CT FS

1. Computed
tomography
BritishengineerGodfreyHounsfieldandphysicist
DrAllanCormackmadethefirstcommerciallyavailable
CTmachinein1972. Basedoffa“3DX-raymachine’Hounsfield
revolutionisedmedicalimagingandwonaNobelprizein1979.The
firstCTwastestonarealpatentin1971,whereradiologistJames
Ambrosecouldvisualisehis41yearoldpatient’sbrain.
Thedatacollectedfromthebrainwasstoredonamagnetictapethen
driveninacartoalab20kmaway.Theresultsofthescanwere
publishedalmostanentireyearlater.
(CatalinaImaging,2019)
Computed Tomography (CT) is a medical imaging modality that uses x-rays and computer processing
software to take detailed internal IMAGES of the body.
Thepatientliesonthebedthatslowlymovesintothegantry,whilea
motorisedx-raysourceisshotthroughthepatientproducingslicesof
manyanglesandprojectionsofthepatient.
Inthegantry,thex-raytubeissituatedoppositeadigitalmultislice
detector,whichcollectsthex-raydataandsendsittothecomputerso
alltheslicescanbecombinedtogenerateathree-dimensionalscanof
thebody.Today,theactualscantakesafewminuteswherepatients
usuallygettheirresultswithinacoupleofweeks.
Acontrastagentcanbeintroducedtothebodytomakesofttissue
structuressuchasvesselsmorevisibleonaCTscan.Thecontrast
agentcontainsaradioopaquesubstancethathasahigher
attenuationtox-rays.Contrastcanhelpidentifybodilyblockagesand
injuriesinamedicalcontext.
(NationalInstituteofBiomedicalImagingandBioengineering,2022)
Acontrastagentcanbe
introducedtothebodytomake
softtissuestructuressuchas
vesselsmorevisibleonaCT
scan.Thecontrastagent
containsaradioopaque
substancethathasahigher
attenuationtox-rays.Contrast
canhelpidentifybodily
blockagesandinjuriesina
medicalcontext.
CTscansfollowthesameprinciplesas
radiographsduetotheuseofx-rays.
Leastdensetissuessuchasairandwater
havealowattenuationsoappeardark/
blackonaCTscan.Whereasbone,the
densesttissueappearswhite/bright.
CTscansproducemoredetailedimagesas
theyareformedbystackingmanyx-ray
imagesandthescancanbeviewedinspace,
formedicalprofessionalstomakeamore
accuratediagnosis(Preston,2023).
CTscansalsoproduceionizingradiationwhichhasthepotentialto
causedamageandbiologicaleffectstolivingtissue.Apatient'sriskof
cancercanincreaseiftheyareoverexposed.Becauseofthis,itis
advisedthatpregnantwomenavoidhavingCTscansasthereareother
imagingmodalitiesthatdonotemitradiationandthereforearesafer
forthemotherandfoetus.