"An excellent primer on medical imaging for all members of the medical profession . . . including non-radiological specialists. It is technically solid and filled with diagrams and clinical images illustrating important points, but it is also easily readable . . . So many outstanding chapters . . . The book uses little mathematics beyond simple algebra [and] presents complex ideas in very understandable terms."
-Melvin E. Clouse, MD, Vice Chairman Emeritus, Department of Radiology, Beth Israel Deaconess Medical Center and Deaconess Professor of Radiology, Harvard Medical School

A well-known medical physicist and author, an interventional radiologist, and an emergency room physician with no special training in radiology have collaborated to write, in the language familiar to physicians, an introduction to the technology and clinical applications of medical imaging. It is intentionally brief and not overly detailed, intended to help clinicians with very little free time rapidly gain enough command of the critically important imaging tools of their trade to be able to discuss them confidently with medical and technical colleagues; to explain the general ideas accurately to students, nurses, and technologists; and to describe them effectively to concerned patients and loved ones. Chapter coverage includes:

• Introduction: Dr. Doe's Headaches
• Sketches of the Standard Imaging Modalities
• Image Quality and Dose
• Creating Subject Contrast in the Primary X-Ray Image
• Twentieth-Century (Analog) Radiography and Fluoroscopy
• Radiation Dose and Radiogenic Cancer Risk
• Twenty-First-Century (Digital) Imaging
• Digital Planar Imaging
• Computed Tomography
• Nuclear Medicine (Including SPECT and PET)
• Diagnostic Ultrasound (Including Doppler)
• MRI in One Dimension and with No Relaxation
• Mapping T1 and T2 Proton Spin Relaxation in 3D
• Evolving and Experimental Modalities

Anthony Brinton Wolbarst, PhD, a physicist formerly at Harvard Medical School, the National Cancer Institute, and the U.S. Environmental Protection Agency, is currently an Associate Professor at the University of Kentucky College of Health Sciences, Division of Radiation Sciences and College of Medicine, Department of Diagnostic Radiology in Lexington, Kentucky, USA.

Patrizio Capasso, MD, is Professor and Division Chief of Vascular & Interventional Radiology in the Departments of Diagnostic Radiology and Surgery at the University of Kentucky Chandler Medical Center Lexington, Kentucky, USA.

Andrew R. Wyant, MD, is Assistant Professor for Physician Assistant Studies at the University of Kentucky Chandler Medical Center Lexington, Kentucky, USA. Among many other courses that he teaches is a popular clinical skills seminar in in Radiographic Interpretation.

Preface x

Acknowledgments xiii

Introduction: Dr. Doe's Headaches: An Imaging Case Study xiv

Computed tomography xiv

Picture archiving and communication system xv

T1, T2, and FLAIR MRI xvi

MR spectroscopy and a virtual biopsy xvii

Functional MRI xviii

Diffusion tensor MR imaging xviii

MR guided biopsy xx

Pathology xxi

Positron emission tomography? xxi

Treatment and follow-up xxii

1 Sketches of the Standard Imaging Modalities: Different Ways of Creating Visible Contrast Among Tissues 1

"Roentgen has surely gone crazy!" 2

Different imaging probes interact with different tissues in different ways and yield different kinds of medical information 4

Twentieth-century (analog) radiography and fluoroscopy: contrast from differential attenuation of X-rays by tissues 7

Twenty-first century (digital) images and digital planar imaging: computer-based images and solid-state image receptors 16

Computed tomography: three-dimensional mapping of X-ray attenuation by tissues 17

Nuclear medicine, including SPECT and PET: contrast from the differential uptake of a radiopharmaceutical by tissues 20

Diagnostic ultrasound: contrast from differences in tissue elasticity or density 26

Magnetic resonance imaging: mapping the spatial distribution of spin-relaxation times of hydrogen nuclei in tissue water and lipids 28

Appendix: selection of imaging modalities to assist in medical diagnosis 30

References 36

2 Image Quality and Dose: What Constitutes a "Good" Medical Image? 37

A brief history of magnetism 37

About those probes and their interactions with matter . . . 39

The image quality quartet: contrast, resolution, stochastic (random) noise, artifacts - and always dose 47

Quality assurance 57

Known medical benefits versus potential radiation risks 61

3 Creating Subject Contrast in the Primary X-ray Image: Projection Maps of the Body from Differential Attenuation of X-rays by Tissues 67

Creating a (nearly) uniform beam of penetrating X-rays 69

Interaction of X-ray and gamma-ray photons with tissues or an image receptor 75

What a body does to the beam: subject contrast in the pattern of X-rays emerging from the patient 83

What the beam does to a body: dose and risk 87

4 Twentieth-century (Analog) Radiography and Fluoroscopy: Capturing the X-ray Shadow with a Film Cassette or an Image Intensifier Tube plus Electronic Optical Camera Combination 91

Recording the X-ray pattern emerging from the patient with a screen-film image receptor 92

Prime determinants/measures of image quality: contrast, resolution, random noise, artifacts, . . . and, always, patient dose 98

Special requirements for mammography 114

Image intensifier-tube fluoroscopy: viewing in real time 122

Conclusion: bringing radiography and fluoroscopy into the twenty-first century with solid-state digital X-ray image receptors 125

Reference 126

5 Radiation Dose and Radiogenic Risk: Ionization-Induced Damage to DNA can cause Stochastic, Deterministic, and Teratogenic Health Effects - And How To Protect Against Them 127

Our exposure to ionizing radiation has doubled over the past few decades 127

Radiation health effects are caused by damage to DNA 129

Stochastic health effects: cancer may arise from mutations in a single cell 132

Deterministic health effects at high doses: radiation killing of a large number of tissue cells 139

The Four Quartets of radiation safety 146

References 151

6 Twenty-first Century (Digital) Imaging: Computer-Based Representation, Acquisition, Processing, Storage, Transmission, and Analysis of Images 152

Digital computers 153

Digital acquisition and representation of an image 157

Digital image processing: enhancing tissue contrast, SNR, edge sharpness, etc. 166

Computer networks: PACS, RIS, and the Internet 168

Image analysis and interpretation: computer-assisted detection 170

Computer and computer-network security 172

Liquid crystal displays and other digital displays 173

The joy of digital 174

7 Digital Planar Imaging: Replacing Film and Image Intensifiers with Solid State, Electronic Image Receptors 176

Digital planar imaging modalities 176

Indirect detection with a fluorescent screen and a CCD 178

Computed radiography 178

Digital radiography with an active matrix flat panel imager 179

Digital mammography 184

Digital fluoroscopy and digital subtraction angiography 186

Digital tomosynthesis: planar imaging in three dimensions 189

References 190

8 Computed Tomography: Superior Contrast in Three-Dimensional X-Ray Attenuation Maps 191

Computed tomography maps out X-ray attenuation in two and th…