Plain film consists of a single shot image using x rays.

What are the different densities in x rays?

1. • Black – gas

2. • White – calcified structures

3. • Grey – soft tissues

4. • Darker grey – fat

5. • Intense white – metallic objects

What are the basics that must not be missed?

Always check:

1. • Name of patient, date of birth and date – this may give information about patient's age and gender, which could elucidate the underlying pathology.

2. • Adequacy of imaging: does the x ray cover the entire area of interest?

3. • Orientation of film: right vs. left – ‘R’ label on corner of film.

4. • Position of patient. For example, a pneumothorax will look different on supine chest x ray vs. erect film; air under the diaphragm will not be seen in a chest x ray of a patient lying flat.

5. • Cervical spine: multiple standardised views (see Chapter 49, Cervical spine x ray).

6. • Distal limbs: minimum of two views. If only one view is shown, ask for a second view.

What are the rules of 2?

1. • 2 sides: in paired structures (e.g. limbs) always compare the affected structure with the contralateral one, which may be normal.

2. • 2 views: obtain two views of the same structure, e.g. anteroposterior and lateral.

3. • 2 times: view images of the same structure at two different points in time: compare current images with previous ones.

4. • 2 joints (in orthopaedics): view the joint above and the joint below the one of interest.

5. • 2 readers: get a second opinion.

What is fluoroscopy?

1. • An imaging modality that uses continuous x ray exposure to get dynamic imaging

2. • Has the capacity to save representative images

3. • Contrast material used to help differentiate pathology.

Introduction

‘This is a post-contrast/non-contrast axial/coronal/sagittal CT of the abdomen and pelvis.’

Summary

1. • Life-threatening pathology

2. • Peritoneal cavity and abdominal wall

3. • Upper abdominal viscera

4. • Small and large bowel

5. • Pelvic viscera

6. • Retroperitoneum

7. • Extra-abdominal structures

Examination notes: general

What are the general principles of CT scanning?

1. • CT scans are normally performed with intravenous contrast, which appears white.

2. • Non-contrast CTs are performed in patients with renal impairment (e.g. eGFR < 45) or contrast allergies, or in CT scans that do not require contrast (e.g. CT KUB for renal calculi).

3. • A basic CT scan uses a venous phase, in which the veins (e.g. IVC) appear dense (‘bright’).

4. • Trauma or acute haemorrhage scans require an arterial phase (e.g. aorta appears dense/‘bright’) to identify contrast extravasation/active arterial bleeding.

5. • CT scans investigating bowel malignancy or strictures require IV and oral contrast (gastrografin). This makes the bowel look dense (‘bright’).

Introduction

‘This is a CT angiogram, in axial/coronal/sagittal view of lower limb arteries’

Summary

1. A Arterial anatomy

2. B Blockage

3. C Contrast extravasation

4. D Dissection

5. E Extra-arterial – bone and soft tissue

6. F Flow improvements: stents, bypasses

Introduction

‘This is an AP/lateral/oblique radiograph of the right/left wrist, or scaphoid series.’

Views

1. • AP and lateral.

Anatomy

Bones

1. • Distal radius and ulna.

2. • Carpal bones: scaphoid, lunate, triquetral, pisiform, trapezium, trapezoid, capitate, hamate.

3. • If the lunate is anteriorly displaced this is termed a lunate dislocation.

4. • If the lunate (which is moon-shaped – with the concave side holding the rest of the carpus) – or cup of the lunate are empty then this is termed a perilunate dislocation – the capitate is displaced dorsally.

5. • Space > 2 mm between scaphoid and lunate is abnormal (scapholunate dissociation) (Terry Thomas sign).

Lines

1. • Normal radius has palmar/volar tilt (2–20°). If lost, suspect a fracture of the radius.

2. • Radial wrist normally more distal than ulna. If lost, this may suggest that the radius has impacted and is shortened.

3. • Dorsal angulation fracture of radius = Colles’ fracture.

4. • Volar angulation fracture of radius = Smith's fracture.

5. • If there is an intra-articular fracture involving either the posterior cortex or more commonly the anterior cortex of the radius, the vertical fracture pattern causes subluxation of the carpal bones= Barton's fracture (unstable).

Pathology

Radius fractures

1. • Fractures involving the growth plate. Salter–Harris classification:

2. I S – Straight through

3. II A – Above/metaphyseal

4. III L – Lower/epiphyseal

5. IV T – Through both metaphyisis and epiphysis

6. V S – Squashed

7. • Colles’ and Smith's fractures: distal radial fracture with no joint involved.

8. • Barton-type fracture: distal radial fracture that is longitudinal and involves the joint space; it can have a volar or dorsal angulation and is associated with carpal displacement (unlike Colles’ or Smith's).

Scaphoid

1. • Tenderness in anatomical snuffbox: ask for four-view scaphoid series.

2. • Normal radiographs but clinical suspicion: treat as fracture and repeat radiographs in 10–14 days.

3. • 80% waist: most common fracture (avascular necrosis likely).

4. • 10% proximal pole (avascular necrosis very likely).

5. • 10% distal pole (avascular necrosis unlikely).

6. • Scaphoid fractures may be associated with perilunate dislocation.

Introduction

‘This is an OM/OPG/PA view x-ray of the face/mandible.’

Views

1. • Occipitomental (OM) view at 0°: frontal sinuses, orbits, maxillary antra, nasal bones and ethmoid air cells

2. • Occipitomental (OM) view at 30°: additional features – zygoma, mandible, infraorbital foramina, odontoid peg

3. • Orthopantomogram (OPG): mandible, maxilla, teeth, TMJ and inferior alveolar canal

4. • PA mandible: mandibular fractures

Anatomy

Bones

1. • Frontal bones and sinuses

2. • Orbits and orbital floor

3. • Maxilla: medial and lateral walls of maxillary antra

4. • Zygomatic arch

5. • Mandible: symphysis, body, angle, ramus, condyle and coronoid process

6. • Teeth

7. • Temporomandibular joint (TMJ)

Circles: broken circle indicates a possible fracture

1. • Frontal sinuses

2. • Orbits

3. • Maxillary sinuses

4. • Nasal and ethmoid spaces

Lines: broken line indicates a possible fracture

1. • Lines of Dolan (OM30)

2. • McGrigor's lines

3. • Elephant trunks of Rogers (zygomatic arch fractures): formed from lines of Dolan

Pathology

Fractures

1. • Maxillary fractures: alveolar process; lateral and medial walls of maxillary antra.

2. • Zygomatic arch fracture: look at ‘elephant trunks’.

3. • Tripod fractures: zygoma detachment (complex zygomaticomaxillary fracture). Suture lines involved are: 1. zygomaticofrontal suture; 2. orbital floor; 3. infraorbital rim; 4. lateral wall of maxillary sinus.

4. • Inferior orbital margin fracture.

5. • Orbital floor ‘blow-out’ fracture.

6. • ‘black eyebrow’ sign: surgical emphysema in the upper orbital rim area

7. • ‘teardrop sign’: herniation of orbital soft tissues in the maxillary antrum

8. • fluid level in antrum of maxilla

9. • Mandibular fractures.

Tumours

1. • Bone: lytic lesions and cysts

2. • Soft tissues: contour changes

Infections

1. • Sinusitis (OPG and OM): opacity of maxillary and frontal sinuses

2. • Osteomyelitis (OPG and OM): opacity of mandible and maxilla

Dislocations

1. • TMJ (OPG).

Teeth

1. • Fractures and caries.

To complete the examination…

1. • If suspecting a complex fracture or inadequate views, ask for CT face/skull to determine.

2. • Facial trauma is associated with C-spine and head injuries, so consider CT head and C-spine imaging.

Introduction

‘This is an x-ray of the cervical spine in AP/lateral/open-mouth view. It is (is not) an adequate film because C1 to C7/T1 junction have (have not) been included.’

Summary

1. A Address

2. A Adequate

3. A Alignment

4. B Bone

5. C Cartilage

6. E Everything else

Introduction

‘This is an abdominal x-ray with the entire abdomen and pelvis imaged.’ Although unlikely, mention if there are any intra-abdominal areas not imaged.

Summary

ABCS:

Examination notes

What are the principles of fluoroscopy?

Introduction

‘This is a chest radiograph in AP/PA erect/supine view with no/some rotation. It is (is not) adequate.’

Summary

Examination sequence ABCDEF:

1. A Address

2. A Adequacy of film

3. A Airway

4. B Breathing

5. B Bones

6. B Breasts

7. C Circulation

8. D Diaphragm

9. D Danger areas

10. E Everything else

11. F Foreign objects

Introduction

‘This is a radiograph of the right/left foot/ankle.’

Views

Anatomy

Bones

1. • Malleoli, talus, calcaneus, tarsal bones, metatarsal bones, phalanges

Lines

1. • Foot DP – 2nd metatarsal medial border lines up with medial border middle cuneiform.

2. • Foot oblique – 3rd metatarsal medial border lines up with medial border of lateral cuneiform.

3. • Ankle AP – talar dome line is smooth throughout.

4. • Ankle lateral – Bohler's angle (normal 28–40°). The angle formed by the intersection of a line drawn from the highest point of the posterior tuberosity to the top of the posterior facet, and a line from the top of posterior facet to the tip of anterior process of calcaneum. If reduced can signify an occult calcaneal fracture.

Pathology

Fractures

1. • March fracture: 2nd or 3rd metatarsal stress fracture.

2. • Inversion injuries: base of 5th metatarsal.

3. • Lisfranc injury: disruption of Lisfranc ligament with or without fracture leads to lateral displacement of the 2nd metatarsal base with respect to the middle cuneiform. Weight-bearing views very useful in unmasking subtle injury.

Diabetic foot

1. • If no obvious fracture is seen, look for signs of osteomyelitis; bone destruction/osteolysis, usually involving calcaneum, 1st/5th metatarsal heads or distal phalanges; or bone changes and deformities suggestive of Charcot foot, typically involving the tarsometatarsal joints.

Foreign object

1. • Look for metallic objects, nails or glass in the soft tissues.

Introduction

‘This is an unenhanced low-dose CT scan of the kidneys, ureter and bladder in axial/coronal/sagittal view.’

Summary

1. AAir: perforation from GI or urinary system

2. BBlood: high-density haemorrhage from tumour, trauma or obstruction

3. CCalcifications: renal, collecting system, ureteric, bladder calculi, prostate calcification

4. DDilatations: renal or ureteric obstruction