iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii Radiationi-iUseiiniMedicaliDiagnosisiandiTreatment.
Identifiediasitheiemissioniandipropagationiofienergyiinitheiformiofiwaves,iraysioriparticles,iRa
diationiisiutilisediiniaidiverseirangeiofiindustrial,imedical,iresearchiandicommunicationsiappli
cations.iRadiationicanibeicategorisediintoitwoisub-groups:
Non-IonisingiRadiation
Consistingiofivisibleiandinonvisiblei(ultravioletiandiinfrared)ilight,ilasers,iultrasound,iandiradi
ofrequencyiradiation,iNonionisingiradiationiisiailowienergyiradiationithatidoesn’tihaveienoug
hienergyitoiremoveianielectroni(negativeiparticle)ifromianiatomiorimolecule.iVariousiexampl
esiofinonionisingitechnologiesiusediinieverydayilifeiinclude:
MagneticiResonanceiImaging
InformallyireferreditoiasianiMRI,ithisiscanneriisioperatedibyimedicaliprofessionalsiwith
i theiintentitoidistinguishiandiidentifyianyimildiorisevereiconditionsianiindividualimayih
ave.i
Additionally,iamiMRIicanidifferentiateibetweenihealthyiandidiseaseditissue,iandicanif
unctioniprovideivitalidataiconcerningitheibrain,ispine,ijointsiandiinternaliorgans.iThisii
siasiairesultiofiallitheitechnologicaliadvancesithatihaveialloweditheiscanneritoidisplayii
magesiquiteiclearly.iConsequently,idoctorsicanidetectitheiillnessiearlierianditreatiit.iA
llithisioccurringiwithoutianyisideieffects.
PrinciplesiofiMagneticiResonanceiImaging
Figurei1.1i–iIllustrationiDipictingiMRIiScanneriiiiiiiii
Asidipictediinifigurei1.1,ianiMRIimachineiisicomposedifromimultipleicomponents,isuch
i asiitsiRadioFrequencyiCoils.iNotionlyidoitheyimaintainitheipowerioutputiofitheimachin
eitoi1kW,ibutitheyiinduceiradioiwavesithati“excite”itheinuclei,iensuingiinitheiproductoi
niofiaisignal,iknowniasitheiNMRi(NucleariMagneticiResonanceiSignal).i
Theimagnetiisitheistructureithatienablesitheimachineitoiproduceihighiqualityiimages.i
Measurediinitesla/
gauss,itheimagneticifieldiisiproducedibyipassingicurrentithroughimultipleicoilsithatiar
1i|iP a g e
, eiinsideitheimagnet,iresultantiiniaistateiofisuperconductivity.iAihighifieldistrengthiofihi
ghistabilityiisimaintained.ii
TheiantennaiisianiexceptionallyidelicateigadgetithatieffectivelyiidentifiesitheiRFisigna
lsiradiatedibyiaipatient'sibodyiwhileigoingithroughiassessmentiandifeedsithisidataiint
oitheicomputerisystem.iTheicomputerisystemifunctionsitoireceive,irecord,iandianalys
eitheiimagesiofitheiindividual’sibodyithatihaveibeeniexamined.iItideciphersitheiinform
ationisentiinibyitheiantenna,iassistingiinimanufacturingianiunderstandableiimageiofit
heibodyipartibeingianalysed.i
TheipatientitableiessentiallyislidesitheipatientiintoiandioutiofitheiX-
rayimachine.iTheipositioniatiwhichitheiindividualirestsionitheitableiisidictatedibyitheire
gioniofitheibodyithatiisibeingiexamined.iWhenitheipieceiofitheibodyiunderiassessmenti
isiinitheispecificifocalipointiofitheimagneticifield,iwhichiisialludeditoiasitheiisocentre,ith
eiscanningiprocessiisisaiditoihaveibegun.i
ProductioniofiaiMagneticiResonanceiImagingiScan
Typicallyitakingiaimaximumiofianihouritoiperform,itheipatientiwillibeiplacedionitheimo
vableiscanningitableiwhileitheitechnologistimovesihimioriheriintoiposition.iAispecialipl
asticideviceicallediaicoilimayibeiencasediarounditheirihead.iTheitableiwillislideiintoithe
i tunnelianditheitechnicianiwillitakeiimagesiofitheihead.i
Toidetectispecificiproblems,isuchiasiaibrainiinjury,itheipatientimayibeiadministerediaic
ontrastisolutionithroughianiIVigoingistraightiintoitheivein.iTheisolutioniwillipin-
pointicertainiareasiofitheibrain,isuchiasibloodivessels,isoidoctorsicaniseeimoreidetail.i
Insideitheimachine,iaimagneticifieldiwilliencaseitheipatient.iTheihydrogeninucleiiinith
eipatient’sibodyiwillialign,iandithenibreakiapart.iThisiisiairesultiofitheishortiinputipulsei
ofielectromagneticiwaves.iTheihydrogeninucleiiwilliattainimoreienergyiifiitiisigivenianii
tsioptimumifrequency.i
Asitheiexamiproceeds,itheipatientiwillihearirepetitiveisoundsifromitheimachine.iOncei
theitechnicianiisifinished,itheiradiofrequencyiwaveiwillibeiturnedioff,ianditheihydroge
ninucleiiwillireturnibackitoiitsioriginaliarrangement.iTheiantennaireceivesitheisignalsia
ndisendsiititoitheicomputer,iwhereiitiwillibeiexaminedibyiairadiologist.
UsesiofiMagneticiResonanceiImagingiScanners
2i|iP a g e
Identifiediasitheiemissioniandipropagationiofienergyiinitheiformiofiwaves,iraysioriparticles,iRa
diationiisiutilisediiniaidiverseirangeiofiindustrial,imedical,iresearchiandicommunicationsiappli
cations.iRadiationicanibeicategorisediintoitwoisub-groups:
Non-IonisingiRadiation
Consistingiofivisibleiandinonvisiblei(ultravioletiandiinfrared)ilight,ilasers,iultrasound,iandiradi
ofrequencyiradiation,iNonionisingiradiationiisiailowienergyiradiationithatidoesn’tihaveienoug
hienergyitoiremoveianielectroni(negativeiparticle)ifromianiatomiorimolecule.iVariousiexampl
esiofinonionisingitechnologiesiusediinieverydayilifeiinclude:
MagneticiResonanceiImaging
InformallyireferreditoiasianiMRI,ithisiscanneriisioperatedibyimedicaliprofessionalsiwith
i theiintentitoidistinguishiandiidentifyianyimildiorisevereiconditionsianiindividualimayih
ave.i
Additionally,iamiMRIicanidifferentiateibetweenihealthyiandidiseaseditissue,iandicanif
unctioniprovideivitalidataiconcerningitheibrain,ispine,ijointsiandiinternaliorgans.iThisii
siasiairesultiofiallitheitechnologicaliadvancesithatihaveialloweditheiscanneritoidisplayii
magesiquiteiclearly.iConsequently,idoctorsicanidetectitheiillnessiearlierianditreatiit.iA
llithisioccurringiwithoutianyisideieffects.
PrinciplesiofiMagneticiResonanceiImaging
Figurei1.1i–iIllustrationiDipictingiMRIiScanneriiiiiiiii
Asidipictediinifigurei1.1,ianiMRIimachineiisicomposedifromimultipleicomponents,isuch
i asiitsiRadioFrequencyiCoils.iNotionlyidoitheyimaintainitheipowerioutputiofitheimachin
eitoi1kW,ibutitheyiinduceiradioiwavesithati“excite”itheinuclei,iensuingiinitheiproductoi
niofiaisignal,iknowniasitheiNMRi(NucleariMagneticiResonanceiSignal).i
Theimagnetiisitheistructureithatienablesitheimachineitoiproduceihighiqualityiimages.i
Measurediinitesla/
gauss,itheimagneticifieldiisiproducedibyipassingicurrentithroughimultipleicoilsithatiar
1i|iP a g e
, eiinsideitheimagnet,iresultantiiniaistateiofisuperconductivity.iAihighifieldistrengthiofihi
ghistabilityiisimaintained.ii
TheiantennaiisianiexceptionallyidelicateigadgetithatieffectivelyiidentifiesitheiRFisigna
lsiradiatedibyiaipatient'sibodyiwhileigoingithroughiassessmentiandifeedsithisidataiint
oitheicomputerisystem.iTheicomputerisystemifunctionsitoireceive,irecord,iandianalys
eitheiimagesiofitheiindividual’sibodyithatihaveibeeniexamined.iItideciphersitheiinform
ationisentiinibyitheiantenna,iassistingiinimanufacturingianiunderstandableiimageiofit
heibodyipartibeingianalysed.i
TheipatientitableiessentiallyislidesitheipatientiintoiandioutiofitheiX-
rayimachine.iTheipositioniatiwhichitheiindividualirestsionitheitableiisidictatedibyitheire
gioniofitheibodyithatiisibeingiexamined.iWhenitheipieceiofitheibodyiunderiassessmenti
isiinitheispecificifocalipointiofitheimagneticifield,iwhichiisialludeditoiasitheiisocentre,ith
eiscanningiprocessiisisaiditoihaveibegun.i
ProductioniofiaiMagneticiResonanceiImagingiScan
Typicallyitakingiaimaximumiofianihouritoiperform,itheipatientiwillibeiplacedionitheimo
vableiscanningitableiwhileitheitechnologistimovesihimioriheriintoiposition.iAispecialipl
asticideviceicallediaicoilimayibeiencasediarounditheirihead.iTheitableiwillislideiintoithe
i tunnelianditheitechnicianiwillitakeiimagesiofitheihead.i
Toidetectispecificiproblems,isuchiasiaibrainiinjury,itheipatientimayibeiadministerediaic
ontrastisolutionithroughianiIVigoingistraightiintoitheivein.iTheisolutioniwillipin-
pointicertainiareasiofitheibrain,isuchiasibloodivessels,isoidoctorsicaniseeimoreidetail.i
Insideitheimachine,iaimagneticifieldiwilliencaseitheipatient.iTheihydrogeninucleiiinith
eipatient’sibodyiwillialign,iandithenibreakiapart.iThisiisiairesultiofitheishortiinputipulsei
ofielectromagneticiwaves.iTheihydrogeninucleiiwilliattainimoreienergyiifiitiisigivenianii
tsioptimumifrequency.i
Asitheiexamiproceeds,itheipatientiwillihearirepetitiveisoundsifromitheimachine.iOncei
theitechnicianiisifinished,itheiradiofrequencyiwaveiwillibeiturnedioff,ianditheihydroge
ninucleiiwillireturnibackitoiitsioriginaliarrangement.iTheiantennaireceivesitheisignalsia
ndisendsiititoitheicomputer,iwhereiitiwillibeiexaminedibyiairadiologist.
UsesiofiMagneticiResonanceiImagingiScanners
2i|iP a g e
