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1、ComputedtomographyComputedtomographyinvolvessectionalanatomyimaging,oranatomyinthesagittal,coronal,andaxial(cross-sectional,transverse)planes.計(jì)算機(jī)斷層攝影術(shù)涉及斷層解剖成像，或者是矢狀面，冠狀面和軸位面（跨斷面或橫向的）的解剖影像。Sectionalanatomyhasalwaysbeenimportanttothephysicianandhealthcareworker,butthenewerimagingmodalitie

2、sofcomputedtomography(CT),magneticresonanceimaging(MRI),andultrasonography(US)demandanin-depthunderstandingofanatomydisplayedinthismanner.斷層解剖影像歷來受到醫(yī)生和衛(wèi)生保健工作者的重視，但是像CT，MRI和US等這些較新的成像方式需要人們對(duì)這種方式顯示的解剖有一個(gè)更深的理解。Computedtomography(CTorCATscan)technologywasdevelopedinthe1970s,andtherockgroupT

3、heBeatlesgaveabigboosttoCTdevelopmentwhentheyinvestedasignificantamountofmoneyinabusinesscalledElectricMusicalInstrumentsLimited(EMI).CT或CAT技術(shù)誕生于十九世紀(jì)七十年代，披頭士(甲殼蟲)搖滾樂樂隊(duì)對(duì)CT的發(fā)展起了非常大的促進(jìn)作用,他們給EMI公司投資一大筆經(jīng)費(fèi)。ItwasEMIengineerswhosubsequentlydevelopedCTtechnology.Initially,EMIscannerswereusedexcl

4、usivelyforbrainimaging,butthistechnologywasrapidlyextendedtotheabdomen,thorax,spine,andextremities.正是EMI公司的工程師，隨后發(fā)展了CT技術(shù)。起初，EMI掃描機(jī)僅使用于腦成像，但是該技術(shù)很快延伸到腹部，胸部，脊柱和四肢。CTimagingisbestunderstoodiftheanatomicsitetobeexaminedisthoughtofasaloafofslicedbread;animageofeachsliceofbreadiscreatedwithout

5、imagingtheotherslices.把被檢部位當(dāng)作一塊夾層面包，是對(duì)CT成像的最好理解。CT掃描只呈現(xiàn)掃描面包層的影像，而其它層面不成像?Thisisincontradistinctiontoaradiograph,whichcapturesthewholeloafofbreadasinaphotograph.這有別于普通X線攝影術(shù)，普通X線攝影在一張圖像顯示整個(gè)面包的影像。CTimagesareproducedbyacombinationofx-ray,computers,anddetectors.Acomputer-controlledcouchtrans

6、fersthepatientinshortincrementsthroughtheopeninginthescannerhousing.CT影像的產(chǎn)生有賴于X線管，計(jì)算機(jī)和探測(cè)器。計(jì)算機(jī)控制的掃描床以較小的間距將病人傳輸?shù)綑C(jī)架中的掃描孔。InthestandardCTunit,thex-raytubelocatedinthehousing(gantry)rotatesaroundthepatient,andeachanatomicslicetobeimagedisexposedtoapencil-thinx-raybeam.Eachimageorslicerequir

7、esonlyafewseconds;thereforebreathholdingisusuallynotanissue.標(biāo)準(zhǔn)的CT機(jī)，位于機(jī)架內(nèi)的X線球管圍繞病人旋轉(zhuǎn)，需要成像的每一解剖層面被鉛筆薄的X線束曝光，每一幅圖像或?qū)用娉上駜H需幾秒鐘，因此屏氣顯得并不是大問題。Thethicknessoftheseaxialimagesorslicescanbevariedfrom1to10mmdependingontheindicationsforstudy.這些軸位圖像的層厚取決于研究的目的，常以1-10mm不等。Forexample,intheabdo