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Radiology at a Glance

Second Edition

Rajat Chowdhury

Consultant Musculoskeletal Radiologist
Oxford University Hospitals, UK

Iain D. C. Wilson

MEng (Oxon), BMedSci, BM BS, MRCS, FRCR
Consultant Interventional Radiologist
Southampton General Hospital, UK

Christopher J. Rofe

BSc (Hons), MB BCh, MRCP, FRCR
Consultant Radiologist
Borders General Hospital, Melrose, UK

Graham Lloyd-Jones

Consultant Radiologist
Salisbury District Hospital, UK

WILEY Blackwell


  1. Madhuchanda Bhattacharyya
    MA (Cantab), MBBS, MRCP, FRCR
    Consultant Breast Radiologist
    Oxford Breast Imaging Centre
    Oxford University Hospitals, UK
  1. Dipanjali Mondal
    Consultant Radiologist
    Oxford University Hospitals, UK


Radiology at a Glance’ – it won’t take most readers very long to realise that radiological images, like those in this book, deserve more than just a glance – in the old adage, ‘a picture is worth a thousand words’. Over the past 120 years since the discovery of X-rays, medical imaging has assumed an ever more central role in patient management. A familiarity with modern medical imaging techniques is an essential prerequisite for the practice of almost all branches of medicine. The past 40 years in particular have been dubbed the Golden Age of Radiology with the arrival on a regular basis of new techniques and modalities depicting human anatomy and disease processes in previously unthinkable detail. Ultrasound, computed tomography (CT), magnetic resonance imaging (MRI) and most recently positron emission tomography (PET) have all helped to shed light on structures and processes within the living human body which previously could only be imagined. The growth of interventional radiology has allowed the replacement of complex surgical procedures with minimally invasive techniques, often avoiding the need for anaesthesia and even hospital admission.

The authors of this excellent book, Rajat Chowdhury, Iain Wilson, Christopher Rofe and Graham Lloyd-Jones, have revised and expanded the bank of images displayed in this second edition to provide an even more comprehensive overview whilst retaining the clarity of presentation which characterised the first edition. New sections have been included on breast imaging, cardiac MRI and CT, CT colonography, and interventional oncology, representing some of the new frontiers in radiological practice. Further chapters on interventional radiology have also been added as well as new opportunities for self-assessment in the form of OSCE.

Medical students, junior doctors and healthcare practitioners from a wide range of backgrounds will find material here relevant to their learning and their daily practice and my hope is that it will fire their enthusiasm for medical imaging. The story of radiology does not end with the exquisite images of the beating heart which you will find in this volume. Functional imaging is with us already and new modalities are coming along in the near future which will enable us to move from imaging of gross anatomy to imaging at the cellular and molecular level and will support the key role that radiology plays in the era of personalised medicine.

Dr Giles Maskell

President of The Royal College of Radiologists (2013–2016)


Following the success of the first edition of Radiology at a Glance, we have implemented the feedback, updated and expanded the book, and maintained the classic at a Glance style to help teach the basics of radiology in a simple and clear fashion. We develop the reader from radiological anatomy through to classic pathological conditions that regularly appear in medical school exams. ‘Classic cases’ are found in separate chapters allowing easy access for doctors on the wards. The companion website now includes practice material for exam preparation.

We have written this book not only with medical students and junior doctors in mind, but trust that it will be a useful aid to students of radiography, nursing and physiotherapy, as well as other health professionals. We therefore hope it will be a valuable tool in gaining an understanding of the essentials of clinical radiology.

We would like to express our gratitude to all our colleagues and teachers for their inspiration, meticulous teaching and expert guidance. We extend warm thanks to Dr Giles Maskell for giving the second edition his prestigious seal of approval. We would also like to thank our publishers for all their enthusiasm and support in developing the renewed concept for the second edition. We would like to dedicate this book to our families who continue to support us along the at a Glance journey, and finally, we thank all our readers for taking the time to read this book, and in return we hope you feel it was time well spent.

Rajat Chowdhury
Iain D. C. Wilson
Christopher J. Rofe
Graham Lloyd-Jones


# fracture
AAA abdominal aortic aneurysm
ACL anterior cruciate ligament
ADC apparent diffusion coefficient
AIIS anterior inferior iliac spine
ALARA as low as reasonably achievable
AP anterior to posterior
APTT activated partial thromboplastin time
ARDS acute respiratory distress syndrome
ARSAC Administration of Radioactive Substances Advisory Committee
ASD atrial septal defect
ASIS anterior superior iliac spine
ATLS Advanced Trauma Life Support
AVN avascular necrosis
AXR abdominal X-ray
Ba barium
CAD coronary artery disease
CAMG coronary artery bypass grafting
CBD common bile duct
CC craniocaudal
CIN contrast-induced nephropathy
COPD chronic obstructive pulmonary disease
CPPD calcium pyrophosphate dehydrate
CR computed radiography
CSF cerebrospinal fluid
C-spine cervical spine
CT computed tomography
CTA computed tomographic angiography
CTCA computed tomographic coronary angiography
CTKUB computed tomography of kidneys, ureters and bladder
CTPA computed tomographic pulmonary angiography
CTSI computed tomography severity index
CXR chest X-ray
DCS ductal carcinoma in situ
DDH developmental dysplasia of the hip
DEXA dual energy X-ray absorptiometry
DIC disseminated intravascular coagulation
DIPJ distal interphalangeal joint
DMSA dimercaptosuccinic acid
DOB date of birth
DP dorsal to plantar
DR digital radiography
DRUJ distal radioulnar joint
DTPA diethylene triamine pentaacetic acid
DVT deep vein thrombosis
DWI diffusion-weighted (magnetic resonance) imaging
Echo echocardiography
EDH extradural haemorrhage/haematoma
EDV end diastolic volume
EF ejection fraction
eGFR estimated glomerular filtration rate
EndoUS endoultrasound
ERCP endoscopic retrograde cholangiopancreatography
ESV end systolic volume
EVAR endovascular aneurysm repair
FB foreign body
FDG fluorodeoxyglucose
FEV1 forced expiratory volume in 1st second
FLAIR fluid attenuated inversion recovery
FNAC fine-needle aspiration cytology
FOB faecal occult blood
FVC forced vital capacity
GI gastrointestinal
GORD gastro-oesophageal reflux disease
HIV human immunodeficiency virus
HOC hypertrophic obstructive cardiomyopathy
HRCT high resolution computed tomography
HSE Health and Safety Executive
IBD inflammatory bowel disease
ICD implantable cardioverter defibrillator
ICH intracerebral haemorrhage
ICP intracranial pressure
ID identification details
INR international normalised ratio
IR interventional radiology
IR(ME)R 2000 Ionising Radiation (Medical Exposure) Regulations 2000
IRR99 Ionising Radiation Regulations 1999
IV intravenous
IVC inferior vena cava
IVU intravenous urography
KUB kidneys, ureters, bladder
LBO large bowel obstruction
LLL left lower lobe
LOS lower oesophageal sphincter
LRTI lower respiratory tract infection
LUL left upper lobe
LUQ left upper quadrant
LV left ventricle
LVF left ventricular failure
MAA macroaggregated albumin
MAG3 mercaptoacetyl triglycine
MARS Medicines (Administration of Radioactive Substances) Regulations
MCPJ metacarpophalangeal joint
MDP methylene diphosphonate
MEN multiple endocrine neoplasia
MLO mediolateral oblique
MR(I) magnetic resonance (imaging)
MRA magnetic resonance angiography
MRCP magnetic resonance cholangiopancreatography
MTPJ metatarsophalangeal joint
MUGA multi-gated acquisition
NBM nil by mouth
Neuro neurological
NGT nasogastric tube
NHS BSCP NHS Bowel Cancer Screening Programme
NHS BSP NHS Breast Screening Programme
NM nuclear medicine
NOFF neck of femur fracture
NSAID non-steroidal anti-inflammatory drug
NSF nephrogenic systemic fibrosis
N-STEMI non-ST elevation myocardial infarction
OGD oesophagogastroduodenoscopy
OM occipitomental view
OPG orthopantomogram
OSCE Objective Structured Clinical Examination
PA posterior to anterior
PACS picture archiving and communications system
PCA percutaneous coronary angioplasty
PCI percutaneous coronary intervention
PCL posterior cruciate ligament
PCNL percutaneous nephrolithotomy
PCS pelvicalyceal system
PD proton density
PE pulmonary embolus
PET positron emission tomography
PET-CT combined positron emission tomography with computed tomography
PICC peripherally inserted central catheter
PIPJ proximal interphalangeal joint
PT prothrombin time
PTC percutaneous transhepatic cholangiography
PUD peptic ulcer disease
RA right atrium
RCR Royal College of Radiologists
RF radiofrequency
RFA radiofrequency ablation
RLL right lower lobe
(R)ML (right) middle lobe
RUL right upper lobe
RUQ right upper quadrant
RV right ventricle
RWMA Regional myocardial wall motion
SAH subarachnoid haemorrhage
SBO small bowel obstruction
SDH subdural haemorrhage/haematoma
SIJ sacroiliac joint
SOL space occupying lesion
SPECT single photon emission computed tomography
STEMI ST elevation myocardial infarction
STIR short tau inversion recovery
SUFE slipped upper femoral epiphysis
SV stroke volume
SVC superior vena cava
TACE transcatheter arterial chemoembolisation
TARE transcatheter arterial radioembolisation
TB tuberculosis
Tc-99m metastable technetium-99
TFCC triangulofibrocartilage complex
TIA transient ischaemic attack
TIPS transjugular intrahepatic portosystemic shunt
TNM tumour, nodes, metastases
UC ulcerative colitis
UGI upper gastrointestinal
US ultrasound
V/Q ventilation-perfusion


Attenuation Gradual loss in intensity of beams and waves including X-rays and ultrasound waves. May also be used synonymously with ‘density’ to describe appearances on CT imaging (areas of high attenuation are bright whereas areas of low attenuation are dark).
Density Used synonymously with ‘attenuation’ to describe appearances on CT imaging (areas of high density are bright whereas areas of low density are dark).
Echogenicity Used synonymously with ‘reflectivity’ to describe appearances on ultrasound imaging (hyperechoic areas are bright whereas hypoechoic areas are dark).
Hotspot/coldspot Used to describe the uptake of radiopharamaceutical agents by tissues in nuclear medicine imaging (increased uptake results in a hotspot whereas reduced uptake results in a coldspot).
PACS The ‘picture archiving and communication systems’ are computer networks that store, retrieve, distribute and present medical images electronically. This permits images to be viewed and manipulated digitally on screen with remote and instant access by multiple users simultaneously and has therefore almost replaced the use of hard-copy films in the UK.
Reflectivity Used synonymously with ‘echogenicity’ to describe appearances on ultrasound imaging (hyperreflective areas are bright whereas hyporeflective areas are dark).
Signal Used to describe appearances on MRI (areas of high signal are bright whereas areas of low signal are dark).

About the companion website

Don’t forget to visit the companion website for this book:


There you will find valuable material designed to enhance your learning, including:

  • Radiology OSCE, case studies and questions
  • Flash cards
  • Figures from the book in PowerPoint format, to download

Part 1
Radiology physics


  1. Plain X-ray imaging
  2. Fluoroscopy
  3. Ultrasound
  4. Computed tomography
  5. Magnetic resonance imaging

Plain X-ray imaging

Image described by caption.

Plain X-ray physics

On 8 November 1895, the German physicist Wilhelm Conrad Röentgen discovered the X-ray, a form of electromagnetic radiation which travels in straight lines at approximately the speed of light. X-rays therefore share the same properties as other forms of electromagnetic radiation and demonstrate characteristics of both waves and particles. X-rays are produced by interactions between accelerated electrons and atoms. When an accelerated electron collides with an atom two outcomes are possible:

  1. An accelerated electron displaces an electron from within a shell of the atom. The vacant position left in the shell is filled by an electron from a higher level shell, which results in the release of X-ray photons of uniform energy. This is known as characteristic radiation.
  2. Accelerated electrons passing near the nucleus of the atom may be deviated from their original course by nuclear forces and thereby transfer some energy into X-ray photons of varying energies. This is known as Bremsstrahlung radiation.

The resultant beam of X-ray photons (X-rays) interacts with the body in a number of ways:

The X-ray machine (tube)

Most modern radiographic machines use electron guns to generate a stream of high energy electrons, which is achieved by heating a filament. The high energy electrons are accelerated towards a target anode. The electrons hit the anode, thereby generating X-rays as described above. This process is very inefficient with 99% of this energy transferred into heat at 60 kV. The dissipation of heat is therefore a key design feature of these machines to sustain their use and maintain their longevity. The material for the target anode is selected depending on the chosen task and the energy of the X-ray beam can be modified by filtration to produce beams of uniform energy.

Most modern radiology departments now employ digital imaging techniques and there are two principal methods in everyday use: computed radiography (CR) and digital radiography (DR). CR uses an exposure plate to create a latent image, which is read by a laser stimulating luminescence, before being read by a digital detector. DR systems convert the X-ray image into visible light, which is then captured by a photo-voltage sensor that converts the light into electricity, and thus a digital image. The final digital images are stored in medical imaging formats and displayed on computer terminals.

Applying physics to practice


Image quality

The clarity of the image can be expressed as ‘unsharpness’. This can be classified into:

Newer digital imaging systems now allow the postprocessing of data to enhance various aspects of the image.


The contrast of an image is dependent on the variation of beam attenuation within the subject. There are five principal densities that can be seen on a plain radiographic image.

The contrast may be increased by lowering the energy of the X-ray beam. However, this has negative impact on image quality and increases the dose of radiation.

Contrast agents are often used to enhance anatomical detail. A desirable contrast agent is one that has high photoelectric absorption at the energy of the X-ray beam. The contrast agents most commonly used in plain X-ray imaging are barium, gastrografin (water soluble) and iodinated compounds. Precautions in the use of iodinated contrast agents are discussed in Chapter 6.


Image described by caption.

Principles of fluoroscopy

Fluoroscopy allows dynamic real-time imaging of the patient, which can provide information regarding the movement of anatomical structures or devices within the patient. Fluoroscopy is based on X-ray imaging and the physical principles are similar to the plain X-ray imaging chain from X-ray beam generation to image display (see Chapter 1). However, the procedure is performed using a specifically designed X-ray machine and uses low dose real-time acquisition techniques and hardware.

The fluoroscopy machine

There are two main types of fluoroscopy machines:

Fluoroscopy machines are designed specifically to manage the heat generated from the repeated exposure in fluoroscopic imaging. They also use lower beam energies and exposures compared with plain X-ray imaging techniques and thus image intensifiers are employed to enhance the image. These convert the X-rays to electrons to amplify the signal several thousand-fold and then convert the electron beams again into visible light. This light image is then transmitted onto a screen.

Static images, which are similar to plain X-ray images, can be acquired. These provide increased contrast and spatial resolution compared to standard fluoroscopy images, but at the cost of increased patient dose.

Applying physics to practice

When using image intensifiers, several factors must be


Contrast fluoroscopy

For the majority of fluoroscopic imaging, contrast agent enhancement is used. Fluoroscopy gives the ability to make real-time adjustments to the patient’s position and image orientation, which often reveals invaluable information to help differentiate the diagnosis. This is most evident when using contrast-enhanced imaging of the bowel.

Applications of fluoroscopy