CT at a Glance E-Book

Euclid Seeram

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Serie: At a Glance
• Sprache: Englisch

Seitenzahl: 120

Veröffentlichungsjahr: 2017

Beschreibung

CT at a Glance gets readers quickly up to speed with the core knowledge and competencies required for computed tomography (CT) scanning, as established by the major radiography organizations around the world, including the ASRT and the CAMRT. This brand new title describes the basic science behind CT with an emphasis on the theory that is essential for practice. Featuring an abundance of illustrations, succinct, straightforward explanations and clear, step-by-step guidance, it includes the fundamental physics, technical principles, and imaging strategies and procedures involved in CT scanning. Over the course of twenty four, concise modular chapters, CT at a Glance covers all the bases for entry-to-practice students, including: * The basic physics underlying CT scanning * State-of-the-art multi-slice technologies * Data acquisition strategies * Equipment components--their functions and applications * Image reconstruction and image quality control * CT dose and dose optimization procedures * Quality control fundamentals CT at a Glance is an indispensable learning resource for students in medical imaging technology courses, including those covering radiography, nuclear medicine, and radiation therapy, as well as for biomedical engineering technology students.

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CTat a Glance

First Edition

Euclid Seeram, PhD, MSc, BSc, FCAMRT

Medical Imaging and Radiation Sciences, Honorary Senior Lecturer, Faculty of Health Science, University of Sydney, Australia;

Adjunct Associate Professor, Medicine, Nursing, and Health Sciences, Monash University, Australia;

Adjunct Professor, Faculty of Science, Charles Sturt University, Australia;

This edition first published 2018

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The 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: CT at a glance / Euclid Seeram, PhD., MSc., BSc., FCAMRT.

Description: Hoboken, NJ : John Wiley & Sons, 2017. | Includes index. |

Identifiers: LCCN 2017025967 (print) | LCCN 2017040984 (ebook) | ISBN

9781118660881 (pdf) | ISBN 9781118660898 (epub) | ISBN 9781118660904 (pbk.)

Subjects: LCSH: Tomography.

Classification: LCC RC78.7.T6 (ebook) | LCC RC78.7.T6 S3715 2017 (print) |

DDC 616.07/57—dc23

LC record available at https://lccn.loc.gov/2017025967

Cover image: © Phil Boorman/Gettyimages

Cover design by Wiley

This book is dedicated with love and affection to my beautiful, smart, and overall cute and witty granddaughters

CLAIRE and CHARLOTTE

You bring so much joy and happiness to our lives

Contents

Foreword

Preface

Acknowledgements

1  Computed tomography: an overview

Introduction

Radiographic imaging

CT imaging

Nobel prize for the invention of the CT scanner

The technical evolution of CT

2  Major components of a CT scanner

Major system components

The imaging system

The computer system

Display, storage, and communication system

CT software

3  How CT scanners work

Essential steps in the production of CT images

The flow of data in a CT scanner

The technical evolution of CT

Advantages and shortcomings of CT

4  Data acquisition principles

Data acquisition methods

Data acquisition geometries

Data acquisition components

5  X-ray tubes and generator technologies

The X-ray generator

X-ray tubes

6  X-ray beam filtration and collimation

What is a filter?

The CT filter

X-ray beam collimation

Adaptive section collimation

7  Essential physics: radiation attenuation

What is radiation attenuation?

Attenuation of a homogeneous beam of radiation

Attenuation of a heterogeneous beam of radiation

Lambert–Beer law

8  Attenuation measurements and CT numbers

Attenuation measurements and CT numbers

CT numbers and the CT gray-scale image

CT numbers for various tissues

9  CT detector technology basics

Location and purpose of the CT detectors

Characteristics of CT detectors

Types of detectors

The data acquisition system

10  CT image reconstruction basics

Major steps in CT

Image reconstruction basics

Categories of reconstruction algorithms

Iterative algorithms

11  CT image display and storage

Three major systems in ct imaging

Image display characteristics

Image storage

12  CT and picture archiving and communication systems (PACS)

Electronic communications: basics

PACS: a definition

Major components of a PACS

Communication protocol standards in digital radiology

13  CT image postprocessing

What is image postprocessing?

Windowing overview

WW (Window Width) and WL (Window Level): definitions

Effect of WW and WL on visual image quality

Volume visualization image processing

14  Multislice CT – essential principles: part 1

Evolution

Terminology

Technical requirements for volume scanning

Advantages for spiral/helical technology

Slip-ring technology

Slice geometry during SSCT data acquisition

Slice geometry during MSCT data acquisition

15  Multislice CT – essential principles: part 2

MSCT detector configurations

Effect of collimation on slice thickness

Interpolation fundamentals

Pitch

Selectable parameters

Dose optimization

16  Image quality: part 1

Definitions

Phantoms for measuring CT image quality

17  Image quality: part 2 – spatial resolution

In-plane spatial resolution

Factors affecting the in-plane spatial resolution

Cross-plane spatial resolution

18  Image quality: part 3 – contrast resolution

Definitions

Measurement of the contrast resolution

Factors affecting contrast resolution

Temporal resolution

19  Image quality: part 4 – noise

Definition

Phantom measurement of the noise

Factors affecting noise

20  Image quality: part 5 – artifacts

Definition

Types of artifacts

Causes of artifacts

Common artifacts

21  CT dose optimization: part 1

Risks of radiation exposure

Dose-response models

Radiation protection philosophy

CT dose measurement

Dose metrics use in CT

22  CT dose optimization: part 2

Factors affecting the dose in CT

Optimization of radiation protection in CT

23  Optimization of radiation protection in CT

Optimization methodologies

24  CT quality control basics

What is quality control?

Major steps in a QC program

Typical phantoms and parameters for QC testing

QC tests

Index

EULA

Guide

Cover

Table of Contents

Preface

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Foreword

Dr Euclid Seeram is a distinguished and rigorous academic who has a proven track record in providing understandable and comprehensive radiological manuscripts. He has decades of experience in the teaching of CT physical principles and medical imaging sciences.

A hallmark of his approach is the ability to convey complex topics in an easy-to-read and manageable way, and this work is no exception. He presents his topics in an organized, progressive, and comprehensive manner so that at the end of each clearly defined chapter, learning objectives are met and the reader comes away with a solid and supported knowledge of specific topics. Euclid has decades of experience in the teaching of CT and medical imaging, and during this time has gained worldwide respect as an educator. Both clinicians and physicists in the field of medical imaging are in agreement with the high level of influence Euclid has on medical imaging education and on the profession as a whole. He is simply a global leader in his field. Euclid’s published works have made an impact on radiologic science and technology education, and in particular computed tomography (CT).

This book, CT at a Glance, is another means of bringing an understanding of CT to radiographers, radiologic technologists, and others interested in CT physical principles. The technical and clinical developments of CT have continued over recent years and its use in medicine has proven that it is significant and an important diagnostic imaging tool for clinicians to aid in their diagnosis. CT at a Glance provides an easy understanding of this complex diagnostic imaging modality.

Euclid must be commended for his continued efforts in making CT and other medical imaging technical knowledge easy to understand by students and clinicians.

Rob Davidson, PhD, MAppSc (MI), BBus, FIR

Professor in Medical Imaging

Head, Discipline of Medical Radiations

University of Canberra

Canberra, Australia

Preface

Computed tomography (CT) has experienced significant technological advances ever since its invention in the early 1970s. These advances are meant to improve the scanning speed and reduce the dose to the patient without compromising the diagnostic quality of the image. A few of these significant and important advances include scanners that can image multiple slices in a single breath-hold (multislice CT systems), new detector technologies, automatic exposure control (tube current modulation), automatic voltage selection (X-ray spectra optimization), X-ray beam collimation strategy, iterative reconstruction algorithms that enable scanning at significantly lower doses while maintaining image quality, dual-energy CT scanners that can image the beating heart with excellent detail, and dose optimization strategies, to mention but a few.

The book describes the physical basis for CT and focuses on theory that is essential for practice. Educationally it is pitched at the entry-level for radiographers and radiological technologists, focusing on fundamental physics and technical principles. The main feature of this book is that it provides alternative descriptions of existing knowledge, through the use of multiple illustrations to describe the essential knowledge base for understanding CT physics and instrumentation. Already various radiography organizations such as the American Society of Radiological Technologists (ASRT) and the Canadian Association of Medical Radiation Technologists (CAMRT) have introduced selected topics in Computed Tomography (CT) for what they label as “entry-to-practice” requirements. The purpose of this text is to meet these requirements, and those of other professional organizations for radiographers and radiological technologists in other parts of the world. This book will serve as a resource for entry-to-practice students in medical imaging technologies such as radiography, nuclear medicine, and radiation therapy. Furthermore, this book can also be used by biomedical engineering technology students studying CT physical principles, CT image quality and quality control as well as radiation protection in CT.

The content and organization are based on 24 chapters ranging from historical perspectives, basic physics concepts, multislice technologies, data acquisition strategies, equipment components, image reconstruction, and image quality considerations to CT dose and dose optimization procedures, and quality control fundamentals.

Read on, learn, and enjoy. Your patients will benefit from your wisdom

Acknowledgements

A very satisfying task in writing a book of this nature is to acknowledge the help and encouragement of those individuals who believe that such brief notes on a topic that has been described and discussed in volumes is a worthwhile contribution to the computed tomography (CT) literature. I am grateful to several individuals whose time and efforts have contributed tremendously to this work. First I must express sincere gratitude to Dr Godfrey Hounsfield (whose signature is included in the textbook as an illustration in Figure 1.6, and Dr Allan Cormack, who shared the Nobel Prize for Medicine and Physiology for their work in the invention and development of the CT scanner. Secondly, I have learned a good deal of CT physics and instrumentation from seven medical physicists whose published works are invaluable to the CT community. In particular, I am indebted to Professor Willi Kalender, PhD, Institute of Medical Physics in Germany; Dr Jiang Hsieh, PhD, Chief Scientist with General Electric Healthcare; Dr Mahadevappa Mahesh, PhD, Chief Physicist, Johns Hopkins Hospital in Baltimore; Dr Michael McNitt-Gray, PhD, University of California; Dr Cynthia McCollough, PhD, Mayo Clinic; Dr Thomas Flohr, PhD, Siemens Medical Solutions, Germany; and last but not least, Dr John Aldrich, PhD, Vancouver General Hospital, University of British Columbia, whose seminars on radiation dose in CT and other topics have taught me quite a bit.