Computed Tomography E-Book

Euclid Seeram

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 173

Veröffentlichungsjahr: 2022

Beschreibung

COMPUTED TOMOGRAPHY: PHYSICS AND TECHNOLOGY

In the newly updated second edition of Computed Tomography: Physics and Technology A Self Assessment Guide, distinguished computed tomography (CT) educator Euclid Seeram delivers a completely revised and expanded collection of multiple-choice questions covering all relevant technological advances, including the use of artificial intelligence, in the field of CT. In the book, readers will find a focused emphasis on physics and technology — an area where students of this discipline have traditionally struggled.

The questions are presented in a format similar to those found on the certification examinations of the American Registry of Radiologic Technologists (ARRT), the Canadian Association of Medical Radiation Technologists (CAMRT), and other professional medical imaging organizations around the world. The author has also included true-false questions, short answer questions, and relevant learning outcomes to aid students in their study of the subject.

Readers will also find brief notes on:

• An introduction to computed tomography, including an overview of the field and a historical perspective
• Digital image processing and the physics of computed tomography
• Data acquisition principles and technology and image reconstruction fundamentals
• Deep learning image reconstruction, the major equipment components of a computed tomography scanner, and image post-processing and visualization
• Multislice CT: Principles and Technology
• Image quality considerations
• CT Dosimetry and dose optimization strategies
• Quality control

Perfect for radiological technology and diagnostic radiography students and practitioners, Computed Tomography: Physics and Technology A Self Assessment Guide, will also earn a place in the libraries of biomedical engineering students and radiology residents in training.

Leseprobe

Table of Contents

Cover

Title Page

Copyright

Dedication

Preface

Acknowledgments

1 Computed Tomography: Pioneering Work and Technical Overview

PRIOR READING ASSIGNMENT

IDENTIFYING AREAS TO STUDY

2 Data Acquisition Principles

PRIOR READING ASSIGNMENT

IDENTIFYING AREAS TO STUDY

3 X‐Ray Tubes, Generators, Filtration, and Collimation in CT

PRIOR READING ASSIGNMENT

IDENTIFYING AREAS TO STUDY

4 Radiation Attenuation in CT: Essential Physics

PRIOR READING ASSIGNMENT

IDENTIFYING AREAS TO STUDY

5 CT Detector Technology: Fundamentals

PRIOR READING ASSIGNMENT

IDENTIFYING AREAS TO STUDY

6 Image Reconstruction in CT: Basic Principles

PRIOR READING ASSIGNMENT

IDENTIFYING AREAS TO STUDY

7 CT Image Display, Storage, Communications, and Image Postprocessing

INTRODUCTION

IDENTIFYING AREAS TO STUDY

8 Multislice CT: Fundamental Principles

PRIOR READING ASSIGNMENT

IDENTIFYING AREAS TO STUDY

9 Image Quality in CT

PRIOR READING ASSIGNMENT

IDENTIFYING AREAS TO STUDY

10 Dose Optimization in CT

PRIOR READING ASSIGNMENT

IDENTIFYING AREAS TO STUDY

11 CT Quality Control for Technologists/Radiographers

PRIOR READING ASSIGNMENT

IDENTIFYING AREAS TO STUDY

12 Practice CT Examination: Physics and Technology

References

FURTHER READING

Appendix A Answers to CT Review Questions

Index

End User License Agreement

List of Illustrations

Chapter 2

Figure 2.1 Essential characteristics of four generations of CT scanners.

Figure 2.2 The major technical data acquisition components of a CT scanner....

Chapter 3

Figure 3.1 The major elements of x‐ray beam filtration used in CT.

Figure 3.2 The basic components of the collimation approach used in a CT sca...

Chapter 7

Figure 7.1 Three essential steps in the production of a CT image.

Chapter 8

Figure 8.1 Two types of MSCT detector arrays.

Figure 8.2 The major difference between low‐voltage and high‐voltage sling C...

Figure 8.3 The major difference between the slice geometry for SSCT and MSCT...

Figure 8.4 Interpolation creates a planar section before image reconstructio...

Chapter 9

Figure 9.1 A simple illustration of the sources and graphic appearance of ty...

Chapter 11

Figure 11.1 Image of the SMPTE test pattern used for gray level assessment o...

Guide

Cover

Table of Contents

Title Page

Copyright

Dedication

Preface

Acknowledgments

Begin Reading

References

Appendix A Answers to CT Review Questions

Index

End User License Agreement

Pages

iii

iv

v

xi

xii

xiii

xiv

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

41

42

43

44

45

46

47

48

49

51

52

53

54

55

56

57

58

59

61

62

63

64

65

66

67

68

69

71

72

73

74

75

76

77

78

79

80

81

82

83

85

86

87

88

89

90

91

92

93

94

95

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

119

120

121

122

123

124

125

126

127

128

129

131

132

133

135

136

137

138

139

140

141

Computed Tomography: Physics and Technology

A Self Assessment Guide

Second Edition

Euclid Seeram, PhD, FCAMRTActive Member, Canadian RadiationProtection Association

HONORARY ACADEMIC APPOINTMENTSAdjunct Associate Professor; Medical Imaging andRadiation Sciences; Monash University, Australia |Adjunct Professor; Faculty of Science;Charles Sturt University, Australia |Adjunct Professor; Medical Radiation Sciences,Faculty of Health; University of Canberra; Australia

REGULAR GUEST LECTURERVision, Compassion, Awareness (VCA) Education Solutions for Health Professionals Inc., Toronto, Ontario, Canada

This second edition first published 2022© 2022 John Wiley & Sons Ltd

Edition HistoryJohn Wiley & Sons, Ltd (1e, 2021)

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions.

The right of Euclid Seeram to be identified as the author of this work has been asserted in accordance with law.

Registered OfficesJohn Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USAJohn Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK

Editorial Office9600 Garsington Road, Oxford, OX4 2DQ, UK

For details of our global editorial offices, customer services, and more information about Wiley products visit us at www.wiley.com.

Wiley also publishes its books in a variety of electronic formats and by print‐on‐demand. Some content that appears in standard print versions of this book may not be available in other formats.

Limit of Liability/Disclaimer of WarrantyThe contents of this work are intended to further general scientific research, understanding, and discussion only and are not intended and should not be relied upon as recommending or promoting scientific method, diagnosis, or treatment by physicians for any particular patient. In view of ongoing research, equipment modifications, changes in governmental regulations, and the constant flow of information relating to the use of medicines, equipment, and devices, the reader is urged to review and evaluate the information provided in the package insert or instructions for each medicine, equipment, or device for, among other things, any changes in the instructions or indication of usage and for added warnings and precautions. While the publisher and authors have used their best efforts in preparing this work, they make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives, written sales materials or promotional statements for this work. The fact that an organization, website, or product is referred to in this work as a citation and/or potential source of further information does not mean that the publisher and authors endorse the information or services the organization, website, or product may provide or recommendations it may make. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for your situation. You should consult with a specialist where appropriate. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this work was written and when it is read. Neither the publisher nor authors shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages.

Library of Congress Cataloging‐in‐Publication Data

Names: Seeram, Euclid, author.Title: Computed tomography : physics and technology : a self assessment guide / Euclid Seeram.Description: Second edition. | Hoboken, NJ : Wiley‐Blackwell, 2022. | Includes bibliographical references and index.Identifiers: LCCN 2022015047 (print) | LCCN 2022015048 (ebook) | ISBN 9781119819325 (paperback) | ISBN 9781119819349 (adobe pdf) | ISBN 9781119819356 (epub)Subjects: MESH: Tomography, X‐Ray Computed | Examination QuestionsClassification: LCC RC78.7.T6 (print) | LCC RC78.7.T6 (ebook) | NLM WN 18.2 | DDC 616.07/5722–dc23/eng/20220603LC record available at https://lccn.loc.gov/2022015047LC ebook record available at https://lccn.loc.gov/2022015048

Cover Design: WileyCover Images: © Canon Medical Systems Canada Limited

Dedication

This book is dedicated with love and affection to Claire and Charlotte, my special, smart, cute, and very witty granddaughters. You bring tremendous joy and happiness to our lives.

Preface

Computed tomography (CT) has experienced several technical innovations in recent years. For example, iterative reconstruction (IR) algorithms are now commonplace, and all CT scanners offer this technology. Additionally, artificial intelligence–based image reconstruction is now offered by several CT vendors. These algorithms address the problems of the filtered back projection (FBP) image reconstruction algorithm and IR algorithms, especially in low‐dose CT examinations. Another important new technical innovation is the photon‐counting detector, which offers advantages over current energy‐integrating CT detectors. These innovations have all resulted in dose optimization efforts in the care and management of the patient undergoing CT examinations. Dose optimization has become an integral part of CT practice.

This book, Computed Tomography: Physics and Technology A Self Assessment Guide, features a wide range of questions focused on topics that address the content requirements of CT physics tnd Technology set by various professional radiologic technology associations, including the American Society of Radiologic Technologists (ASRT), the American Registry of Radiologic Technologists (ARRT), the Canadian Association of Medical Radiation Technologists (CAMRT), the College of Radiographers in the United Kingdom, and professional medical imaging organizations in Africa, Asia, Australia, and continental Europe. Additionally, this book may serve as a resource for biomedical engineering technology programs that include CT systems in their curricula, residents in radiology, and medical physics students studying the use of CT in medical imaging.

Self‐assessment questions use the true/false, multiple choice, and short answer formats, as listed for each chapters in the table of contents. These formats are typical of the radiologic technology/radiography organizations listed previously and are characteristic of CT certification examinations.

Enjoy the questions that follow, and best wishes for any examination you take. And remember – your patients will benefit from your wisdom.

Euclid Seeram, PhD, MSc, BSc, FCAMRTBritish ColumbiaCanada

Acknowledgments

The single most important and satisfying task in writing a book of this nature is to acknowledge the help and encouragement of those individuals who perceive the value of its contribution to the medical imaging science literature. It is a pleasure to express sincere thanks to several individuals whose time and effort have contributed tremendously to this second edition.

The content on which the questions in this book are based is centered around the published works and expertise of several noted medical physicists, radiologists, computer scientists, and biomedical engineers (too numerous to mention here) who did the original research. They are the tacit authors of this text, and I am truly grateful to all of them, in particular Dr. Rob Davidson, PhD, MAppSc (MI), BBus, FASMIRT, professor of medical imaging, University of Canberra, Australia. Dr. Davidson has taught CT physics and instrumentation for decades and provided me with the opportunity to develop a course of studies on CT physics and instrumentation for the Medical Imaging Program at the University of Canberra, Australia. Thanks, mate.

Yet another notable individual to whom I am grateful is Valentina Al Hamouche, MRT, MSc, and CEO of Vision, Compassion, Awareness (VCA) Education Solutions for Health Professionals, Inc. (Toronto, Ontario, Canada). Valentina has given me the opportunity to present face‐to‐face lectures and live webinars on CT physics and instrumentation and other topics in the radiographic sciences, and I have earned the title Regular Guest Lecturer with her organization (www.VCAeducation.ca). Thank you, Valentina, for bringing continuing education opportunities to students and technologists worldwide.

The people at John Wiley and Sons deserve special thanks for their hard work, encouragement, and support of this project. They include James Watson, senior commissioning editor in health sciences, who accepted the proposal for this work and also provided support to bring it to fruition. Additionally, Anne Hunt and Mandy Collison maintained continuous communications about my writing progress and always offered their assistance on matters relating to this project, and they are to be credited as well. Thank you both. I must also thank the individuals in the production department at Wiley for doing a wonderful job bringing the manuscript to its final form. In particular, I am grateful to members of the production team, who have worked exceptionally hard during the production of this book, especially in the page‐proof stage.

I must acknowledge the support and praise I receive from my beautiful family. First, my lovely wife, Trish, is a warm, smart, caring, and very special person in my life. Thanks, babe. Second, my caring and brilliant son, David, and his family deserve special mention for their love, support, and encouragement.

Last but not least, I must thank my students in Canada and all over the world who have diligently completed my CT physics and instrumentation courses at both the diploma and degree levels. Thanks for all the challenging questions, which have always kept me on my toes.

1Computed Tomography: Pioneering Work and Technical Overview

PRIOR READING ASSIGNMENT

Challenge Questions

IDENTIFYING AREAS TO STUDY

PRIOR READING ASSIGNMENT

Before attempting to answer these review questions, read the following brief summary notes on this topic.

In radiography, images are usually referred to as planar images. These images have the following limitations: superimposition of all structures on the image receptor (film‐screen detector) and the qualitative nature of radiographic imaging. The latter simply means that it is difficult to distinguish between a homogeneous object (one tissue type) of non‐uniform thickness and a heterogeneous object (bone, soft tissue, and air) of uniform thickness. Furthermore, the beam used in radiography is an open beam (wide beam), and this creates more scattered rays that reach the image and essentially destroy the image contrast.

Computed tomography (CT) overcomes these limitations by removing the superimposition of structures, improving image contrast, and imaging very small differences in tissue contrast, using a more sensitive detector. In particular, CT produces cross‐sectional images of patient anatomy, referred to as transverse axial images. These sections are perpendicular to the long axis of the patient. The invention of the CT scanner is credited to two individuals: Godfrey Hounsfield (who worked at EMI[Electric and Musical Industries] in England) and Allan Cormack, who shared the Nobel Prize in Medicine in 1979 for their contributions to the development of the scanner. Both of these pioneers worked out the mathematical solutions to the problem in CT, but Hounsfield is credited with the development of the first useful clinical CT scanner.

The technical evolution of the CT scanner is marked by the development of more efficient data collection methods leading to multislice CT imaging (as opposed to single‐slice CT imaging), faster image reconstruction algorithms resulting in low‐dose CT scanning, and improved image postprocessing methods such as three‐dimensional images.

The major components of a CT scanner include the data acquisition system, the computer system, and the image display, storage, and communications system. The data acquisition system contains imaging system components designed to collect radiation attenuation values from the patient using an x‐ray tube and special detectors coupled to detector electronics. These components are housed in what is referred to as the CT gantry. The computer is a central and integral component in CT. The primary role of the computer is image reconstruction and image postprocessing. A graphics processing unit (GPU) is now used to reduce the processing requirements of the computer's central processing unit (CPU). Image reconstruction uses special algorithms to create the image using the attenuation values collected from the patient. Today these algorithms are iterative reconstruction algorithms and are much faster than the previous algorithm (the filtered back‐projection algorithm).

CT examinations generate large amounts of data; hence large storage space on the order of gigabytes (GB) is required. Storage devices for CT include magnetic tape and disks, digital videotape, optical disks, and optical tape. Communications refer to electronic networking or connectivity by using a local area network or wide area network (LAN or WAN). Connectivity ensures the transfer of data and images from multivendor and multimodality equipment according to a defined standard. A popular standard for medical images is the Digital Imaging and Communications in Medicine (DICOM) standard. CT scanners are now connected to Picture Archiving and Communications Systems (PACS).

In general, the software used in CT includes image reconstruction software, preprocessing software, and image postprocessing software. Image reconstruction software uses algorithms to build up the image from the raw data collected from the detectors. Preprocessing software performs corrections (such as correcting a bad detector reading, for example) on the data collected from the detectors before the data is sent to the computer. Image postprocessing software operates on reconstructed images displayed for viewing and interpretation and typically includes visualization and analysis software.

Self‐Assessment Questions will be based on the following Keywords and Concepts

Major differences between CT and radiography

Godfrey Hounsfield

Allan Cormack

Major components of a CT scanner

Technical evolution overview

The imaging system

The computer system

Storage capacity

Connectivity

CT software

Challenge Questions

Answer the following questions to check your understanding of the materials studied.

True (T)/False (F)

CT is a planar radiographic imaging modality.

CT was developed by EMI.

Godfrey Hounsfield was awarded the Nobel Prize in Medicine for his contributions to the development of the first useful CT scanner.

Allan Cormack did not share the Nobel Prize in Medicine with Hounsfield.

Radiographic imaging produces planar images of the patient's body.

CT can show very small differences in tissue attenuation compared to radiography.

CT shows soft tissue contrast much better than radiography.

CT uses rendering algorithms to create three‐dimensional images to enhance diagnostic interpretation.

Images produced by the CT scanner are generally referred to as planar images.

Two notable technical innovations for CT scanners are the development of multislice detectors and iterative reconstruction algorithms.

Data acquisition in CT refers to the process of converting attenuation data to electrical signals that are subsequently converted into digital data.

GPUs are now used in CT to reduce the processing requirements of the CPU.

Multiple Choice

Which company pioneered the development of the CT scanner?

General Electric Healthcare

Siemens Healthineers

Philips Healthcare

EMI (now called Thorn EMI)

Which type of image does radiography produce?

Planar static image

Cross‐sectional image

Three‐dimensional image

Both A and C are correct.

A significant difference between CT and radiography is that:

CT shows very small differences in soft tissue contrast compared to radiography.

CT shows better image sharpness compared to radiography.

CT images show better image contrast than radiographic images.

A and C are correct.

Which of the following problems of radiography are overcome by CT?

Superimposition of all structures on the image receptor

The open‐beam geometry of radiography, which causes more scattered radiation to reach the image receptor

The qualitative nature of radiography

The radiographic image receptor sensitivity to radiation

1 only

1 and 2

1, 2, and 3

1, 2, 3, and 4

The major system component of the CT scanner responsible for image reconstruction is the:

Data acquisition components

CT detector

Computer system

Picture archiving and communication system (PACS)

Which of the following data sets is used by the CT image reconstruction algorithm to create CT images?

Attenuation data from the patient

Demographic data sets about the patient

Exposure factors (kV and mAs)

The computer storage capacity

The anatomical section that is perpendicular to the longitudinal axis of the patient is called the:

Planar section

Transverse axial section

Cross section

B and C are correct.

Who developed the first clinically useful CT scanner?

Dr. Euclid Seeram

Dr. Godfrey Hounsfield

Dr. Allan Cormack

B and C are correct.

The first CT scanner was limited to scanning only the:

Brain

Chest

Abdomen

Whole body

Which of the following recent technical innovations in CT are intended to improve image quality and reduce radiation dose?

Multislice detectors

Iterative algorithms

Dose optimization tools

Quality control tests

1 only

2 and 3

3 and 4

1, 2, 3, and 4

The purpose of the data acquisition system components in CT is to:

Produce x‐rays

Shape and filter the x‐ray beam falling upon the patient

Detect the radiation passing through the patient

Convert the transmitted x‐ray photons into digital information

1 only

2 and 3

3 and 4

1, 2, 3, and 4

A term used to describe the transfer of data and images from multivendor and multimodality equipment according to a defined standard is:

Digital Imaging and Communications Standard in Medicine (DICOM)

Connectivity

PACS

Preprocessing of raw CT data

Short Answers

What are the basic limitations of radiography that have been overcome by CT scanning?

How does CT overcome the limitations of radiography?