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WorksheetsFinal Exam Review (RAD 147)
Total questions: 93
Worksheet time: 2hrs 33mins
__________ is primarily responsible for the dose to the radiographer, while ______________ contributes to the patient dose.
Compton scatter, photoelectric effect
photoelectric effect, Compton scatter
coherent scatter, Compton scatter
Compton scatter, coherent scatter
The relationship between frequency and wavelength is:
inverse
direct
no correlation
AMA stands for:
Active matrix array
American medical administration
Attenuation matter acceleration
Available matrix aperture
A pixel (picture element) is two dimensional, while a ____ has three dimensions.
voxel
matrix
image
photon
Photoelectric effect involve the interaction of an incident photon with
outer shell electrons
inner shell electrons
recoil electrons
atomic nuclei
The by-products of the photoelectric interaction are:
photoelectron, characteristic radiation
Compton electron, photoelectron
recoil electron, scatter radiation
positron, characteristic radiation
Attenuation is increased by
higher atomic number
higher tissue mass density
greater part thickness
higher beam quality
Digital image quality is improved with:
larger matrix size
larger pixel sizes
increased tissue density
smaller pixel bit depths
The photons that pass through matter without undergoing any interactions are
transmitted
attenuated
absorbed
scattered
Which of the following is the most radiolucent?
lung
muscle
bone
fat
Differential absorption is the process that gives the image
contrast
fog
receptor exposure
brighness
Which of the following will increase as the kVp setting is increased?
Compton interactions
photelectric effect
differential absorption
receptor exposure
Which of the following are true regarding digital imaging?
digital image quality decreases as matrix size increases
digital image quality increases as matrix size increases
digital image quality increases as matrix size decreases
matrix size has no impact on digital image quality
In order to remove a k-shell electron from an atom, producing characteristic radiation, the incident photon must possess an energy of
69.5 kVp or higher
30 kVp or higher
Less than 69.5 kVp
50 mAs or greater
Which matter interaction is occurring?
Compton
Photelectric
Bremsstrahlung
Coherent
Photons with higher ______ have a higher energy level.
frequency
charge
mass
wavelength
What percentage of the beam is attenuated by the tissue?
50% for every 4-5 cm
75% for every 10 cm
25% for every 5-6 cm
99% for every 1 cm
The invisible image present on the IR immediately after exposure is the:
latent image
manifest image
digital image
ghost image
The binding energies, or energy levels, of electrons are represented by their ___________.
shells
isotopes
ions
atomic mass
Compton interaction is responsible for image
fog
contrast
detail
resolution
Higher kVp techniques result in:
lower contrast
higher penetrability
less receptor exposure
more absorption
The number of pixels present in a 512 x 512 matrix is
262144
4096
1024
134217728
Bit depth is determined by the formula
2n
n2
22n
n2
Which of the following determine the visibility of detail?
contrast
distortion
brightness
spatial resolution
What may happen when the digital image receptor is extremely over exposed?
insufficient density
increased distortion
excessive contrast
saturation
A radiographic image that has few brightness levels that are very different from each other
has high contrast.
has low contrast.
has long-scale contrast.
has mid-scale contrast.
__________________ is a term used to evaluate accuracy of the anatomic structural lines recorded.
Contrast resolution
Spatial resolution
Brightness
Detective quantum efficiency
The radiographic misrepresentation of either the size or the shape of the anatomic part is called
distortion
contrast
blur
noise
Which of the following combinations would result in an image with the greatest amount of magnification?
Decreased OID and decreased SID
Decreased OID and increased SID
Increased OID and decreased SID
Increased OID and increased SID
In order to minimize shape distortion in the image, what factors should be properly aligned?
x-ray tube
OID
image receptor
anatomic part
When OID cannot be reduced, it is possible to reduce size distortion by
increasing mAs.
increasing SID.
using a small focal spot size.
decreasing SID.
If the original exposure factors are 20 mAs @ 70 kVp, which of the following factors produce a radiographic image with the same IR exposure but higher contrast?
10 mAs @ 81 kVp.
10 mAs @ 70 kVp.
40 mAs @ 70 kVp.
40 mAs @ 60 kVp.
An exposure is made using 60 kVp @ 15 mAs. A second exposure is made using the same mAs, but the kVp is increased to 90. What will be the result?
increased IR exposure
increased scatter reaching the IR
decreased contrast
increased contrast.
decreased receptor exposure
Changes in the SID will affect:
Receptor exposure
Focal spot size
Magnification
Contrast resolution
A significant amount of collimation will have what effect on the amount of radiation reaching the IR?
receptor exposure is reduced
receptor exposure is increased
receptor exposure is not affected
Increased collimation means:
Decreased field size
Increased field size
More tissue being irradiated
More receptor exposure
The advantage to using a larger actual focal spot is
the image is sharper.
higher exposures can be used.
the image is less magnified.
the image has higher contrast.
Standard radiographic x-ray tubes have focal spots that measure approximately
0.5 mm - 1.2 mm
5 mm - 12 mm
1.5 mm - 2.0 mm
0.5 mm - 2.0 mm
The primary purpose of AEC is to
control the amount of radiation reaching the IR.
control image contrast.
eliminate the need for the radiographer to think critically.
eliminate repeat radiographs due to technologist error.
Ionization chamber AEC detectors are entrance-type devices because the x-rays must
enter the ionization chamber after passing through the IR.
enter the ionization chamber before entering the patient.
enter the ionization chamber before getting to the IR.
The maximum length of time that an exposure lasts when using AEC is the
mAs readout.
back-up time.
minimum response time.
exposure adjustment.
Receptor exposure is affected by:
mAs
kVp
SID
FSS
Matrix size
X-ray tubes capable of producing greater than 70 kVp are required to have ______ of total filtration.
2.5 mm Al/eq
3.5 mm Al/eq
0.5 Al/eq
2.0 Al/eq
The purpose of filtration is to:
reduce the radiation dose to the patient
increase receptor exposure
increase image contrast
improve diagnostic quality
Added filtration has the effect of __________ the beam quality.
decreasing
increasing
does not affect
An exposure was made using 70 kVp @ 8 mAs. In order to maintain receptor exposure, what mAs value should be selected if the kVp is increased to 106?
1 mAs
2 mAs
16 mAs
4 mAs
The intensity of radiation on an object is reduced with distance because the radiation ___________.
reduces its velocity
increases in wavelength
loses its energy
diverges
Compared to film-screen imaging, digital systems are (select the two that apply)
Less sensitive to low-energy radiation
More sensitive to low-energy radiation
Less sensitive to scatter radiation
More sensitive to scatter radiation
When x-ray exposure to the digital image receptor is too low (select the two that apply)
Brightness is acceptable
Quantum noise is increased
Quantum noise is decreased
Brightness is unacceptable
What effect does switching to a large focal spot have on the image?
Scale of contrast decreases
Image unsharpness increases
Size distortion increases
Image density decreases
From the following list, select the 2 factors having the most impact on receptor exposure:
focal spot size
SID
OID
kVp
Which of the following are considered “entrance type” AEC devices?
Phototimer
Ionization chamber (ion chamber)
Image receptor (IR)
Anatomically programmed radiography (APR)
An increase in mA is associated with
decreased SNR
increased SNR
decreased photon intensity
decreased photon wavelength
What is the name of the computerized system in which the radiographer has a selection of exams available on the console from which to choose?
Anatomical radiography
Programmed radiography (anatomical)
Anatomically programmed radiography
Automatic Exposure Control
All the following are related to spatial resolution except
motion
focal-spot size
OID
scattered radiation
For the same FOV, arrange the following radiography matrix sizes would result in the highest spatial resolution?
1500 x 1500
2500 x 2500
750 x 750
224 x 224
In digital imaging, a 2D array of numbers comprised of columns and rows is known as
a field of view (FOV)
a matrix
pixel density
an exposure indicator
Which aspect of image quality does a grid influence?
Contrast
Size distortion
Shape distortion
Spatial resolution
With AEC, the area of interest must be placed directly over the selected detectors in order to avoid which two of the following? (select the two that apply)
Overexposure
Decrease in contrast
Underexposure
Increase in contrast
A histogram is
a graphical representation of the amount of radiation that stuck the IR
the combination of window width and window level settings that determine the appearance of the image
a measurement metric that determines if the optimal receptor exposure was reached for a given examination
the physical location of the x-ray photons striking the IR as they relate to the matrix
The purpose of the air gap technique is to:
reduce the amount of scatter reaching the IR, improving image contrast.
reduce the amount of scatter reaching the IR, increasing the spatial resolution.
reduce the amount of scatter reaching the IR, increasing the recorded detail.
reduce the amount of scatter reaching the IR, improving the contrast resolution of the system.
Which of the following is (are) a result of grid usage?
improved contrast
decreased receptor exposure
increased receptor exposure
reduced patient dose
Which of the following combinations would result in an image with the least amount of magnification?
Decreased OID and decreased SID
Decreased OID and increased SID
Increased OID and decreased SID
Increased OID and increased SID
Benefits of compression devices include:
lower patient dose
lower SNR
increased photoelectric absorption
reduced scatter production
increased scatter production
The two types of digital imaging systems are:
PSP
FPD
DEL
AMA
The purpose of automatic collimation is
improved image quality.
limiting patient exposure.
increasing the cost of equipment.
none of these.
Which of the following is the formula used to determine grid ratio?
Grid ratio = distance between the lead strips/height of the lead strips.
Grid ratio = width of the lead strips/height of the lead strips.
Grid ratio = height of the lead strips/distance between the lead strips.
Grid ratio = height of the lead strips/width of the lead strips.
A linear grid
has lead strips that cross each other.
has lead strips that travel in one direction.
has lead strips that can be removed.
has no lead strips.
A focused grid’s lead strips are angled to match
the anode angle.
the angle of the x-rays in the primary beam.
the angle of the scattered photons leaving the patient.
the tube angulation.
To compensate for the reduction of radiation reaching the IR when a grid is used, ___________ is typically increased.
SID
kVp
mAs
OID
If a shoulder examination is done using an 8:1 ratio grid and 12 mAs, how much mAs should be used if the examination must be done tabletop (no grid)?
1.5 mAs
3 mAs
48 mAs
96 mAs
The air gap technique is based on creating a gap by increasing the ______.
SID
SOD
OID
mAs
Amorphous silicon is used as the
photoconductor for indirect capture DR imaging.
photodetector for indirect capture DR imaging.
photoconductor for direct capture DR imaging.
photodetector for direct capture DR imaging.
As a general rule, a grid should be used when imaging tissue that is greater than ____ thick.
4-5 cm
8-12 cm
10 cm
6 cm
The most commonly used beam restriction device is the
Cones and cylinders
Aperture-diaphragm
Variable-aperture
Positive beam limitation (PBL)
Increasing collimation results in:
Larger field size, lower receptor exposure
Smaller field size, higher receptor exposure
Larger field size, lower contrast
Smaller field size, higher contrast
At a higher kVp _____ interactions occur overall, and of those that occur a greater percentage are ______ interactions.
fewer, Compton
more, Photoelectric
fewer, Photoelectric
more, Compton
Which of the following is true regarding scatter radiation?
Scattered photons can strike the IR, contributing useful diagnostic information.
Scattered photons gain energy when they interact with the tissue, posing significant danger to the technologist.
Scattered photons will always continue to undergo interactions within the tissue until they are completely absorbed.
Scattered photons can strike the IR, contributing no useful information.
PSP plates are read using:
helium neon laser
fluorescent light
electron beams
active matrix array
As compared with lower kVp exposures, when using high kVp will result in a scattered photon that is of ________ energy.
lower
higher
the same
half
Two major factors that affect the amount of scatter radiation produced and exiting the patient are
kVp and mAs.
volume of tissue irradiated and mAs.
volume of tissue irradiated and kVp.
kVp and the use of a grid.
The simplest type of beam-restricting device is a flat piece of lead with a hole in it called a(n)
aperture diaphragm.
collimator.
cone or cylinder.
none of these.
The purpose of automatic collimation is
improved image quality.
limiting patient exposure.
increasing the cost of equipment.
none of these.
Grids absorb scatter radiation because the scattered photons
have high energy.
have extremely low energy.
travel in the same direction as the transmitted photons.
travel at an angle to the transmitted photons.
The number of lead lines per inch or centimeter is the grid
number.
ratio.
frequency.
rating.
Which of the following is the formula used to determine grid ratio?
Grid ratio = distance between the lead strips/height of the lead strips.
Grid ratio = width of the lead strips/height of the lead strips.
Grid ratio = height of the lead strips/distance between the lead strips.
Grid ratio = height of the lead strips/width of the lead strips.
The grid is part of a device located just below the tabletop that also includes a tray to hold the IR. This device is the
wafer grid.
bucky.
grid cap.
grid cassette.
To compensate for the reduction of radiation reaching the IR when a grid is used, ___________ is typically increased.
SID
kVp
mAs
OID
When the x-ray beam is not lined up with the center of the grid you have _________ cutoff.
upside-down focused
off-level
off-center
off-focus
The type of phosphor found in the PSP plate for computed radiography is
plastic.
amorphous selenium.
barium fluorohalide.
cesium iodide.
The part of the reader that senses the light released from the PSP plate is the
photomultiplier.
optical system.
drive mechanism.
photostimulable luminescence.
The scintillator for the indirect capture DR system that utilizes a CCD is
cesium iodide.
barium fluorohalide.
amorphous selenium.
crystalline silicon.
Amorphous silicon is used as the
photoconductor for indirect capture DR imaging.
photodetector for indirect capture DR imaging.
photoconductor for direct capture DR imaging.
photodetector for direct capture DR imaging.
