Flashcards in Physics 2 Deck (25):
What are the 5 imaging modalities?
Magnetic resonance imaging
What are Roentgen (imaging) signs?
A visual clue or signal that is produced by a pathologic change of tissue and may be detected in a medical image
What are the 6 observations made with Roentgen signs?
What are the 5 opacities?
Soft tissue = fluid
What are some additional imaging signs?
What are the 5 diagnostic pitfalls of DI?
Error rates are high
Interpretation is the result of complex perceptual mechanisms
Previous experience provides a large portion of perceived image
Attitude affects interpretation
Multiple readings reduce errors
What are some visual disabilities of DI (5)?
Length, angle, size are hard to 'see'
Contrast background effect
What is the Mach phenomenon
Mach lines are false white or black lines that appear at sharp boundaries. These optical illusions enhance boundaries but can mimic lesions
What is the contrast background effect?
The eye is a poor judge of absolute brightness--based on the background color, the shade of an object can appear lighter/darker than it really is
What is the difference between vision and perception?
Vision = what the eye sees
Perception = what the brain sees
Previous experience influences your perception; visual signals are compared to memory and most likely explanations are 'seen'
Images of shades: 2-dimensional contours of 3-dimensional objects
Complex summations of several categories of shades; perception of contours is primary visual mechanism used to 'see' radiographs
Perceived when there is change in brightness or color between adjacent objects; can occur without changes--results from mental completion of partial lines to form something expected
T/F: False masses (even kidneys) can be created by loops of bowel
What are the 6 key concepts to radiographic interpretation?
What are the 5 opacities?
Fluid = soft tissue opacity
Bone = mineral opacity
What determines the opacity (5 factors)?
Manifested as "shades of gray" on film or computer monitor
What is an analog gray scale?
Continuous scale from black to white
Blackest images = ___; whitest images = ____.
dense bone to metal
What does difference in opacity determine?
An area of increased radiopacity ('whiteness') occurring when two OVERLAPPING objects are in the path of the x-ray beam and are NOT in contact with one another
Margins of 2 objects cannot be distinguished because of similar opacity and margins are IN CONTACT
What must you consider when interpreting radiographs (5)?
Normal or normal anatomic variation or age-related change
True lesions: incidental or clinically relevant
Conclusions about findings
Recommendations or the 'next step'
T/F: A systematic approach to interpretation is fundamental
How are radiographic projections named?
Named according to the direction of the primary x-ray beam as it penetrates the area of a body--from point of entrance to point of exit