医学影像诊断学(英文版)

DiagnosticofUltrasonographyFoundationsofUltrasonographyHistoricalperspectiveofsoundIn1947,K.Dussickmadeoneoftheearliestapplicationsofultrasoundtomedicaldiagnosis.In1948,Dr.HowrydevelopedthefirstultrasoundscannerIn1954,echocardiographictechniquesweredevelopedbyDrs.C.H.HertzandI.EdlerinSweden.In1962,thedevelopmentofthecontactstaticscannerinNorthAmerica.In1972,thenewrevolutionarygray-scaleimagingandimprovedresolutionreal-timescannersweredevelopedClinicalchoiceofimagingtechnique

Simple→complicationone→many(convenient)Nodamage→lessdamage→moredamage(safe)Lowexpense→highexpense(cheap)ComparedwithCT&MRI

灰阶超声成像(greyscaleultrasonictomography)。Advantage:NotexpensiveasCT&MRI,sectionalimaging,real-time,noradiationDisadvantage:ContrastandspatialresolutionofimagingisnotasgoodasCT&MRI.QualitiesofaSonographerIntellectualcuriosityPerseverancetoobtainhigh-qualityimagesAbilitytoconceptualize2Dimagesintoa3DformatQuick-thinkingandanalyticcapabilitiesGoodphysicalheathCommunicationskillsDedicationBasicultrasoundprinciples

Ultrasound:f>20,000Hertz(Hz)Awaveisapropagationofenergythatmovesbackandforthorvibratesatasteadyrate.Soundwavesaremechanicaloscillationsthataretransmittedbyparticlesinagas,liquidorsolidmedium.ComparedwithAudiblesound

Common:essentialqualities;akindofmechanicalvibration;longitudinalwave;spreadinelasticitymedium;akindofenergyconvertDifference:highfrequencyofwave,shortwavelength,spreadalongstraightline,gooddirectivityBasicultrasoundprinciples

Wavelength:representsthedistanceoccupiedbyeachcycle,theoperatingfrequencyofthetransducer,andthevelocityofsound.ThetotaldistanceoccupiedbyasoundpulseisthewavelengthmultipliedbythenumberofcyclesinthepulseandcalledthespatialpulselengthMeasurementofSound:thedecibel(dB)unitisoftenusedtomeasurethestrengthormaderegardingtheratiooftwointensitiesoftwoamplitudesBasicultrasoundprinciples

Frequency:Soundischaracterizedaccordingtoitsfrequency.Inultrasound,frequencyreferstothenumberofoscillationspersecondperformedbytheparticlesofthemediuminwhichthewaveispropagating:1oscillation/sec=1cycle/sec=1hertz(1Hz)1000oscillation/sec=1kilocycle/sec=1kilohertz(1kHz)1,000,000oscillation/sec=1magacycle/sec=1megahertz(1MHz)BasicultrasoundprinciplesVelocityofSound

:determinedbythedensityandelasticpropertiesofthemedium.Thevelocityofsounddiffersgreatlybetweenair,bone,andsofttissue.Thevelocityofsoundvariesbyonlyafewpercentfromonesofttissuetoanother,Air-filledstructures,suchasthelungsandstomach,orgas-filledstructures,suchasthebowel,impedethesoundtransmission.BasicultrasoundprinciplesC=f×λ频率(f):unit(Hz)声速(c):unit(m/s)Average:1540m/s,resembleto1500m/s波长(λ):unit(mm).Thefrequencyandwavelengthofcommonlyusedultrasound

f(MHz)0.81.252.53.05.07.510.015.0λ(mm)1.881.200.60.50.30.20.150.1超声的束射性定义:当声源的直径甚大于传播介质内的波长时,超声的能量高度集中,呈束状向前传播从声源发出的超声波最近的一段声束几乎平行,这段区域为近场区。远离此区后,声束向前稍有扩散，为远场区。扩散角（θ):扩散的声束与平行声束间形成的夹角）;扩散角越小，束射性越好，则方向性越强，探测效果越好;探头的半径r越大，则半扩散角就越小BasicultrasoundprinciplesPiezoelectricEffect:thesoundbeamsusedindiagnosticultrasoundareproducedfromatransducerbythePiezoelectricEffect.Thetransducerisameansforconvertingonefromofenergyintoanother(e.g.,electricalenergyintomechanicalsoundwaves).Mostdiagnosticapplicationsuseshort,pulsedultrasoundwavesforoptimumresolution正压电效应

a.晶体未受外力时，两侧不带电荷

b.晶体受压力；c.晶体受拉力。逆压电效应a.晶体两侧加电场时，长度伸展

c.晶体两侧加与a相反的电场时，长度压压缩。BasicultrasoundprinciplesPulse-Echo:therearetwobasicmodesoftransduceroperationthatareusedinmedicaldiagnosticapplications,continuousandpulsed.ThecontinuoussignalisusuallyfoundinDopplerequipment.Pulse-Echotransducersfunctionbysendingoutshortburstsofsoundenergyandthenlisteningforreturnechoinformation.BasicultrasoundprinciplesLongitudinalWaves:ultrasoundisaformofnonionizingradiationinwhichLongitudinalpressureWavesofhigh-frequencyaretransmittedthroughamedium.Therewavesareformedbytheoscillationofparticlesormoleculesare“squeezed”closertogether,orcompressed,andpartundergoexpansion,orrarefaction,bywhichthemoleculesarepulledfartherapart.Assoundtravelsamaterial,alternateregionsofcompressionandrarefactionoccur.BasicultrasoundprinciplesAcousticImpedance:theultrasoundwaveisverysimilartoalightbeaminthatitmaybefocused,refracted,reflected,orscatteredatinterfacesbetweendifferentmedia.Atthejunctionoftwomediaofdifferentacousticproperties,anultrasoundbeammaybereflecteddependingonthedifferenceinacousticimpedancebetweenthetwomediaandtheangleatwhichthebeamhitstheinterface(angleofincidence)人体正常组织的声阻抗组织器官

密度

g/cm3声速

m/s声阻抗（×105瑞利）大脑

1.03815401.588小脑1.03014701.514脂肪0.95514761.410软组织1.01615001.590肌肉1.07415681.648肝脏1.05015701.648肾脏-1560-颅骨1.65833605.570胎体1.02315051.579羊水

1.01314741.463血液

1.05515701.656眼晶体1.13616501.874肺及肠腔气体0.001293320.000428SoundReflections:reflectionsmostfrequentlyreceivedarethosethatoccurredataperpendicularincidence.Theangleofreflectionisequaltotheangleofincidence.thisoccursatmostspecularinterfaceswheretheboundaryissmoothandwherethedimensionsoftheinterfacearelarderthanthewavelength(i.e.,diaphragm,wallsofvessels)Soundnotreflectedistransmittedthroughtheinterface.Refraction(changeindirectionofsound)canoccuriftheincidentangleisnotzeroandifthevelocitiesofsoundofthetwomaterialsformingtheboundaryarenotequal.Nonspecularreferstointerfacesthataresmallerthanwavelengthornotsmooth,(l.e.,redbloodcells,liverparenchyma,etc)超声传播图示a发射；b绕射；c散射BasicultrasoundprinciplesImageResolution:

Resolutionistheabilitytoseparatethesmallestreflectorsfromoneanother.Axialresolutionistheminimumreflectorseparationalongthesoundpathrequiredtoproduceseparateechoes.Lateralresolutionistheabilitytoproduceseparateechoesperpendiculartothesoundpathandisaffectedbytransducerdiameterandfocusing.BasicultrasoundprinciplesAttenuation:itisthesumofacousticenergylossesresultingfromaborption,scatteringfromaborption,scattering,andreflection.Inhumansofttissue,soundisattenuatedattherateof0.5dBpercentimeterpermillionhertz.Ifairorboneiscoupledwithsofttissue,moreenergywillbeattenuated.Attenuationthroughacalciuminterfacesuchasagallstonewillproduceashadowwithsharpbordersonthereal-timeimage.中文小结

对人体器官进行探测的基础：在介质中以直线传播，有良好的指向性

当超声经两种声阻抗不同相邻介质的界面时，其声阻抗差大于0.1％，而界面又明显大于波长，即大界面时，则发生反射，一部分声能在界面后方的相邻介质中产生折射，超声继续传播，遇到另一个界面又产生反射，直至声能耗竭。反射回来的超声为回声。声阻抗差越大，则反射越强，如果界面比波长小，即小界面时，则发生散射。

衰减：即振幅与强度减小。衰减与介质的衰减系数呈正比，与距离平方呈反比，还与介质的吸收与散射有关。

多普勒效应（Dopplereffect）：活动的界面对声源作相对运动可改变反射回声的频率。这种效应使超声能检查心脏活动和胎儿活动以及血流状态。

InstrumentationInstrumentation

DisplayModesA-Mode(amplitudemode):producesaone-dimentionalimagedisplayingtheamplitudestrengthofthereturningechosignalsalongtheverticalaxisandthetime(distance)alongthehorizontalaxis.Theamplitudedisplayrepresentsthetimeordistanceittakesthebeamtostrikeaninterfaceandreturnthedigaltothetransducer.Thegreatertherefectionattheinterface,thetallertheamolitudespikewillappear.大脑A型超声仪波形图

Instrumentation

DisplayModesB-Mode

(brightnessmode):methoddisplaystheintensityofanechobyvaryingthebrightnessofadottocorrespondtoechostrength.Grayscalereferstotheconditionofassigningeachlevelofamplitudeaparticularshadeofgray.TheB-Modeisthebasisforallreal-timeimaginginultrasound.肝脏切面的B型超声成像图（二维）

DisplayModes

M-Mode(MotionMode):displaystimealongthehorizontalaxisanddepthalongtheverticalaxistodepictmovement,especiallyincardiacstrutures.心脏左室长轴M型超声心动图DisplayModes

Real-time:Real-timeimagingprovidesadynamicpresentationofmultipleimageframespersecondoverselectedareasofthebody.Theframerateisdependentinthefrequencyanddepthofthetransduceranddepthselection.DisplayModes

Three-DimensionalReconstruction:Imagesareacquiredontheirx,yandzaxes,manuallyrealigned,andthenreconstructedintoathree-Dimensionalformat.Thistechniquehasbeenusefulinreconstructingthefetalface,ankle,andextremitiesinthesecond-andthird-trimesterfetus.Clinicalinvestigationsarecurrentlyunderwaytodiscoveradditionalapplicationsofthree-Dimensionalimaging.四维：即实时的三维成像技术，可动态的观察三维图象；DisplayModes

Doppler:TheDopplerPrinciplereferstoachangeinfrequencywhenthemotionoflaminarorturbulentflowisdetectedwithinavascularstructure.InthemedicalapplicationoftheDopplerPrinciplethesoundwaveisbouncedoffamovingredbloodcell.Ifthecellmovesawayalongthelineoftheultrasoundbeam,theDopplershiftisdirectlyproportionaltothevelocityoftheredcell.Ifthecellmovesawayfromthetransducerintheplaneofthebeam,thefallinfrequencyisdirectlyproportionaltothevelocityanddirectionoftheredbloodcellmovement.DisplayModesColorFlowDoppler:Velocitiesarequantitatedbyallocatingapixeltoflowtowardthetransducerandflowawayfromawayfromthetransducer.Eachvelocityfrequencychangeisallocatedacolor.Colormapsmaybeadjustedtoobtaindifferentcolorassignmentsforthevelocitylevels;usuallyredisassignedtoflowtowardthetransducerandbluetoflowawayfromthetransducer.DisplayModesPulse-EchoInstrumentationComponentpartsincludethepulserandthereceiver.Timegaincompensation(TCG)equalizesdifferencesinreceivedechoamplitudescausedbyreflectordepth.Dynamicrangeistheratioofthelargestsignaltothesmallestsignalthatasystemcanhandle.正常肾动脉血流频谱图肾动脉狭窄的血流频谱图超声设备：主要由超声换能器即探头（prode）和发射与接收、显示与记录以及电源等部分组成DisplayModesTransducerSelectionCurvedarray:lineararraytransducerwithacurvedscanheadandelectronicfocusingLineararray:multiplesmalltransducerelementselectronicallycoordinatedtoproducearectangularimageSector:smalltransducerheadthatproducesapie-shapedimageTransrectaltransducer:specialtransducerthatisintroducedintotherectumtoevaluatetheprostate,bladder,andrectumTransvaginal(endovaginal)transducer:ahigh-frequencyprobethatisinsertedintothevaginatoimgaetheuterus,ovaries,andadnexalarea.

a)线性扫描；b)扇形扫描；c)旋转扫描Artifacts

Instrumentproblem:occurwhentheequipmentisnotfunctioningproperlyTechnique-dependentartifacts:

theappearanceisproducedbyunsatisfactoryoperatortechniqueUnavoidableartifactsresultingfromthewaytissuesaffectsound.KEYTERMS

Acousticimpedance(声阻抗):measureofamaterial’sresistancetothepropagationofsound;expressedastheproductofacousticvelocityofthemediumandthedensityofthemedium.Amplitude(波幅):strengthoftheultrasoundwavemeasuredindecibels.KEYTERMS

Angleofincidence(入射角):anglefromthenormalatwhichthesoundbeamsstrikestheinterfaceAngleofreflection(反射角):theamplitudeofthereflectedwavedependsonthedifferencebetweentheacousticimpedancesofthetwomaterialsformingtheinterfaceKEYTERMS

Attenuation(衰减):reductionintheamplitudeandintensityofasoundwaveasitpropagatesthroughamedium;attenuationofultrasoundwavesintissueiscausedbyabsotptionandbyscatteringandreflectionKEYTERMS

Dynamicrange(动态幅度):ratioofthelargesttosmallestsignalsthataninstrumentorcomponentofaninstrumentcanrespondtowithoutdistortion.Framerate(帧速度):rateatwhichimagesareupdatedonthedisplay;dependentonfrequencyofthetransduceranddepthselection.KEYTERMS

Frequency(频率):numberofcyclespersecondthataperiodiceventorfunctionundergoes;thefrequencyofasoundwaveisdeterminedbythenumberofoscillationspersecondofthevibratingsourceVelocity(速率):inultrasoundthetissuedensitydeterminesthespeedoftheultrasoundwaveWavelength(波长):distanceoverwhichawaverepeatsitselfduringoneperiodofoscillationKEYTERMS

Grayscale(灰阶):B-modescanningtechniquethatpermitstheB-modedotstobedisplayedinvariousshadesofgraytorepresentdifferentechoamplitudesKEYTERMS

Realtime(实时):ultrasoundinstrumentationthatallowstheimagetobedisplayedmanytimespersecondtoachievea“realtime”imageofanatomicstructuresandtheirmotionpatternsKEYTERMS

Refraction(折射):changeinthedirectionofpropagationofasoundwavetransmittedacrossaninterfacewherethespeedofsoundvariesResolution(分辨力):abilityofthetransducertodistinguishbetweentwostructuresadjacenttooneanotherKEYTERMS

Piezoelectriceffect(压电效应):generationofelectricsignalsasaresultofanincidentsoundbeamonamaterialthathasPiezoelectricproperties;intheconverse(orreverse)Piezoelectriceffect,thematerialexpandsorcontractswhenanelectricsignalisapplied.KEYTERMS

Transducer(传感器):anydevicethatconvertssignalsfromoneformtoanother.Spatialpulselength(空间脉冲长度):spatialextentofanultrasoundpulseburstPulseduration(脉冲期):measureoftheringdowntimeofatransducerafterexcitationKEYTERMS

Colorflow:velocityineachdirectionisquantitatedbyallocatingapixeltoeacharea.Eachvelocityfrequencyisallocatingacolor;flowtowardthetransducermaybered;flowawayfromthetransducermaybeblue.KEYTERMS

Frequencyshift(频移):amountofchangeinthereturningfrequency,comparedwiththetransmittingfrequencywhenthesoundwavehitsamovingtarget,suchasbloodinanartery.Dopplershift(多普勒频移)：changeinfrequencyofareflectedwave;causedbymotionbetweenthereflectorandthetransducer’sbeam.KEYTERMS

Continuouswave(CW)Doppler:onetransducercontinuouslytransmitssound,andonecontinuouslyreceivessound;usedinhigher-velocityflowpatternsPulsedwave(PW)Doppler:soundistransmittedandreceivedintermittentlywithonetransducer.KEYTERMS

Timegaincompensation(TGC)(时间增益补偿)：alsoreferredtoasdepthgaincompensation;abilitytocompensateforattenuationofthetransmittedbeamasthesoundwavetravelsthroughtissuesinthebody;usually,individualpodcontrolsallowtheoperatortomanuallychangetheamountofcompensationnecessaryforeachpatienttoproduceaqualityimage.DescriptiveTerminology

Anechoicorsonolucent(无回声)Well-definedechogenicwallswithoutinternalechoes;thisstructureidfluid-filledandtransmitssoundeasily.Example:vascularstructure,distentedurinarybladder,gallblander,amnioticcavity.正常血管呈无回声管状结构，动脉管壁厚，回声强，搏动明显

均质性无回声：生理：淋巴结病理：淋巴瘤等

DescriptiveTerminologyEcchogenicorhyperechioc(oppositeofanechoic):echo-producingstructure;reflectssoundwithabrighterintensity.Example:gallstone、renalcalyx、bone、fat、fissures、ligaments.皮肤均呈线状回声表现。需观察皮肤有无增厚、变薄或凸出、凹陷时应通过水耦合方式进行

正常皮下脂肪及体内层状分布的脂肪呈低水平回声。当有筋膜包裹时，在脂肪与筋膜之间有时显出强回声界限

体内纤维组织与其他组织交错分布，一般回声较强。某些排列均匀的纤维组织其回声相对较弱。

成骨近探头侧的骨皮质回声反射很强，后方拖有声影，骨内结构显示不清。

DescriptiveTerminologyHeterogeneous(不均匀)：notuniformintextureorcomposition.Example:manytumorshavecharacteristicsofboth“cystic”andsolidtypesofpatterns.DescriptiveTerminologyHomogeneous(oppositeofheterogeneous):Completelyuniformintextureorcomposition.Example:thetextureoftheliver,thyroid,scrotum,andmyometriumarehomogeneous.DescriptiveTerminologyHypoechoic(低回声):low-levelechoeswithinastructure

Example:lymphnodesandthegastrointestinaltract.软骨的表现为两带状回声之间呈为低回声区。

静脉管壁薄，回声弱，搏动不明显。

DescriptiveTerminologyIsoechoic(等回声):veryclosetothenormalparenchymaechogenicitypattern.Example:metastaticdiseaseDescriptiveTerminologyIrregularborder:bordersarenotwell-defined,areilldefined,orarenotpresent.Example:abscess,thrombus,metastases.;DescriptiveTerminologyLoculatedmass:well-definedborderswithinternalechoes;theseptamaybethin(likelybenign)orthick(likelymalignant)DescriptiveTerminologyShadowing(声影):thesoundbeamisattenuatedbyasolidorcalcifiedobject.Thisreflectionorabsorptionmaybepartialorcomplete.Astonewouldcauseasharpshadowposteriortoitsborder.UltrasoundcriteriaTheborderofthestructuremaybesmoothandwell-defined.orirregular.Thetexture(orparenchyma)ofthestructureiseitherhomogeneousorheterogeneous;ifamassispresent,itmaybehypoechoic,echogenic,orisoechoictotherestoftheparenchyma.UltrasoundcriteriaThethroughtransmissionofthesoundiseitherincreased,unchanged,ordecreased.ananechoicmasswillshowincreasedtransmissionofsound,whereasadermiodtumorwillshowdecreasedtransmission.Thecharacteristicofanorganormassissaidtobeeitheranechoic,hypoechoic,isoechoic,hyperechoice,orechgenic.UltrasoundcriteriaTransmissionisalteredbywhetherastructureisacyst,complex,orsolid.Cyst:Smooth,well-definedborders,anechoic,increasedtransmission.Complex:Hascharacteristicsofbothcystandsolid(abscess)Solid:lrregularborders,intemalechosedtransmission.正常人体组织回声反射的强弱规律

强反射：乳房内纤维护组织→胎盘→胰腺→肝脏。较强反射：骨肉→脂肪→甲状腺实质。弱反射：脂肪。甚弱反射：无髓鞘中枢神经系统组

织表面反射衰减程度纤维组织强大软组织中一般脂肪弱小液性无衰减几不增加钙化甚强甚大（后方极为模糊）良性病变中一般恶性病变弱大病变在B型（单扫描）图上的一般规律

囊性与实质性病变的声象特征

囊性病变实质性病变边缘回声光滑光滑或不光滑肿块形态圆球或椭球形不规则或规则边缘折射效应有无（如具纤维包膜，同样存在）内部回声无有后部情况加强阴影周围组织被压反应性良性、恶性病变声象图比较

良性病变恶性病变边缘回声光滑不光滑（不一定）肿块形态较规则常较不规则（不一定）内部回声中度、均匀或不均匀低弱、部份可增强、不均匀，分布常不规则后部情况衰减程度一般通常衰减甚大（不一定）周围组织反应性浸滑润性（不一定）USG检查技术多用仰卧位，也可其他体位。切面方位可用横切、纵切或斜切面。患者采取适宜体位，露出皮肤，涂耦合剂，以排除探头与皮肤间的空气，探头紧贴皮肤扫描，扫描中观察图像，必要时冻结，即停帧，行细致观察，做好记录，并摄片或录像。应注意器官的大小、形状、周边回声，尤其是后壁回声、内部回声、活动状态、器官与临近器官的关系及活动度等。超声实时显像图像方位标准腹面横切面图：图左为人体的右，图右为人体的左，图上为腹，图下为背。腹面纵切面图：图左为头端，图右为足端，图上为腹，图下为背。背面横切面图：图左为人体左侧，图右为人体右，侧图上为背，图下为腹。背面纵面图：图左为头端，图右为足端，图上为背，图下为腹。腹面斜切成图：图左为人体的右侧，图右为人体的左侧，图上为腹，图下为背。

常用切面：横切面常用切面：纵切面

常用切面：斜切面

常用切面：冠切面横切面

纵切面

NeuroradiologyofBrainTumors

(IntracranialTumors)投影片2之44NeuroradiologyofBrainTumors

(IntracranialTumors)投影片2之44ImagingDiagnosisofRespirotarySystemOverviewofRSTissuecomponentofchestDensitydifferenceintheareaNaturalcomparisonImagingmodalitieswhichcanbechosenforRSTissuecomponentofchestSofttissueSkin,muscle,mediastinum,breast,diaphragmBonerib,thoracicspine,scapula,clavicle,sternumTracheaandbronchuslungNaturalcomparisonVerygoodnaturalcomparisonHighdensityMediumdensityLowdensityX-rayexaminationsaredependentuponthedensityresolutionImagingmodalitiesforRSX-rayConventionalM:fluoroscopy&radiographySpecialM:tomography&highvoltageradiographyBronchographyCTUltrasoundMRIAdvantagesofConventionalMFluoroscopyfast,convenient,cheap,rotatethepatient,functionalchangeofthelung,massscreenRadiographyfast,convenient,staticimagewithsharp&clearmargin,storageofthecase’sinformationforteaching,review,research,andlegalpurposes,etcDisadvantagesofConventionalMFluoroscopyobscureimage,norecordRadiographycan’trotatethepatient,nofunctionalchangescanbeseenMechanismoftomographyTubemotionFilmmotionBronchographyMethodInsertatubeAnesthesiathecarinibifurcationSelectthetargetedbronchustoinjectthecontrastmediaTakingphotographofthebronchus

IndicationofBronchographyBronchiectasisAnyreasonofhemptylysisBronchogeniccarcinomaoflungAbscesses……HazardsmayhappenAllergytoIodineandpurucaine\lidocaine,etcDisseminationofinfection(tuberculosis)throughthebronchusCT:AdvantagesVerysensitivemethodCanusethepost-processingsoftwareanddocoronal,sagittalreformationsHRCTenablesthedetaileddelineationoffinestructuresofthelungCE-CTenablesthedifferentiationofvesselsfromnon-vascularstructures,especiallyusefulforthefindingoflymphadenopathy,TNMstaging,etcCT:disadvantagesIonizationsTransversescaninthepast,howeverwiththedevelopmentofrecenttechnologyofpostprocessingprogramstheproblemisbeingresolvedMRI:AdvantagesWithoutradiationandionizationCandoanysectionscanlikecoronal,sagittal,oraxial,obliqueWiththeflowingvoideffect,thelargevesselsareeasytobedifferentiatedfromothersolidstructureslikeLNs,masses,etcMRI:DisadvantagesNotsensitiveinthedetectionofair,calcification,andvesselsSpatialresolutionisnotashighastheCTimagesDetailedinformationisnotasgoodasCT,HRCTCost:expensiveUltrasoundOnlyusedinthedetectionofpleuralfluidinthepastNowit’sstillusefulintheexaminationofdisordersadjacenttothechestwall,orwholelungopacityinordertofindtheinnerstructureofthecorrespondinglungtissueOverviewofDiagnosticRadiologyWilhelmConradRöentgenProfessorofExperimentalPhysicsWürzburgUniversityDiscoveredx-rays8November,1895AwardedfirstNobelPrizeforPhysics1901ProductionofX-raysHighspeede-strikemetalx-rayse-=electronX-raypropertyPenetrationPhotographiceffectPhosphorescentefectIonizationeffectMakingaRadiographAnimalbetweenx-raytubeandx-rayfilmLowenergyphotonsabsorbedbypatientNotusefulforimageproductionFiltersreducepatientexposureOnlypossiblebecauseofdifferentialabsorptionofx-raysPhotoelectriceffectFilmBlacknessEmulsioncrystalsexposedX-raysorlightPrecipitateonfilmduringdevelopmentBlackspotEmulsioncrystalsnotexposedRemovedduringfixingprocessWhitespotFilmBlacknessDegreeofblacknessaffectedbynumberofphotonsstrikingfilmmAnumbertofilmkVpenergynumbertofilmFactorsAffectingImageDetailMotionFilmSpeedFocalspotsizeFocalspot-filmdistanceObject-filmdistanceGriduseDistorsionMotionBigprobleminveterinaryimagingTubehead,patient&/orcassetteSedateoranesthetizeanimalUseshortexposuretimeFocalSpotWheretargetstruckbye-SmallerfocalspothassharperimageLesspenumbraDependsonsizeofcathodefilamentSmallerfilamentswearoutquickere-=electronIntensifyingScreensMoreefficienttoturnx-raystolighttoexposefilmScreenscomposedoflayersofphosphorescentcrystalsThicknessandsizeofcrystalscanbevariedDeterminesspeedofcassetteDecreasedetailwithincreasesize/thicknessFactorsAffectingContrastContrast=differencesinfilmblacknessbetweenareasinradiographSubjectcontrastFilmcontrastFogandscatterSubjectContrastThicknessdifferencesPhysicaldensitydifferencesAtomicnumberdifferencesX-raybeamenergy(kVp)SubjectContrastHighkVpLongscaleDecreasedcontrastManyx-raysreachfilmLowkVpShortscaleIncreasedcontrastFewerx-raysreachfilmFog&ScatterDecreasedcontrastGriduseincreasescontrastbecausescatterremovedbeforereachingfilmCausesScatterradiationPressureHightemperatureAccidentallightSpontaneous(time)IonizationMakesx-raysbiologicallyhazardousOccurswhenphotonstrikesatomejectinge-CausesfreeradicalformationDNAmostsensitiveSizeTurnoverrateDNAIonizationIncreasedrateofMutationsAbortionsandfetalabnormalitiesSusceptibilitytodiseaseDecreasedlifespanRiskofcancerRiskofcataractsRadiationProtectionObtainmaximumdiagnosticinformationwithminimumexposuretopersonnelandgeneralpublicBlindadherencetorulescannotsubstitutefortheexerciseofgoodjudgement!RadiationSafetyNationalRegulatoryCommission(NRC)OfficialsourceforestablishingguidelinesforradiationprotectionTwoclassesRadiationworkersGeneralpublicALARAsowseasonablychievableRadiationSafetyDistanceIntensity1/(distance)2TimeShieldingComputedTomographyCTisthecombinationoftomographyandcomputertechnologyFirstinventedbyHounsfieldin1969andreportedin1972,awardedNobelPrizein1979HigherdensityresolutioncomparedwithX-rayHigheraccuracyindiagnosisVeryrapidadvancesinrecentyearsMostup-to-dateadvancesofCTHigherscanningspeedFromslicescantovolumescanHigherefficiencyofX-raytubeHigherprocessingspeedofcomputerHigherresolutionindetailedstructuresPowerfulpost-processingsoftwareApplicableclinicalindicationsSafercontrastagentsdevelopedCommonterminologyofCTVoxelPixelPartialvolumeeffectDensityresolutionSpatialresolutionPlainscanContrastenhancementscanHRCTArtifact……OverviewofDiagnosticRadiologyWilhelmConradRöentgenProfessorofExperimentalPhysicsWürzburgUniversityDiscoveredx-rays8November,1895AwardedfirstNobelPrizeforPhysics1901ProductionofX-raysHighspeede-strikemetalx-rayse-=electronX-raypropertyPenetrationPhotographiceffectPhosphorescentefectIonizationeffectMakingaRadiographAnimalbetweenx-raytubeandx-rayfilmLowenergyphotonsabsorbedbypatientNotusefulforimageproductionFiltersreducepatientexposureOnlypossiblebecauseofdifferentialabsorptionofx-raysPhotoelectriceffectFilmBlacknessEmulsioncrystalsexposedX-raysorlightPrecipitateonfilmduringdevelopmentBlackspotEmulsioncrystalsnotexposedRemovedduringfixingprocessWhitespotFilmBlacknessDegreeof