Essentials of Medical Ultrasound

Transcription

1 Essentials of Medical Ultrasound

2 Medical Methods Essentials of Medical Ultrasound: A Practical Introduction to the Principles, Techniques, and Biomedical Applications, Edited by Michael H. Repacholi and Deirdre A. Benwell, 1982

3 Essentials of Medical Ultrasound A Practical Introduction to the Principles, Techniques, and Biomedical Applications Edited by Michael H. Repacholi and Deirdre A. Benwell Health and Welfare Canada Ottawa, Ontario, Canada

4 Library of Congress Cataloging in Publication Data Main entry under title: Essentials of medical ultrasound. (Medical methods) Includes bibliographies and index. 1. Ultrasonic waves-physiological effect. 2. Ultrasonics in medicine. I. Repacholi, Michael H. II. Benwell, Deirdre A. III. Series. [DNLM: 1. Ultrasonics. OT 34 E775] OP82.2.U37E ' ISBN-13: e-isbn-13: : / The HUMANA Press Inc. Softcover reprint of the hardcover 15t Edition 1982 Crescent Manor PO Box 2148 Clifton, NJ All rights reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise without written permission from the Publisher.

5 Preface One of the first applications of ultrasound was in submarine sonar equipment. Since then ultrasound has found increasing applications, particularly in industry, but increasingly in biomedicine. For many years ultrasound has been used in physical therapy, although only in the past decade or two has it evolved from laboratory curiosity to a well-established diagnostic imaging modality. Ultrasound is now a widely accepted, indeed pervasive, diagnostic and therapeutic tool in the medical field, and its applications are increasing rapidly. Our intent in developing this book is to provide a coherent tutorial introduction to the field of medical ultrasound at a level suitable for those entering the area from either medical or scientific backgrounds. The topics discussed should be of interest to nearly all medical and health care personnel needing to understand or operate ultrasonic devices, including clinicians, medical technicians, physiotherapists, medical physicists, and other biomedical scientists interested in the field. The book opens with a description of the basic principles of propagating acoustic waves, explains how they interact with a wide range of biological systems, and outlines the effects they produce. To provide practical information to operators of ultrasound equipment, we have included thorough coverage of the details of ultrasonic instrumentation and measurement techniques, and set forth the framework for an effective quality assurance program. Regulations and safe-use guidelines have also been described and distinguished in an effort to acquaint people with the philosophy upon which standards are based, as well as some of the details of those currently proposed or in use. This is especially important in medical ultrasound, and even now a number of professional organizations have developed, or are drafting, standards on ultrasound equipment and its proper uses, standards that will effect operators directly. Although each chapter was written by an expert in the particular area of ultrasound covered, an attempt has also been made to ensure that the chapters are interactive. Topics discussed in one article are often intended to complement information provided in others, so that readers are ultiv

6 vi PREFACE mately provided with an integrated, but practical survey of all the basic concepts, instrumentation, techniques, standards, and applications likely to be encountered in the day-to-day use of medical ultrasound. We would like to thank our coauthors for their enthusiam and forbearance during the compilation of this text. Ottawa, Canada May, 1982 Michael H. Repacholi Deirdre A. Benwell

7 Table of Contents Preface... v Chapter 1 Physical Characteristics of Ultrasound Alan J. Mortimer 1. Introduction Acoustic Waves Wave Motion Periodic Wave Motion Parameters on an Ultrasonic Wave Modes of Wave Propagation Standing Waves Ultrasonic Transducers Piezoelectric Materials Medical Transducers Characteristics of Ultrasound Beams Huygen's Principle Circular Transducers Far Field Near Field Pulsed Transducers Reflection and Refraction Matching Mode Conversion Absorption and Scattering Absorption Dispersion Scattering Doppler Effect Conclusion Appendix: Mathematical Derivations of Physical Characteristics vii

8 viii CONTENTS A.1. Acoustic Waves A.2. Modes of Propagation of Acoustic Waves References Chapter 2 Biophysical Mechanisms of Ultrasound Wesley L. Nyborg 1. Introduction Thermal Mechanism Temperature Rise Without Heat Transfer Temperature Rise During a Single Pulse-No Heat Transfer Thermal Method of Intensity Measurement-No Heat Transfer Temperature Rise with Heat Transfer Temperature vs Time in an Absorbing Sphere-Influence of Conduction Applications to Biomedical Ultrasound Summary of Findings for Thermal Mechanism Stress Mechanisms First-Order and Second-Order Quantities-Radiation Pressure Radiation Force Radiation Torque Acoustic Microstreaming Stress Fields of Gas-Filled Pores-Low Megahertz Frequencies Summary of Findings for Stress Mechanism Cavitation Conclusions References Chapter 3 Ultrasonic Measurement Techniques and Equipment Output Levels Harold F. Stewart 1. ~ntroduction Measurement Parameters

9 CONTENTS ~ 3. Techniques and Instrumentation Total Power-Radiation Force Radiation Force-Intensity Techniques Thermal Methods Optical Techniques Reciprocity Calibration Electrical Determination of Ultrasonic Output for Quartz Transducers Miniature Hydrophones Ultrasound Equipment Output Levels Therapy Equipment Diagnostic Equipment..., Output Levels and Biological Effect Levels References Chapter 4 Selected Biological Effects of Ultrasound F.Dunn 1. Introduction Whole-Body Radiation Vertebrates Insects Tissues and Organs Central Nervous System Liver Testes Blood Stasis Tissue Regeneration Neoplastic Tissues and Synergism Cells and Microorganisms Biomacromolecules and Their Assemblages Biomacromolecules Macromolecular Assemblages Concluding Remarks Acknowledgments References

10 x CONTENTS Chapter 5 Clinical Applications of Diagnostic Ultrasound Edward A. Lyons 1. Introduction Limited Significance Method Useful Ancillary Method of Investigation Most Efficacious Method of Non-Invasive Examination... '" Sole Investigative Tool Head Brain Eyes Neck Thyroid and Parathyroid Glands Carotid Artery Chest Heart Pleural Space Breast... " Abdomen Liver Kidneys Pancreas Spleen Biliary Tract Aorta Lymph Nodes Peritoneal Space Pelvis Uterus (Pregnant) Uterus (Nonpregnant) Fallopian Tubes and Ovaries Bladder Prostate and Scrotum Extremities Conclusion

11 CONTENTS xi Chapter 6 Ultrasound Therapy by Harold F. Stewart, Michael H. Repacholi, and Deirdre A. Benwell 1. Introduction Therapeutic Devices and the Ultrasound Field Ultrasound Therapy Devices Temporal (Time) Variations of the Ultrasound Field Spatial Variations of Ultrasound Fields Qual ity Assurance and Standards Power and Intensity Power Output and Exposure Time Quality Assurance of Equipment Ultrasound Transmission and Absorption in Biolog ical Materials Applications of Therapeutic Ultrasound Minimizing Operator and Patient Exposure Contraindications for the Application of Ultrasound in Therapy Summary References Chapter 7 Quality Assurance in Diagnostic Ultrasound Albert Goldstein 1. Introduction Description of Equipment Displays A-Mode B-Mode M-Mode Two-Dimensional Cross-Section Images Gray-Scale Real-Time Displays... " Continuous-Wave Techniques Holographic Display

12 xii CONTENTS 3. Equipment Operation Operator Controls Scanning Technique Potential Hazards Warmup Procedure Hardcopy Care Hospital Electrical Noise Routine Preventive Maintenance Hard Copy Air Filters Scanning Arm Stability Integrity of Enclosures Worn or Frayed Cables System Performance and Testing Transducer... " Receiver Analog Scan Converter Digital Scan Converter Gray-Scale Display B-Mode Reg istration Display Size and Linearity Document System Performance Routine Performance Tests Introduction AlUM 1 OO-mm Test Object Test of Test Object Liquid Acoustic Velocity Other Performance Tests Performance Test Worksheets Summary Sample Service Logs References Bibliography: Selected Quality Assurance Publications Chapter 8 Ultrasound Standards: Regulations and Guidelines Michael H. Repacholi and Deirdre A. Benwell 1. Philosophy of Developing Standards Biological Effects

13 CONTENTS xiii 3. Types of Standards Device or Emission Standards Diagnostic Ultrasound Therapy Devices Surgical Devices Dentistry Safe-Use Guidelines and Education Guidelines Education International Activities National Standards Summary References Glossary of Ultrasound Terminology Index

14 Contributors DEIRDRE A. BENWELL Radiation Protection Bureau, Health and Welfare Canada, Ottawa, Ontario, Canada F. DUNN Department of Electrical Engineering, University of Illinois, Urbana Illinois ALBERT GOLDSTEIN Department of Diagnostic Radiology, Henry Ford Hospital, Detroit, Michigan EDWARD A. LYONS Department of Diagnostic Ultrasound, Health Sciences Centre, Winnipeg, Manitoba, Canada ALAN J. MORTIMER National Research Council, Ottawa, Ontario Canada WESLEY L. NYBORG Department of Physics, The University of Vermont, Burlington, Vermont MICHAEL H. REPACHOLI Radiation Protection Bureau, Health and Welfare Canada, Ottawa, Ontario, Canada HAROLD F. STEWART Bureau of Radiological Health, Food and Drug Administration, Rockville, Maryland xv