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28 Cards in this Set
- Front
- Back
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What should be considered when a radiograph is interpreted?
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-history
-clinical signs -physical exam findings -lab data |
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Differential List is provided by:
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Roentgen signs + History/PE/Lab
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Is a specific diagnosis very possible with the use of radiography?
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-no
-the radiographic signs are rarely pathognomonic |
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Why is radiographic labeling important?
What labels should be included on a radiograph? |
-a radiograph is a medical legal document
Labels: -patient/owners name/owner case # -date -clinic name/doctor -R/L markers |
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Billars Pillars to Successful Radiology
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-normal anatomy
-systemic evaluation -description, description, description |
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Reasons for different opacities
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-x-rays have a potential to penetrate tissues
-x-rays pass through tissue and interact and ultimately expose film -x-rays are in part attenuated by tissues they pass through -absorption of x-rays as a function of: energy of x-ray, physical density of tissue, atomic number -thickness of tissue -differential absorption causing shades of grey between the black and whites |
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How does the atomic number affect opacity?
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-higher atomic number --> greater absorption --> fewer x-rays that reach the film --> more radiopaque
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Effective atomic numbers of the different opacities
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-gas = 1-2
-fat = 6-7 -soft tissue/fluid = 7-8 -bone = 14 -metal = 82 |
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What is a benefit of the gas opacity?
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-allows for contrast between structures
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Fat opacity locations
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-omentum
-mesentery -falciform ligament -retroperitoneal space |
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What are some normal variations in opacity within the same bone and between bones?
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-compact vs. spongy bone
-cortical vs. medullary bone |
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Why is metal so radiopaque?
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-absorbs all diagnostic x-rays
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What is necessary in order to interpret radiographs?
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-need at least 2 orthoganol views
-need a dark quiet room with at least 2 viewboxes -take your time -shield high intenstiy |
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Luxated total hip replacement
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How should one go about interpreting a radiography?
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-use systemic evaluation
-ex) extrathoracic structures then intrathoracic |
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A "high quality" radiograph has what characteristics?
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-good exposure and processing
-good positioning -centering -no motion -collimation -free of artifacts |
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What are the 3 phases of radiograph interpretation?
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-recognition phase
-descriptive phase -analysis phase |
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Recognition phase of radiographic interpretation
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-compare all parts of the radiographic image to normal
-need to figure out if abnormality is a normal variant, artifacts or improper patient positioning |
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Descriptive phase of radiographic interpratation
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-describe how the lesion varies from the normal
-use LMNOSS&Function also describe the extent of the lesion ad the distribution |
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Analysis Phase of Radiographic Interpretation
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-take all of the information regarding radiographic changes from normal, history, and abnormalities from the PE and develop differential diagnoses
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Descriptive Phase
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-distal radius and ulna
-soft tissue swelling -aggressive bony lesion (lysis and irregular periosteum) |
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Analysis Phase
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DDx:
-primary bone neoplasia -metastatic neoplasia -infection |
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What does the ability to describe function often require?
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-the use of contrast or multiple films over time
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Summation
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-a shadow of increased opacity due to areas of overlap
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Border effacement
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-loss of border between objects of similar opacity when in anatomic contact
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Mock Line
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-an optical illusion as a result of retinal physiology
-lateral inhibition to create edge enhancement is responsible for the light/dark lines at interfaces of dissimilar densities |
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Magnification
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-occurs when increasing object film distace
-exaggerate on short film at distance |
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Distortion
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-unequal magnification of an object due to its axis not being parallel to the film/cassette
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