Physical Principles of Medical Ultrasonics PhysicalPrinciplesofMedicalUltrasonics,SecondEdition.EditedbyC.R.Hill,J.C.BamberandG.R.terHaar. &2004JohnWiley&Sons,Ltd:ISBN0471970026 Physical Principles of Medical Ultrasonics Second Edition Editors C.R. Hill J. C. Bamber G.R. ter Haar PhysicsDepartment,InstituteofCancerResearch, RoyalMarsdenHospital,Sutton,Surrey,UK FirstEditionpublishedin1986byEllisHorwoodLimited,Chichester,WestSussex Copyrightu2004 JohnWiley&SonsLtd,TheAtrium,SouthernGate,Chichester, WestSussexPO198SQ,England Telephone(+44)1243779777 Email(forordersandcustomerserviceenquiries):[email protected] VisitourHomePageonwww.wileyeurope.comorwww.wiley.com AllRightsReserved.Nopartofthispublicationmaybereproduced,storedinaretrieval systemortransmittedinanyformorbyanymeans,electronic,mechanical,photocopying, recording,scanningorotherwise,exceptunderthetermsoftheCopyright,Designsand PatentsAct1988orunderthetermsofalicenceissuedbytheCopyrightLicensingAgency Ltd,90TottenhamCourtRoad,LondonW1T4LP,UK,withoutthepermissioninwritingof thePublisher.RequeststothePublishershouldbeaddressedtothePermissionsDepartment, JohnWiley&SonsLtd,TheAtrium,SouthernGate,Chichester,WestSussexPO198SQ, England,[email protected],orfaxedto(+44)1243770620. 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BritishLibraryCataloguinginPublicationData AcataloguerecordforthisbookisavailablefromtheBritishLibrary ISBN0471970026 Typesetin9/11ptTimesbyDobbieTypesettingLtd,Tavistock,Devon PrintedandboundinGreatBritainbyTJInternationalLtd,Padstow,Cornwall Thisbookisprintedonacid-freepaperresponsiblymanufacturedfromsustainableforestry inwhichatleasttwotreesareplantedforeachoneusedforpaperproduction. ToDr John Wild – Whohadthe vision– ‘MyDear Strutt, I am glad you are writing a book on Acoustics....You speak modestly of a want of Sound books in English. In what language are there such, except Helmholtz, who is sound not because he is German but because he is Helmholtz....’ (Letter from James Clerk Maxwell to John William Strutt, Lord Rayleigh, 20th May 1873, referring to Rayleigh’s Theory of Sound, which he had started writing earlier that year whilst on a honeymoon tripup the riverNile) ‘Compoundutterancesaddressedthemselvestotheirsenses,anditwaspossibleto view by ear the features of the neighbourhood. Acoustic pictures were returned from the darkenedscenery;...’ (FromThe Returnof theNative, 1878,Thomas Hardy) Contents List ofContributors . .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. . xi Preface . .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. . xiii Chapter1 BasicAcousticTheory . . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. . 1 S.J.Leeman 1.1 Introduction .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. 1 1.2 TheCanonical InhomogeneousWaveEquation of LinearAcoustics.. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. 2 1.3 Acoustic WaveVariables .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. 7 1.4 SomeSpecial Solutions . .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. 9 1.5 Green’s Function andRayleigh’s Integral . .. .. .. .. .. . .. .. .. . 13 1.6 TransducerFields . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. . 15 1.7 PropagationAcross PlanarBoundaries . .. .. .. .. .. .. . .. .. .. . 26 1.8 Finite Amplitude Waves. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. . 34 References . .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. . 39 Chapter2 GenerationandStructure of AcousticFields . . .. .. .. .. .. .. . .. .. .. . 41 C.R.Hill 2.1 Introduction .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. . 41 2.2 Piezoelectric Devices . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. . 42 2.3 TheFields of‘Simple’, CW ExcitedSources.. .. .. .. .. . .. .. .. . 46 2.4 ThePulsed Acoustic Field . .. .. .. .. . .. .. .. .. .. .. . .. .. .. . 48 2.5 FocusedFields .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. . 48 2.6 Effectsof the Human Bodyon BeamPropagation . .. .. . .. .. .. . 56 2.7 BeamFormation byTransducerArrays. .. .. .. .. .. .. . .. .. .. . 56 2.8 TheField ofthe TorontoHybrid .. .. . .. .. .. .. .. .. . .. .. .. . 59 2.9 Generationof TherapyFields. .. .. .. . .. .. .. .. .. .. . .. .. .. . 59 2.10 Magnitudes ofAcoustic Field Variables. .. .. .. .. .. .. . .. .. .. . 62 References . .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. . 63 Chapter3 DetectionandMeasurement ofAcousticFields .. .. .. .. .. .. . .. .. .. . 69 C.R.Hill 3.1 Introduction .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. . 69 3.2 Piezoelectric Devices . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. . 70 3.3 Displacement Detectors . .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. . 77 viii CONTENTS 3.4 Radiation Force Measurements .. .. .. . .. .. .. .. .. .. .. . .. .. 78 3.5 Calorimetry.. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. 83 3.6 Optical DiffractionMethods. .. .. .. .. . .. .. .. .. .. .. .. . .. .. 84 3.7 Miscellaneous Methods and Techniques . .. .. .. .. .. .. .. . .. .. 86 3.8 Measurement of Biologically Effective Exposureand Dose .. . .. .. 86 References .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. 88 Chapter4 Attenuation andAbsorption.. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. 93 J. C.Bamber 4.1 Introduction . .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. 93 4.2 Tissue–Ultrasound Interaction Cross-Sections . .. .. .. .. .. . .. .. 94 4.3 Theory of Mechanisms for theAbsorption of Ultrasonic Longitudinal Waves. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. 96 4.4 Measurement of Attenuation andAbsorption Coefficients in Tissue . .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 119 4.5 PublishedData onAttenuation and AbsorptionCoefficients. . .. . 143 4.6 Conclusion .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 155 References .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 156 Chapter5 Speed ofSound. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. 167 J. C.Bamber 5.1 Introduction . .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 167 5.2 Measurement of the Speedof Ultrasoundin Tissues. .. .. .. . .. . 167 5.3 PublishedData for SpeedofSound Values . .. .. .. .. .. .. . .. . 176 5.4 Finite Amplitude (‘Non-Linear’) Propagation.. .. .. .. .. .. . .. . 183 5.5 Conclusion .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 185 References .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 186 Chapter6 Reflection andScattering . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. 191 R.J. DickinsonandD. K.Nassiri 6.1 Introduction . .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 191 6.2 Scattering Theory . . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 193 6.3 Scattering Measurements . .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 204 6.4 Models. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 211 6.5 Scattering and theB-Mode Image. .. .. . .. .. .. .. .. .. .. . .. . 215 6.6 Concluding Remarks.. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 219 References. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 220 Chapter7 Physical Chemistry of theUltrasound–Tissue Interaction .. .. .. .. . .. .. 223 A.P. Sarvazyan andC.R.Hill 7.1 Introduction . .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 223 7.2 Acoustic Properties ReflectingDifferent Levelsof TissueOrganisation. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 223 7.3 Molecular Aspects of SoftTissue Mechanics .. .. .. .. .. .. . .. . 225 7.4 Relationship Between Ultrasonic ParametersandFundamental Thermodynamic Potentials of a Medium. .. .. .. .. .. .. .. . .. . 228 7.5 Structural Contribution to Bulk andShearAcoustic Properties of Tissues. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 232 7.6 Relevance toTissue Characterisation. .. . .. .. .. .. .. .. .. . .. . 233 References .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 234 CONTENTS ix Chapter8 Ultrasonic Images andtheEye ofthe Observer.. .. .. .. .. .. . .. .. .. . 237 C.R.Hill 8.1 Introduction .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 237 8.2 QuantitativeMeasures of ImagingandPerception . .. .. . .. .. .. 238 8.3 Images andHuman VisualPerception. . .. .. .. .. .. .. . .. .. .. 239 8.4 ThePlace of Ultrasoundin MedicalImaging. .. .. .. .. . .. .. .. 248 8.5 TheSystematics of ImageInterpretation .. .. .. .. .. .. . .. .. .. 249 References . .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 252 Chapter9 MethodologyforClinical Investigation. .. .. . .. .. .. .. .. .. . .. .. .. . 255 C.R.HillandJ. C.Bamber 9.1 Introduction .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 255 9.2 ImagingandMeasurement: State of thePulse–Echo Art. . .. .. .. 256 9.3 ABroader Look: Performance Criteria . .. .. .. .. .. .. . .. .. .. 284 9.4 FurtherProspects for Ultrasonologyand ImageParameterisation . 288 9.5 Summaryand Conclusions. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 295 References . .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 296 Chapter10 Methodologyfor ImagingTime-Dependent Phenomena.. .. .. . .. .. .. . 303 R.J. EckersleyandJ.C. Bamber 10.1 Introduction .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 303 10.2 ThePrinciples of UltrasoundMotion Detection . .. .. . .. .. .. 304 10.3 Techniques forMeasuring TargetVelocity . .. .. .. .. . .. .. .. 305 10.4 Phase Fluctuation(Doppler) Methods .. .. .. .. .. .. . .. .. .. 305 10.5 EnvelopeFluctuation Methods .. .. . .. .. .. .. .. .. . .. .. .. 320 10.6 Phase TrackingMethods. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 321 10.7 EnvelopeTracking Techniques .. .. . .. .. .. .. .. .. . .. .. .. 325 10.8 Considerations Specific to Colour Flow Imaging. .. .. . .. .. .. 326 10.9 Angle-Independent VelocityMotion Imaging . .. .. .. . .. .. .. 326 10.10 TissueElasticity and Echo Strain Imaging . .. .. .. .. . .. .. .. 328 10.11 Performance Criteria . .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 329 10.12 Use of ContrastMedia.. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 330 10.13 Concluding Remarks . .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 332 References.. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 333 Chapter11 TheWiderContext ofSonography. .. .. .. . .. .. .. .. .. .. . .. .. .. . 337 C.R.Hill 11.1 Introduction .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 337 11.2 MacroscopicTechniques. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 337 11.3 Acoustic Microscopy . .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 341 References.. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 346 Chapter12 Ultrasonic Biophysics. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. . 349 Gail R.ter Haar 12.1 Introduction .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 349 12.2 ThermalMechanisms . .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 350 12.3 Cavitation.. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 358 12.4 Radiation Pressure,Acoustic Streaming and‘Other’Non-Thermal Mechanisms. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. 378 12.5 Non-CavitationalSources of Shear Stress.. .. .. .. .. . .. .. .. 389 x CONTENTS 12.6 Evidence for Non-Thermal Effects in StructuredTissues .. . .. . 390 12.7 Thermal andMechanical Indices.. .. . .. .. .. .. .. .. .. . .. . 396 12.8 Conclusion .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 398 References. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 398 Chapter13 Therapeutic andSurgical Applications . .. .. . .. .. .. .. .. .. .. . .. .. 407 Gail R.ter Haar 13.1 Introduction . .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 407 13.2 Physiological Basis for UltrasoundTherapy. .. .. .. .. .. . .. . 407 13.3 Physiotherapy .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 413 13.4 Ultrasound in TumourControl. .. .. . .. .. .. .. .. .. .. . .. . 422 13.5 Surgery. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 428 References. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 443 Chapter14 Assessment of Possible Hazardin Use . .. .. . .. .. .. .. .. .. .. . .. .. 457 Gail R.ter Haar 14.1 Introduction . .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 457 14.2 ExposurePractice andLevels .. .. .. . .. .. .. .. .. .. .. . .. . 457 14.3 Studies ofIsolated Cells .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 459 14.4 Studies onMulticellular Organisms .. . .. .. .. .. .. .. .. . .. . 462 14.5 Human Fetal Studies .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 471 14.6 Summary of Recommendations andGuidelines for Exposure.. . 475 14.7 Conclusion .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 479 References. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 480 Chapter15 Epilogue: Historical Perspectives . .. .. .. .. . .. .. .. .. .. .. .. . .. .. 487 C.R. Hill References . .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. . 489 Listof Symbols .. . .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. 491 Index.. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. 497 List of Contributors J. C. BAMBER Physics Department, Institute of Cancer Research, Royal Marsden Hospital, Sutton, Surrey, UK R. J. DICKINSON Department of Bioengineering, Imperial College, London, UK R. J. ECKERSLEY Imaging Science Department, Imperial College School of Medicine, London, UK G. R. TER HAAR Physics Department, Institute of Cancer Research, Royal Marsden Hospital, Sutton, Surrey, UK C. R. HILL Physics Department, Institute of Cancer Research, Royal Marsden Hospital, Sutton, Surrey, UK S. J. LEEMAN Medical Engineering & Physics Department, King’s College Hospital Medical School, London, UK D. K. NASSIRI Department of Medical Physics and Bioengineering, St George’s Hospital, London, UK A. P. SARVAZYAN Artann Laboratories, NJ, USA Preface Ancient Hebrew and Christian tradition relates that the universe was created in six days, followingwhichtherewasadayofrest.Whattheoldchroniclesneverrecordedwasthat,on theeighthday,theCreatormusthavedroppedbackintothelabtodosometidyingup.Only then, coming across his rough notes for Maxwell’s and the acoustic wave equations, did the thought occur that the creation of light and sound could be logically extrapolated to x-rays and ultrasound. The practical outcome of this realisation took some time to materialise but eventually, in the twentieth century, it led to a revolution in the practice of medicine. This bookisconcernedwithonestrandofthatrevolution,andattemptstoexploreitsfoundations in basic mathematical andscientific principles. Within the past 30 years the clinical application of ultrasound imaging has grown from beingarareodditytothepointthatitnowaccountsforwellover20%ofallmedicalimaging proceduresworld-wide;secondonlytoplainX-rays,andstillgrowing.Inaddition,thelonger- establishedtherapeuticusesofultrasoundhavecontinuedtodevelopandarenowbeingjoined bymethodsemployingstrongly focusedbeamsof ultrasoundforminimally invasivesurgical destructionof deep tissuestructures. Technologically,muchofthisdevelopmenthasbeenempirical;oftenwithoutbenefitofany systematic knowledge of the physics and biophysics underlying the essential phenomena. Valuable though much of this development has been, when viewed with the benefit of hindsight it can be seen that many opportunities were missed and much time and effort was spenttravellingupblindalleys.Thefirsteditionofthisbookwasthereforewritteninthehope that it might contribute to deeper and more general understanding in this field of applied science, and thus perhaps point the way to further, more scientifically based practical developments and clinicalapplications. Thatfirsteditionwaspublishedin1986,hasnowsoldout,butremainsuniqueofitskind.In the meantime scientific knowledge has advanced and so also, with much help from constructively critical readers, have our ideas on what now seems to be needed in a bookof this sort. Thus, much of the material in this edition has been completely rewritten, often by newauthors.Therestwehavethoroughlyrevisedandbroughtuptodate.Asbefore,thebook is aimed, broadly, at graduate students in the Physical Sciences and Engineering. It should also, however, have plenty to offer, for example, to undergraduates specialising in Physics- Applied-to-Medicine,andalsotothatincreasinglycommonbreed:physics-literatephysicians. Thebookisdivided,somewhatarbitrarily,intofourparts:theory,basics,investigation,and intervention. Acoustics – the branch of Physics to which this subject belongs – has a well-developed theoretical background, that provides the essential basis for a proper understanding of the