Scientific basis of the Royal College of Radiologists

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Scientific Basis of the Royal
College of Radiologists
Fellowship
Illustrated questions and answers
Scientific Basis of the Royal
College of Radiologists
Fellowship
Illustrated questions and answers
Malcolm Sperrin
Royal Berkshire Hospital, Reading, UK
John Winder
University of Ulster, Newton Abbey, UK
IOP Publishing, Bristol, UK
ª IOP Publishing Ltd 2014
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, without the prior permission of the publisher, or as expressly permitted by law or
under terms agreed with the appropriate rights organization. Multiple copying is permitted in
accordance with the terms of licences issued by the Copyright Licensing Agency, the Copyright
Clearance Centre and other reproduction rights organisations.
Permission to make use of IOP Publishing content other than as set out above may be sought
at [email protected].
Malcolm Sperrin and John Winder have asserted their rights to be identified as author of this work
in accordance with sections 77 and 78 of the Copyright, Designs and Patents Act 1988.
ISBN
ISBN
ISBN
978-0-7503-1058-1 (ebook)
978-0-7503-1059-8 (print)
978-0-7503-1122-9 (mobi)
DOI 10.1088/978-0-7503-1058-1
Version: 20141201
IOP Expanding Physics
ISSN 2053-2563 (online)
ISSN 2054-7315 (print)
British Library Cataloguing-in-Publication Data: A catalogue record for this book is available
from 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
ix
Author biographies
x
1
Basic physics
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
1.10
1.11
1.12
1.13
1.14
1.15
1.16
1.17
The structure of the atom
Characteristic radiation and atomic shells
The electromagnetic spectrum I
The electromagnetic spectrum II
Luminescence
Transverse waves
Longitudinal waves
The inverse square law
Radioactivity in medicine
Radioactive decay
Exponential decay
The half-life of a radionuclide
Units and measurement
Prefixes to units
Full width at half maximum
The point spread function
Mathematical considerations
2
X-ray imaging
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.12
Projection imaging
Radiography
Magnification in radiography
The quality of an x-ray beam
Image quality
Plain film x-ray tomography
Fluoroscopy technology
Image intensifier
Fluoroscopy radiation dose
Image quality in fluoroscopy
The high kV technique
Mammography x-ray spectra
1-1
1-3
1-5
1-7
1-9
1-11
1-13
1-15
1-17
1-19
1-21
1-23
1-25
1-27
1-29
1-31
1-33
1-35
2-1
2-3
2-5
2-7
2-9
2-11
2-13
2-15
2-17
2-19
2-21
2-23
2-25
v
Scientific Basis of the Royal College of Radiologists Fellowship
2.13
2.14
2.15
2.16
2.17
2.18
2.19
2.20
2.21
2.22
2.23
2.24
Mammography spatial resolution
Image quality in mammography
Mammography technology
Mammography compression
Digital mammography
Computed radiography I
Computed radiography II
Computed radiography: dynamic range
Computed radiography cassettes
Computed radiography detection process
Direct (digital) radiography
Detectors in direct radiography
2-27
2-29
2-31
2-33
2-35
2-37
2-39
2-41
2-43
2-45
2-47
2-49
3
Imaging theory
3.1
3.2
3.3
3.4
3.5
3.6
3.7
Digital imaging fundamentals
The isotropic voxel
Digital image presentation
Image digitization
Digital image matrix
Digital image computer displays
Spatial resolution in imaging systems
4
Radiation protection
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
Radiation dose reduction in pregnancy
The ALARA principle
Types of radiation effects
Stochastic effects of radiation
Absorbed dose
Dose area product
Radiation controlled areas
Radiation biology
Radiation safety of staff
Practical radiation exposure reduction
5
Computed tomography
5-1
5.1
5.2
Profile diagram and reformatting or back projection
Technology in cone beam computed tomography
5-3
5-5
3-1
3-3
3-5
3-7
3-9
3-11
3-13
3-15
4-1
vi
4-3
4-5
4-7
4-9
4-11
4-13
4-15
4-17
4-19
4-21
Scientific Basis of the Royal College of Radiologists Fellowship
5.3
5.4
5.5
5.6
5.7
5.8
The cone beam effect in computed tomography scanning
Principles of computed tomography operation
Multislice detectors in computed tomography
Spatial resolution in computed tomography
Computed tomography image reconstruction
Computed tomography image presentation
6
Ultrasound
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
6.9
6.10
6.11
6.12
6.13
6.14
6.15
6.16
6.17
6.18
Ultrasound imaging: routine
Ultrasound imaging: obstetric
Ultrasound imaging: image process
Ultrasound imaging: transducer
Harmonic imaging I
Acoustic field
Thermal index and mechanical index
Image formation
Artefacts
Bioeffects
Contrast agents
The Doppler effect
Power Doppler
Duplex Doppler
Harmonic imaging II
Transducer design
Improving the image
Basic physics
7
Magnetic resonance
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
The source of the magnetic resonance signal
Magnetic resonance signal: the net magnetic moment
Magnetic resonance image contrast (image weighting)
Transverse magnetization
Metal artefacts in magnetic resonance imaging
The spin echo pulse sequence
Magnetic resonance safety: main magnetic field
Magnetic resonance imaging parameters
Magnetic resonance technology
5-7
5-9
5-11
5-13
5-15
5-17
6-1
6-3
6-5
6-7
6-9
6-11
6-13
6-15
6-17
6-19
6-21
6-23
6-25
6-27
6-29
6-31
6-33
6-35
6-37
7-1
vii
7-3
7-5
7-7
7-9
7-11
7-13
7-15
7-17
7-19
Scientific Basis of the Royal College of Radiologists Fellowship
7.10
7.11
7.12
7.13
7.14
7.15
7.16
7.17
7.18
7.19
Gradient magnetic fields
Relaxation times in magnetic resonance imaging
Fast/turbo spin echo magnetic resonance imaging
Fat suppression techniques
Radio frequency safety
Magnetic resonance image artefacts
Magnetic resonance safety
Magnetic resonance controlled area
Risks associated with magnetic resonance scanning
Magnetic resonance safety
8
Nuclear medicine
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
8.10
8.11
8.12
Gamma camera design
The ideal isotope
Quality assurance tests
Dynamic studies
Nuclear medicine risks
Positron emission tomography
Single-photon emission computed tomography
Combined positron emission tomography/computed tomography
Collimators
Resolution
Bone scans
Photomultiplier tubes
7-21
7-23
7-25
7-27
7-29
7-31
7-33
7-35
7-37
7-39
8-1
viii
8-3
8-5
8-7
8-9
8-11
8-13
8-15
8-17
8-19
8-21
8-23
8-25
Introduction
Science and medicine have long been close partners. This is particularly true in
radiology where the availability of imaging techniques is central to diagnosis. In its
simplest sense, imaging can be thought of as a technique which uses some measurable parameter of the patient to provide a basis for contrast in an image and the
science is the connection between the patient and the image.
However, science is far more than just providing a vehicle for understanding an
imaging or therapeutic process. An understanding of the science underlying a process enables the right person to develop new techniques, understand imaging limitations and develop a portfolio of research.
A knowledge of scientific principles is also mandated as a result of a need to
understand best and safest practice especially in the use of ionizing radiation where
legislation, 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 physics
exams. Such exams do present a considerable challenge and the authors of this work
recognize and sympathize with that challenge and have set about creating a volume
which is intended to be an educational resource and not just a pre-exam ‘crammer’.
Both authors have considerable experience in teaching, supporting and examining in
medical science and have developed an awareness of where those sitting professional
exams have traditionally struggled. This text is a distillation of that experience.
The text itself is arranged in a manner to encourage learning and understanding
of the key concepts rather than just provide a vehicle to pass the exams. The images
and diagrams which accompany each question should provide a stimulus to the
concepts being challenged rather than be directly related to the question. The
answers also contain some explanation that in many instances goes beyond a simple
explanation to support true/false.
The authors hope that the text continues to be used beyond the awarding of
Fellowship to the reader and future revisions will include updates, new questions and
feedback from those who have found the book to be a usable resource.
The authors acknowledge with thanks Siemens Medical Systems and Leeds Test
Objects Ltd for permission to use various images in this book.
Professor Malcolm Sperrin
Director of Medical Physics
Royal Berkshire Hospital
Reading, UK
Dr John Winder
Reader in Healthcare Science
University of Ulster, Newton Abbey, UK
ix
Author biographies
Professor Malcolm Sperrin
Malcolm was born in Cuba of diplomatic parents in 1963 and
attended The Harvey Grammar School in Folkestone leaving there
in 1981 to study physics with maths at Reading University. His first
job was working on artificial intelligence and then with the UK
Atomic Energy Authority on reactor fault analysis. This experience
placed him in a good position to provide insight into both the
Chernobyl and Fukushima incidents.
After further study at Reading University, Malcolm joined the Medical Physics
team at the Churchill Hospital in Oxford with responsibility for non-ionizing
radiation. In 1995, Malcolm moved to the Princess Margaret Hospital in Swindon
acting as Deputy Head of Department and then, in 2002, he moved to The Royal
Berkshire Hospital in Reading taking on the role of Departmental Director.
Malcolm has a special interest in radiation medicine, especially nuclear medicine
and radiotherapy. He also plays a significant role in radiation protection and
contingency planning. In parallel to his conventional hospital duties, Malcolm also
spends a lot of time teaching and lecturing with organizations including Oxford
Postgraduate Medical School, The Open University and various Royal Colleges, not
to mention lectureships at Guildford and the University of the West of England.
Malcolm was made visiting professor at Reading, Guildford and Open
Universities and visiting academic at Oxford University and plays a role on the
national stage with the Institute of Physics, Royal Institution, Science Media Centre
and the British Association for the Advancement of Science. Malcolm also feeds into
activities centred on science and health policy at the Department of Health.
Malcolm’s down-to-earth approach to medical science has led to him being
frequently sought by the media for comment on mobile phone use, WiFi safety
and even the risks from the Fukushima reactor. He is very active in developing
innovation, whether operational or scientific, and has recently been involved in
initiatives with Microsoft and other multi-national companies with a drive to
improve patient outcomes.
Malcolm is a keen adventure sports enthusiast and likes to climb, cave and canoe
and has been known to parachute. He has a partner, Nicki (who is not sure about the
parachuting), a nine-year-old son and a spaniel called Harvey.
x
Scientific Basis of the Royal College of Radiologists Fellowship
Dr John Winder
Dr John Winder was born in Belfast and attended the University of
Ulster from 1980 to 1983, studying a Combined Science Degree
in Physics and Chemistry. He subsequently completed a Masters
in Physics of the Atmosphere at University College of Wales
Aberystwyth in 1985. After working as a research assistant in the
Physics Department of Queens University, Belfast, John became a
Medical Physicist at the Royal Victoria Hospital, Belfast. After training, he gained
Membership of the Institute of Physics and Engineering in Medicine. In 1992, John
became the first MR physicist for Northern Ireland as well as providing scientific
support for equipment purchasing, Picture Archiving and Communication Systems
and image processing. He was the Physics co-ordinator for the Northern Ireland
Part 1 Radiology Fellowship Training and taught on the programme for many years.
He was a member of the Royal College of Radiologists Physics Working Group from
2008 to 2012 and was awarded honorary membership of the College in 2013.
John is known for his communication of science and has been guest speaker at the
British Society of Paediatric Radiology and Imaging Group, Irish Neurological
Society, British Association of Magnetic Resonance Radiographers, Irish Association of Physical Scientists in Medicine and the Institute of Medical Illustrators.
He joined the University of Ulster in 2002 and his primary functions within the
School of Health Sciences are teaching, research and academic enterprise, contributing to Healthcare Science and Radiography undergraduate and post graduate
programmes. His research interests are in 3D medical imaging and rapid prototyping. He has published 55 research papers, five book chapters and supervised nine
PhD students.
xi