CXR Teaching Session

• What is a CXR?


  Radiation fired from emitter, through pt & onto detector

  Denser the anatomical structure, the more X-rays will be absorbed

  Leaves anatomical image on the detector that we can interpret
• What colour is air on a CXR?


  Black
• What colour is fluid & bone on CXR?


  White
• What colour is soft tissue on CXR?


  Grey
• Average cost of CXR


  £25
• What are the higher risk pts for CXR?


  Pregnant women

  Breastfeeding women

  Children

  
  

  Have to think about risk & benefit -> give more of a thought is these pts
• What are the limitations of CXRs?


  Limited views of soft tissue

  Flat, 2D image -> can be difficult to interpret (can ask for multiple views to make easier)

  For the best images, need pts to be able to listen & follow instructions

  Reliant on operator experience/technique
• Interpretation of CXR (method)

  Demographics

  RIPE (image quality)

  Airway

  Breathing

  Circulation (heart, mediastinum & vessels)

  Diaphragm

  Everything else (bones, soft tissue, tubes)
• What is RIPE?


  Rotation - film should be taken head-on with as little twisting of the chest

  Inspiration - should be taken at maximum inspiration

  Projection

  • AP - facing emitter, back against the detector (only way possibly is pt lying in bed)
  • PA - facing detector, back towards emitter (ideal method)

  Exposure - calibration of the emitter & detector
• What is important to look at in terms of Rotation?


  Are the clavicles equidistant to the vertebrae?

  Do the spinous processes run down the centre of the vertebral column?

  If yes, then no significant rotation that will affect measurements

  
• Fill in the blanks

  A) Spinous processes

  B) Clavicle

  C) Clavicle

  D) Cardiac width

  E) Thoracic width

  
• What is important to look at in terms of Inspiration?


  Image should include the whole thoracic rib cage, and be able to see up to the 6th anterior ribe

  Without full inspiration, lungs do not contain enough air & appear denser & smaller

  -> makes it harder to see denser structures

  
• What is important to note about CXR projection?

  AP projection of CXR magnifies the heart size

  So, if cardiothoracic ratio (CTR) is enlarged on an AP film -> cannot comment on it due to magnification

  However, can say that CTR is normal if < 0.5 on AP film

  
• What is important to note about Exposure in CXR?


  Under exposure can cause 'blown out' image with loss of detail (image on left)

  Better exposure image -> means we can see transitions between structures (image on right)

  
• What to look at in Airway on CXR?

  Trachea - should be central, or slightly right due to aortic knuckle

  L & R main bronchi

  
• Fill in the blanks

  A) Trachea

  B) Right main bronchus

  C) Left main bronchus

  D) Aortic knuckle

  E) Carina

  
• What is shown in this XR?


  Steeple sign - narrowed airway

  Seen in children with croup

  
• What is shown in this CXR?

  Foreign body in R main bronchus

  
• Pneumothorax with mediastinal shift 


  Tension pneumothorax -> medical emergency
• Tension pneumothorax


  Pneumothorax causing mediastinal shift
• What can cause tracheal deviation (away from pathology)?

  
  

  Pneumothorax

  Severe fluid/consolidation

  
  

  Due to increase in hemithoracic pressure/volume -> pushes trachea away from pathology
• What is shown in this image?

  Tension pneumothorax (in R lung)

  
• What is shown in the image?

  Pleural effusion (in R lung) causing tracheal deviation

  
• What can cause tracheal deviation (towards pathology)?

  Lung collapse

  Fibrosis

  Pneumonectomies

  Decrease in lung volume in affected hemithorax -> pulls trachea towards pathology
• What is shown in the image?

  Lung collapse (in R lung) -> pulling trachea towards pathology

  
• What is important to look at for Breathing on CXR?


  Don't comment on the 'lobes' as CXR is a 2D image (some exceptions - in other FCs)

  Divide image into thirds -> zones

  • look through each zone in turn for any abnormalities

  
• What is consolidation?


  Patch of increased opacification (whiteness) in lungs

  Happens when alveoli that are normally filled with air (black) becoming filled with denser material (fluid, blood, pus, exudate)

  Generally due inflammatory process (e.g. pneumonia)

  Presence of air bronchograms (visible bronchioles within consolidation) -> suggests consolidation

  
• What is shown in the image?

  Consolidation in L upper/middle zone

  -> L upper zone pneumonia

  
• What is shown in the image?

  Consolidation in L upper/middle zone

  -> L upper zone pneumonia

  
• How does lobar pneumonia look on CXR?


  Consolidation confined to above/below the line of fissure (just in 1 lobe)
• What is shown in the image?

  Consolidation in R upper zone -> doesn't cross horizontal fissure -> R upper lobe consolidation

  = Lobar pneumonia (R upper lobe)

  NOTE: if you look at the trachea, this is deviated towards pathology -> suggests partial collapse of R upper lobe

  
• Can use transitions between lungs & heart/mediastinum/diaphragm/other structures to detect increased opacification/consolidation.

  
• What is shown in the image?

  R lower zone consolidation - due to loss of R heart border

  
• What is shown in the image?

  L lower zone consolidation - due to loss of L heart border

  NOTE: the bowel is higher up, but this can be due to pt being constipated

  
• What can border loss on CXR also be called?

  Silhouette Sign
• What is pulmonary fibrosis?


  Progressive restrictive lung condition caused by accumulation of fibrotic scar tissue in the lungs

  Scar tissue causes lungs to lose elasticity. leading to reduced expansion & loss of lung volume
• How does pulmonary fibrosis look on CXR?


  Reticular (net-like) shadowing of lung peripheries -> typically more prominent towards the lung bases

  Usually bilateral

  Can get 'shaggy' heart borders

  
• What is shown in these images?

  Pulmonary fibrosis (R image is later is disease progression)

  
• What is shown in this image? (LOOK CLOSE)

  Small pneumothorax (L upper zone)

  
• Normal lung tissue should have vasculature all the way up to the edges of the lungs.

  Important to track this all around the edges of the lung fields when interpreting CXR