The amount of filtration required to reduce the exposure of the beam to half of its original intensity is defined as:
Select one:
a. Wedge filtration
b. HVL
c. mA linearity
d. mAs compensator
HVL
What is filtration's relationship with density?
Select one:
a. estranged
b. inverse
c. direct
d. no relation
inverse
Setting identical exposure factors, which type of x-ray unit will produce the greatest heat?
Select one:
a. Single phase
b. Three phase
c. Double phase
d. High frequency
High frequency
What causes the anode heel effect to occur?
Select one:
a. The mAs-distance formula
b. Bernoulli's principle
c. The angle of the target
d. kVp settings
The angle of the target
Total filtration in the x-ray beam includes:
Select one:
a. compensating filters
b. inherent filtration
c. added filtration
d. B and C
e. all of the above
B and C
Which element is added filtration usually made of?
Select one:
a. Al
b. Au
c. W
d. Ag
Al
Which of the following constitute inherent filtration? Choose all that apply
Select one or more:
a. Oil surrounding the tube
b. Glass envelpoe
c. Mirror inside the collimator
d. The anatomical part to be imaged
e. Port window
f. Air in the collimator
Oil surrounding the tube
Glass envelope
Mirror inside the collimator
Due to the anode heel effect, the differences in intensities between the ends of the x-ray field can be as much as:
Select one:
a. 60%
b. 25%
c. 10%
d. 45%
45%
The amount the voltage varies during an x-ray exposure is known as:
Select one:
a. kVp
b. Voltage ripple
c. mA
d. Tube current
Voltage ripple
____________ will extend x-ray tube life.
Select one:
a. Selecting higher tube currents
b. Using small focal spot when possible
c. Producing exposures with a wide range of kVp values
d. Warming up the tube after 2 hours of nonuse
Warming up the tube after 2 hours of nonuse
An exposure of 100 kVp, 800 mA, and 0.1 seconds is a safe expsoure.
Select one:
True
False
False
What is the MAIN purpose of filtration?
Select one:
a. Produce a better image
b. Decrease patient dose
c. Find a use for Aluminum besides foil wrap
d. Focus the x-ray beam
Decrease patient dose
Which of the following types of filtration produce a more uniform exposure to the image receptor?
Select one:
a. Inherent
b. Half-value
c. Spatial
d. Compensating
Compensating
What is the most common type of generator used today?
Select one:
a. Three phase 12 pulse
b. Single phase
c. Three phase 6 pulse
d. High frequency
High frequency
Effective compensation for the anode heel effect would involve positioning:
Select one:
a. the thinnest portion of the part under the anode
b. The thickest portion of the part under the anode
c. The thinnest portion of the part under the cathode
d. B and C
the thinnest portion of the part under the anode
Why are instantaneous load tube rating charts used?
An instantaneous load tube rating chart is used to determine whether a particular exposure would be safe to make and to determine what limits on kVp, mA, and exposure time must be made to make a safe exposure. (p.37)
X-ray tubes operating above 70 kVp must have total filtration of at least _________ of aluminum, or its equivalent.
Select one:
a. 0.5 mm
b. 1 mm
c. 2.5 mm
d. 2 mm
2.5 mm
Which of the following practices will extend the life of the x-ray tube?
1. Use low mA and longer exposure time.
2. Warm up the tube as appropriate.
3. Hold down the rotor button for a long time, to keep the tube warmed up.
Select one:
a. 1 & 2 only
b. 1 & 3 only
c. 2 & 3 only
d. 1, 2, & 3
1 & 2 only
Low energy photons are desirable in the x-ray beam because they contribute to image quality.
Select one:
True
False
False
How many heat units (in HU) will result from an exposure made on a single phase x-ray unit using 400 mA, 0.2 seconds, and 70 kVp?
5600 HU
What is the formula for heat units?
Select one:
a. mA x exposure time x kVp x generator factor
b. 2 all-beef patties, special sauce, lettuce, cheese, pickles, onions, on a sesame-seed bun
c. inverse of the squares in a direct relationship
d. voltage ripple x HU x time
mA x exposure time x kVp x generator factor
An exposure of 80 kVp, 1000 mA, and 0.01 seconds is a safe expsoure.
Select one:
True
False
True
What is filtration's relationship with contrast?
Select one:
a. estranged
b. inverse
c. direct
d. no relation
inverse
The intensity of the x-ray beam is greater on the
Select one:
B. cathode side of the tube.
The differences in intensities on the anode and cathode sides can be as much as?
45%
Define "half-value layer"
"Half-value layer" is the amount of filtration that reduces the intensity of the beam to one-half its original value.
Filtration of the x-ray beam results in:
Select one:
a. Increased beam quantity
b. Increased beam quality
c. Lower average energy photons
d. B and C
Increased beam quality
As collimation decreases, exposure to the IR increases.
Select one:
True
False
True
Significant collimation requires an increase of _____________ of the mAs.
Select one:
a. 0%
b. 1 to 5%
c. 10 to 20%
d. 30 to 50%
30 to 50%
What effect does increasing the kVp have on scatter radiation?
Select one:
a. increases or decreases
b. decreases
c. no effect
d. increases
increases
Technologist should always be aware of limiting the x-ray field size for which 2 reasons?
Select one or more:
a. scatter
b. brightness of the colimator light
c. patient dose
d. added filtration
scatter
patient dose
What occurs when scatter radiation strikes the film?
Select one:
a. Radiographic contrast increases.
b. Radiographic contrast decreases.
c. Visibility of recorded detail improves.
d. Geometric unsharpness decreases.
Radiographic contrast decreases.
What effect does body part size have on scatter radiation?
Select one:
a. The thinner the part, the more scatter
b. The thicker the part, the less scatter
c. The thicker the part, the more scatter
d. The thinner the part, increased scatter
The thicker the part, the more scatter
Which of the following beam restricting devices is best at limiting unsharpness surrounding the radiographic image?
Select one:
a. aperture diaphragm
b. cyclone
c. focused grid
d. collimator
collimator
The purpose of the mirror inside the collimator is to:
Select one:
a. Allow the patient to see the radiographer
b. Allow the radiographer to see the patient
c. Project a light field onto the patient
d. None of the above
Project a light field onto the patient
What shape is the unrestricted x-ray beam?
Select one:
a. rectangle
b. cylinder
c. square
d. cone
cone
As collimation decreases, density:
Select one:
a. decreases
b. absorbs very little of the x-ray beam
c. increases
d. stays the same
increases
A beam restricting device that has 2 or 3 sets of lead shutters is a(n):
Select one:
a. Cone
b. Collimator
c. Cylinder
d. Aperture diaphragm
Collimator
Decreasing collimation results in:
Select one:
a. A larger field size
b. A smaller field size
c. Decreased patient dose
d. Less scatter production
A larger field size
When using a digital flat-panel detector:
Select one:
a. The radiographer must adjust the collimator to the area of interest.
b. The console will take a scout image of the patient to evaluate the area of interest.
c. The x-ray beam will automatically collimate to the appropriate size for the part.
d. The entire detector should be exposed.
The radiographer must adjust the collimator to the area of interest.
What is the MAIN purpose for automatic collimators?
Select one:
a. decrease scatter radiation
b. improve image quality
c. radiation hormesis
d. reduce patient exposure
reduce patient exposure
BRIEFLY explain 2 general problems with the collimator light.
The two general problems with a collimator light is that the light can go out and the light field can be misaligned depending on the angle of the mirror.
Which exposure factor should you change to compensate for increasing collimation?
Select one:
a. mAs
b. table top
c. kVp
d. focal spot size
mAs
An aperture diaphragm with an attached elongated tube is a(n):
Select one:
a. Aperture diaphragm
b. Cone
c. Collimator
d. Cylinder
Cylinder
Increasing collimation results in reduced patient exposure, increased field size, and reduced scatter production.
Select one:
True
False
False
The smaller the volume of tissue irradiated, the:
Select one:
a. Greater the amount of scatter produced
b. Less the amount of scatter produced
c. Greater the need to use a grid
d. A and C
Less the amount of scatter produced
As collimation increases, contrast:
Select one:
a. increases
b. decreases
c. absorbs very little of the x-ray beam
d. stays the same
increases
Name 3 types of beam restriction devices.
Three types of beam restricting devices are: aperture diaphragms, cones and cylinders, and collimators.
Which beam restriction device can be cut to the size needed?
Select one:
a. A collimator
b. A cylinder
c. An aperture diaphragm
d. A cone
An aperture diaphragm
What effect does increasing collimation have on patient dose?
Select one:
a. decreases
b. Incandescence
c. no effect
d. increases
decreases
What does PBL stand for?
Select one:
a. peanut-butter lornadoone
b. problem-based learning
c. positive beam limitation
d. projective beam likeness
positive beam limitation
What is the best type of beam restriction device?
Select one:
a. collimator
b. aperture diaphragm
c. cylinder
d. cone
collimator
What purpose does positive beam limitation serve?
Select one:
a. To prevent the technologist from placing an image receptor in the Bucky tray that is too large for the study performed
b. To prevent first-year students from having to repeat studies by not aligning the Bucky tray with the image receptor
c. To reduce patient exposure by limiting the exposure field to the same size as the image receptor in the Bucky tray
d. To allow the technologist to use an exposure field larger than the image receptor size
To reduce patient exposure by limiting the exposure field to the same size as the image receptor in the Bucky tray
What is another name for PBL?
Select one:
a. filtration
b. collimation mirror
c. automatic collimation
d. aperture diaphragms
automatic collimation
Why is scatter radiation bad?
Select one:
a. Focuses the x-ray beam
b. Deacreases image quality
c. Reduces fog
d. Increases contrast
Decreases image quality
Which of the following 2 factors would you use to help determine if you will use a grid for a particular exam?
Select one:
a. >60 kVp and >10 cm thick body part
b. >60 kVp and 5 cm body part
c. any exposre >65 kVp
d. >50 kVp and 10 cm body part
>60 kVp and >10 cm thick body part
In a grid, what are the 2 types of orientation of the lead lines in relationship to one another? (Choose all that apply)
Select one or more:
a. parallel
b. focused
c. cross-hatched
d. linear
parallel
focused
What is focal range and why does it matter?
Focal range is the recommended SID range that the beam should be from a focused grid. Focused grids are made with specific angles that can absorb and restrict the beam if placed at the wrong distance. This may make the image undiagnostic.
A grid whose lead strips run perpendicular to the long axis of the grid is called a(n):
Select one:
a. Alternating grid
b. Cross-hatch grid
c. Long dimension grid
d. Short dimension grid
Short dimension grid
The recommended SIDs that can be used with a focused grid describes the:
Select one:
a. Focal range
b. Convergent line
c. Convergent point
d. Focal distance
Focal range
Which of the following statements is true?
Select one:
a. As grid ratio increases, the removal of scatter increases.
b. A low ratio grid is more effective at removing scatter than a high ratio grid.
c. High ratio grids are less effective at removing scatter than low ratio grids.
d. A high ratio grid prevents the production of scatter better than a low ratio grid.
As grid ratio increases, the removal of scatter increases.
What is the most common type of grid cutoff error?
Select one:
a. upside-down focused
b. off-focus
c. off-level
d. off-center
off-level
Why is Aluminum used at interspace material in grids?
Aluminum is used because it is strong enough to support the grid but is also easily penetrated by photons.
Grid frequencies can range from:
Select one:
a. 10 to 30 lines per centimeter
b. 25 to 80 lines per centimeter
c. 60 to 120 lines per centimeter
d. 25 to 80 lines per inch
25 to 80 lines per centimeter
An adult's knee measuring 14 cm should be done without a grid.
Select one:
True
False
False
Increasing grid ratio has what effect on density?
Select one:
a. decreases
b. increases
c. no effect
decreases
Who invented radiographic grids?
Select one:
a. Gustave Bucky
b. Sherman Potter
c. William Roentgen
d. Alfred Nobel
Gustave Bucky
What is the MOST effective means for limiting scatter that hits the IR?
Select one:
a. grids
b. OID
c. collimation
d. filtration
grids
Patient dose increases when:
1. Changing from a higher to a lower grid ratio
2. Changing from a lower to a higher grid ratio
3. A grid is used
Select one:
a. 1 & 2 only
b. 1 & 3 only
c. 2 & 3 only
d. 1, 2, & 3
2 & 3 only
If you have a good technique at 5 mAs with a 5:1 grid, what technique would you need to use when switching to a 16:1 grid? (Units in mAs)
15 mAs
Which grid design is manufactured to match the divergence of the x-ray beam?
Select one:
a. The parallel grid
b. The crossed grid
c. The focused grid
d. The reciprocating grid
The focused grid
What occurs when the x-ray beam is not properly aligned with the grid strips?
Select one:
a. Nothing
b. Increased exposure to the IR
c. Bucky delamination
d. Grid cutoff
Grid cutoff
Briefly expain why scatter radation is bad.
Scatter adds unwanted density without adding to patient information. Scatter ruins image quality.
Increasing grid ratio has what effect on contrast?
Select one:
a. decreases
b. increases
c. no effect
increases
The only type of grid cutoff that occurs with both focused and parallel grids is due to:
Select one:
a. Off-level misalignment
b. Off-center misalignment
c. Off-focus misalignment
d. Using a focused grid upside down
Off-level misalignment
Which type of grid pattern is the MOST popular?
Select one:
a. cross-hatched
b. linear
c. focused
d. parallel
linear
If you have a good technique at 10 mAs without a grid, what mAs would you need to use when switching to a 6:1 grid? (Units in mAs)
30 mAs
What is the focal range for a parallel grid?
Select one:
a. 66" to 74"
b. parallel grids have no focal range
c. 36" to 42"
d. 36" to 74"
parallel grids have no focal range
Explain how the air gap technique works in terms of scatter radiation.
When OID is increased, scatter from the patient is less likely to reach the IR. The greater the gap, the greater the reduction on scatter reaching the IR. The smaller the gap, the greater chance scatter has to reach the IR to contaminate the image. mAs needs to be manipulated depending on OID to retain image density.
Grids that move during the exposure:
Select one:
a. Are reciprocating grids
b. Move from top to bottom
c. Are part of the Potter-Bucky diaphragm
d. A and C
A and C
Due to increased potential grid cutoff, which would be the most challenging grid to use?
Select one:
a. Parallel linear grid
b. Focused linear grid
c. Reciprocrating grid
d. Cross-hatched grid
Cross-hatched grid
Which of the following is not a way to reduce the production of scatter radiation?
Select one:
a. Reduce the exposure field size.
b. Ask a patient with a large abdomen to lie prone instead of supine.
c. Reduce the tissue thickness.
d. Increase the grid ratio.
Increase the grid ratio.
Changing from an 8:1 grid to a 12:1 grid, along with making the appropriate adjustments, will result in:
1. Increased patient dose
2. An image with increased contrast
3. Using more mAs
Select one:
a. 1 & 2 only
b. 1 & 3 only
c. 2 & 3 only
d. 1, 2, & 3
1, 2, & 3
If the height of the grid strip is 16 mm, the distance between the strips is 2 mm, and the strip is 0.3 mm thick, what is the grid ratio?
Select one:
a. 8:1
b. 10:1
c. 12:1
d. 16:1
8:1
What type of grid error results in appropriate exposure to the middle of the IR and marked underexposure along the sides of the IR?
Select one:
a. Upside-down focused grid
b. Stationary grid
c. Off-level
d. Lateral decentering
Upside-down focused grid
What is grid ratio?
Select one:
a. ratio of the height of the lead strips to the distance between them
b. ratio of kVp used to the amount of scatter absorbed by the grid
c. number of lead lines per unit of length
d. how many times a particular grid has been used
ratio of the height of the lead strips to the distance between them
Off-focus grid cutoff only occurs when the SID exceeds the focal range.
Select one:
True
False
False
What is grid frequency?
Select one:
a. how many times a particular grid has been used
b. ratio of kVp used to the amount of scatter absorbed by the grid
c. ratio of the height of the lead strips to the distance between them
d. number of lead lines per unit of length
number of lead lines per unit of length
What is the grid conversion factor for a 12:1 ratio grid?
Select one:
a. 3x
b. 4x
c. 5x
d. 6x
5x
An optimal AP abdomen radiograph can be produced using 40 mAs, 75 kVp, and a 12:1 grid. How much mAs would be needed if the only grid available is a 6:1 ratio grid? (Units in mAs)
24 mAs
Which of the following influences the amount of scatter radiation striking the image receptor but not the production of scatter radiation?
Select one:
a. Reduce the tissue thickness.
b. Reduce the exposure field size.
c. Increase the grid ratio.
d. Ask a patient with a large abdomen to lie prone instead of supine.
Increase the grid ratio.
Which type of grid cutoff error is shown in this image?
Select one:
a. off-focus
b. off-level
c. off-center
d. upside-down focused
off-center
Which type of grid error is shown in this radiograph?
Select one:
a. off-focus
b. off-level
c. off-center
d. upside-down focused
upside-down focused
If an excellent knee radiograph is produced using 10 mAs and an 8:1 ratio grid, how much mAs will be needed if no grid is available?
Select one:
a. 2.5 mAs
b. 4 mAs
c. 8 mAs
d. 10 mAs
2.5 mAs
Which of the following statements is true?
Select one:
a. If the height of the lead strips increases and the space between the grid strips decreases, the grid will be more effective at scatter removal.
b. A high ratio grid removes little scatter.
c. A grid decreases scatter production.
d. If the height of the lead strip decreases and the space between the grid strips increases, the grid will be more effective at removing scatter radiation.
If the height of the lead strips increases and the space between the grid strips decreases, the grid will be more effective at scatter removal.
Inherent filtration
Glass envelope
Oil around tube
mirror
Total filtration
Inherent filtration + Added filtration
Half-value layer
The amount of filtration that reduces the intensity of the beam to 1/2 its original value.
Indirect measure of total filtration.
Hardening the beam
is filtration
What are the three types of generators?
Single-phase (voltage ripple = 100%)
Three-phase ( 6 phase = 13%, 12 phase = 4%)
High frequency (<1%)
Filtration
Process whereby the average energy of a heterogeneous radiation beam in increased by passing it through an absorber.
What are the two purposes of beam restriction?
limit patient exposure
reduce scatter
What are 2 problems with the collimator light?
light goes out
light field (mirror) is misaligned
When were grids invented?
1913
Grid frequency
The number of lead lines per unit of length.
Range = 25 to 45 lines/cm, or 60 to 110 lines/inch.
Grid ratio
The ratio of the height of the lead strips over the distance between them.
GR = h/D.
Grid ratio ranges:
5:1 2×mAs
6:1 3×mAs
8:1 4×mAs
12:1 5×mAs
16:1 6×mAs
Grid patterns
Linear (lead lines run in one direction, most popular, allows tube angulation)
Crossed (crossed-hatched, lead lines run in 2 directions, removes more scatter, doesn't allow angulation)
Grid focus
Refers to the orientation of the lead lines to one another.
Parallel or non-focused grid - mostly use in fluoro and mobile imaging.
Focused grid - allows more photons to hit IR.
Convergent Point
Imaginary line drawn from each of the lead lines.
Convergent Line
Points of convergence connected along the length of a linear focused grid.
Focal distance
distance between the grid and the convergent line or point.
Focal Range
recommended range of SIDs that can be used with a focused grid.
Focal range at 40" focal distance?
36" to 42"
Focal range at 72" focal distance?
66" to 74"
Wafer Grid
matches size of cassette, placed on top of IR, usually taped.
Grid Cassette
IR with a permanently built-in grid mounted to its surface.
Grid cap
Permanently mounted grid that allows an IR to slide in behind it.
A short dimension grid has lead strips running perpendicular to the long axis of the grid.
A long dimension grid has lead strips running parallel to the long axis of the grid.
Grid cutoff
a decrease in the number of transmitted photons that reach the image receptor because of some misalignment of the grid.
