Imaging Flashcards
Colour air appears on a CXR
Black
Colour that soft tissue/ muscle appears on a CXR
Grey/white
What shows up grey on a CXR
Fat
What shows up white on a CXR
Bone
What colour does metal appear on a CXR
Bright white
What are the relative CT densities of: Air Lungs Fat Water
AIR -1000
LUNGS - 500
FAT - 100
WATER 0
What are the relative CT densities of: Muscle Bone Contrast Metal
MUSCLE + 50
BONE + 200
CONTRAST + 500
METAL + 1000
In an ultrasound, what allows the passage of sound waves and what colour does it appear (2)
Fluid- appears black
Soft tissue- appears bright
In an ultrasound, what blocks the passage of sound waves and what colour does it appear?
Air- appears as shadow
Bone- appears as shadow
Why are the shoulders braced forward during a CXR?
So the scapulae do not obscure the lungs
What direction does a CXR pass from?
From posterior to anterior producing a PA radiograph
What level inspiration/expiration is a CXR taken at?
Full inspiration
What are the disadvantages of having to take an AP radiograph when the patient is acutely unwell?
Can be difficult for the patient to take an adequate inspiration
The heart shadow is magnified so heart size cannot be assessed accurately
The scapulae overlie and partly obscure the lungs
What criteria must a CXR meet for it to be technically accurate?
Inspiration
Rotation
Penetration (enough radiation)
How you can tell if a CXR is adequately inspired?
The anterior ends of at least 6 ribs should be visible
How can you tell if a CXR is correctly centered?
The medial ends of the clavicles should be equidistant from the spinous processes of the upper thoracic vertebrae
Mediastinal borders (8)
Aorta Pulmonary artery Left auricle Left ventricle Right atrium Trachea Hemidiaphragm (right) Stomach bubble Horizontal fissure
Where is the disease if the left heart border is obscured?
Lingula
Where is the disease if the right heart border is obscured?
Middle lobe
Where is the disease if the right hemidiaphragm is obscured?
Right lower lobe
Lobar collapse
Occurs as a result of obstruction of a lobar bronchus e.g. by tumours, aspirated foodstuffs, mucus impaction
The lobe supplied by an obstructed bronchus is no longer ventilated
Pleural effusion
Pleural cavity filled with fluid
Pneumothroax
Follows spontaneous rupture of visceral pleura allowing air to rush in from the lungs
Iatrogenic pneumothorax
Pneumothorax due to complications of a medical prodcedure
Tension pneumothorax
If the pneumothorax accumulates large amounts of air, it will squash the lungs so that the patient cannot ventilate them
Examples of lines/tubes
Nasogastric tube
Endotracheal tube
Central venous lines
