Estimation of the collective ionizing dose in the Portuguese population for the years 2011 and 2012, due to nuclear medicine exams

Original

Estimation

of

the

collective

ionizing

dose

in

the

Portuguese

population

for

the

years

2011

and

2012,

due

to

nuclear

medicine

exams

F.

Costa

_,

_P.

_Teles

_,

_A.

_Nogueira

_,

_A.

_Barreto

_,

_A.I.

_Santos

_,

_A.

_Carvalho

_,

_B.

_Martins

_,

_C.

_Oliveira

_,

C.

Gaspar

_,

_C.

_Barros

_,

_D.

_Neves

_,

_D.

_Costa

_,

_E.

_Rodrigues

_,

_F.

_Godinho

_,

_F.

_Alves

_,

_G.

_Cardoso

_,

G.

Cantinho

_,

_I.

_Conde

_,

_J.

_Vale

_,

_J.

_Santos

_,

_J.

_Isidoro

_,

_J.

_Pereira

_,

_L.

_Salgado

_,

_M.

_Rézio

_,

M.

Vieira

_,

_P.

_Simãozinho

_,

_P.

_Almeida

_,

_R.

_Castro

_,

_R.

_Parafita

_,

_S.

_Pintão

_,

_T.

_Lúcio

_,

_T.

_Reis

_,

P.

Vaz

a_{InstitutoTecnológicoeNuclear,CampusTecnológicoeNuclear,UniversidadeTécnicadeLisboa,EstradaNacional10(km139,7),2695-066BobadelaLRS,Portugal} b_{NuclearMed,HPA–HospitalParticulardeAlmada,RuaManuelFebrero,85,2800-455Almada,Portugal}

c_{HospitalGarciadeOrta,Av.TorradodaSilva,2801-951Almada,Portugal}

d_{CentroHospitalarS.João,AlamedaProf.HernâniMonteiro,4200-319Porto,Portugal} e_{Fundac¸ãoChampalimaud,Av.Brasília,1400-038Lisboa,Portugal}

f_{MedicalConsult,SA,CampoGrande,n}◦_56–8◦_{A,1700-093Lisboa,Portugal}

g_{HospitaldeSantaCruz,CentroHospitalardeLisboaOcidental,AvenidaProf.Dr.ReinaldodosSantos,2790-134Carnaxide,Portugal} h_{InstitutoPortuguêsdeOncologiadeCoimbra,FranciscoGentil,EPE,Av.BissayaBarreto,n}◦_{98,3000-075Coimbra,Portugal} i_{Diaton,UnidadedeDiagnósticodeLeiria,RuadasOlhalvas,Pousos,2410-197Leiria,Portugal}

j_{Quadrantes–UnidadedeRadioterapiadoFunchal,RuadeSantaRita,S.Martinho,9000-238Funchal,Portugal} k_{Atomedical,RuaHelenaFélix,11D,1600-121Lisboa,Portugal}

l_{FaculdadedeMedicinadaUniversidadedeLisboa,Av.Prof.EgasMoniz,HospitaldeSantaMaria,CidadeUniversitária,1649-028Lisboa,Portugal} m_{ICNAS–InstitutodeCiênciasNuclearesAplicadasàSaúde,AzinhagadeSantaComba,3000-548Coimbra,Portugal}

n_{EscolaSuperiordeTecnologiadaSaúdedeCoimbra,Rua5deOutubro,Apartado,70063046-854Coimbra,Portugal} o_{ClínicaQuadrantesMiraflores,Av.GeneralNortondeMatos,71R/CMiraflores,1495-068Algés,Portugal} p_{HPP–MedicinaMolecular,Av.daBoavista,1194050-115Porto,Portugal}

q_{InstitutoPortuguêsdeOncologiadoPorto,FranciscoGentil,EPE,RuaDr.AntónioBernardinodeAlmeida,4200-072Porto,Portugal} r_{HospitaisdaUniversidadedeCoimbra,AvenidaBissayaBarreto,3000-076Coimbra,Portugal}

s_{InstitutoPortuguêsdeOncologiadeLisboa,FranciscoGentil,EPE,R.Prof.LimaBasto,1099-023Lisboa,Portugal} t_{HospitaldaLuz,AvenidaLusíada,100,1500-650Lisboa,Portugal}

u_{Administrac¸ãoRegionaldeSaúde–Algarve,LargodeSãoPedro,n.}◦_{15,8000-145Faro,Portugal}

v_{InstitutodeBiofísicaeEngenhariaBiomédica,FaculdadedeCiênciasdaUniversidadedeLisboa,CampoGrande,1749-016Lisboa,Portugal} w_{HospitalGeraldeSantoAntónio,LargoProf.AbelSalazar–EdifícioNeoclássico,4099-001Porto,Portugal}

x_{HospitalCufDescobertas,RuaMárioBotas,ParquedasNac¸ões,1998-018Lisboa,Portugal} y_{HospitalBeatrizÂngelo,AvenidaCarlosTeixeira,3,2674-514Loures,Portugal}

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Articlehistory:

Received21January2014 Accepted31March2014 Availableonline17June2014 Keywords: Nuclearmedicine Portuguesepopulation Collectivedose Effectivedose DoseDatamedII

a

b

s

t

r

a

c

t

Objectives:In2009–2010aPortugueseconsortiumwascreatedtoimplementthemethodologies pro-posedbytheDoseDatamedII(DDM2)project,aimingtocollectdatafromdiagnosticX-rayandnuclear medicine(NM)procedures,inordertodeterminethemostfrequentlyprescribedexamsandthe associ-atedionizingradiationdosesforthePortuguesepopulation.Thecurrentstudyisthecontinuationofthis work,althoughitfocusesonlyonNMexamsfortheyears2011and2012.

Materialandmethods:Theannualfrequencyofeachofthe28selectedNMexamsandtheaverage admin-isteredactivityperprocedurewasobtainedbymeansofanationwidesurveysenttothe35NMcentres inPortugal.

Results: Theresultsshowareductionofthenumberofcardiacexamsperformedinthelasttwoyears comparedwith2010,leadingtoareductionoftheannualaverageeffectivedoseofPortuguese pop-ulationduetoNMexamsfrom0.08mSv±0.017mSv/caputto0.059±0.011mSv/caputin2011and 0.054±0.011mSv/caputin2012.Portuguesetotalannualaveragecollectiveeffectivedosedueto med-icalprocedureswasestimatedtobe625.6±110.9manSvin2011and565.1±117.3manSvin2012,a reductionincomparisonwith2010(840.3±183.8manSv).

Conclusions:Themostfrequentexamsandtheonesthatcontributedthemostfortotalpopulationdose werethecardiacandboneexams,althoughadecreaseobservedin2011andin2012wasverified.The authorsintendtoperformthisstudyperiodicallytoidentifytrendsintheannualPortugueseaverage effectivedoseandtohelptoraiseawarenessaboutthepotentialdoseoptimization.

©2014ElsevierEspaña,S.L.U.andSEMNIM.Allrightsreserved.

∗ Correspondingauthor.

E-mailaddress:filipa.apbcosta@gmail.com(F.Costa).

http://dx.doi.org/10.1016/j.remn.2014.03.009

Palabrasclave: MedicinaNuclear PoblaciónPortuguesa Dosiscolectiva Dosisefectiva DoseDatamedII

Estimación

de

la

dosis

colectiva

en

la

población

portuguesa

de

los

a ˜

nos

2011

y

2012,

debido

a

los

exámenes

de

medicina

nuclear

r

e

s

u

m

e

n

Objetivo: En2009y2010unconsorcioportuguéshasidocreadoparaimplementarlasmetodologías propuestasporelproyectoeuropeoDatamedII(DDM2),conelobjetivodecoleccionardatosde proced-imientosderadiologíadediagnósticoymedicinanuclear(MN)másfrecuentes,asícomoladosisasociada enlapoblaciónportuguesa.Esteestudioesunacontinuacióndeltrabajo,quesecentraráenlosdatosde MNparalosa ˜nosde2011y2012.

MaterialyMétodos: Lafrecuenciaanualdecadaunodelos28exámenesdeMNseleccionadosyla actividadmediaadministradaporprocedimientoseobtuvieronatravésdeunaencuestaenviadaalos35 departamentosdeMNenPortugal.

Resultados: Losresultadosmuestranunareduccióndrásticaenelnúmerodeprocedimientoscardiacos enlosúltimosdosa ˜nos,loquetienecomoconsecuenciaunareduccióndeladosisefectivaanualen lapoblaciónportuguesaderivadodeprocedimientosdeMNde0,08mSv±0,017mSv/caputen2010,a 0,059±0,011mSv/caputin2011y0,054±0,011mSv/caputin2012.Ladosisefectivacolectivamediaen lapoblaciónportuguesaesestimadaen625.6±110.9manSven2011,y565.1±117.3manSven2012. Conclusiones: Losexámenescardiacosyóseosfueronmásfrecuentesylosquemáscontribuyeronpara ladosistotaldelapoblación,aunqueseverificóunadisminuciónen2011yen2012.Losautoresde estetrabajopretendenrealizarestetipodeestudiosperiódicamenteparaidentificartendenciasenlos diferentesprocedimientosdeMNyayudaraaumentarlaconcienciadelosprofesionalesdeMNsobre esteasunto.

©2014ElsevierEspaña,S.L.U.ySEMNIM.Todoslosderechosreservados.

Introduction

Theuseofionizingradiationformedicalpurposeshasincreased over thepast decades, contributing to over 95% of man-made radiationexposure.1_{Evenifimagequalityimproved,allowingfor} moreaccuratediagnoses,asignificantincreaseofthedose deliv-eredtoeachpatientalsooccurred.Proceduressuchascomputed tomography(CT),interventionalprocedures,andcardiacnuclear medicine are thought to be the main contributors to such an increaseinexposure.InternationalorganizationssuchastheUnited NationsScientificCommitteeontheEffectsof AtomicRadiation (UNSCEAR)andtheEuropeanCommission(EC)publishedseveral reports inwhich increasedvalues of worldwide collectivedose arepresented.2,3_{TheEChasconcernsaboutthewidedifferences} betweenthereportedresultsofpopulationdoseestimationsfrom differentEuropeancountrieswithsimilarhealthcarelevels,which maybeduetotheabsenceofacommonEuropeanmethodology. ThisledtothecreationofamultinationalEuropeanproject,in2004, theDoseDatamedI(DDM1),inwhichagroupofcountrieswith tra-ditioninconductingstudiesofpopulationexposureparticipated, withtheaimoffindingacommonmethodology.Basedonthe expe-rienceof10Europeancountries,RadiationProtectionno.154was created.4 _{Thisdocumentprovidespracticalguidancetocreatea} harmonizedsystemforassessingpatientdosesinMemberStatesin ordertocomparenationalpopulationdosesinthefuture.Guidance isprovidedtoassessdoseduetomedicalX-rayimagingandnuclear medicine(NM)procedures.Itshouldbenotedthattherehasbeen alonghistoryofcarryingoutperiodicreviewsofthepopulation exposureinmostcountriesparticipatinginDDMI,incontrastwith whathappensinPortugal.

In2009–2010theEuropeanCommissionfinancedtheproject Dose Datamed II (DDM2),5 _{a follow-up study of DDM1, also} called“StudyonEuropeanPopulationDosesFromMedical Expo-sure”,aimingtocollectdatafromdiagnostic X-rayandnuclear medicineproceduresinordertodeterminethemostfrequently prescribedexamsandtheassociatedcollectivedosesinthe Euro-pean population.6 _{Portugal, together with other 35 countries} participatedinthisstudy.7_{Forsuch,aPortugueseconsortiumwas} created,topotentiatetheimplementationofthemethodologies proposedbyDDM2.8_{Thisledtoanestimationofthedosetothe} PortuguesePopulationof∼1mSvcaput−1fortheyear2010and,of

particularinteresttothiswork,of0.080±0.0017mSv/caputdueto nuclearmedicineexaminations.9

The current study aims to be both a continuation and an improvement ofthepreviouswork,focusingonlyonthe popu-lationdosestonuclearmedicineprocedures,fortheyears 2011 and2012,andcomparingthemwiththeresultsobtainedin2010. Radiationdosesduetoradiodiagnosticexamswillbeanalyzed else-where.Themostfrequentnuclearmedicineexamsandthosethat contributethemostfortheannualcollectivedosewereassessed. ThePortugueseresultsarealsocomparedwiththoseavailablefor otherEuropeanCountries.Finally,theyearlytrendsofpopulation doseandannualfrequenciesofdifferentnuclearmedicineexams werealsoanalyzed.

Materialandmethods

Themethodologyusedinthisstudywasbasedonthereport RadiationProtection154(RP154).Fornuclearmedicinepractices, theRP154recommendstheimplementationofanationwide sur-veytotheextantnuclearmedicinecentres.4_{Atablewiththemost} commonnuclearmedicineproceduresisproposedinthereport, involving the most utilized radionuclides divided in six major typesofdiagnosticexams(bone,heart,thyroid,lung,kidneyand theremainders).Thisconsistsof28NMexaminations(procedure, radionuclideandchemicalform)aspresentedinTable1.

Anationwidesurveywassenttoall35nuclearmedicine cen-tresinPortugal.Thecentreswereinvitedtofillinafilewiththe annualfrequencyofeachexam,aswellastheaverageadministered activityperprocedure.Inaddition,eachNMcentrecouldinclude alistofexamstheyconsideredrelevant(highnumberofpatients performingtheexamorhighadministeredactivity).FortheNM centreswhichhadthisinformationavailable,onlydatafromadults (>18yrs)wereincluded.InPortugal,atotalof34NMdepartments wereidentifiedin2011and35in2012,unlikethe32centresin 2010.Theuseofdifferentradionuclideshighlyaffectsthe effec-tivedoseperexamination,soitisimportanttoguaranteethesame radionuclideisbeingusedforthesameprocedure.

Ofthe34identifiedcentresin2011,fourdidnotpossessany statisticaldataandtheothersixdidnotreply.In2012fromthe universeof35centres,fourdidnotpossessanystatisticaldataand

Table1

Conversioncoefficientsusedforthe28nuclearmedicineradiopharmaceuticalsconsideredinthisstudy.ThevaluesarewithagreementwithDDM2-PortugalandICRP53,10

8011_and106.12

Nuclearmedicineprocedure Radionuclideandchemicalform Conversioncoefficient(mSv/MBq)

1.Boneimaging 99m_{Tc–phosphatesandphosphonates 5.70×10}−3

2.Myocardialperfusionwiththallium 201_{Tl–chloride 2.20×10}−1

3.MyocardialperfusionwithTetrofosmin(rest) 99m_{Tc–tetrofosmin 7.60×10}−3

4.MyocardialperfusionwithTetrofosmin(exercise) 99m_{Tc–tetrofosmin 7.00×10}−3

5.MyocardialperfusionwithMIBI(rest) 99m_{Tc–MIBI 9.00×10}−3

6.MyocardialperfusionwithMIBI(exercise) 99m_{Tc–MIBI 7.90×10}−3

7.Myocardialperfusion(PET) 18_{F–FDG 1.90×10}−2

8.Myocardialperfusion(PET) 15_O–H

2O 9.30×10−4

9.Positronemissiontomography 18_{F–FDG 1.90×10}−2

10.Positronemissiontomography+diagnosticCT 18_{F–FDG 1.90×10}−2

11.Thyroidmetastases(afterablation,uptake0%) 131_{I–iodide 6.10×10}−2

12.Thyroidimaging(oraluptake,noblocking) 99m_{Tc–pertechnetate 1.40×10}−2

13.Thyroidimaging(35%thyroiduptake) 123_{I–iodide 2.20×10}−2

14.MUGA,cardiacbloodpool,cardiacbloodflow(equilibrium) 99m_{Tc–DTPA 4.90×10}−3

15.MUGA,cardiacbloodpool,cardiacbloodflow(equilibrium) 99m_{Tc–Tc-labellederythrocytes 7.00×10}−3

16.Dopaminetransporterimaging(parkinsonism) 123_{I–␤CIT 5.00×10}−2

17.Dopaminetransporterimaging(parkinsonism) 123_{I–ioflupane(DatScan) 2.40×10}−2

18.Lungperfusion 99m_{Tc–MAA 1.10×10}−2

19.Neuroendocrinetumours/somatostatinreceptorsimaging 111_{In–pentetreotide(OctreoScan) 1.20×10}−1

20.Renalimaging 99m_{Tc–DMSA 8.80×10}−3

21.Renalimaging 99m_{Tc–MAG3 7.00×10}−3

22.Renalimaging 99m_{Tc–DTPA 4.90×10}−3

23.Parathyroidimaging 99m_{Tc–MIBI 9.00×10}−3

24.Cerebralbloodflow 99m_{Tc–exametazine(HMPAO) 9.30×10}−3

25.Cerebralbloodflow 99m_{Tc–ECD(neurolite) 2.20×10}−3

26.Infection/inflammationimaging 67_{Ga–galliumcitrate 1.00×10}−1

27.Infection/inflammationimaging 99m_{Tc–Tc-labelledleucocytes 1.10×10}−2

28.Infection/inflammationimaging 99m_{Tc–monoclonalantibody(LeucoScan) 8.00×10}−3

sixdidnotreply,giving25answerstothesurvey.Thisgivesa par-ticipationratioofanswerstothesurveyof80%and81%for2011 and2012,respectively.Thisisanimprovementincomparisonwith the73%answerratioin2010(19NMcentresansweredthesurvey, sevenhadnostatisticaldataandsixdidnotreply).

Theeffectivedoseforeachexamandthecollectiveeffectivedose werecalculated.Inordertodothat,theaverageweightedactivity for(Aavg(x))eachnuclearmedicineprocedurexwascalculated,

Aavg(x)=





nuclearmedicineprocedurex.Thetotalnumberofparticipant cen-tresisgiven bynand freqi(x) representsthefrequency ofeach

examination xin centre i. The dosepercaput for each nuclear medicineprocedureisdeterminedasfollows:

D caput(x)=

Aavg(x)·ex·



population (2)

existheeffectivedose [] takenfromtheInternationalCommission

onRadiologicalProtection(ICRP),thesameoneappliedinthe pre-viousstudyofDDM2inPortugal.9_{Thevariablepopulationrefersto} thetotalpopulationofPortugal(10,555,853inhabitants).13

ThetotaldosepercaputduetoallNMexaminationisgiven bythesumofeach dosedeterminedfor eachprocedure. A lin-earcorrectionfactorwascalculatedfor 2011and2012inorder toextrapolatetheobtainedvaluesbasedonthepositiveresponse ratio.Thisvalueis1.25(=1/0.80)for2011and1.23(=1/0.81)for 2012.

Aquestionnairewasalsosenttothe25nuclearmedicine partic-ipantcentresinordertogetmoreinformationabouteachcentre,to understandthedifficultiesexperiencedbyhealthcare profession-alsindoseassessmentandtoassessopinionsinsomeimportant matterssuchasthecreationofPortugueseguidelines.The ques-tionnaire sent tothenuclearmedicinecentres consistedof the followingfivequestions:

• Whichprotocolisusedatyourcentretodeterminetheactivity administeredinapatient?

• Ifnationalguidelineswereestablishedinordertostandardize theprotocolsusedinmedicalservices,wouldyourcentrefollow them?

• Do you usually register the activity values when injecting a patient,orjustthereferredprotocolvalue?

• Howeasilydidyouseparatetheactivityvaluesandthe num-berofexamsforadultpatientsfrompaediatricpatients,ifthisis possibleinyourcentre?

• Incaseaseparationofthesentdatabythepatient’sageandsex wouldberequested,woulditbeeasyforyoutodoit?

Results

PopulationexposureinPortugalfortheyears2010,2011and2012 Frequencies

Inthiswork,datafortheyears2011and2012wereobtainedand comparedwiththeoneobtainedfor2010.Datashowedthat17.97 NMproceduresper1000populationwereperformedinPortugalin 2010,13.34in2011and11.60in2012.InFig.1agraphisdisplayed showingthetrendsintheannualfrequencyofnuclearmedicine examsperformedfrom2010to2012.Areductiononthenumber oftotalnuclearmedicineexamsandcardiacexamsperformedin 2011comparedwith2010isobserved.Atinydecreaseonthetotal andcardiacexamsperformedisalsoobservedin2012inrelation to2011.

Cardiacexamsandtheirinfluenceintheresults

Thecardiacexamsconsideredinthisworkare:(i)myocardial perfusionwithtetrofosmin(exerciseandrest),(ii)myocardial per-fusionwithMIBI(exerciseandrest),(iii)myocardialperfusionwith thallium,(iv)MUGA–cardiacbloodpool,cardiacbloodflow (equi-librium), and(v)positron emissiontomography (PET)– cardiac study(metabolismandperfusion).InFig.2theannualfrequency ofeachcardiacexampresentedinthisstudyisshown,exceptfor

190 000 180 000 170 000 160 000 150 000 140 000 130 000

Annual frequency of NM exams

120 000 110 000 100 000 90 000 80 000 70 000 60 000 50 000 40 000 2014 Total NM exams

Total NM exams w/o cardiac Total NM exams w/o cardiac and bone Cardiac exams

Bone exams

2011 Year

2012

Fig.1.TotalannualfrequencyofNMexams.Influenceofcardiacandbone exami-nationsonthetotalannualfrequencyofNMexams.

PETsincethereisnorelevantstatisticaldata.Asharpdecreasein theannualfrequencyofmyocardialperfusiontetrofosminandMIBI examinationisobservedinthelasttwoyearscomparedwith2010. TheMUGA–cardiacbloodpoolexaminationdidnotinfluencethe decreaseofannualfrequency,asitsfrequencyremainsconstant alongthethreeyears.Finally,myocardiumperfusionimagingwith thalliumdisplaysaconstantandalownumberofexamsperformed annually.

Collectivedose

Applying the conversion factors, as given in Table 1, the Portuguese total annual average collective effective dose due to diagnostic nuclear medicine exams was estimated to be 625.6±110.9manSv(0.059±0.011mSv per caput)in 2011 and 565.1±117.3manSv(0.054±0.011mSv)in2012.Thedosevalues decreasedconsiderablyrelativetothevalueestimatedfor2010, 840.3±183.8manSv(0.080±0.017mSvpercaput).The uncertain-tieswerecalculatedusingtheweightedstandardsdeviationofthe reportedactivitiesforeachcentre.Expandingtheuncertaintyfor

eachdeterminedcollectivedoseperexam,theuncertaintyinthe totalcollectivedosewasestimated.Table2 showsthatthe col-lectivedosein2010duetocardiacexamsismorethantwicethe valueofcollectivedosecalculatedin2012.Thevaluesoftotal col-lectivedosewithoutcardiacexamsareverysimilaramongstthe threeyears.Finally,thetotalcollectivedoseisinferiorin2012also duetothereducedvalueofboneimagingexaminations.

Examtypes

Eachofthesixdifferentexaminationgroups’contribution(bone, heart, thyroid, lung, kidney and remainder) tothe annual fre-quenciesandtothetotalcollectivedosefromnuclearmedicine proceduresis shown inFig.3.Cardiacproceduresare themost frequentlyacquired nuclearmedicine exams and theonesthat contributethemostforthetotal collectivedosereceivedbythe Portuguesepopulation,althoughthiscontributionisdiminishing. Heartandboneexamstogethercorrespondtoapproximately70% ofthetotalamountofnuclearmedicineexamsperformedduring thethreeyearsstudied.In2010bothcategoriescontributedto84% ofthetotalannualdoseduetoNMprocedures,whilein2011and 2012thatcontributionwas70%and68%,respectively.

Thefourexamsthatcontributedthemosttothehighvalueof annualcollectivedoseshownintheremainderexamsin2011and 2012areneuroendocrinetumours/somatostatinreceptors imag-ing,infection/inflammationimagingwithgallium,wholebodyPET andwholebodyPET+CT.In2010thosewerethesameexamsthat contributedthemostforthetotalvalueofcollectiveeffectivedose, amongsttheremainderexams,exceptthecontributionof somato-statinreceptorsimagingwhichwaslower(Fig.4).

TOP10ofthenuclearmedicineexams

In2010,the10nuclearmedicineexamsthatcontributedthe mosttothetotalcollectiveeffectivedosewereidentifiedinthe DDM2-Portugalstudy(TOP10).Thecontributionofeachexamis showninFig.5for2010,2011and2012.In2011and2012the 10examsthatcontributedthemosttothetotalcollectiveeffective doseweredifferentthantheonesfoundin2010.InTable3isshown theTOP10examswithhighercontributiontothecollective effec-tivedosefortheyears2010,2011and2012.In2011,myocardium perfusionwiththalliumcontributed 1.7% tothetotal collective effective dose, which is no longer onthe top 10 exams. Neu-roendocrinetumours/somatostatinreceptorsimagingcontributed moretothetotalcollectiveeffectivedosein2011(3.2%).In2012, thecontributionofmyocardiumperfusionexaminationswith thal-lium decreased even further to 0.2%, and whole body PET+CT

0 5000 10 000 15 000 20 000 25 000 30 000 35 000 40 000 Myocardial perfusion with tetrofosmin (exercise) Myocardial perfusion with tetrofosmin (rest) Myocardial perfusion with MIBI (rest) Myocardial perfusion with MIBI (exercise)

MUGA, cardiac blood pool, cardiac blood flow (equilibrium) Myocardial perfusion with

thalium Annual f requen cy of NM ex am s 2010 2011 2012

Table2

Annualcollectivedoseduetoallnuclearmedicineexamsandonlycardiacandbonenuclearmedicineexams.

Year Totalcollective

dose(manSv)

Collectivedosedue tocardiacexams (manSv)

Collectivedosedue toboneexams (manSv)

Totalcollective dosew/ocardiac exams(manSv)

Totalcollectivedosew/o cardiacandboneexams (manSv) 2010 840.3 453.7 183.28 372.5 189.2 2011 625.6 248.3 178.99 377.4 198.4 2012 565.1 219.3 156.80 343.7 186.9 0% 10% 20% 30% 40% 50% 60% 70%

Bone Heart Thyroid Lung Kidney remainder Year 2010

Frequency distribution Dose distribution 0% 10% 20% 30% 40% 50%

Bone Heart Thyroid Lung Kidney remainder Year 2011 0% 10% 20% 30% 40% 50%

Bone Heart Thyroid Lung Kidney remainder Year 2012

Fig.3. Relativecontribution(%)ofsixnuclearmedicinegroupstothetotalfrequency andtotalpopulationdoseofnuclearmedicineexaminations.

0% 5% 10% 15%

Neuroendocrine tumors/ somatostatin receptors imaging Infection/inflammation

imaging with gallium PET-whole body + CT

PET-whole body

2010 2011 2012

Fig.4. Relativecontribution(%)ofremainderexamstothetotalcollectiveeffective dose.

Table3

TOP10examsfortheyear2010,2011and2012. TOP10exams(2010–2012)

Boneimaging

Myocardialperfusionwithtetrofosmin(exercise) Myocardialperfusionwithtetrofosmin(rest) PET–wholebody

MyocardialperfusionwithMIBI(rest) MyocardialperfusionwithMIBI(exercise) MUGA,cbp,cbf(equilibrium)

Thyroidimaging(oraluptake,noblocking) PET–wholebody+CT

Myocardialperfusionwiththallium

decreased to1.7%, being no longerin the top 10 exams. Neu-roendocrinetumours/somatostatinreceptorsimagingandthyroid metastases(afterablation,uptake0%)contributedmoretothe pop-ulation’sexposurewith3.94%and2.9%respectively,morethanthe aforementionedexaminations.

PortugalandotherEuropeancountries

The relativecontributionof NMprocedurestothecollective effectivedose(manSv)wascalculatedforthe35countriesthat par-ticipatedinDDM2.6_{Thereportsuggestedagroupoftop7exams,} selectingthehighestexaminations’contributorstothecollective effective dosein allDDM2countries. Thesetop7 examsarein fact11examinations.DDM2reportgroupedthemyocardial per-fusion withMIBIexamination(rest andstress)withmyocardial perfusionwithtetrofosmin(restandstress)inonlyone examina-tioncalledheartexamwith99m_{Tc,whilewholebodyPET+CTand}

PETwerealsogroupedinonlyoneexam.Theminimum,maximum andmedianvalueswereestimatedfortheidentifiedexams.The samecalculationswereperformedtostudythePortuguesereality basedonthecollectivedosedatafortheyear2010,2011and2012. TheresultsobtainedforPortugalandDDM2countriesareshown in Fig.6. Therest andstress myocardialperfusionexams were grouped,sincenoinformationwasavailableinseparateforDDM2 participantcountries.6Thebarsrepresenttheminimumand max-imumvaluesidentifiedforallcountriesparticipatinginDDM2and thePortugueseresultsbetween2010and2012.Theresultsdiffer greatlybetweenthePortugalandtheremainderDDM2countries, particularlyregarding boneimaging and myocardiumperfusion withMIBI.

Forthesame11examinationsinconsideration,nowseparating therestfromthestressmyocardialperfusionsexams,thedoseper procedureinmSvwascalculatedbasedonthePortugueseresults between2010and2012.Thevalueswerecomparedagainwith DDM2countries’resultsasshowninFig.7,andevenmoresowith thevaluesobtainedforneighbouringSpain.14_{Intermsofabsorbed} doseperprocedure,theresultsaresimilarbetweenPortugal,Spain andEuropeancountries,exceptformyocardiumperfusionimage withthallium,wherethedifferenceishigherthan10mSv(higher valueinPortugalandinexistentinSpain).Thedoseperprocedure ofthyroidmetastases(afterablation,uptake0%)andwholebody PETexamalsoshowhighervaluesinPortugal.

0% 10% 20% 30% Bone imaging

Myocardial perfusion with tetrofosmin (exercise) Myocardial perfusion with tetrofosmin (rest) PET-whole body Myocardial perfusion with MIBI (rest) Myocardial perfusion with MIBI (exercise) MUGA, cbp,cbf (equilibrium) Thyroid imaging (oral uptake, no blocking) PET-whole body + CT Myocardial perfusion with thalium Remainder

Contribution

2010 2011 2012

Fig.5.TOP10of2010NMexamsthatcontribute(%)themosttothetotalcollectiveeffectivedoseofPortuguesepopulationintheyears2010,2011and2012.

90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Bone imaging Myocardial perfusion with thalium Myocardial perfusion with tetrofosmin (rest and stress) Myocardial perfusion with MIBI (rest and stress) Positron emission tomography-whole body Positron emission tomography-whole body + TC Thyroid imaging (oral uptake, no blocking) Thyroid metastases (after ablation, uptake 0 %) Lung perfusion

Contribution to the collective effective dose DDM2 countries Portugal

Fig.6. TheexaminationsthathaveahighercontributiontothecollectiveeffectivedoseoftheEuropeancountriesreportedintheDDM2study.Relativecollectiveeffective doseforDDM2countriesandPortugal.

Questionnaire

From the 25 nuclear medicine participant centres, only 12 repliedtothesurvey,althoughtheresultsgivenwereassumedto berepresentativeofPortugueseNMcentrereality.Ofthe respon-dent centres, more than 80% of the NM centres respondedto question1thattheyfollowtheEuropeanAssociationofNuclear Medicine(EANM)guidelines,15_{theSocietyofNuclearMedicineand}

MolecularImaging(SNMMI)guidelines16_{andtheBritishNuclear} MedicineSociety(BNMS)protocol,17_{orsomeformofadaptation.} WhenaskediftheywillfollowPortugueseguidelinesinthesecond question,80%respondedpositively,howeversomereferredthey hadtocomparethemwiththeguidelinestheyalreadyhaveand followforqualityassurance.Thethirdquestionrevealstheconcern toknowifthePortugueseNMcentresregistertheactivity admin-isteredtoeachpatientorjusttheprotocolvalues.Asaresponseto

0 5 10 15 20 25

Lung perfusion Thyroid imaging (oral uptake, no blocking) Myocardial perfusion with tetrofosmin (rest) Bone imaging Myocardial perfusion with MIBI (exercise) Myocardial perfusion with tetrofosmin (exercise) Myocardial perfusion with MIBI (rest) PET-whole body PET-whole body + CT Thyroid metastases (after ablation, uptake 0 %) Myocardial perfusion with thalium

Dose / procedure (mSv) DDM2 countries Portugal Spain

it,75%ofthesurveyedcentresregistertheactivityvaluesforeach patient,andtheothersjustsavetheprotocolvalues.Concerning question4,only25%(threecentres)hadthedataalreadyseparated frompaediatricandadultpatientsandfor33%(fourcentres)itwas easytoseparatethedata.Inquestion5onlythreecentresofthe 12respondedthattheycanprovidethedataseparatedbyageand sex.

Discussion

In 2011and 2012it waspossibletocollectdatafrommore NMcentresinPortugalthanin2010.Neverthelessadecreasein thenumberofNMexamswasobserved.Thiswasmostlyduetoa considerablereductioninthenumberofperformedcardiac exam-inations butalsodue toadecrease inthebone imagingexams performed.Amongthereasonswhythenumberofcardiacexams diminishedisduetotheimplementationofimprovedtechniques fordiagnostics(suchasechograms)whichdonotutilizeionizing radiation.Anothercontributorcouldbethefinancialcrisis,which mayhaveaffectedthenumberofprescribedcardiacexamsinthe Health carecentres.To reinforcethis idea,thetotal number of NMexaminationperformedduringthethreeyears,notcounting thecardiacand boneexaminations,areapproximatelyconstant duringthethreeyears.Thedecreasewasparticularlyevidentin themyocardialperfusionwithtetrofosmin(exerciseandrest)and myocardialperfusionwithMIBI(exerciseandrest)examinations. Thisexplainsthereductioninthetotalannualaveragecollective dosefortheyear2011and2012,aswellasareductioninthedose percaputforeachnuclearmedicine,whencomparedwith2010.

Nonetheless a reduction is observed; cardiac exams contin-uedtobetheexaminationthatcontributedthemostintermsof numberofexamsperformedandtotalannualdosein2011and 2012,although,withalowerpercentagecomparedwith2010.The reduced proportionofcardiacexaminationsexplainsthehigher relativecontributionofthefiveothergroupsofexaminationsin thelasttwoyears,comparedwiththeresultsobtainedin2010, especially theincrease in the percentage of bone imaging and remainder examsperformed (Fig.3). Wholebody PET was the examthatcontributedmoreforthehighpercentageofremainder exams,increasingthepercentagein 2011and 2012.This incre-mentwasduetoanincreaseonthenumberofwholebodyPET exams performedin Portugal, while deaverage collectivedose wasapproximatelyconstant.Also, somatostatinreceptors imag-ingexaminationwhichhadcontributionthatwaslowin2010,but in2011and2012itshowedahighcontribution(Fig.4).Thiscould beexplainedbyagreatvariabilityontheaverageactivity admin-isteredtothepatientsforsomatostatinreceptorsimagingamong theparticipantNMcentresinPortugal.

Theexaminationsthathaveahighercontributiontothe rela-tivecollectiveeffectivedoseoftheEuropeancountriesreported inDDM2differfromthePortugueseresults,inparticularforbone imagingandmyocardiumperfusionwithMIBI(Fig.6). Neverthe-less,alargerangeisobservedinthedatacompiledintheDDM2 report,inwhichminimumandmaximumvaluesareverydifferent dependingontheconsideredEuropeancountry.Intermsofaverage effectivedoseperNMprocedure,theresultsobtainedforPortugal aresimilarwithDDM2reportedvalues,exceptformyocardial per-fusionwiththallium.Thiscouldbeduetolessrobustnessinthe availablePortuguesedata,sincethisexaminationisrareinPortugal (Fig.2),beingonlyperformedinthreenuclearmedicinecentres.

ThequestionnairewasimportanttocharacterizetheNM cen-tresinPortugalandtoidentifymeasuresthatshouldbetakenin ordertostandardizetheprotocolsandthewaytheinformationis collectedin eachcentre.Thesurveyrevealsthatthecreationof Portugueseguidelinesisapossibilityandshouldbedeveloped.The

questionnairewasalsoalertforthefactthat25%ofthesurveyed didnotregistertheactivityvalueadministered toeach patient, which meansthat some centressent theprotocol activity val-ues,whichalthoughareagoodapproximationtothereality,they might bebiased.Question4 wasalsoessentialtounderstandif thePortuguesehealthcaresystemispreparedtoefficientlyprovide periodicdetailedinformationifneeded.Morethan50%could eas-ily providethedataforadultpatientsonly, onecentrereferred difficultiestoseparatethedatawhilefoursaiditwasimpossible toseparate.Thisisaconcernbecauseitmeansthatsomeofthe resultssentarebeinginfluencedbylowactivityvalues adminis-teredtopaediatricpatients,thusdecreasingestimatedvaluesof collective effectivedoseof Portuguese populationcalculated in thisstudy.InotherEuropeancountries,dataontheage distribu-tionofpatientsundergoingnuclearmedicineexaminationswere available.4_{Inordertounderstandifthisstudyisfeasiblein} Portu-galquestion5wasasked,howeverthemajorityofthecentresisnot preparedtoprovidethistypeofinformation,sinceitwillbetime consuminginsomecasesandevenimpossibleinotherswherethey donotkeeprecordoftheagesofthepatients.

Conclusion

ThisstudyisacontinuityofDDM2–Portugal,andprovidesan estimationofthedosereceivedbyPortuguesepopulationinnuclear medicineexams,followingtheRP154methodology.Itwas possi-bletocompiledatafrommoreNMcentresintheyears2011and 2012comparedwiththedatacollectedin2010.Themainnuclear medicinecentresinPortugal,whichannuallyperformmore exam-ination,participatedin thisstudy,allowingustostatethatthis studywillbevery representativeofthePortuguese reality.The annualaverageeffectivedosedecreasedin2011and2012dueto thereductionofthenumberofNMexamsperformed,particularly duetocardiacexamsbutalsoduetoboneimaging.Nevertheless, thesetwoexamscontinuetobethemostfrequentexamsandthe onesthatcontributedthemostfortotalpopulationdose.Contact withnuclearmedicine centresisrequired tobetterunderstand thedecreaseofNMexamsperformed,althoughfinancialproblems seemtobethereason.Thehighcontributionofneuroendocrine tumours/somatostatinreceptorsimagingtotheannualcollective dose in theyears 2011 and 2012is also of great concern,and thereasonswillbeinvestigatedthroughdirectcontactwiththe healthcareprofessionals.ThePortugueseresultsofaveragedose perprocedurearesimilarwiththeresultspresentedontheDose Datamed2report,withanexceptionofmyocardialperfusionwith thallium.Thecontributionofwholebody PETexaminationshas alsoincreased,anditisthusimportanttokeeptrackofthese val-uesinfutureevaluationsoftheannualcollectivedose.Inaddition itisimportanttonotethatinhybridtechniquessuchasPET/CTand SPECT/CT,thedosereceivedbythepatientwillbehigherduetothe dosereceivedbytheCTexams,whichisnottakenintoaccountin thisstudy.Improvementsarestillneededtoguaranteethatallthe centressendtheaverageactivityadministeredtoadultpatientsand caneventuallyseparateactivityvaluesbetweenadultsand chil-dren.ItisalsoexpectedtoexpandtheparticipationofNMcentres inPortugalto100%,throughthecreationofanon-lineplatform tosimplifythedatashare.Nonetheless,werecommend thatall nuclearmedicinecentresstarttoorganizethedataintheDDM2 dataformat,sinceitisexpectedtoperformthisstudyperiodically, inordertoidentifytrendsintheannualeffectivedoseandannual collectivedoseofPortuguesePopulation.Thiswillallowfor rais-ingawarenessinmedicalprofessionals,staffandmembersofthe publicandforpotentialdoseoptimization.Inaddition,the avail-abilityofsuchdatawillfacilitatetheimplementationofradiation protectionrequirementsinPortugal.

Acknowledgements

Theauthorsthankallthenuclearmedicinecentresand institu-tionsthatsupplieddataforthiswork:Cimo–CentrodeImagem Molecular,HospitaldeS. João,HospitalGeraldeSanto António, Instituto Portuguêsde Oncologia FranciscoGentil, EPE– Porto, InstitutoPortuguêsdeOncologiaFranciscoGentil,EPE–Coimbra, InstitutoPortuguêsdeOncologiaFranciscoGentil,EPE–Lisboa,HPP –MedicinaMolecularPorto,HospitaisdaUniversidadedeCoimbra, ICNAS–InstitutodeCiênciasNucleares AplicadasàSaúde, DIA-TON,FaculdadedeMedicinadaUniversidadedeLisboa,Hospital daForc¸aAérea,Atomedical,HospitalCUFDescobertas,Hospitalda Luz,HospitaldosLusíadas,Fundac¸ãoChampalimaud,Hospitalde SantaCruz,CentroOncológicoDr.aNatáliaChaves,Clínica Quad-rantesMiraflores,HospitalBeatrizÂngelo,HospitalGarciadeOrta, NuclearMed–HospitalParticulardeAlmada,HospitalParticulardo Algarve,andQuadrantes–UnidadedeRadioterapiadoFunchal.

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