Chest X-rays

Question 1

Process

Answer 1

> Electromagnetic beams are passes through the thorax to silver plate/film
plate will turn black as X-rays hit it

Question 2

Radiodensity

Answer 2

> RADIOLUCENT = less dense structures (air filled) = black
RADIOPAQUE = more dense structure (bone/metal) = white
*soft tissue/fat will appear grey

Question 3

Types of X-ray

Answer 3

> PA (‘department’)
- patient is upright + scapulae are rotated away from lung fields
AP (‘mobile’)
- comes to patient so usually in supine/sitting
- heart appears bigger (closer to source)
- scapulae may be in the way
*No difference in reading different views (always as if looking at patient - ie right is left)
**If problem is spotted may use other view/scan
- Oblique = diagonal (projects abnormalities away from overlying structures)
- Lateral - allows visualisation of lung bases + lung tissue behind heart
- Lateral Decubitus - show presence of free pleural fluid or to confirm air-fluid level
- Expiratory - demonstrate small pneumothorax or unilateral airway obstruction
- Lordotic - better view of top 2/3 of lungs
*Or use MRI/CT scan

Question 4

Exposure

Answer 4

> Overexposed = too black
- too high frequency or for too long
Underexposed = too silver
- too low frequency or not for long enough

Question 5

Interpretation - 4WH

Answer 5

> Who - right patient
What - Chest X-ray?
When - most recent X-ray (within 24 hours?)
Why - what is patients clinical status
How - Position (AP/PA)

*Step back to gain different perspective

Question 6

Interpretation - ABCD

Answer 6

> Alignment
- proximal clavicle ends vs spinous processes (rotated?)
Bones
- fractures/displacements?
Cardiac/Mediastinum
- Clear heart border
- Normal size (1/3 chest diameter)
- Shifted? (1/3 on right, 2/3 on left)
- anything else of note in mediastinum
Diaphragms
- Both hemi-diaphragms visible (right should be higher as liver is less compressible than stomach)
- Cardiophrenic angle - between heart and diaphragm should be rounded
- Costophrenic - between ribs and diaphragm should be sharp

Question 7

Interpretation - EFG

Answer 7

> Expansion
- max inspiration (expiration can hide areas of collapse)
- 10th rib posteriorly/6th rib anteriorly
Fields
- lung fields should be black with ‘cobweb’ like effect
- Density - increased/decreased areas
- lung edge
- fluid levels
Gadgets
- drips/drains/tubes/lines
- in/on/around patient

• Spearmints - white dots in hilum = blood vessels
• Polos - white rings (black centre) = airways

Question 8

Pathologies - Consolidation

Answer 8

> Lung tissue = firm + solid (accumulated fluids/tissue debris)
Appears - white/grey with no loss of volume
Causes
- pneumonia
- chest infection
- lung contusion post trauma
*may cause collapse behind consolidated areas

Question 9

Pathologies - Atelectasis/Collapse

Answer 9

> Airless state of lung tissue (may affect part or whole of lung)
Appears: white/grey with loss of volume
+ shifting structures if significant collapse (pull mediastinum to affected side)
Causes
- Shallow breathing
- bronchial obstruction
- absorption of trapped gas
- surfactant depletion
- pleural disorder
- external compression
- surgery

Question 10

Pleural Effusion

Answer 10

> Excess fluid in pleural cavity 
> Appears: white
                 : over 500ml = loss of costophrenic angle
                 : fluid line may be visible on lateral pleura
                 : may push mediastinum towards affected side
> Causes
- Pneumonia 
- TB
- malignancy
- disturbed pressure in plasma
- changed membrane permeability
- heart/liver/kidney failure
- surgery

Question 11

Pneumothorax

Answer 11

> Air in pleural space due to rupture in either pleura layer (lung is squashed towards hilum = where vessels pass from bronchus to lungs *anchors lungs in place*
> Appears - black (no cobweb affect)
                   - if severe lung will appear white towards hilum + mediastinum will be displaced to non-affected side 
> Causes 
- Smoking
- Trauma 
- Fast growth 
- Barotrauma 
- Emphysema

Question 12

Pulmonary Oedema

Answer 12

> Extravascular water in lungs (interstitial + alveoli)
Appears - bilateral bats wings (flecky opacities spreading from hila)
- heart may be enlarged (pathology dependent)
Causes
- fluid overload
- back pressure from failing left heart
- osmotic or hydrostatic pressure changes
- increased capillary permeability

Question 13

Other imaging

Answer 13

> Computerised Tomography (CT scan)

• differentiate between lung + pleural tissue
• Bony/thoracic lesion = shown clearly
• allows visualisation of mediastinum (cross sectional view)
• supplement to CXR

> MRI (magnetic resonance imaging)

• Mediastinal vascular problems e.g aneurysm
• viewed in any plane
• pancoast tumour of lung