Chapter 27 (Module 1) Flashcards
The recorded detail of a digital radiographic image is primarily visible because of
a. sufficient contrast.
b. sufficient receptor exposure.
c. low signal to noise ratios (SNR).
d. both a and b.
both a and b
The difference between two adjacent gray shades on a radiographic image is
a. recorded detail.
b. quantum mottle.
c. radiographic contrast.
d. distortion.
radiographic contrast
A radiograph with few shades of gray exhibits
a. low contrast.
b. high contrast.
c. medium contrast.
d. long scale contrast.
high contrast
Which type of radiograph provides the most clinical information?
a. an image with quantum mottle
b. short-scale contrast images
c. low-density images
d. low-contrast images
low-contrast images
The principal controlling factor of radiographic contrast using film-screen technology is
a. kVp.
b. mAs.
c. focal spot size.
d. anode angle.
kVp
A radiograph that demonstrates considerable differences between gray shades is said to have
a. short scale.
b. high contrast.
c. increased contrast.
d. all of the above.
all of the above
A radiograph that demonstrates minimal differences between gray shades is said to have
a. long scale.
b. low contrast.
c. decreased contrast.
d. all of the above.
all of the above
With digital imaging technologies, the final brightness and contrast appearance of an image is due to
a. kVp.
b. window and level controls.
c. look-up table (LUT) application.
d. image rescaling.
look-up table (LUT) application
A frontal projection chest radiograph that demonstrates a faint outline of the thoracic spine and many shades of gray to show the pulmonary markings of the lungs illustrates
a. underpenetration.
b. long-scale contrast and adequate penetration.
c. overpenetration.
d. short-scale contrast and adequate penetration.
long-scale contrast and adequate penetration
Image receptor contrast of radiographic film is expressed as the ____ of the D log E curve.
a. slope
b. toe
c. shoulder
d. speed
slope
In digital imaging using a DR detector, image contrast decreases with
a. excessive kVp values.
b. underexposure.
c. mAs values that are too low.
d. radiographic grids.
excessive kVp values
Varying tissue thicknesses and densities is referred to as
a. differential absorption
b. attenuation
c. subject contrast
d. image contrast
subject contrast
As kVp ____, a ____ range of photon energies is produced.
a. increases; wider
b. increases; narrower
c. decreases; wider
d. decreases; longer
increases; wider
A high contrast LUT applied to a chest radiograph would yield
a. dark lung fields and poorly demonstrated lung mediastinal anatomy.
b. very few gray shades between the darkest and lightest regions of the chest.
c. underpenetrated lung fields and a clear silhouette of the thoracic spine.
d. excellent visualization of the bronchopulmonary markings and ribs.
very few gray shades between the darkest and lightest regions of the chest
High contrast is directly related to
a. the number of photoelectric interactions.
b. high kVp.
c. the amount of Compton scatter.
d. mAs.
the number of photoelectric interactions
Immediately after exposure and before a digitally acquired image is post-processed, the initial image shown demonstrates
a. very low contrast
b. the heel effect
c. focal spot blur
d. extremely high contrast
very low contrast
Which of the choices below does not increase contrast?
a. increasing grid ratio
b. increasing the amount of irradiated tissue
c. decreasing filtration
d. decreasing kVp
increasing the amount of irradiated tissue
Radiographic image contrast is a combination of
a. grid ratio and field size
b. receptor contrast and subject contrast
c. filtration thickness and field size
d. data rescaling and look-up tables
receptor contrast and subject contrast
As kVp increases, the percentage of Compton interactions _______ and contrast_______.
a. decreases; decreases
b. decreases; increases
c. increases; decreases
d. increases; increases
increases; decreases
When the tissue structure of the ankle joint is considered, the dramatic tissue differences between the muscles and bones of the ankle produce
a. high subject contrast.
b. low subject contrast.
c. high receptor contrast.
d. low receptor contrast.
high subject contrast
A fluoroscopic examination that uses barium as a contrast material would typically produce images with
a. long scale contrast.
b. short scale contrast.
c. low contrast.
d. both a and c.
short scale contrast
The total amount of irradiated material is a function of
a. tissue thickness and tissue density.
b. body part thickness and area of exposure.
c. field size and anode angle.
d. body position and focal spot size.
body part thickness and area of exposure
A radiographic grid with a K-factor of 1 would offer
a. a 100 percent increase in contrast.
b. no change in image contrast.
c. a reduction in image contrast.
d. an increase in exposure with a decrease in contrast.
no change in image contrast
In order to reduce patient entrance skin exposure (ESE), higher kVp exposures are a consideration. It is important to remember that
a. kVp values that are too high can short-circuit a digital detector.
b. kVp values that are excessively high can negatively impact the data histogram.
c. a significant loss of image contrast is not a reason to avoid higher kVp values in order to reduce ESE.
d. the digital processing software will correct for any kVp value regardless of how high it is in value.
kVp values that are excessively high can negatively impact the data histogram
With increasing kVp levels, it is important to remember that with digital receptors and DR technologies
a. less differential absorption occurs and a narrower histogram results.
b. the difference between minimum and maximum incoming photon energies is reduced.
c. more anatomical data can be recorded with a lower patient dose.
d. all of the above.
all of the above
Kilovoltage peak (kVp) controls the proportional relationship of
a. mAs and kVp.
b. Compton and photoelectric interactions.
c. photoelectric and characteristic interactions.
d. SID and patient thickness.
Compton and photoelectric interactions
What should you expect to occur with a decrease in kVp, using digital receptors?
a. an increase in Bremsstrahlung tissue interactions
b. more Compton interactions
c. a narrower histogram
d. more photoelectric interactions
more photoelectric interactions
When digital imaging receptors are used,
a. kVp is not a consideration.
b. radiographic grids are not necessary.
c. an exposure at 90 kVp would require a grid.
d. Compton scatter is not a factor.
an exposure at 90 kVp would require a grid
All of the following factors would affect radiographic subject contrast EXCEPT
a. part thickness.
b. average tissue density.
c. using barium as a contrast agent.
d. LUT selection.
LUT selection
An increase in x-ray beam filtration
a. increases the number of Compton interactions.
b. reduces contrast.
c. increases the average photon energy.
d. all of the above.
All of the above
When choosing between two radiographic grids, the k factor is different. Choosing a grid with the higher K factor
a. produces an image with lower contrast.
b. results in a higher degree of scatter and secondary radiation clean-up.
c. will improve recorded detail.
d. requires a reduction in mA to compensate for the added subject contrast.
results in a higher degree of scatter and secondary radiation clean-up
With digital imaging systems, the primary factors affecting final image contrast are the
a. window level and brightness.
b. histogram and look-up table (LUT).
c. EI numbers and S numbers.
d. kVp and mAs.
histogram and look-up table (LUT)
Selecting an open-mouth odontoid LUT and applying this LUT to a KUB, will yield a final image with
a. low contrast and reduced visibility of detail.
b. many subtle gray shades and a longer scale of contrast.
c. high contrast visualization of lumbar spine anatomy.
d. the look of a high kVp exposure and quantum noise.
High contrast visualization of lumbar spine anatomy
