This document<\/p>\n
provides definitions for the transmitted field characteristics of focusing and nonfocusing transducers for applications in medical ultrasound;<\/p>\n<\/li>\n
relates these definitions to theoretical descriptions, design, and measurement of the transmitted fields of focusing transducers;<\/p>\n<\/li>\n
gives measurement methods for obtaining defined field characteristics of focusing and nonfocusing transducers;<\/p>\n<\/li>\n
specifies beam axis alignment methods appropriate for focusing and nonfocusing transducers.<\/p>\n<\/li>\n<\/ul>\n
This document relates to focusing ultrasonic transducers operating in the frequency range appropriate to medical ultrasound (0,5 MHz to 40 MHz) for both therapeutic and diagnostic applications. It shows how the characteristics of the transmitted field of transducers can be described from the point of view of design, as well as measured by someone with no prior knowledge of the construction details of a particular device. The transmitted ultrasound field for a specified excitation is measured by a hydrophone in either a standard test medium (for example, water) or in a given medium. This document applies only to media where the field behaviour is essentially like that in a fluid (i.e. where the influence of shear waves and elastic anisotropy is small), including soft tissues and tissue-mimicking gels. Any aspects of the field that affect their theoretical description or are important in design are also included. These definitions would have use in scientific communications, system design and description of the performance and safety of systems using these devices.<\/p>\n
This document incorporates definitions from other related standards where possible, and supplies more specific terminology, both for defining focusing characteristics and for providing a basis for measurement of these characteristics.<\/p>\n
| PDF Pages<\/th>\n | PDF Title<\/th>\n<\/tr>\n | ||||||
|---|---|---|---|---|---|---|---|
| 2<\/td>\n | undefined <\/td>\n<\/tr>\n | ||||||
| 5<\/td>\n | Annex ZA(normative)Normative references to international publicationswith their corresponding European publications <\/td>\n<\/tr>\n | ||||||
| 7<\/td>\n | English CONTENTS <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | FOREWORD <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | INTRODUCTION <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | 1 Scope 2 Normative references <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | 3 Terms and definitions <\/td>\n<\/tr>\n | ||||||
| 46<\/td>\n | 4 Symbols <\/td>\n<\/tr>\n | ||||||
| 49<\/td>\n | 5 Independent measurement of total acoustic output power 6 Acoustic field measurement: equipment 6.1 Hydrophone 6.1.1 General 6.1.2 Sensitivity of a hydrophone <\/td>\n<\/tr>\n | ||||||
| 50<\/td>\n | 6.1.3 Directional response of a hydrophone 6.1.4 Effective hydrophone radius 6.1.5 Choice of the size of a hydrophone active element <\/td>\n<\/tr>\n | ||||||
| 51<\/td>\n | 6.1.6 Hydrophone pressure limits 6.1.7 Hydrophone intensity limits <\/td>\n<\/tr>\n | ||||||
| 52<\/td>\n | 6.1.8 Hydrophone cable length and amplifiers 6.2 Requirements for positioning and water baths 6.2.1 General 6.2.2 Positioning systems <\/td>\n<\/tr>\n | ||||||
| 53<\/td>\n | 6.2.3 Water bath <\/td>\n<\/tr>\n | ||||||
| 54<\/td>\n | 6.3 Requirements for data acquisition and analysis systems <\/td>\n<\/tr>\n | ||||||
| 55<\/td>\n | 6.4 Requirements and recommendations for ultrasonic equipment being characterized 7 Measurement procedure 7.1 General 7.2 Preparation and alignment 7.2.1 General drive and field conditions <\/td>\n<\/tr>\n | ||||||
| 56<\/td>\n | 7.2.2 Initial adjustment to driving voltage <\/td>\n<\/tr>\n | ||||||
| 57<\/td>\n | 7.2.3 Preparation of source transducer 7.2.4 Aligning an ultrasonic transducer and hydrophone <\/td>\n<\/tr>\n | ||||||
| 58<\/td>\n | 7.2.5 Finding the beam axis <\/td>\n<\/tr>\n | ||||||
| 60<\/td>\n | 7.2.6 Measurements to determine field level conditions <\/td>\n<\/tr>\n | ||||||
| 61<\/td>\n | 7.2.7 Determining if transducer is focusing <\/td>\n<\/tr>\n | ||||||
| 62<\/td>\n | 7.2.8 Measuring other beamwidth parameters of a focusing transducer <\/td>\n<\/tr>\n | ||||||
| 63<\/td>\n | 7.2.9 Measuring the beam area parameters <\/td>\n<\/tr>\n | ||||||
| 64<\/td>\n | 7.2.10 Measuring additional beam maximum based parameters <\/td>\n<\/tr>\n | ||||||
| 65<\/td>\n | 7.2.11 Alternative: calculation of focal parameters using numerical projection <\/td>\n<\/tr>\n | ||||||
| 66<\/td>\n | 7.2.12 Plane wave transmitted fields 7.2.13 Steered plane waves 7.2.14 Measurements of high intensity therapeutic ultrasound fields <\/td>\n<\/tr>\n | ||||||
| 67<\/td>\n | 7.2.15 Calculation of Isa <\/td>\n<\/tr>\n | ||||||
| 68<\/td>\n | 7.2.16 Further evaluation for sidelobes and pre-focal maxima <\/td>\n<\/tr>\n | ||||||
| 70<\/td>\n | 7.3 Considerations for scanning transducers and transducers with multiple sources 7.3.1 Automatic scanning transducers 7.4 Spatial impulse response and beamplots 7.4.1 General <\/td>\n<\/tr>\n | ||||||
| 71<\/td>\n | 7.4.2 Point target 7.4.3 Beamplots and beam contour plots 7.5 Plane wave compounding <\/td>\n<\/tr>\n | ||||||
| 72<\/td>\n | Annex A (informative)Background for the transmission\/ Characteristics of focusing transducers A.1 General <\/td>\n<\/tr>\n | ||||||
| 73<\/td>\n | A.2 Field of piston source A.3 Focusing with a lens <\/td>\n<\/tr>\n | ||||||
| 76<\/td>\n | A.4 Focusing with a concave transducer <\/td>\n<\/tr>\n | ||||||
| 78<\/td>\n | A.5 Geometric focusing gains <\/td>\n<\/tr>\n | ||||||
| 79<\/td>\n | A.6 Beamwidth estimation <\/td>\n<\/tr>\n | ||||||
| 81<\/td>\n | Figures Figure A.1 \u2013 Beam contour plot: contours at \u22126 dB, \u221212 dB, and \u221220 dBfor a 5 MHz transducer with a radius of curvature of D = 50 mmcentred at location 0,0 (bottom centre of graph) Figure A.2 \u2013 Types of geometric focusing <\/td>\n<\/tr>\n | ||||||
| 82<\/td>\n | Figure A.3 \u2013 Transducer options <\/td>\n<\/tr>\n | ||||||
| 83<\/td>\n | Figure A.4 \u2013 Parameters for describing a focusing transducer of known geometry Figure A.5 \u2013 Path difference parameters for describinga focusing transducer of known geometry <\/td>\n<\/tr>\n | ||||||
| 84<\/td>\n | Annex B (informative)Rationale for focusing and nonfocusing definitions B.1 Overview B.1.1 Background information B.1.2 General B.1.3 Focusing transducers <\/td>\n<\/tr>\n | ||||||
| 85<\/td>\n | B.1.4 Focusing methods <\/td>\n<\/tr>\n | ||||||
| 86<\/td>\n | B.1.5 Known and unknown focusing transducers B.1.6 Focusing and beamwidth <\/td>\n<\/tr>\n | ||||||
| 87<\/td>\n | B.1.7 Focusing parameter definitions B.1.8 Applications of focusing definitions B.1.9 Relation of present definitions to physiotherapy transducers (treatment heads) B.1.10 Relation of present definitions to therapeutic transducers <\/td>\n<\/tr>\n | ||||||
| 88<\/td>\n | B.2 System and measurement requirements B.2.1 General B.2.2 Transmitted pressure waveforms B.2.3 Transmitted fields B.2.4 The scan plane and the steering of beams <\/td>\n<\/tr>\n | ||||||
| 89<\/td>\n | B.2.5 Pulse echo field measurements Figure B.1 \u2013 Electronic focusing along z by transmit beamforming in the scan plane xz <\/td>\n<\/tr>\n | ||||||
| 90<\/td>\n | Figure B.2 \u2013 Field parameters for a nonfocusing transducer of known geometry.For example, for a circularly symmetric geometry,transducers have a diameter 2a and a beam axis along z Figure B.3 \u2013 Phased array geometry and construction for electronic focusing in the azimuth plane and mechanical lens focusing in the elevation plane <\/td>\n<\/tr>\n | ||||||
| 91<\/td>\n | Figure B.4 \u2013 Field parameters for a focusing transducer of known geometry Figure B.5 \u2013 Definitions for pressure-based field measurementsfor an unknown transducer geometry <\/td>\n<\/tr>\n | ||||||
| 92<\/td>\n | Figure B.6 \u2013 Beamwidth focus for transducers of known and unknown geometry <\/td>\n<\/tr>\n | ||||||
| 93<\/td>\n | Figure B.7 \u2013 Beam maximum parameters Figure B.8 \u2013 Pressure focus for a transducer of known geometry (design case) <\/td>\n<\/tr>\n | ||||||
| 94<\/td>\n | Figure B.9 \u2013 Pressure focus for a transducer of unknown geometry (measurement case) Figure B.10 \u2013 Beam area parameters <\/td>\n<\/tr>\n | ||||||
| 95<\/td>\n | Figure B.11 \u2013 Beam axis parameters: pulse-pressure-squared-integral level relative to the beam maximum in decibels (dB) plotted against axial distance <\/td>\n<\/tr>\n | ||||||
| 96<\/td>\n | Figure B.12 \u2013 Beamplot parameters <\/td>\n<\/tr>\n | ||||||
| 97<\/td>\n | Figure B.13 \u2013 Schematic diagram of the different planes and linesin an ultrasonic field for a rectangular transducer <\/td>\n<\/tr>\n | ||||||
| 98<\/td>\n | Figure B.14 \u2013 Schematic diagram of the different planes andlines in an ultrasonic field for a circular transducer <\/td>\n<\/tr>\n | ||||||
| 99<\/td>\n | Annex C (informative)Methods for determining the beam axis for well-behaved beams C.1 Comparisons of beam axis search methods Tables Table C.1 \u2013 Standard deviations for x and y scans usingthree methods of determining the centre of the beam <\/td>\n<\/tr>\n | ||||||
| 100<\/td>\n | C.2 Beamwidth midpoint method Figure C.1 \u2013 x-axis scan at 9 cm depth for the first focal zone with beam centre Figure C.2 \u2013 x-axis scan at 4,4 cm depth for the second focal zone <\/td>\n<\/tr>\n | ||||||
| 101<\/td>\n | Table C.2 \u2013 Decibel beamwidth levels for determining midpoints <\/td>\n<\/tr>\n | ||||||
| 102<\/td>\n | Annex D (informative)Methods for determining the beam axisfor beams that are not well behaved <\/td>\n<\/tr>\n | ||||||
| 103<\/td>\n | Figure D.1 \u2013 Asymmetric beam showing relative acoustic pressure versus sample number for the beamwidth midpoint method <\/td>\n<\/tr>\n | ||||||
| 104<\/td>\n | Annex E (informative)Uncertainties E.1 General E.2 Overall (expanded) uncertainty E.3 Common sources of uncertainty <\/td>\n<\/tr>\n | ||||||
| 106<\/td>\n | Annex F (informative)Transducer and hydrophone positioning systems Figure F.1 \u2013 Schematic diagram of the ultrasonic transducer andhydrophone degrees of freedom <\/td>\n<\/tr>\n | ||||||
| 107<\/td>\n | Annex G (informative)Planar scanning of a hydrophone to determine acoustic output power G.1 Overview G.2 General principle <\/td>\n<\/tr>\n | ||||||
| 108<\/td>\n | G.3 Hydrophone scanning methodology G.3.1 General methodology <\/td>\n<\/tr>\n | ||||||
| 109<\/td>\n | G.3.2 Particular considerations for implementation for HITU fields G.4 Corrections and sources of measurement uncertainty G.4.1 Uncertainty in the hydrophone calibration G.4.2 Planar scanning G.4.3 Attenuation factor of water: unfocusing transducers <\/td>\n<\/tr>\n | ||||||
| 110<\/td>\n | G.4.4 Attenuation factor of water: focusing transducers G.4.5 Received hydrophone signal G.4.6 Integration <\/td>\n<\/tr>\n | ||||||
| 111<\/td>\n | G.4.7 Finite size of the hydrophone G.4.8 Partial extent of integration G.4.9 Non-linear propagation G.4.10 Directional response <\/td>\n<\/tr>\n | ||||||
| 112<\/td>\n | G.4.11 Noise G.4.12 Intensity approximated by derived intensity <\/td>\n<\/tr>\n | ||||||
| 113<\/td>\n | Annex H (informative)Properties of water H.1 General Table H.1 \u2013 Speed of sound, c, and characteristic acoustic impedance, \u03c1\u200ac,as a function of temperature, for propagation in water <\/td>\n<\/tr>\n | ||||||
| 114<\/td>\n | H.2 Attenuation coefficient for propagation in water <\/td>\n<\/tr>\n | ||||||
| 115<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Ultrasonics. Transducers. Definitions and measurement methods regarding focusing for the transmitted fields<\/b><\/p>\n |