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Scientific Basis of the RoyalCollege of RadiologistsFellowship (2nd Edition)

Illustrated questions and answers

IPEM–IOP Series in Physics and Engineering in Medicine and Biology

Editorial Advisory Board MembersFrank VerhaegenMaastro Clinic, the Netherlands

Carmel CaruanaUniversity of Malta, Malta

Penelope Allisy-Robertsformerly of BIPM, Sèvres, France

Rory CooperUniversity of Pittsburgh, USA

Alicia El HajUniversity of Birmingham, UK

Ng Kwan HoongUniversity of Malaysia, Malaysia

John HossackUniversity of Virginia, USA

Tingting ZhuUniversity of Oxford, UK

Dennis SchaartTU Delft, the Netherlands

Indra J DasNew York University, USA

About the SeriesSeries in Physics and Engineering in Medicine and Biology will allow IPEM toenhance its mission to ‘advance physics and engineering applied to medicine andbiology for the public good.’

Focusing on key areas including, but not limited to:• clinical engineering• diagnostic radiology• informatics and computing• magnetic resonance imaging• nuclear medicine• physiological measurement• radiation protection• radiotherapy• rehabilitation engineering• ultrasound and non-ionizing radiation.

A number of IPEM–IOP titles are published as part of the EUTEMPE NetworkSeries for Medical Physics Experts.

Scientific Basis of the RoyalCollege of RadiologistsFellowship (2nd Edition)

Illustrated questions and answers

Malcolm SperrinOxford University Hospitals, Oxford, UK

John WinderRJ Imaging, Belfast, UK

IOP Publishing, Bristol, UK

ª IOP Publishing Ltd 2020

All rights reserved. No part of this publication may be reproduced, stored in a retrieval systemor transmitted in any form or by any means, electronic, mechanical, photocopying, recordingor otherwise, without the prior permission of the publisher, or as expressly permitted by law orunder terms agreed with the appropriate rights organization. Multiple copying is permitted inaccordance with the terms of licences issued by the Copyright Licensing Agency, the CopyrightClearance Centre and other reproduction rights organizations.

Certain images in this publication have been obtained by the authors from the Wikipedia/Wikimedia website, where they were made available under a Creative Commons licence or statedto be in the public domain. Please see individual figure captions in this publication for details. Tothe extent that the law allows, IOP Publishing disclaim any liability that any person may suffer as aresult of accessing, using or forwarding the images. Any reuse rights should be checked andpermission should be sought if necessary from Wikipedia/Wikimedia and/or the copyright owner(as appropriate) before using or forwarding the images

Permission to make use of IOP Publishing content other than as set out above may be soughtat permissions@ioppublishing.org.

Malcolm Sperrin and John Winder have asserted their right to be identified as the authors of thiswork in accordance with sections 77 and 78 of the Copyright, Designs and Patents Act 1988.

ISBN 978-0-7503-2148-8 (ebook)ISBN 978-0-7503-2146-4 (print)ISBN 978-0-7503-2149-5 (myPrint)ISBN 978-0-7503-2147-1 (mobi)

DOI 10.1088/978-0-7503-2148-8

Version: 20191101

IOP ebooks

British Library Cataloguing-in-Publication Data: A catalogue record for this book is availablefrom the British Library.

Published by IOP Publishing, wholly owned by The Institute of Physics, London

IOP Publishing, Temple Circus, Temple Way, Bristol, BS1 6HG, UK

US Office: IOP Publishing, Inc., 190 North Independence Mall West, Suite 601, Philadelphia,PA 19106, USA

Contents

Introduction xi

Author biographies xii

1 Basic physics 1-1

1.1 The structure of the atom 1-3

1.2 Characteristic radiation and atomic shells 1-5

1.3 The electromagnetic spectrum I 1-7

1.4 The electromagnetic spectrum II 1-9

1.5 Luminescence 1-11

1.6 Transverse waves 1-13

1.7 Longitudinal waves 1-15

1.8 The inverse square law 1-17

1.9 Radioactivity in medicine 1-19

1.10 Radioactive decay 1-21

1.11 Exponential decay 1-23

1.12 The half-life of a radionuclide 1-25

1.13 Units and measurement 1-27

1.14 Prefixes to units 1-29

1.15 Full width at half maximum 1-31

1.16 The point spread function 1-33

1.17 Mathematical considerations 1-35

1.18 Contrast agents I 1-37

1.19 Contrast agents II 1-39

2 X-ray imaging 2-1

2.1 Projection imaging 2-3

2.2 Radiography 2-5

2.3 Magnification in radiography 2-7

2.4 The quality of an x-ray beam 2-9

2.5 Image quality 2-11

2.6 Plain film x-ray tomography 2-13

2.7 Fluoroscopy technology 2-15

2.8 Image intensifier 2-17

2.9 Fluoroscopy radiation dose 2-19

2.10 Image quality in fluoroscopy 2-21

v

2.11 High kV technique 2-23

2.12 Mammography x-ray spectra 2-25

2.13 Mammography spatial resolution 2-27

2.14 Image quality in mammography 2-29

2.15 Mammography technology 2-31

2.16 Mammography compression 2-33

2.17 Digital mammography 2-35

2.18 Computed radiography I 2-37

2.19 Computed radiography II 2-39

2.20 Computed radiography: dynamic range 2-41

2.21 Computed radiography cassettes 2-43

2.22 Computed radiography detection process 2-45

2.23 Direct (digital) radiography 2-47

2.24 Detectors in direct radiography 2-49

2.25 Breast tomosynthesis 2-51

2.26 Fluoroscopy 2-53

2.27 Fluouoscopy entrance surface dose 2-55

3 Imaging theory 3-1

3.1 Digital imaging fundamentals 3-3

3.2 The isotropic voxel 3-5

3.3 Digital image presentation 3-7

3.4 Image digitisation 3-9

3.5 Digital image matrix 3-11

3.6 Digital image computer displays 3-13

3.7 Spatial resolution in imaging systems 3-15

3.8 Picture archive and communication system I 3-17

3.9 Picture archive and communication system II 3-19

3.10 Image quality 3-21

3.11 Partial volume effect 3-23

3.12 Image processing in radiological imaging 3-25

3.13 Spatial resolution in medical imaging 3-27

3.14 Multimodality imaging 3-29

3.15 Common imaging themes I 3-31

3.16 Common imaging themes II 3-33

3.17 Common imaging themes III 3-35

3.18 Modulation transfer function 3-37

Scientific Basis of the Royal College of Radiologists Fellowship (2nd Edition)

vi

4 Radiation protection 4-1

4.1 Radiation dose reduction in pregnancy 4-3

4.2 The ALARA principle 4-5

4.3 Types of radiation effects 4-7

4.4 Stochastic effects of radiation 4-9

4.5 Absorbed dose 4-11

4.6 Dose area product 4-13

4.7 Radiation controlled areas 4-15

4.8 Radiation biology 4-17

4.9 Radiation safety of staff 4-19

4.10 Practical radiation exposure reduction 4-21

4.11 Ionizing radiation dose I 4-23

4.12 Ionizing radiation dose II 4-25

4.13 Safety in radiography I 4-27

4.14 Safety in radiography II 4-29

4.15 Safety in radionuclide imaging I 4-31

4.16 Safety in radionuclide imaging II 4-33

4.17 Radionuclide radiation protection 4-35

5 Computed tomography 5-1

5.1 Computed tomography back projection 5-3

5.2 Technology in cone beam computed tomography 5-5

5.3 The cone beam effect in computed tomography scanning 5-7

5.4 Principles of computed tomography operation 5-9

5.5 Multislice detectors in computed tomography 5-11

5.6 Spatial resolution in computed tomography 5-13

5.7 Computed tomography image reconstruction 5-15

5.8 Computed tomography image presentation 5-17

5.9 Computed tomography 5-19

5.10 Computed tomography radiation dose 5-21

5.11 Spectral computed tomography 5-23

6 Ultrasound 6-1

6.1 Ultrasound imaging: routine 6-3

6.2 Ultrasound imaging: obstetrics 6-5

Scientific Basis of the Royal College of Radiologists Fellowship (2nd Edition)

vii

6.3 Ultrasound imaging: image process 6-7

6.4 Ultrasound imaging: transducer 6-9

6.5 Harmonic imaging I 6-11

6.6 Acoustic field 6-13

6.7 Thermal index and mechanical index 6-15

6.8 Image formation 6-17

6.9 Artefacts 6-19

6.10 Bioeffects 6-21

6.11 Contrast agents 6-23

6.12 The Doppler effect 6-25

6.13 Power Doppler 6-27

6.14 Duplex Doppler 6-29

6.15 Harmonic imaging II 6-31

6.16 Transducer design 6-33

6.17 Improving the image 6-35

6.18 Basic physics 6-37

6.19 Physics of ultrasound I 6-39

6.20 Physics of ultrasound II 6-41

6.21 Ultrasound 6-43

6.22 Safety in ultrasound 6-45

7 Magnetic resonance imaging 7-1

7.1 The source of the magnetic resonance signal 7-3

7.2 Magnetic resonance signal: the net magnetic moment 7-5

7.3 Magnetic resonance image contrast (image weighting) 7-7

7.4 Transverse magnetization 7-9

7.5 Metal artefacts in magnetic resonance imaging 7-11

7.6 The spin echo pulse sequence 7-13

7.7 Magnetic resonance safety: main magnetic field 7-15

7.8 Magnetic resonance imaging parameters 7-17

7.9 Magnetic resonance technology 7-19

7.10 Gradient magnetic fields 7-21

7.11 Relaxation times in magnetic resonance imaging 7-23

7.12 Fast/turbo spin echo magnetic resonance imaging 7-25

7.13 Fat suppression techniques 7-27

7.14 Radio frequency safety 7-29

7.15 Magnetic resonance image artefacts 7-31

Scientific Basis of the Royal College of Radiologists Fellowship (2nd Edition)

viii

7.16 Magnetic resonance safety I 7-33

7.17 Magnetic resonance controlled area 7-35

7.18 Risks associated with magnetic resonance imaging 7-37

7.19 Magnetic resonance safety II 7-39

7.20 Magnetic resonance imaging environment 7-41

7.21 Magnetic resonance safety III 7-43

7.22 Magnetic resonance safety IV 7-45

7.23 Gradient echo imaging 7-47

7.24 Magnetic resonance imaging spatial encoding 7-49

7.25 Magnetic resonance signal 7-51

8 Nuclear medicine 8-1

8.1 Gamma camera design 8-3

8.2 The ideal isotope 8-5

8.3 Quality assurance tests 8-7

8.4 Dynamic studies 8-9

8.5 Nuclear medicine risks 8-11

8.6 Positron emission tomography I 8-13

8.7 Single photon emission computed tomography I 8-15

8.8 Combined positron emission tomography/computed tomography 8-17

8.9 Collimators 8-19

8.10 Resolution 8-21

8.11 Bone scans 8-23

8.12 Photomultiplier tubes 8-25

8.13 Single photon emission computed tomography II 8-27

8.14 Positron emission tomography II 8-29

8.15 Positron emission tomography III 8-31

8.16 Isotopes 8-33

8.17 Radionuclide imaging I 8-35

8.18 Radionuclide imaging II 8-37

8.19 Positron emission tomography IV 8-39

8.20 Positron emission tomography V 8-41

9 Functional and molecular imaging 9-1

9.1 Molecular imaging 9-3

9.2 Functional and molecular imaging I 9-5

Scientific Basis of the Royal College of Radiologists Fellowship (2nd Edition)

ix

9.3 Optical imaging 9-7

9.4 Functional and molecular imaging II 9-9

9.5 Functional and molecular imaging III 9-11

9.6 Biological processes for functional and molecular imaging I 9-13

9.7 Biological processes for functional and molecular imaging II 9-15

Scientific Basis of the Royal College of Radiologists Fellowship (2nd Edition)

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Introduction

Science and medicine have long been close partners. This is particularly true inradiology where the availability of imaging techniques is central to diagnosis. In itssimplest sense, imaging can be thought of as a technique which uses somemeasurable parameter of the patient to provide a basis for contrast in an imageand the science is the connection between the patient and the image.

However, science is far more than just providing a vehicle for understanding animaging or therapeutic process. An understanding of the science underlying aprocess enables the right person to develop new techniques, understand imaginglimitations and develop a portfolio of research.

A knowledge of scientific principles is also mandated as a result of a need tounderstand best and safest practice especially in the use of ionizing radiation wherelegislation, guidance and risk all form part of medical specialists’ pressures at work.

It is no surprise therefore that radiologists are obliged to study and pass physicsexams. Such exams do present a considerable challenge and the authors of this workrecognise and sympathise with that challenge and have set about to create a volumewhich is intended to be an educational resource and not just a pre-exam ‘crammer’.Both authors have considerable experience in teaching, supporting and examining inmedical science and have developed an awareness of where those sitting professionalexams have traditionally struggled. This text is a distillation of that experience.

The text itself is arranged in a manner to encourage learning and understandingof the key concepts rather than just provide a vehicle to pass the exams. The imagesand diagrams which accompany each question should provide a stimulus to theconcepts being challenged rather than be directed related to the question. Theanswers also contain some explanation that in many instances goes beyond a simpleexplanation to support true/false.

The authors hope that the text continues to be used beyond the awarding ofFellowship to the reader and future revisions will include updates, new questions andfeedback from those who have found the book to be a usable resource.

Professor Malcolm SperrinOxford University HosptalsOxford

Dr John WinderRJ Imaging

Belfast

xi

Author biographies

Malcolm Sperrin

Malcolm Sperrin was born in Cuba of diplomatic parents in 1963,and attended The Harvey Grammar School in Folkestone leavingthere in 1981 to study Physics with Maths at Reading University.His first job was working on Artificial Intelligence and then with theUK Atomic Energy Authority on reactor fault analysis. Thisexperience placed him in a good position to provide insight intoboth the Chernobyl and Fukushima incidents.

After further study at Reading University, Malcolm joined Medical Physics at theChurchill Hospital in Oxford with responsibility for non-ionizing radiation. In 1995,Malcolm moved to the Princess Margaret Hospital in Swindon acting as DeputyHead of Department and then, in 2002, he moved to The Royal Berkshire Hospitalin Reading taking on the role of Departmental Director. More recently Malcolmmoved to the Oxford University Hospitals as Director of Medical Physics andClinical Engineering and Trust Lead Scientist.

Malcolm has a special interest in radiation medicine, especially Nuclear Medicineand Radiotherapy. He also plays a significant role in radiation protection andcontingency planning. In parallel to his conventional hospital duties, Malcolm alsospends a lot of time teaching and lecturing with organisations including OxfordPostgraduate Medical School, The Open University and various Royal Colleges notto mention lectureships at Guildford and the University of the West of England.

Malcolm was made visiting Professor at Reading, Guildford and Open Universitiesand visiting academic at Oxford University and plays a role on the national stage withthe Institute of Physics, Royal Institution, Science Media Centre and the BritishAssociation for the Advancement of Science. Malcolm also feeds into activitiescentred on science and health policy at the DoH.

Malcolm’s down-to-earth approach to Medical Science has led to him beingfrequently sought by the media for comment on mobile phone use, WiFi safety andeven the risks from the Fukushima reactor. He is very active in developinginnovation whether operational or scientific and has recently been involved ininitiatives with Microsoft and other multi-national companies with a drive toimprove patient outcomes.

Malcolm is a keen adventure sports enthusiast and likes to climb, cave and canoeand has been known to parachute. He has a partner, Nicki (who is not sure about theparachuting), an 9-year-old son and a spaniel called Harvey.

xii

John Winder

Dr John Winder was born in Belfast, United Kingdom and attendedthe University of Ulster from 1980 to 1983 studying Physics andChemistry in a Combined Science degree. He subsequently completeda Master of Science in Physics of the Atmosphere at UniversityCollege of Wales, Aberystwyth, in 1985 and was awarded a PhDentitled ‘3D medical imaging and rapid prototyping’ in 2004 by the

University of Ulster.After working as a Research Assistant in Physics at Queens University of Belfast,

he became a Clinical Scientist (medical physics) at the Royal Victoria Hospital,Belfast. After training he became a Member of the Institute of Physics andEngineering in Medicine in 1992 and gained his Fellowship in 2014. In 1992, Johnbecame the first MR physicist for Northern Ireland, as well as providing scientificand research support to Radiology. He was the physics tutor for the NorthernIreland Part 1 Radiology Training Fellowship and taught on the programme for15 years. He was a member of the Royal College of Radiologists Physics WorkingGroup from 2008 to 2012 and was awarded honorary membership of the Collegein 2013.

John worked at The University of Ulster from 2002 until 2017 as a Reader inHealthcare Science as a lecturer and researcher, contributing to the HealthcareScience and Radiography programmes. His research interests are in 3D medicalimaging, rapid prototyping (3D printing) and has published over 100 researchpapers, 7 book chapters and supervised 11 PhD students. He is known for his clearcommunication of science and has been guest speaker at a range of UK Radiologyand other clinical conferences.

John is self-employed at RJ imaging, Belfast, and works on scientific writing andcreating customised anatomical models for the Northern Ireland National HealthService.

Scientific Basis of the Royal College of Radiologists Fellowship (2nd Edition)

xiii