Chest X-rays Flashcards
Describe how x-rays work
An electromagnetic wave of high energy and a very short wavelength
Absorbed to different degrees by different tissues due to density
What colour is gas on an x-ray?
Black
What colour is fat on an xray?
Grey
What colour is calcification on an xray?
Almost white
What is the normal projection of a chest x-ray?
PA
Posterior to anterior on the patient
When would an AP projection CXR be performed?
If the patient was very unwell
Sitting for this
What can’t we comment on in AP CXRs?
Size of the heart
Will be enlarge due to being AP
What is the correct inclusion of a chest xray?
Just above the 1st to the costophrenic angles
Past the lateral margins of the ribs
How do we check for rotation in a CXR?
Look at the alignment of the spinous processes and the clavicles
Where do the lungs come down to an a CXR normally?
Between the 5th and 7th anterior ribs at the mid-clavicular line
We ask the patient to breathe in and hold it
What differs on the CXR if the patient gives incomplete inspiration?
Heart looks bigger
Increases lung markings (can see more clearly)
What is the penetration and what is adequate for a CXR?
The degree to which to x-rays have passed through the body
Adequate = vertebrae just visible through the heart and the complete left hemidiaphragm is visible
What is an artifact on a CXR?
External/iatrogenic material which obstructs view
Eg. Buttons, hair, vascular lines, pacemakers
How do we talk about the position of something in the lungs on a CXR?
Talk about zones
Upper, middle and lower
Don’t mention lobes unless you are absolutely sure
Describe the things to note/look for when checking the anatomy of a CXR
Trachea - deviated Hila - left should be slightly higher than right Lungs Diaphragm - sharp angles Cardiac contours Aortic knuckle on the left Ribs Scapulae Breasts Bowel/stomach gas
Should you be able to see the pleura?
No
Unless pleural effusion
Describe the systematic approach to CXR evaluation
Patient demographics Comment on projection and adequacy (rotation, inspiration and penetration) A = airway B = breathing C= circulation D = diaphragm E = everything else - bones and soft tissues Check review areas
What are review areas?
Areas that we commonly miss pathology on CXRs
Name the review areas for CXRs
Apices Thoracic inlet Paratracheal stripe (lymph nodes) AP window (between aortic arch and pulmonary artery) Hila Behind heart Below diaphragm Bones Edges of films
What is silhouette sign on a CXR?
Adjacent structures of differing densities form a crisp silhouette
Loss of this contour can locate pathology
‘Loss of the silhouette sign’
What things can push the mediastinum away?
Pleural effusions
Tension pneumothorax
What things can pull the mediastinum towards?
Collapsed lung
Fibrosis of lung
What is a pneumothorax?
Air trapped in the pleural space
What is the most common cause of pneumothorax?
Trauma
Laceration of pleura eg from fractured rib
In people with which diseases is a spontaneous pneumothorax most likely to occur?
Asthma
emphysema
Marfan’s
How do we define a large pneumothorax?
Lung edge > 2 cm from the inner chest wall at the level of the hilum
What signs do we see of pneumothorax on a CXR?
Area of blackness
Mediastinal shift away
Depressed hemidiaphragm
Visible pleural edge
What is a pleural effusion?
Collection of fluid in the pleural space
Describe what you see for a pleural effusion on a CXR
Uniform white areas
Loss of costophrenic angles
Hemidiaphragm obscured
Meniscus
Why do we need to be aware of supine CXRs?
Pleural effusions
Fluid will be spread out across the lungs not collecting at the bottom
Grey/hazy
What is a lobe lung collapse?
Volume loss within a lung lobe
Give some causes of lobar lung collapse
Aspirated foreign material Mucus plugging Iatrogenic Bronchogenic carcinoma Compression by adjacent mass
What are the general CXR findings for a lobar collapse?
Elevation of diaphragm
Crowding of ribs
Shift of mediastinum towards it
Crowding of pulmonary vessels
Define atelectasis
Complete or partial collapse of a lung or lobe of a lung
What does it look like if the left lower lobe collapses?
Sail sign
What does it look like if the left upper lobe collapses?
Veil sign
What does it look like if the right upper lobe collapses?
Pull up the horizontal fissure
What does it look like if the right middle lobe collapses?
Cannot see the right heart border
Consolidation is filling of the alveoli with …
Pus
Blood
Fluid
Cells
What is an air bronchogram?
Consolidation on a CXR leads to air filled bronchi made visible because of opacification of surrounding alveoli
What do we call space occupying lesions of less and greater than 3cm?
< 3 cm = nodule
> 3 cm = mass
Give some causes of space occupying lesions
Malignancy (primary/mets)
Benign mass
Inflammatory (eg. Rounded pneumonia)
Congenital
What is the normal cardiac index?
Ratio of heart to chest < 50%
Must be on a PA image
