when an object is derived from the
19、 transmitted energies,when an object is illuminated from a particular angle;illuminated from a particular angle;the phrase“diffracted the phrase“diffracted projection”may be used when energy sources are diffracting,projection”may be used when energy sources are diffracting,as is the case with ultras
20、ound and microwaves.as is the case with ultrasound and microwaves.2 2 Unit 7Unit 79对于如何根据投影数据重建图象这一问题对于如何根据投影数据重建图象这一问题对于如何根据投影数据重建图象这一问题对于如何根据投影数据重建图象这一问题的解要追溯到的解要追溯到的解要追溯到的解要追溯到19171917年年年年RadonRadon的论文的论文的论文的论文 当前在断层成像方面令人激动的成就源自当前在断层成像方面令人激动的成就源自当前在断层成像方面令人激动的成就源自当前在断层成像方面令人激动的成就源自HounsfieldHoun
21、sfield发明的发明的发明的发明的X X光光光光CTCT扫描,他因此项发扫描,他因此项发扫描,他因此项发扫描,他因此项发明而于明而于明而于明而于19791979年获得了诺贝尔奖。年获得了诺贝尔奖。年获得了诺贝尔奖。年获得了诺贝尔奖。Although,from a purely mathematical standpoint,Although,from a purely mathematical standpoint,the the solution to the problem of how to reconstruct a function from solution to the pro
22、blem of how to reconstruct a function from its projections dates back to the paper by Radon in 1917its projections dates back to the paper by Radon in 1917,the the current excitement in current excitement in tomographictomographic imaging originated with imaging originated with HounsfieldHounsfields
23、 invention of the x-ray computed s invention of the x-ray computed tomographictomographic scanner for which he received a Nobel prize in 1979.scanner for which he received a Nobel prize in 1979.3 3Unit 7Unit 710有可能得到精度达千分之一的有可能得到精度达千分之一的有可能得到精度达千分之一的有可能得到精度达千分之一的高质量断面图象高质量断面图象高质量断面图象高质量断面图象 投影数据并未严格
24、满足有效实现重投影数据并未严格满足有效实现重投影数据并未严格满足有效实现重投影数据并未严格满足有效实现重建算法赖以成立的理论模型建算法赖以成立的理论模型建算法赖以成立的理论模型建算法赖以成立的理论模型 He shared the prize with Allan He shared the prize with Allan CormackCormack who independently who independently discovered some of the algorithms.His invention showed that discovered some of the alg
25、orithms.His invention showed that it is possible to compute high-quality cross-sectional images it is possible to compute high-quality cross-sectional images with an accuracy now reaching one part in a thousandwith an accuracy now reaching one part in a thousand in spite in spite of the fact that of
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