Digital Imaging Systems for Plain Radiography PDF
Preview Digital Imaging Systems for Plain Radiography
Digital Imaging Systems for Plain Radiography Lu´ıs Lanc¸a • Augusto Silva Digital Imaging Systems for Plain Radiography Foreword by Eugene D. Frank Lu´ısLanc¸a AugustoSilva Departamentodas DepartamentodeElectro´nica, CieˆnciaseTecnologiasdas Telecomunicac¸o˜eseInforma´tica Radiac¸o˜eseBiossinaisdaSau´de UniversidadedeAveiro EscolaSuperiordeTecnologiada CampusUniversita´riodeSantiago Sau´dedeLisboa(ESTeSL)- Aveiro,Portugal InstitutoPolite´cnicodeLisboa Lisboa,Portugal ISBN978-1-4614-5066-5 ISBN978-1-4614-5067-2(eBook) DOI10.1007/978-1-4614-5067-2 SpringerNewYorkHeidelbergDordrechtLondon LibraryofCongressControlNumber:2012948764 #SpringerScience+BusinessMediaNewYork2013 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation,broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmissionor informationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped.Exemptedfromthislegalreservationarebriefexcerpts inconnectionwithreviewsorscholarlyanalysisormaterialsuppliedspecificallyforthepurposeofbeing enteredandexecutedonacomputersystem,forexclusiveusebythepurchaserofthework.Duplication ofthispublicationorpartsthereofispermittedonlyundertheprovisionsoftheCopyrightLawofthe Publisher’s location, in its current version, and permission for use must always be obtained from Springer.PermissionsforusemaybeobtainedthroughRightsLinkattheCopyrightClearanceCenter. ViolationsareliabletoprosecutionundertherespectiveCopyrightLaw. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexempt fromtherelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. While the advice and information in this book are believed to be true and accurate at the date of publication,neithertheauthorsnortheeditorsnorthepublishercanacceptanylegalresponsibilityfor anyerrorsoromissionsthatmaybemade.Thepublishermakesnowarranty,expressorimplied,with respecttothematerialcontainedherein. Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Foreword The first edition of this text is a welcome work in the radiography community. Digital imaging came into very widespread use in a short period of time. Many radiographers,andothersworkingwithdigitalimaging,wereoverwhelmedbythe newinformationandtechnologicalaspectsassociatedwiththistechnology.Books have recently come out as reference texts for radiography students to learn this importantaspectofradiographyimaging.Everyoneinvolvedinthedirectapplica- tion of digital imaging must understand its technical aspects in order to use it effectivelyandtomaintainradiationdoses.Havingmoretextbooksonthetopicof digitalimaging,especiallyfromauthorsthroughouttheworld,ishighlybeneficial forradiography. Drs. Lanc¸a and Silva are esteemed Portuguese radiographers, researchers, and professors. They have included in this book the latest information on the topic of digitalimaging.Thematerialinthetextiscomprehensiveandwillgivethereadera completelookatthetechnologyandhowtouseiteffectively.Someofthematerial isfromtheirownresearchandpublications. Introductorychaptersinthe bookdiscussthebasicsofboth CR andDRimage receptors. Details of the detectors and how they function, along with excellent diagrams,providethereaderwithabroadunderstandingofhowthephotonenergy is captured digitally. This information should be particularly helpful for new radiographystudentsandresidentradiologistsbecauseitenablesthemtocompre- hend the difference between the old film/screen technology and the new digital technology.Mostimportantlyforthenewpersoncomingintoradiologyisthatthe authors include a comprehensive description of the modulation transfer function, noise spectra, and quantum efficiency factors. The advantages of digital imaging are also presented asit relatesto X-ray production, exposure techniques, collima- tion,scatter,andgrids.Thereaderwillnoteespeciallythatcollimation,scatter,and kVpfactorsarecriticalindigitalimaging. Oneofthemoreimportantchaptersinthistext,andanespeciallyimportantone for students and residents, is the chapter on patient dose. The authors present comprehensive information on absorbed, equivalent, and effective doses as it relatedtothedigitalenvironment.Thenewexposureindexvaluesforthedifferent v vi Foreword manufacturer’ssystemsarediscussed.Thesefactorsareimportantfortheradiogra- pher so that he or she will be able to adjust exposure techniques accordingly to obtainanoptimalimageatthelowestpossibledose.Doseaffectsimagequality,and sectionsofthetextcontaininformationoftheimageitself.Thisincludesdiscussion ofthespatialresolution,graylevels,andobserverperformance.Lookingatdigital images requires a different operator/observer thinking process, which the authors present. Safety in using digital systems is very important in the radiology department today. The authors discuss this critical aspect by including discussions of the key aspects related to performance of the different digital technologies and dose optimization and its relation to image quality. The exposure parameters required toobtainoptimaldigitalimagesarepresentedwellthroughoutthetext. Final chapters in this book detail an aspect of digital imaging that is both new and unique—post-processing. With post-processing, which includes subtraction, linearfiltering,histogramshaping,andde-noisingtechniques,theoperatorisableto createtheimageinawidevarietyofways.Afinalsectionofthetextdiscussesthe storageandarchivalsystem,PACS.Withthis,theinternationalstandardfordigital communications,DICOM,isalsopresented. Therearenotmanybooksdedicatedspecificallytodigitalimaging.Thisbookis a very welcome addition to the radiology departments of the world. The authors’ approachindevelopingthistextwastointegrateradiographytechniquesalongwith engineering and physics theory to create a comprehensive look at the topic. Practicing radiographers and radiologists, and students entering these fields will findthistextusefulintheireverydaywork. EugeneD.Frank,M.A.,RT(R), FASRT,FAEIRS AssociateProfessor,Emeritus MayoClinicCollegeofMedicine Rochester,Minnesota,USA Preface AdvancesindigitaltechnologyallowedthedevelopmentofdigitalX-raydetectors that are currently available for projection radiography. Computed Radiography (CR)andDigitalRadiography(DR)aredigitaltechnologieswidelyspreadinhealth care institutions nowadays. These technologies have been replacing traditional Screen–Film (SF) systems, and this constitutes a challenge for radiographers and otherhealthcareprofessionals.Thereplacementofconventionalfluoroscopicand radiographic equipment with digital imaging systems has increased rapidly in developedcountries.Digitalradiographydetectors—basedondifferenttechnolog- icalsolutions—havebecomeavailableforclinicalapplications. Digitaldetectorsofferseveraladvantageswhencomparedtoanaloguedetectors such as wide dynamic range, adjustable image processing, better image quality, rapidimageacquisition,andimageaccessatremotelocations. Themanagementofdiagnosticqualityandpatientdoseisaveryimportantissue tobeconsideredbyradiographerswhenworkingwithdigitalsystems.Exposurehas adirectinfluenceinimagequalityrepresentation,anddosedeliveredtothepatient could be inappropriate for diagnostic purpose. Diagnostic accuracy could be affected byinadequateexposureandthusanappropriateexposurelevelshouldbe achieved. Thisbookwouldconstituteacontributiontothosewhowanttolearnthissubject asstudentsandreflecttheirownpracticeasprofessionalswhileperformingradio- logicalexaminationswhenusingdigitalsystems. Thisbookwillfocusonabroadrangeoftopicsthatarerelevantforacompre- hensive knowledge about digital radiology systems. The book is intended to provide a practical approach resulting from the authors work in recent years. An integratedvisionfromradiography,engineering,andphysicswillbetheoutputof thisbook. Wehopethatthisbookconstitutesavalidcontributionfortheimprovementof knowledge of radiographers, radiography students, radiologists, radiology residents, medical students, and medical physicists, among other health care staff workingintheradiologyfield. vii viii Preface WearegratefultoElektraMcDermott,ourDevelopmentalEditorfromSpringer, for her excellent support and work in editing and reviewing all the chapters’ manuscripts. We thank Andrew Moyer, from Springer, for his interest in this publication. We thank both whose support and encouragement have made this bookpossible. Lisbon,Portugal Lu´ısLanc¸a,Ph.D Aveiro,Portugal AugustoSilva,Ph.D Acknowledgements TomywholefamilywithaspecialdedicationtomyparentsA´ureaeRoge´rio,who gavemealltheloveandanexampleoflife. TomytwosonsManuelandTiago,withlove... TomywifeCarla,forbeingagreatwomanandanextraordinarywife... TomyradiographystudentsandcolleaguesfromESTeSL AspecialdedicationtoProfessorManuelCorreia,whotaughtmewhatistobea radiographerandaneducator. Lu´ısLanc¸a TothememoryofmyFatherforallwearestillsharing... ToSara,Pedro,andDulce,myongoinglifeachievements... AugustoSilva ix
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