Image Brightness/Contrast Flashcards
T/F: Radiography does not include understanding how to set a control panel.
False
T/F: In radiography, optical density is a visible representation of the quantity of X-ray photons reaching the IR.
True
T/F: Increasing mAs increases optical density.
True
T/F: Increasing mAs increases brightness.
False
Controls scale of contrast in the radiographic image
kVp
Controls optical density in the radiographic image
mAs
A radiograph that has sharp differences in optical density is called ___ contrast
high
A radiograph with a small number of widely varying optical density values is said to possess ___ scale contrast
short
has a short gray scale and used a low kVp
High scale of contrast
has a long gray scale and used a high kVp
Low scale of contrast
scale of contrast increases as kVp is ___
decreased
scale of contrast decreases as kVp is ___
increased
gray scale increases as kVp is ___
increased
gray scale decreases as kVp is ____
decreased
Doubling the mAs will result in:
1. increased patient dose
2. twice as many photons in the x-ray beam
3. increased radiographic density
1, 2 and 3
If all other factors are unchanged and mA is decreased, image optical density will:
directly decrease
If all other factors are unchanged and time is decreased, image optical density will:
directly decrease
According to the reciprocity law, a technique of 200 mA, .5 second and 68 kVp can be changed to 400 mA, _______ second and 68 kVp.
0.25
For the 1st exposure, 10 mA @ .5 seconds were used. There was considerable motion on the finished image. For the repeat, the time was decreased to .05 seconds. What mA would need to be used in order to maintain density?
100
In the term kVp, the ‘p’ actually stands for:
highest voltage [peak]
Long wavelength radiation will produce a radiograph with ___ scale contrast
short
If an image (if the anatomical anatomy) is under-penetrated, the cause would be:
not enough kVp
If an image (if the anatomical anatomy) is under-exposed, the cause would be
not enough mAs
Which of the following would result in the shortest scale of contrast?
300 mA
1/30 sec
70 kVp
300 mA
1/60 sec
80 kVp
200 mA
1/20 sec
70 kVp
100 mA
2/10 sec
60 kVp
100 mA
2/10 sec
60 kVp
T/F: Radiographic contrast and optical density of the manifest image in a digital image is primarily affected by predetermined algorithms in the computer.
True
T/F: Differential absorption results in the process of image formation, whereby the x-ray beam interacts with the anatomic tissue and a portion of the beam strikes the image receptor.
True
Limiting the size of the primary beam:
Beam restriction
Refers to the radiation field size:
Exposure to the IR
The range of colors of gray (the differences) in a radiograph including the dark areas and the bright (or clear areas)
Contrast scale
A color of gray in the image
Density
Differences in the brightness levels on the radiographic image is called:
Image contrast
A longer scale of contrast (many shades of gray) within the part can be obtained by
increasing kVp
An image with a brief range of widely different densities possesses
1. short scale contrast
2. long scale contrast
3. high contrast
4. low contrast
1 and 3
In order to maintain the same density level and the mA is doubled, you should:
Half the time
T/F: an additive disease requires an increase in kVp
True
T/F: an additive disease requires a decrease in mAs
False
Select the factors that affect subject contrast
1. physique
2. age
3. development (muscle vs. soft tissue)
4. pathology
1, 2, 3 and 4
The thorax represents high subject contrast. Therefore, which of the following is most appropriate; high or low kVp?
high kVp
Which of the following is not a primary factor in the production of a radiograph?
-mA
-seconds
-intensification factor
-kVp
intensification factor
Which of the following does not belong in this group?
-intensity
-wavelength
-penetration
-kV
intensity
The use of 15% kilovoltage rule in the maintenance of OD as mAs is halved offers the advantage of:
-lower patient dose
-shorter exposure times
-all of the above
all of the above
The 15% rule states:
That a change of 15% in kVp will result in approximately the the same change in density as doubling, or halving the mAs.
At 30 inch SID, 200 mR of radiation reaches the IR changing the distance to 72 inches, the new intensity of radiation will be:
To solve this problem, use the
Inverse square law
An exposure is made at 40 inches using 100 mAs. At 60 inches, what is the new mAs to maintain density?
To solve this problem, use the
Direct square law
A technique of 160 mAs and 60 kV has been employed in producing a satisfactory image. In order to reduce patient exposure and to maintain density, _______ mAs and ______ kVp should be used.
To solve this problem, use the:
15% rule
“The intensity or exposure rate of radiation at a given distance from a point source is inversely proportional to the square of the distance” defines
Inverse square law
Which affect the quality of a radiographic image?
(1) Patient positioning
(2) Selection of technique factors
1 and 2
The amount of energy absorbed by an irradiated object is primarily controlled by:
- Energy of incident photon
- Atomic number of the tissue
- Speed of the incident photon
1 and 2
“…the ability of the imaging system to distinguish between small objects that attenuate the x-ray beam similarly…”
contrast resolution
The function of radiographic contrast in a radiograph is to:
Make detail visible
The number of different shades of gray that can be stored and displayed by a computer system is termed:
Scale of contrast / grayscale
For an analog image, the primary function of the mAs is to:
Regulate OD
In an analog image, which of the following is primarily responsible for the scale of contrast on a radiograph?
kVp
Which of the body tissues has the highest absorption when exposed to diagnostic x-rays?
Bone
Which of the primary exposure factors has the greatest effect on beam quality, attenuation, and exposure latitude?
kV
Which term might be used to describe an x-ray image that has a few shades of gray with marked visible differences between the ODs?
Short-scale contrast
kVp is the controlling factor for which of the following?
-quantity of x-rays
-size of focal spot
-OD
-none of the above
None; kVp influences quantity but is not the controlling factor.
The ability of an IR to display different definition shades of gray from light to dark.
Exposure latitude
The range of exposure intensities an IR can accurately detect.
Dynamic range
