A Comprehensive Guide to Radiographic Sciences and Technology
Description
The guide begins with an overview of the radiographic sciences and technology, followed by detailed descriptions of the major components of digital radiographic imaging systems. Subsequent sections discuss the essential aspects of diagnostic radiography and computed tomography, including basic physics, imaging modalities, digital image processing, quality control, imaging informatics, and basic concepts of radiobiology and radiation protection. Throughout the book, concise chapters summarise the critical knowledge required for effective and efficient imaging of the patient while emphasising the important, yet commonly misunderstood, relationship between radiation dose and image quality. Written by an internationally recognised expert in the field, this invaluable reference and guide:
* Provides easy access to basic physics, techniques, equipment, and safety guidelines for radiographic imaging
* Reflects the educational requirements of the American Society of Radiologic Technologists (ASRT), the Canadian Association of Medical Radiation Technologists (CAMRT), the College of Radiographers(CoR), and other radiography societies and associations worldwide
* Offers a range of pedagogical tools such as chapter outlines, key term definitions, bulleted lists, practical examples, and links to current references and additional resources
* Includes charts, diagrams, photographs, and x-ray images
A Comprehensive Guide to Radiographic Sciences and Technology is required reading for students in programs using ionizing radiation, those preparing for the ARRT and other global radiography certification exams, and practising technologists wanting to refresh their knowledge.
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Dr Euclid Seeram, PhD, MSc, BSc, FCAMRT, currently serves as honorary senior lecturer at the University of Sydney-Faculty of Health Sciences; adjunct associate professor at Monash University-Medicine, Nursing, and Health Sciences; adjunct professor at Charles Sturt University-Faculty of Science; and Adjunct Associate Professor-Faculty of Health, University of Canberra; in Australia. He has published more than 50 papers in professional radiologic technology journals and has had 20 textbooks published on computed tomography, computers in radiology, radiographic instrumentation, digital radiography, and radiation protection. He is a founding member of the Journal of Medical Imaging and Radiation Sciences and is now on editorial boards for Radiography; Biomedical Imaging and Intervention Journal; Open Journal of Radiology; Journal of Allied Health; Journal of Social Science & Allied Health Professions. Euclid also serves on the international advisory panel for the Journal of Medical Radiation Sciences.
Content
Foreword xiii
Preface xiv
Acknowledgments xvii
Section 1: Introduction
Chapter 1 Radiographic sciences and technology: an overview 3
RADIOGRAPHIC IMAGING SYSTEMS: MAJOR MODALITIES AND COMPONENTS 4
RADIOGRAPHIC PHYSICS AND TECHNOLOGY 5
Essential physics of diagnostic imaging 5
Digital radiographic imaging modalities 5
Radiographic exposure technique 6
Image quality considerations 6
Computed tomography - physics and instrumentation 7
Quality control 8
Imaging informatics at a glance 9
RADIATION PROTECTION AND DOSE OPTIMIZATION 10
Radiobiology 10
Radiation protection in diagnostic radiography 10
Technical factors affecting dose in radiographic imaging 11
Radiation protection regulations 12
Optimization of radiation protection 13
Bibliography 13
Chapter 2 Digital radiographic imaging systems: major components 14
FILM-SCREEN RADIOGRAPHY: SHORT REVIEW OF PRINCIPLES 14
DIGITAL RADIOGRAPHY MODALITIES: MAJOR SYSTEM COMPONENTS 18
Computed radiography 19
Flat-panel digital radiography 19
Digital fluoroscopy 19
Digital mammography 21
Computed tomography 21
IMAGE COMMUNICATION SYSTEMS 22
Picture archiving and communication system 23
References 23
Section 2: Basic Radiographic Sciences and Technology
Chapter 3 Basic physics of diagnostic radiography 27
STRUCTURE OF THE ATOM 28
Nucleus 28
Electrons, quantum levels, binding energy, electron volts 28
ENERGY DISSIPATION IN MATTER 29
Excitation 29
Ionization 30
TYPES OF RADIATION 30
Electromagnetic radiation 31
Particulate radiation 32
X-RAY GENERATION 32
X-RAY PRODUCTION 32
Properties of x-rays 33
Origin of x-rays 33
Characteristic radiation 33
Bremsstrahlung radiation 34
X-RAY EMISSION 34
X-RAY BEAM QUANTITY AND QUALITY 35
Factors affecting x-ray beam quantity and quality 36
INTERACTION OF RADIATION WITH MATTER 39
Mechanisms of interaction in diagnostic x-ray imaging 40
RADIATION ATTENUATION 43
Linear attenuation coefficient 43
Mass attenuation coefficient 43
Half value layer 44
RADIATION QUANTITIES AND UNITS 45
Bibliography 45
Chapter 4 X-ray tubes and generators 46
PHYSICAL COMPONENTS OF THE X-RAY MACHINE 47
COMPONENTS OF THE X-RAY CIRCUIT 48
The power supply to the x-ray circuit 49
The low-voltage section control console) 49
The high-voltage section 50
TYPES OF X-RAY GENERATORS 51
Three-phase generators 52
High-frequency generators 52
Power ratings 53
THE X-RAY TUBE: STRUCTURE AND FUNCTION 53
Major components 54
SPECIAL X-RAY TUBES: BASIC DESIGN FEATURES 57
Double-bearing axle 58
HEAT CAPACITY AND HEAT DISSIPATION CONSIDERATIONS 58
X-RAY BEAM FILTRATION AND COLLIMATION 58
Inherent and added filtration 59
Effects of filtration on x-ray tube output intensity 59
Half-value layer 60
Collimation 60
References 60
Chapter 5 Digital image processing at a glance 61
DIGITAL IMAGE PROCESSING 61
Definition 62
Image formation and representation 62
Processing operations 63
CHARACTERISTICS OF DIGITAL IMAGES 63
GRAY SCALE PROCESSING 64
Windowing 67
CONCLUSION 69
References 69
Chapter 6 Digital radiographic imaging modalities: principles and technology 70
COMPUTED RADIOGRAPHY 71
Essential steps 71
Basic physical principles 71
Response of the IP to radiation exposure 73
The standardized exposure indicator 73
FLAT-PANEL DIGITAL RADIOGRAPHY 76
What is FPDR? 76
Types of FPDR systems 76
Basic physical principles of indirect and direct flat-panel detectors 76
The fill factor of the pixel in the flat-panel detector 78
Exposure indicator 79
Image quality descriptors for DR systems 79
Continuous quality improvement for DR systems 79
DIGITAL FLUOROSCOPY 80
Digital fluoroscopy modes 80
II-Based digital fluoroscopy characteristics 80
Flat-panel digital fluoroscopy characteristics 83
DIGITAL MAMMOGRAPHY 85
Screen-film mammography - basic principles 85
Full-field digital mammography -major elements 86
DIGITAL TOMOSYNTHESIS AT A GLANCE 87
Imaging system characteristics 87
Synthesized 2D digital mammography 89
References 90
Chapter 7 Image quality and dose 91
THE PROCESS OF CREATING AN IMAGE 92
IMAGE QUALITY METRICS 93
Contrast 93
Contrast resolution 94
Spatial resolution 96
Noise 98
Contrast-to-noise ratio 101
Signal-to-noise ratio 101
ARTIFACTS 102
IMAGE QUALITY AND DOSE 103
Digital detector response to the dose 103
Detective quantum efficiency 104
References 105
Section 3: Computed Tomography: Basic Physics and Technology
Chapter 8 The essential technical aspects of computed tomography 109
BASIC PHYSICS 110
Radiation attenuation 111
TECHNOLOGY 116
Data acquisition: principles and components 117
Image reconstruction 118
Image display, storage, and communication 120
MULTISLICE CT: PRINCIPLES AND TECHNOLOGY 121
Slip-ring technology 122
X-ray tube technology 122
Interpolation algorithms 123
MSCT detector technology 124
Selectable scan parameters 125
Isotropic CT imaging 127
MSCT image processing 127
IMAGE POSTPROCESSING 128
Windowing 128
3-D image display techniques 129
IMAGE QUALITY 130
Spatial resolution 130
Contrast resolution 131
Noise 131
RADIATION PROTECTION 131
CT dosimetry 132
Factors affecting patient dose 132
Optimizing radiation protection 133
CONCLUSION 134
References 134
Section 4: Continuous Quality Improvement
Chapter 9 Fundamentals of quality control 139
INTRODUCTION 139
DEFINITIONS 140
ESSENTIAL STEPS OF QC 141
QC RESPONSIBILITIES 142
STEPS IN CONDUCTING A QC TEST 142
THE TOLERANCE LIMIT OR ACCEPTANCE CRITERIA 143
PARAMETERS FOR QC MONITORING 145
Major parameters of imaging systems 145
QC TESTING FREQUENCY 145
TOOLS FOR QC TESTING 146
THE FORMAT OF A QC TEST 146
PERFORMANCE CRITERIA/TOLERANCE LIMITS FOR COMMON QC TESTS 147
Radiography 147
Fluoroscopy 150
REPEAT IMAGE ANALYSIS 151
Corrective action/Reasons for rejection 151
COMPUTED TOMOGRAPHY QC TESTS FOR TECHNOLOGISTS 152
The ACR CT accreditation phantom 152
The ACR action limits for tests done by technologists 153
Artifact evaluation 155
References 156
Section 5: PACS and Imaging Informatics
Chapter 10 PACS and imaging informatics at a glance 159
INTRODUCTION 159
PACS CHARACTERISTIC FEATURES 160
Definition 160
Core technical components 160
IMAGING INFORMATICS 163
Enterprise imaging 164
Cloud computing 164
Big data 164
Artificial intelligence 164
Machine learning 165
Deep learning 165
APPLICATIONS OF AI IN MEDICAL IMAGING 165
AI in CT image reconstruction 166
Ethics of AI in radiology 166
References 166
Section 6: Radiation Protection
Chapter 11 Basic concepts of radiobiology 171
WHAT IS RADIOBIOLOGY? 172
BASIC CONCEPTS OF RADIOBIOLOGY 173
Generalizations about radiation effects on living organisms 173
Relevant physical processes 174
Radiosensitivity 175
Dose-response models 176
Radiation interactions in tissue: target theory, direct and indirect action 177
DNA and chromosome damage 178
EFFECTS OF RADIATION EXPOSURE TO THE TOTAL BODY 179
Hematopoietic of bone marrow syndrome 180
Gastrointestinal syndrome 180
Central nervous system (CNS) syndrome 180
DETERMINISTIC EFFECTS 180
STOCHASTIC EFFECTS 181
Tissue effects 181
Life-span shortening 181
Radiation-induced cancers 181
Hereditary effects 182
RADIATION EXPOSURE DURING PREGNANCY 183
References 183
Chapter 12 Technical dose factors in radiography, fluoroscopy, and CT 185
DOSE FACTORS IN DIGITAL RADIOGRAPHY 186
The x-ray generator 186
Exposure technique factors 187
X-ray beam filtration 187
Collimation and field size 188
The SID and SSD 188
Patient thickness and density 188
Scattered radiation grid 189
The sensitivity of the image receptor 190
DOSE FACTORS IN FLUOROSCOPY 190
Fluoroscopic exposure factors 190
Fluoroscopic equipment factors 191
CT RADIATION DOSE FACTORS AND DOSE OPTIMIZATION CONSIDERATIONS 194
Dose distribution in the patient 194
CT dose metrics 195
Factors affecting the dose in CT 196
Dose optimization overview 197
References 198
Chapter 13 Essential principles of radiation protection 200
INTRODUCTION 201
WHY RADIATION PROTECTION? 201
Categories of data from human exposure 201
Radiation dose-risk models 201
Summary of biological effects 202
Radiation protection organizations/reports 202
OBJECTIVES OF RADIATION PROTECTION 203
RADIATION PROTECTION PHILOSOPHY 203
Justification 203
Optimization 204
Dose limits 204
Personal actions 205
Time 205
Shielding 206
Distance 206
RADIATION QUANTITIES AND UNITS 206
Sources of radiation exposure 207
Quantities and units 207
PERSONNEL DOSIMETRY 209
OPTIMIZATION OF RADIATION PROTECTION 211
Regulatory and guidance recommendations 211
Diagnostic reference levels (DRLs) 212
Gonadal shielding: past considerations 213
X-ray room shielding 214
CURRENT STATE OF GONADAL SHIELDING 215
References 215
Index 217
1
Radiographic sciences and technology: an overview
RADIOGRAPHIC IMAGING SYSTEMS: MAJOR MODALITIES AND COMPONENTS
RADIOGRAPHIC PHYSICS AND TECHNOLOGY
Essential physics of diagnostic imaging
Digital radiographic imaging modalities
Radiographic exposure technique
Computed tomography - physics and instrumentation
Imaging informatics at a glance
RADIATION PROTECTION AND DOSE OPTIMIZATION
Radiation protection in diagnostic radiography
Technical factors affecting dose in radiographic imaging
Radiation protection regulations
Optimization of radiation protection
Radiographic Science and Technology have evolved through the years, ever since the discovery and use of x-rays in 1895. This evolution has resulted in the introduction of physical principles and technology with the major goal of improving the care and management of the patient. Furthermore, a significant benefit of these innovations is focused on reducing the radiation dose to the patient without compromising image quality. Radiographic sciences deal with the physics of various diagnostic imaging modalities (radiography, fluoroscopy, mammography, and computed tomography [CT]) and include x-ray generation, x-ray production, x-ray emission, and x-ray interaction with tissues. Furthermore, radiographic sciences also address radiation risks and radiation protection. Radiographic technology, on the other hand, addresses the equipment components and how they function to produce diagnostic images, image quality characteristics, and quality control (QC) aspects of these imaging modalities.
The workhorse of radiology has been film-screen radiography which is now obsolete and has been replaced globally with digital imaging. The scope of digital imaging is extremely wide and now involves a basic understanding of computer sciences, to explain how the new digital imaging modalities work. These modalities include computed radiography (CR), flat-panel digital radiography (FPDR), digital fluoroscopy (DF), digital mammography (DM), digital tomosynthesis, and CT. In addition, the digital imaging environment now demands that operators understand what has been referred to as "imaging informatics," an area of study that involves picture archiving and communication systems (PACS), enterprise imaging, Big Data, machine learning (ML), deep learning (DL), and artificial intelligence (AI).
With the above in mind, various professional organizations such as the American Society of Radiologic Technologists (ASRT), the Canadian Association of Medical Radiation Technologists (CAMRT), and other professional medical imaging organizations throughout the world have prescribed curricula for diagnostic imaging programs which provide guiding, principles that assist academic program leaders in designing foundational learning outcomes that are intended to meet the professional standards, and more importantly meet the entry requirements for clinical practice. Institutions offering educational programs in diagnostic imaging should be then able to raise the level of these foundational learning outcomes and content to meet the requirements of degree programs, including graduate degree programs in diagnostic imaging.
A good example of the above is offered by the ASRT curriculum content which is organized around the following subject matter [1]: Introduction to Radiologic Science and Health Care; Ethics and Law in the Radiologic Sciences; Human Anatomy and Physiology; Pharmacology and Venipuncture; Imaging Equipment; Radiation Production and Characteristics; Principles of Exposure and Image Production; Digital Image Acquisition and Display; Image Analysis; Radiation Biology; Radiation Protection; Clinical Practice; Patient Care in Radiologic Sciences; Radiographic Procedures; Radiographic Pathology; Additional Modalities and Radiation Therapy; Basic Principles of Computed Tomography and Sectional Anatomy. Similar content is characteristic of other curricula offered by other medical imaging professional organizations around the world.
Keeping the above ideas in mind, this book will address content that are considered radiographic sciences and technology. Specifically, the chapters included present a summary of the critical knowledge base needed for effective and efficient imaging of the patient, and wise use of the technical factors that play a significant role in optimization of the dose to the patient without compromising the image quality necessary for diagnostic interpretation. Furthermore, the summaries of the technical elements of radiographic sciences and technology will assist the student in preparing to write certification examinations. As such, the major and significant principles and concepts will be reviewed in three sections as follows:
- Section 1: Radiographic imaging systems: major modalities and components
- Section 2: Radiographic physics and technology
- Section 3: Radiation protection and dose optimization
RADIOGRAPHIC IMAGING SYSTEMS: MAJOR MODALITIES AND COMPONENTS
In this book, the following radiographic imaging systems will be reviewed. These include x-ray imaging modalities such as digital radiography (DR) which includes CR and FPDR, DF, DM, digital radiographic and breast tomosynthesis, and CT. Furthermore, these systems include imaging informatics which has become commonplace since radiology and more importantly hospitals are now all operating in the digital environment; that is, all data acquired from the patient are now in digital form and are stored and communicated using digital technologies. Informatics topics of importance include that nature and scope of PACS, enterprise imaging, cloud computing, Big Data, and the more recent of computer applications in medical imaging: AI. More details of these major technologies and how they work will be presented in Chapter 6 on Digital Imaging Modalities and Chapter 10 on Imaging Informatics.
RADIOGRAPHIC PHYSICS AND TECHNOLOGY
Radiographic physics and technology subject matter include basic physics concepts, and more specifically the physics of diagnostic imaging; technical aspects of the modalities; radiographic exposure technique; image quality, quality assurance (QA), and QC; CT physical principles; imaging informatics; radiobiology and radiation protection.
Essential physics of diagnostic imaging
The physics of diagnostic imaging is an important and vital topic that explains the nature of how these imaging modalities work to produce diagnostic images of the patient. Understanding the fundamental physics will provide the user with the tools not only needed to produce optimum image quality but more importantly to protect the patient from unnecessary radiation. As such, it is now a common characteristic of imaging departments to optimize radiation dose and work within the International Commission on Radiological Protection (ICRP) philosophy of as low as reasonably achievable (ALARA) to reduce the dose to the patient but not compromise the diagnostic quality of the images used to make a diagnosis of the patient's medical condition.
In this book, the topics in physics that will emphasize the imaging modalities are the nature of radiation, x-ray generation, x-ray production, x-ray emission, x-ray attenuation, and x-ray interaction with matter. Furthermore, other physics topics of significance are radiation quantities and their associated units and measurement concepts. These topics and more fall in the domain of Health Physics. Three radiation quantities that are important to radiation protection of the patient are exposure, absorbed dose, and effective dose (ED). The units associated with each of these include coulombs per kilogram (C/kg), Grays (Gy), and Sieverts (Sv), respectively. In order to measure radiation, it must first be detected.
Digital radiographic imaging modalities
As listed earlier in this chapter, these modalities include CR, FPDR or DR as it is sometimes referred to, DF, DM, digital radiographic tomosynthesis (DRT), digital breast tomosynthesis (DBT), and last but not least CT. Additionally, since all of the above-mentioned modalities include image processing using computers, the concepts of Digital Image Processing will be reviewed since it has become an essential tool for technologists, radiologists, and medical physicists working in a digital radiology department.
These imaging modalities include specific physics concepts that must be understood for optimum results. For example, CR is based on the use of photostimulable phosphors (PSP) which are based on the physical principle of photostimulable luminescence (PSL). An example of one such phosphor is barium fluoro halide (BaFX) where the halide (X) can be chlorine (Cl), bromine (Br), iodine (I), or a mixture of them. When the PSP imaging plate (IP) is exposed to x-rays, electrons are moved from the ground state (valence band) to a higher energy level (conducting band) and are trapped there until the PSP plate is exposed to a laser light and subsequently the electrons in the higher energy state return to their ground state, thus emitting a bluish-purple...
