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Flashcards in Physics 2 Deck (25):
1

What are the 5 imaging modalities?

Radiography
Ultrasonography
Nuclear scintigraphy
Computed tomography
Magnetic resonance imaging

2

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

3

What are the 6 observations made with Roentgen signs?

Size
Shape
Margin
Opacity
Number
Location

4

What are the 5 opacities?

Gas
Fat
Soft tissue = fluid
Mineral
Metal

5

What are some additional imaging signs?

Function
Alignmeent
Through-transmission
Contrast uptake

6

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

7

What are some visual disabilities of DI (5)?

Dark adaptation
Glare
Length, angle, size are hard to 'see'
Mach phenomenon
Contrast background effect

8

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

9

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

10

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'

11

Radiographs

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

12

Contours

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

13

T/F: False masses (even kidneys) can be created by loops of bowel

TRUE

14

What are the 6 key concepts to radiographic interpretation?

Opacity
Summation
Silhouetting
Orientation
Conventions
Systematic approach

15

What are the 5 opacities?

Gas opacity
Fat opacity
Fluid = soft tissue opacity
Bone = mineral opacity
Metal opacity

16

What determines the opacity (5 factors)?

Molecular structure
Atomic elements
Thickness
Density
Manifested as "shades of gray" on film or computer monitor

17

What is an analog gray scale?

Continuous scale from black to white

18

Blackest images = ___; whitest images = ____.

gas;
dense bone to metal

19

What does difference in opacity determine?

Contrast

20

Summation

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

21

Silhouette sign

Margins of 2 objects cannot be distinguished because of similar opacity and margins are IN CONTACT

22

What must you consider when interpreting radiographs (5)?

Technical characteristics
Normal or normal anatomic variation or age-related change
True lesions: incidental or clinically relevant
Conclusions about findings
Recommendations or the 'next step'

23

T/F: A systematic approach to interpretation is fundamental

TRUE

24

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

25

How are oblique/special radiographic views named?

Should be named in the same method used in naming the standard views
Can add angles of obliquity
Angle, measured in degrees is added after the first directional designation
Clinical jargon can be added, and any special positioning should be mentioned