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What device produces a constant simulated xray exposure using a light source?
What is known for measuring the sensitivity of photographic material?
Sensitometer measures a film's response to what 2 factors?
exposure & development
What's used to evaluate the effects of exposure & processing of film quality?
Name the device use to measure density.
What device measures the amt of light transmitted through the film?
What xray technique influences density?
On an H&D Curve, what axis measures density?
On an H&D Curve, what axis represents mAs/exposure?
X-axis =step numbers or mAs
Does a sensitometry measure [contrast or density]?
When & why would a sensitometry be used?
monitors normal functions of the processor & detects problems BEFORE they appear on the xray
What's the relationship bw density units & radiographic density?
radiographic density increases as density units increase
Name the aluminum device that increases in thickness in steps.
What does a pentrometer measure?
What does the densitometer assign to the different shades of black, white & gray?
The amt of light that passes through the film is converted into ________.
What does a 0 log value represent?
0 = white film or 100% of transmitted light
What number is represented in the darkest/blackest film?
4.0 = dark film = .01% of trasmitted light
As the % of light transmitted decreases, density unit ________ which means film density _______.
increase in density unity = increase density
(more density = DARKER film)
In a mostly black film, how would the density unit number be effected?
higher a number with darker film
An increase of ____ density units doubles radiographic density.
.3 units = double of density
What occurs to % of Transmitted Light when density units become larger?
reduced by 1 (or in half)
each Density Unit increase = % of light cut in half
increase of Unit = density increases = darker image
Where are the most useful ranges of densities found on the H&D Curce?
Name the darkest portion of the H&D Curve.
What film information can be obtained from the H&D Curve? (4)
1. contrast 2. latitude 3. speed 4. developing
Which axis represents the numbers from the 21 Step Wedge?
Which axis represents readings per the Densitometer?
_____ portion of the H&D Curve are the thick steps of the Pentrometer.
What part of the Pentrometer measures thick/dense body parts?
(Thickest step is also the LIGHTEST density level)
Where should contrast be evaluated on the curve?
What does the steepness of the Straight Line indicate?
What part of the H&D Curve receives the maximum amt of light?
(also shows THINNEST body parts)
How does the H&D Curve appear with higher contrast?
(more black & white w higher contrast/steeper)
A slope with higher contrast has a ________ latitude.
(also faster bc its steeper)
How are latitude & contrast related?
Does higher contrast mean an [decrease or increase] in latitude?
decrease in latitude
How is the response of digital imaging when compared to film?
linear response due to a wider exposure latitude (dynamic range)
What range of densities is displayed in digital imaging?
When the film becomes .3% darker how does this increase effect density?
double in density
Name the portion of the H&D Curve which can be imaged?
Give 3 other names of the H&D Curve.
Characteristic Curve, Sensitometic Curve, D Log E Curve
What part of the wedge represents the densest body parts?
thick steps = dense/thick parts
What part of the H&D Curve is affected by fog?
What does the steepness of the Curve indicate?
contrast of line
Would a [thinner or thicker] body part create less attenuation?
thinner = less
Where's the maximum amt of exposure recorded in the Curve?
What part of the Curve is least effected by fog?
(darker = fog effects the least)
Name the 4 factors that is readable on the H&D Curve.
1. film CONTRAST
2. film SPEED
3. film LATITUDE
4. processor info
the slope/curve of ________ portion of the H&D Curve tells you ________
Straight line tells you the CONTRAST level
____________ curve informs there's more or higher contrast in the image.
Steeper or more vertical
(more black & white = higher contrast/steeper)
What does a flatter or more horizontal curve inform?
= lower contrast
What's the slope of the straight line aka?
What does it mean to evaluate the speed of film?
how fast it reponds to xrays/light
What dictates mAs needed to produce a given film density?
speed of film
_______ determines density.
What info can be determine from the location of the curve?
speed of film (aka which 2 are faster)
A film curve closer to Y-axis says the film is ________.
faster = Y
[less or more] mAs would be required in in a faster film speed.
Less mAs w/ fast film
Why is less mAs required w fast film speeds?
bs it makes less mAs to produce the same density as a slower film
What is charted on the X-axis of the H&D Curve?
step numbers = X-axis
A range of exposures will produce densities w/in the ___________ range.
Latitude recorded as the _______ of the range of exposures that will produce density.
What can be said about a Wide Latitude film?
permits variation in exposures w/ densities in range
What does a Narrow Latitude do to density?
compress all density into shades of black & white
How are contrast & latitude related?
If contrast is increases, what is the result in latitude?
decrease or NARROW latitude
(high contrast = narrow latitude)
What amt of contrast is seen in a wide latitude?
(low contrast = increased/WIDE latitude
How effect does contrast have on the H&D Curve?
effects shape of curve
A change in film _______ results in different film contrast & latitude.
What range of densities does digital imaging response to?
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