imaging the thorax Flashcards
what are the strengths of radiography?
- great spatial resolution (especially bone)
- cheap and available
- easy interpretation
what are the weaknesses of radiography?
- projection
- ionising radiation
- very limited soft tissue visualisation
what do you have to consider when assessing an x-ray?
- rotation
- exposure
- coverage
what are the review areas of an x-ray?
- apices
- costo-phrenic angle
- behind the heart
- hila
- peripheries
what is the equation for the cardiothoracic ratio?
C/T
width of heart/width of lungs
what is the normal cardiothoracic ratio on a PA?
<0.5
what does a CT scan of the lungs do?
- shows greater detail
- resolve small structures
- resolve small differences in attenuation
what are the strengths of a CT scan?
- cross sectional
- spatial resolution
- widely available
what are the weaknesses of a CT scan?
- ionising radiation
- limit soft tissue contrast
what does CT stand for?
computed tomography
what thickness are the slices of a CT thorax?
between 1 & 5mm
what is the secondary pulmonary lobule?
functional unit of the lung
what diameter are the primary and secondary pulmonary lobules?
primary = 6-10mm secondary = 5-20mm
how many alveoli does the average adult have?
300 million
what are the 4 functions of the lung?
- gas exchange
- ventilation
- perfusion
- diffusion
