Introduction to physics in modern medicine

449 Pages·2009·13.484 MB·English

by  Suzanne Amador Kane

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S E C O N D E D I T I O N
SUZANNE AMADOR KANE
Haverford College
Pennsylvania, USA
Boca Raton London New York
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Library of Congress Cataloging-in-Publication Data
Amador Kane, Suzanne.
Introduction to physics in modern medicine / Suzanne Amador Kane. -- 2nd
ed.
p. cm.
Includes bibliographical references and index.
ISBN 978-1-58488-943-4 (pbk. : alk. paper)
1. Medical physics. I. Title.
R895.A518 2009
610.1’53--dc22 2009011772
Visit the Taylor & Francis Web site at
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To my husband, Charlie
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Contents
Instructor’s preface x i
Student preface xiii
Preface to the second edition x v
Acknowledgments xvii
1 Introduction and overview 1
Suggested reading 8
2 Telescopes for inner space: Fiber optics and endoscopes 1 1
2.1 Introduction 11
2.2 Optics: The science of light 15
2.2.1 How to see around corners 15
2.2.2 Reflecting and bending light 18
2.2.3 Why does light bend? The index of refraction 19
2.2.4 Optional: How lenses form images 23
2.2.5 Making pipes for light 26
2.3 Fiber optics applications in medicine:
Endoscopes and laparoscopes 33
2.3.1 Different types of endoscopes and
their typical construction 33
2.3.2 Some advantages and disadvantages 42
2.3.3 Laparoscopic gallbladder removals 43
2.4 New and future directions 44
2.4.1 Robotic surgery and virtual
reality in the operating room 44
2.4.2 Telemedicine and military applications 46
2.4.3 Innovations on the horizon 48
Resources 49
Questions 50
Problems 50
Reflection and refraction 50
Total internal reflection and fiber optics 50
Advanced problems 53
vii
viii Contents
3 Lasers in medicine: Healing with light 5 5
3.1 Introduction 55
3.2 What is a laser? 56
3.3 More on the science of light: Beyond the rainbow 59
3.4 How lasers work 63
3.5 How light interacts with body tissues 70
3.6 Laser beams and spatial coherence 72
3.7 Cooking with light: Photocoagulation 77
3.8 Trade-offs in photocoagulation: Power density
and heat flow 78
3.9 Cutting with light: Photovaporization 80
3.10 More power: Pulsed lasers 81
3.11 Lasers and color 84
3.12 The atomic origins of absorption 87
3.13 How selective absorption is used in laser surgery 91
3.14 Lasers in dermatology 95
3.15 Laser surgery on the eye 97
3.16 New directions: Lasers in dentistry 101
3.17 Advantages and drawbacks of lasers for medicine 102
3.18 New directions: Photodynamic therapy—Killing
tumors with light 103
3.19 New directions: Diffusive optical imaging 106
Suggested reading 108
Questions 109
Problems 110
4 Seeing with sound: Diagnostic ultrasound imaging 115
4.1 Introduction 115
4.2 Sound waves 118
4.3 What is ultrasound? 121
4.4 Ultrasound and energy 124
4.5 How echoes are formed 125
4.6 How to produce ultrasound 129
4.7 Images from echoes 132
4.8 Ultrasound scanner design 139
4.9 Ultrasound is absorbed by the body 143
4.10 Limitations of ultrasound: Image quality and artifacts 151
4.11 How safe is ultrasound imaging? 157
4.12 Obstetrical ultrasound imaging 161
4.13 Echocardiography: Ultrasound images of the heart 165
4.14 Origins of the Doppler effect 166
4.15 Using the Doppler effect to measure blood flow 171
4.16 Color flow images 173
Contents ix
4.17 Three-dimensional ultrasound 174
4.18 Portable ultrasound—Appropriate
technology for the developing world 176
Suggested reading 178
Questions 180
Problems 181
Basic physics of sound waves 181
Echo ranging and echo intensity 181
Absorption of ultrasound 183
Sources of distortion 183
Doppler ultrasound 184
Another useful source of problems on ultrasound imaging 185
5 X-ray vision: Diagnostic X-rays and CT scans 187
5.1 Introduction 187
5.2 Diagnostic x-rays: The body’s x-ray shadow 190
5.3 Types of x-ray interactions with matter 191
5.4 Basic issues in x-ray image formation 198
5.5 Contrast media make soft tissues visible on an x-ray 206
5.6 How x-rays are generated 210
5.7 X-ray detectors 217
5.8 Mammography: X-ray screening for breast cancer 225
5.9 Digital radiography 231
5.10 Computed tomography (CT) 238
5.11 Application: Spotting brittle bones—Bone mineral scans
for osteoporosis 249
Suggested reading 252
Questions 253
Problems 255
Interaction of x-rays with matter 255
Contrast, contrast media, and x-ray absorption 255
X-ray sources and detectors 256
6 Images from radioactivity: Radionuclide scans, SPECT,
and PET 259
6.1 Introduction: Radioactivity and medicine 259
6.2 Nuclear physics basics 261
6.3 Radioactivity fades with time: The concept of half-lives 264
6.4 Gamma camera imaging 270
6.5 Emission tomography with radionuclides: SPECT and PET 278
6.6 Application: Emission computer tomography studies
of the brain 290
6.7 Hybrid scanners 293