DevelopmentofVirtualDoseMonitoringSystemforInterventionalRadiology-Radiologist(VIR-R)

Abstract

중재방사선시술자는방사선에노출되는모든의료진중방사선량이가장높은편에속하며,특히손과수정체와같은국부위치의경우국제방사선방호위원회에서권고한선량한도를초과할수있다고보고되고있다.하지만개인선량계를이용한기존선량감시시스템에는크게두가지한계점이있다.우선,보통TLD뱃지등의개인선량계는납치마안쪽허리나가슴부근에착용하게되는데,이위치에서측정된값을이용하여손이나눈과같이납치마에의해차폐되지않는부위의선량을추정하는것은사실상불가능하다.뿐만아니라,중재방사선시술실과같은저에너지저선량방사선장에서는개인선량계의정확도가심각하게저하된다.이에,국제방사선방호위원회에서는물리적선량계를필요로하지않는전산모사기법에기반한중재방사선시술자에대한선량감시시스템개발을권고하고있다. 중재술을위한버추얼선량감시시스템(virtualdosemonitoringsystemforinterventionalradiology,VIR)은기존시스템보다정확하고상세한선량값을보다빠르게제공하는것을목표로개발되었다.VIR시스템은크게기기추적모듈,신체추적모듈,선량계산모듈,세가지로구성되어있다.각모듈의이름에서유추할수있듯,기기추적모듈은C-arm장비와납유리의상태를추적하고,신체추적모듈은의료진의위치및자세를추적하고이에맞게인체전산팬텀을구현하는역할을수행한다.선량계산모듈의경우,피부선량분포와수정체선량에대한즉각적인피드백을주는RDC(real-timedosecalculation)서브모듈과피부및수정체를포함한장기및유효선량을보다정확하게계산하여일일피드백을주는PDC(post-proceduredosecalculation)서브모듈로구분되어있다. 본연구에서는VIR시스템의시연을위해,이를서울한양대병원혈관조영실에설치하고가상시술에대한선량을산출해보았다.시연을통해RDC서브모듈이실시간으로작동함을확인하였고,PDC서브모듈또한시술량에맞는클러스터를구축할경우충분히일일피드백을제공할수있음을확인하였다.RDC와PDC서브모듈에서계산된선량값을상호비교해보았을때,일반적으로RDC서브모듈이PDC서브모듈에비해피부및수정체선량을다소과대평가하는경향이있었다.하지만,선량감시에서의일반적인불확도를고려하였을때그차이가문제가될수준은아니었으며즉각적인피드백을주는RDC서브모듈에서의약간의선량과대평가는오히려시술자들에게경각심을주어긍적적인방향으로작용할수있다. VIR시스템에대한기본모델은본연구를통해성공적으로개발되었으나,추후기존선량감시시스템을완전히대체하기위한상용화작업을위해서는아직해결해야할이슈들이있다.이를위한후속연구가지속적으로진행될계획이며,이를통해완성된VIR시스템은중재방사선시술자들에게정확하고상세한선량값을제공할것으로기대된다.나아가,VIR시스템이현재유럽에서개발중인온라인선량관리시스템과통합될경우보다체계적이고편리하게개인선량을관리할수있을것이며,중재방사선시술자들에게본인의피폭선량감소노력을위한지침을제공할수있을것이다. |Interventionalradiologistsareamongthemosthighlyradiation-exposedpersonnelinmedicine,andespeciallyhandsandeyelensesreceivehighdosesatriskofexceedingthedoselimitsrecommendedbytheInternationalCommissiononRadiologicalProtection(ICRP).However,theconventionaldosemonitoringsystembyusingapersonaldosimeterhastwosignificantlimitations.Firstly,thepersonaldosimeters(e.g.,TLDbadge)arewornundertheleadapronatthewaistoronthechest,whichcanbeusedforeffectivedoseassessmentbutispracticallyinappropriatetoestimatedosestounshieldedbodyparts.Inaddition,theaccuracyofthepersonaldosimeterissignificantlylowforlow-dose,low-energyradiationsintheangiographyroom.Recognizingthelimitationsofpersonalphysicaldosimetersfordosemonitoringofinterventionalradiologists,theICRPstatedthenecessityofthedevelopmentofcomputationaltechnologies–notrequiringphysicaldosimeters–tomonitortheindividualdosesofpersonnelinvolvedininterventionalprocedures. Thevirtualdosemonitoringsystemforinterventionalradiology(VIR)wasdevelopedwiththeaimofprovidingfastfeedbackonratherreliableanddetaileddosevalues.TheVIRsystemconsistsofthreemainmodules:machinetracking,bodytracking,anddosecalculationmodules.Ascanbeexpectedintheirnames,themachinetrackingmoduletracksthestatusoftheC-armandlead-glassshield,andthebodytrackingmoduletracksthemedicalstaffandaccordinglyimitatesthemwithcomputationalhumanphantoms.Thedosecalculationmoduleissubdividedintoareal-timedosecalculation(RDC)submoduleforimmediatefeedbackontheskinandeyelensdoseandapost-proceduredosecalculation(PDC)submodulefordailyfeedbackoneffectiveandorgandoses,aswellasmoreaccurateskinandeyelensdoses. ForthedemonstrationoftheVIRsystem,itwasdeployedinanactualangiographyroomofHanyangUniversitySeoulHospital,andtheradiationdoseswerecalculatedformockoperations.Thedemonstrationconfirmedthereal-timeoperationcapabilityoftheRDCsubmoduleandshowedthefeasibilityofthedailyfeedbackofthePDCsubmodulewithanappropriateamountofcomputerresources.TheintercomparisonbetweentheresultsbytwodosecalculationsubmodulesshowedthattheRDCsubmoduleslightlyoverestimatesbothskinandeyelensdosescomparedtothePDCsubmodule.Thedifferences,however,wereconsideredacceptable,andtheslightoverestimationofthedoseforthereal-timefeedbackisconsideredtobeevenadvantageousinthatitcanalerttheradiologistsbeforereceivinglargerdoses.PreliminaryexperimentalvalidationwasalsoperformedfortheVIRsystembymeasuringthedosesbyTLelements.ThemeasureddatawerecomparedtothosecalculatedbytheRDCandPDCsubmodules,anditwasshownthatthecalculatedvaluesweregenerallyingoodagreementwiththemeasuredvalues. AlthoughthebasicmodeloftheVIRsystemwassuccessfullydevelopedinthepresentstudy,therearestillsomeissuestobeaddressedforthecommercializationtobeacompletealternativetotheconventionalphysicaldosimeters.Furtherstudieswillbeconductedtoresolvetheseissues,andattheendofthisproject,theVIRsystemisexpectedtoprovideaccuratevaluesforskin,lens,andeffectivedoses,convenienceinmanagingradiationdosedatawhenincorporatedwithanonlinedosimetrysystem,andguidanceforradiologiststoefforttoreducetheirownradiationdoses.