Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
21 Cards in this Set
- Front
- Back
- 3rd side (hint)
|
Contrast allows the ________ of the image to be seen but do not _________ the details of the image
|
Contrast allows the details of the image to be seen but do not control the details of the image.
It is like having the correct setting on your camera |
|
|
|
What is the definition of contrast?
|
The difference between adjacent densities
|
|
|
|
Why is contrast a difficult quality to evaluate?
|
It is a subjective opinion, some people like a darker image and some like it lighter
|
|
|
|
What is the proper scale of contrast?
|
The correct contrast for the anatomy of interest allowing you to see the essential anatomy for diagnostic purposes.
|
|
|
|
What is contrast called in CR and DR?
|
It is called dynamic range
|
|
|
|
Why is dealing with contrast or dynamic range in CR/DR an advantage over film?
|
Because you can adjust it to make it acceptable
|
|
|
|
In CR/DR contrast is adjusted by controlling window _______. when dealing with density it is controlled by window ___________.
|
In CR/DR contrast is adjusted by controlling window width. when dealing with density it is controlled by window level
|
|
|
|
Describe an image with high contrast
|
more or increased contrast with few shades of gray, short scale taken at low kVp
|
|
|
|
Describe an image with low contrast
|
less or decreased contrast with many shades of gray, long scale taken at high kVp
|
|
|
|
An image that is under penetrated always has __________ contrast
|
An image that is under penetrated always has high contrast.
it is always too black and white |
|
|
|
What is the definition of manipulating contrast?
|
It is the compression or expansion of the range of visible densities
And how is this achieved? |
1. change in D log E curve of film
2. adjustment to kVp 3. adjustment of window width |
|
|
When you have increased fog the contrast will be _____________
|
When you have increased fog the contrast will be decreased
|
|
|
|
True or false:
Focal spot has no influence on contrast |
True
|
|
|
|
What is the influence of mAs on constrast?
|
1. Under or overexposure moves contrast out of visibility
2. Contrast cannot be evaluated until proper density has been achieved |
|
|
|
Increased collimation _________ contrast
|
Increased collimation increases contrast
|
|
|
|
More latitude and a shallower slope on D log E curve gives us more or less contrast?
|
Less contrast (more grays)
|
|
|
|
Increasing contrast results from using intensifying screens, true or false
|
True
|
|
|
|
Any factor that increases fog _______ contrast
|
Any factor that increases fog decreases contrast
|
|
|
|
Subject contrast is dependent on 3 things:
|
1. amount of irradiated material
2. Type of irradiated material (pathology, atomic #) 3. KVP |
|
|
|
The wider you collimate (less you restrict the beam) the ________ the image will be
|
grayer
|
|
|
|
Increased contrast results from increased OID, true or false
|
True (air gap - acts like grid, takes out scatter)
|
|
