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Imagesofthehumanbodyarederivedfromtheinteractionofenergywithhumantissue.Theenergycanbeintheformofradiation,magneticorelectricfields,oracousticenergy.Theenergyusuallyinteractsatthemolecularoratomiclevels,soaclearunderstandingofthestructureoftheatomisnecessary.Inadditiontounderstandingthephysicsoftheatom,learningimagingjargonisalsonecessary.Forexample人体的图像来自能源与人类之间的相互作用的组织。能量可以以辐射的形式,磁场或电场,或声波能量,能量通常在分子或原子水平相互作用,所以清楚地了解原子的结构是必要的。除了了解原子的物理,学习成像术语也是必要的。例如:•Tomography:across-sectionalimageformedfromasetofprojectionimages.TheGreekwordtomomeanscut.•断层扫描:横断面图像由一组投影图像。希腊语tomo意味着削减。•CT:Computed(orComputerized)Tomography•CT:(或计算机)计算层析成象技术•MR,orMRI:MagneticResonanceImaging.Thiswasfirstcallednuclearmagneticresonance(NMR),butthementionofanythingnuclearscaredpatients,sothe“N”wasdropped.•先生,或MRI:磁共振成像,这是第一次被称为核磁共振(NMR),但提到任何核害怕病人,所以“N”掉了。•PET[1]:PositronEmissionTomography.Understandingthisphenomenonrequiresacceptanceofthetheorythatthereisantimatterintheuniverse,andwhenantimattermeetsmatter,thenbothkindsofmatterareannihilated,andpureenergyisformed.•宠物[1]:正电子发射断层扫描,理解这种现象需要接受的理论,宇宙中有反物质,反物质与物质,这两种物质是湮灭,纯粹的能量就形成了。•SPECT[2]:SinglePhotonEmissionTomography•Ultrasound:Sonarinthebody•SPECT[2]:单光子发射断层扫描•超声波:声纳•OCT:OpticalCoherentTomography–theuseofinfraredlighttoimage(particularity)thewallsofanart•10月:光学相干断层扫描,使用红外线图像(特殊性)动脉的城墙Amodalityisamethodforacquiringanimage.MR,CT,etc.areallimagingmodalities.Modalitiesaresometimescategorizedbasedontheamountofenergyappliedtothebody.Forexample,theX-raymodalityproducesenergythatissufficienttoionizeatoms(i.e.,ejectanelectronfromanorbitofanatom,therebycreatingapositivelychargedionthatdamageshumantissue).ThemodalitiesthatcauseionizingradiationareX-rays,CT,SPECT,andPET.Non-ionizingmodalitiesincludeMRandultrasound.形态是一个方法获取图像。先生,CT,等等都是成像模式。模式有时被分类基础上的能量应用到身体。例如,x射线形态产生的能量足以电离原子(即,逐出一个电子从一个原子的轨道,从而创建一个带正电的离子,损害人体组织)。引起电离辐射x射线的形式,CT,SPECT和PET。非电离形式包括先生和超声波。Lesson8BasicKnowledgeonX-raysinMedicalRadiologyPart1X-RAYSThediscoveryandnatureofX-raysX-rayswerediscoveredbyWilhelmKonradRöntgen[1]in1895.Theyareoftencalled‘roentgenrays’(particularlyintheUSA).Theyareemittedfromthepositiveelectrodeinanelectricaldischargetubethroughwhichacurrentispassing.Oneoftheirfirstapplicationswasinthe‘medical’field:Röntgenmadearadiographofhiswife’shandshowingthesofttissueandbonestructureandthegreatradiopacityoftheweddingring.ThepropertiesofX-raysthatareofsignificanceinmedicalradiologyare:(1)theypenetratemattertoagreaterorlesserdegree;(2)theyproduceionizationandexcitationintheatomsofmatter;(3)theyproducefluorescenceandhencevisiblelightfromcertainmaterials;(4)theyaffectphotographicemulsions[2];and(5)theyproducebiologicaleffectsinlivingtissues.x射线的发现和性质x射线是由威廉·康拉德·伦琴发现[1]1895年。他们通常被称为“伦琴射线”(特别是在美国)。它们发出正极的放电管,通过它的电流通过。他们的第一个应用程序是在医学的领域:伦琴射线照片了妻子的手显示软组织和骨骼结构和大辐射不能透过的结婚戒指。x射线的特性在医学放射学的意义是:(1)他们穿透物质或多或少;(2)产生电离和激发的原子物质;(3)产生荧光,因此可见光从某些材料;(4)他们影响感光乳剂[2];(5)他们在生活组织产生生物效应。WhenabeamofX-raysfromanX-raytubefallsonapatient,interactionstakeplacebetweenenergyandmatter,andpartoftheenergyisremovedfromthebeameitherbyabsorptionorbyscattering.Theenergyremaininginthebeamthatemergesunmodifiedfromthepatientcarriesinformationabouttheinternalstructuresofthebodyintheformofadistributionofintensityperpendiculartothebeamaxis.ThisdistributioninanygivenplanemaybecalledtheX-rayimage,andtheprocessmaybecalledX-rayimageformation.当一束x射线从落在一个x线管病人,能量和物质之间的相互作用发生,能量从光束的一部分通过吸收或散射。剩余的能量产生的光束从病人携带的信息修改的内部结构体的形式分布的强度垂直于声束轴线。这在任何给定平面分布可能所谓的x射线图像,这个过程可以称为x射线成像。Part2TheproductionofX-rays:X-rayspectraThiscreatesacrucialdifficultyfortheX-raytubedesigner,whomustensurethattheheatisremovedfromthebombardedarea(thefocalarea)ofthetargetsufficientlyfasttoensurethatthefocalareadoesnotbecomeexcessivelyhotandthereforedeteriorateorevenmelt.Thisisdoneinseveralways,ofwhichtwoareimportantindiagnosticradiologyandareshowninfigure1.2.First,thetargetismadeintheformofadisc(withabevelededge)whichiscausedtorotatewheneverX-rayemissionisrequired;thustheheatisspreadoutovertheperipheryofthediscfromwhichitismainlyradiatedbutpartiallyconductedaway.这将创建一个至关重要的困难x射线管的设计师,他们必须确保热量从轰炸区(焦区)中删除目标足够快,以确保核心地带不会变得过于热,因此恶化,甚至融化。这样做是在几个方面,其中两个是重要的诊断放射学和图1.2所示。首先,目标是在光盘的形式(斜边)是引起旋转时x射线辐射是必需的,因此,热量在盘的外围的主要辐射但部分进行Thenatureofthetargetmaterialisimportant.Forclinicalworktungstenisinalmostuniversalusebecauseithasahighmeltingpoint,reasonablethermalconductivity,desirablemechanicalpropertiesandahighatomicnumberwhichincreasestheefficiencyofX-rayproduction.目标材料的性质是非常重要的。临床工作钨几乎普遍使用,因为它有一个高熔点、导热系数合理,理想的机械性能和较高的原子序数增加x光生产的效率。X-raysofhighquantumenergy(hardX-rays)aremorepenetratingthanthoseoflowquantumenergy(softX-rays).Henceifafilterofaluminiumorcopperisplacedinthebeam,thesoftX-raysareattenuatedtoagreaterextentthanarethehardX-rays;thewholebeambecomesmorepenetratingandissaidtobeharder.ThistechniqueisofimportanceinclinicalradiologybecausethesoftercomponentsinaspectrumarepreferentiallyabsorbedinthesuperficiallayersofpatienttissuenearesttotheX-raytube,withunwantedbiologicaleffects.Thereforeitiscustomarypartiallytoremovethesoftco